51
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Zhou J, Zhang B, Liu X, Shi L, Zhu J, Wei D, Zhong J, Sun G, He D. Facile method to prepare silk fibroin/hyaluronic acid films for vascular endothelial growth factor release. Carbohydr Polym 2016; 143:301-9. [DOI: 10.1016/j.carbpol.2016.01.023] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Revised: 12/18/2015] [Accepted: 01/08/2016] [Indexed: 02/01/2023]
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52
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Biomaterial-based regional chemotherapy: Local anticancer drug delivery to enhance chemotherapy and minimize its side-effects. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2016; 62:927-42. [DOI: 10.1016/j.msec.2016.01.063] [Citation(s) in RCA: 111] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Revised: 01/19/2016] [Accepted: 01/24/2016] [Indexed: 02/06/2023]
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53
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Altinkaynak C, Yilmaz I, Koksal Z, Özdemir H, Ocsoy I, Özdemir N. Preparation of lactoperoxidase incorporated hybrid nanoflower and its excellent activity and stability. Int J Biol Macromol 2016; 84:402-9. [DOI: 10.1016/j.ijbiomac.2015.12.018] [Citation(s) in RCA: 90] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2015] [Revised: 12/08/2015] [Accepted: 12/10/2015] [Indexed: 12/01/2022]
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54
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Mitropoulos AN, Marelli B, Perotto G, Amsden J, Kaplan DL, Omenetto FG. Towards the fabrication of biohybrid silk fibroin materials: entrapment and preservation of chloroplast organelles in silk fibroin films. RSC Adv 2016. [DOI: 10.1039/c6ra13228f] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Chloroplasts extracted from spinach leaves were entrapped in B. mori silk fibroin films to investigate the maintenance of their photosynthetic activity in a dry environment.
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Affiliation(s)
| | | | | | - Jason Amsden
- Department
- of Biomedical Engineering
- Tufts University
- Medford
- USA
| | - David L. Kaplan
- Department
- of Biomedical Engineering
- Tufts University
- Medford
- USA
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55
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Li AB, Kluge JA, Guziewicz NA, Omenetto FG, Kaplan DL. Silk-based stabilization of biomacromolecules. J Control Release 2015; 219:416-430. [PMID: 26403801 PMCID: PMC4656123 DOI: 10.1016/j.jconrel.2015.09.037] [Citation(s) in RCA: 95] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 09/19/2015] [Indexed: 11/26/2022]
Abstract
Silk fibroin is a high molecular weight amphiphilic protein that self-assembles into robust biomaterials with remarkable properties including stabilization of biologicals and tunable release kinetics correlated to processing conditions. Cells, antibiotics,monoclonal antibodies and peptides, among other biologics, have been encapsulated in silk using various processing approaches and material formats. The mechanistic basis for the entrapment and stabilization features, along with insights into the modulation of release of the entrained compounds from silks will be reviewed with a focus on stabilization of bioactive molecules.
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Affiliation(s)
- Adrian B Li
- Department of Chemical and Biological Engineering, Tufts University, 4 Colby Street, Medford, MA 02155, USA
| | - Jonathan A Kluge
- Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, MA 02155, USA
| | - Nicholas A Guziewicz
- Drug Product Technologies, Amgen, 1 Amgen Center Drive, Thousand Oaks, CA 91320, USA
| | - Fiorenzo G Omenetto
- Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, MA 02155, USA
| | - David L Kaplan
- Department of Chemical and Biological Engineering, Tufts University, 4 Colby Street, Medford, MA 02155, USA; Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, MA 02155, USA.
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56
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Somturk B, Yilmaz I, Altinkaynak C, Karatepe A, Özdemir N, Ocsoy I. Synthesis of urease hybrid nanoflowers and their enhanced catalytic properties. Enzyme Microb Technol 2015; 86:134-42. [PMID: 26992802 DOI: 10.1016/j.enzmictec.2015.09.005] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Revised: 09/09/2015] [Accepted: 09/12/2015] [Indexed: 11/25/2022]
Abstract
Increasing numbers of materials have been extensively used as platforms for enzyme immobilization to enhance catalytic activity and stability. Although stability of enzyme was accomplished with immobilization approaches, activity of the most of the enzymes was declined after immobilization. Herein, we synthesize the flower shaped-hybrid nanomaterials called hybrid nanoflower (HNF) consisting of urease enzyme and copper ions (Cu(2+)) and report a mechanistic elucidation of enhancement in both activity and stability of the HNF. We demonstrated how experimental factors influence morphology of the HNF. We proved that the HNF (synthesized from 0.02mgmL(-1) urease in 10mM PBS (pH 7.4) at +4°C) exhibited the highest catalytic activity of ∼2000% and ∼4000% when stored at +4°C and RT, respectively compared to free urease. The highest stability was also achieved by this HNF by maintaining 96.3% and 90.28% of its initial activity within storage of 30 days at +4°C and RT, respectively. This dramatically enhanced activity is attributed to high surface area, nanoscale-entrapped urease and favorable urease conformation of the HNF. The exceptional catalytic activity and stability properties of HNF can be taken advantage of to use it in fields of biomedicine and chemistry.
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Affiliation(s)
- Burcu Somturk
- Department of Chemistry, Faculty of Science, Erciyes University, Kayseri 38039, Turkey
| | - Ismail Yilmaz
- Department of Chemistry, Faculty of Science, Erciyes University, Kayseri 38039, Turkey
| | - Cevahir Altinkaynak
- Department of Analytical Chemistry, Faculty of Pharmacy, Erciyes University, 38039 Kayseri, Turkey; Nanotechnology Research Center, Erciyes University, Kayseri 38039, Turkey
| | - Aslıhan Karatepe
- Department of Chemistry, Faculty of Arts and Science, Nevşehir Hacı Bektaş Veli University, 50300 Nevşehir, Turkey
| | - Nalan Özdemir
- Department of Chemistry, Faculty of Science, Erciyes University, Kayseri 38039, Turkey.
| | - Ismail Ocsoy
- Department of Analytical Chemistry, Faculty of Pharmacy, Erciyes University, 38039 Kayseri, Turkey; Nanotechnology Research Center, Erciyes University, Kayseri 38039, Turkey.
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57
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Kambe Y, Kojima K, Tamada Y, Tomita N, Kameda T. Silk fibroin sponges with cell growth-promoting activity induced by genetically fused basic fibroblast growth factor. J Biomed Mater Res A 2015; 104:82-93. [PMID: 26190702 DOI: 10.1002/jbm.a.35543] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Revised: 06/30/2015] [Accepted: 07/14/2015] [Indexed: 11/12/2022]
Abstract
Transgenic silkworm technology has enabled the biological properties of silk fibroin protein to be altered by fusion to recombinant bioactive proteins. However, few studies have reported the fabrication of genetically modified fibroin proteins into three-dimensional spongy structures to serve as scaffolds for tissue engineering. We generated a transgenic silkworm strain that produces fibroin fused to basic fibroblast growth factor (bFGF) and processed the fibroin into a spongy structure using a simple freeze/thaw method. NIH3T3 mouse embryonic fibroblasts grown on bFGF-fused fibroin sponges proliferated and spread out well, showing half the population doubling time of cells cultured on wild-type fibroin sponges. Furthermore, the number of primary rabbit articular chondrocytes growing on bFGF-fused fibroin sponges was around five-times higher than that of the wild-type control at 3-days post cell-seeding. As the physical properties of wild-type and bFGF-fused fibroin sponges were almost identical, it is suggested that bFGF fused to fibroin retained its biological activity, even after the bFGF-fused fibroin was fabricated into the spongy structure. The bFGF-fused fibroin sponge has the potential for widespread application in the field of tissue engineering, and the method of fabricating this structure could be applicable to other recombinant bioactive fibroin proteins.
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Affiliation(s)
- Yusuke Kambe
- Silk Materials Research Unit, National Institute of Agrobiological Sciences (NIAS), 1-2 Owashi, Tsukuba, Ibaraki, 305-8634, Japan
| | - Katsura Kojima
- Silk Materials Research Unit, National Institute of Agrobiological Sciences (NIAS), 1-2 Owashi, Tsukuba, Ibaraki, 305-8634, Japan
| | - Yasushi Tamada
- Faculty of Textile Science and Technology, Shinshu University, 3-15-1 Tokida, Ueda, Nagano, 386-8567, Japan
| | - Naohide Tomita
- Department of Mechanical Engineering and Science, Graduate School of Engineering, Kyoto University, Kyoto-Daigaku-Katsura, Nishikyo-Ku, Kyoto, 615-8540, Japan
| | - Tsunenori Kameda
- Silk Materials Research Unit, National Institute of Agrobiological Sciences (NIAS), 1-2 Owashi, Tsukuba, Ibaraki, 305-8634, Japan
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58
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Koh LD, Cheng Y, Teng CP, Khin YW, Loh XJ, Tee SY, Low M, Ye E, Yu HD, Zhang YW, Han MY. Structures, mechanical properties and applications of silk fibroin materials. Prog Polym Sci 2015. [DOI: 10.1016/j.progpolymsci.2015.02.001] [Citation(s) in RCA: 608] [Impact Index Per Article: 67.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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59
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Di Buduo CA, Wray LS, Tozzi L, Malara A, Chen Y, Ghezzi CE, Smoot D, Sfara C, Antonelli A, Spedden E, Bruni G, Staii C, De Marco L, Magnani M, Kaplan DL, Balduini A. Programmable 3D silk bone marrow niche for platelet generation ex vivo and modeling of megakaryopoiesis pathologies. Blood 2015; 125:2254-64. [PMID: 25575540 PMCID: PMC4383799 DOI: 10.1182/blood-2014-08-595561] [Citation(s) in RCA: 118] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Accepted: 01/03/2015] [Indexed: 01/16/2023] Open
Abstract
We present a programmable bioengineered 3-dimensional silk-based bone marrow niche tissue system that successfully mimics the physiology of human bone marrow environment allowing us to manufacture functional human platelets ex vivo. Using stem/progenitor cells, megakaryocyte function and platelet generation were recorded in response to variations in extracellular matrix components, surface topography, stiffness, coculture with endothelial cells, and shear forces. Millions of human platelets were produced and showed to be functional based on multiple activation tests. Using adult hematopoietic progenitor cells our system demonstrated the ability to reproduce key steps of thrombopoiesis, including alterations observed in diseased states. A critical feature of the system is the use of natural silk protein biomaterial allowing us to leverage its biocompatibility, nonthrombogenic features, programmable mechanical properties, and surface binding of cytokines, extracellular matrix components, and endothelial-derived proteins. This in turn offers new opportunities for the study of blood component production ex vivo and provides a superior tissue system for the study of pathologic mechanisms of human platelet production.
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Affiliation(s)
- Christian A Di Buduo
- Department of Molecular Medicine, University of Pavia, Pavia, Italy; Biotechnology Research Laboratories, Istituto di Ricovero e Cura a Carattere Scientifico San Matteo Foundation, Pavia, Italy
| | - Lindsay S Wray
- Department of Molecular Medicine, University of Pavia, Pavia, Italy; Biotechnology Research Laboratories, Istituto di Ricovero e Cura a Carattere Scientifico San Matteo Foundation, Pavia, Italy; Department of Biomedical Engineering, Tufts University, Medford, MA
| | - Lorenzo Tozzi
- Department of Molecular Medicine, University of Pavia, Pavia, Italy; Biotechnology Research Laboratories, Istituto di Ricovero e Cura a Carattere Scientifico San Matteo Foundation, Pavia, Italy; Department of Biomedical Engineering, Tufts University, Medford, MA
| | - Alessandro Malara
- Department of Molecular Medicine, University of Pavia, Pavia, Italy; Biotechnology Research Laboratories, Istituto di Ricovero e Cura a Carattere Scientifico San Matteo Foundation, Pavia, Italy
| | - Ying Chen
- Department of Biomedical Engineering, Tufts University, Medford, MA
| | - Chiara E Ghezzi
- Department of Biomedical Engineering, Tufts University, Medford, MA
| | - Daniel Smoot
- Department of Biomedical Engineering, Tufts University, Medford, MA
| | - Carla Sfara
- Department of Biomolecular Sciences, Biochemistry and Molecular Biology Section, University of Urbino "Carlo Bo," Urbino, Italy
| | - Antonella Antonelli
- Department of Biomolecular Sciences, Biochemistry and Molecular Biology Section, University of Urbino "Carlo Bo," Urbino, Italy
| | - Elise Spedden
- Department of Physics, Tufts University, Medford, MA
| | - Giovanna Bruni
- Department of Chemistry, Physical Chemistry Section, University of Pavia, Pavia, Italy
| | | | - Luigi De Marco
- Department of Translational Research, Stem Cells Unit, Istituto di Ricovero e Cura a Carattere Scientifico Centro di Riferimento Oncologico, Aviano, Italy; and Department of Molecular and Experimental Research, The Scripps Research Institute, La Jolla, CA
| | - Mauro Magnani
- Department of Biomolecular Sciences, Biochemistry and Molecular Biology Section, University of Urbino "Carlo Bo," Urbino, Italy
| | - David L Kaplan
- Department of Biomedical Engineering, Tufts University, Medford, MA
| | - Alessandra Balduini
- Department of Molecular Medicine, University of Pavia, Pavia, Italy; Biotechnology Research Laboratories, Istituto di Ricovero e Cura a Carattere Scientifico San Matteo Foundation, Pavia, Italy; Department of Biomedical Engineering, Tufts University, Medford, MA
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60
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Ibrahim AMS, Koolen PGL, Kim K, Perrone GS, Kaplan DL, Lin SJ. Absorbable biologically based internal fixation. Clin Podiatr Med Surg 2015; 32:61-72. [PMID: 25440418 DOI: 10.1016/j.cpm.2014.09.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Absorbable devices for use in internal fixation have advanced over the years to become reliable and cost-effective alternatives to metallic hardware. In the past, biodegradable fixation involved a laborious implantation process, and induced osteolysis and inflammatory reactions. Modern iterations exhibit increased strength, smoother resorption, and lower rates of reactivity. A newer generation manufactured from silk has emerged that may address existing limitations and provide a greater range of fixation applications.
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Affiliation(s)
- Ahmed M S Ibrahim
- Division of Plastic Surgery, Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, 110 Francis Street, Boston, MA 02215, USA
| | - Pieter G L Koolen
- Division of Plastic Surgery, Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, 110 Francis Street, Boston, MA 02215, USA
| | - Kuylhee Kim
- Division of Plastic Surgery, Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, 110 Francis Street, Boston, MA 02215, USA
| | - Gabe S Perrone
- Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, MA 02155, USA
| | - David L Kaplan
- Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, MA 02155, USA
| | - Samuel J Lin
- Division of Plastic Surgery, Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, 110 Francis Street, Boston, MA 02215, USA.
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61
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Elia R, Michelson CD, Perera AL, Brunner TF, Harsono M, Leisk GG, Kugel G, Kaplan DL. Electrodeposited silk coatings for bone implants. J Biomed Mater Res B Appl Biomater 2014; 103:1602-9. [PMID: 25545462 DOI: 10.1002/jbm.b.33351] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Revised: 10/29/2014] [Accepted: 11/18/2014] [Indexed: 11/07/2022]
Abstract
The aim of this study was to characterize the mechanical properties and drug elution features of silk protein-based electrodeposited dental implant coatings. Silk processing conditions were modified to obtain coatings with a range of mechanical properties on titanium studs. These coatings were assessed for adhesive strength and dissolution, with properties tuned using water vapor annealing or glycerol incorporation to modulate crystalline content. Coating reproducibility was demonstrated over a range of silk concentrations from 1% to 10%. Surface roughness of titanium substrates was altered using industry relevant acid etching and grit blasting, and the effect of surface topography on silk coating adhesion was assessed. Florescent compounds were incorporated into the silk coatings, which were modulated for crystalline content, to achieve four days of sustained release of the compounds. This silk electrogelation technique offers a safe and relatively simple approach to generate mechanically robust, biocompatible, and degradable implant coatings that can also be functionalized with bioactive compounds to modulate the local regenerative tissue environment.
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Affiliation(s)
- Roberto Elia
- Department of Biomedical Engineering, Tufts University, Medford, Massachusetts, 02155
| | | | - Austin L Perera
- School of Dental Medicine, Tufts University, Boston, Massachusetts, 02111
| | - Teresa F Brunner
- Department of Biomedical Engineering, Tufts University, Medford, Massachusetts, 02155
- Department of Maxilo-Facial Surgery University Hospital Rechts der Isar, Technical University of Munich, Munich, Germany, 81675
| | - Masly Harsono
- School of Dental Medicine, Tufts University, Boston, Massachusetts, 02111
| | - Gray G Leisk
- Department of Mechanical Engineering, Tufts University, Medford, Massachusetts, 02155
| | - Gerard Kugel
- School of Dental Medicine, Tufts University, Boston, Massachusetts, 02111
| | - David L Kaplan
- Department of Biomedical Engineering, Tufts University, Medford, Massachusetts, 02155
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62
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Zhou J, Zhang B, Shi L, Zhong J, Zhu J, Yan J, Wang P, Cao C, He D. Regenerated silk fibroin films with controllable nanostructure size and secondary structure for drug delivery. ACS APPLIED MATERIALS & INTERFACES 2014; 6:21813-21821. [PMID: 25536875 DOI: 10.1021/am502278b] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The ability of drug release from SF materials was governed largely by their secondary structure. It is known that the breakage degree of the peptide chain during the silk fibroin (SF) dissolution can affect the structure, property, and applications of SF materials. To deeply understand this effect, we designed a reaction system based on CaCl2/H2O/C2H5OH ternary solvent with different ethanol content to obtain the regenerated SF films with different morphologies and secondary structures. The results showed that the globule-like nanostructure was observed in all regenerated SF films, and their size decreased significantly with reducing the ethanol content in the solvent. Correspondingly, the β-sheet structure content of the SF films increased. In addition, the contact angle and the elongation ratio increased, and water absorption decreased significantly with decreasing the ethanol content in the solvent. The accumulated release percents of doxorubicin from these SF films were significantly different with increasing the time. With smaller nanostructure size and more β-sheet content, the SF films had a slower drug release at the beginning. This study indicated the importance of the ethanol content in the solvent in controlling the structure and properties of the regenerated SF films, which would improve the application of SF in drug delivery.
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Affiliation(s)
- Juan Zhou
- National Engineering Research Center for Nanotechnology, Shanghai 200241, People's Republic of China
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63
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Silk-based resorbable electronic devices for remotely controlled therapy and in vivo infection abatement. Proc Natl Acad Sci U S A 2014; 111:17385-9. [PMID: 25422476 DOI: 10.1073/pnas.1407743111] [Citation(s) in RCA: 160] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
A paradigm shift for implantable medical devices lies at the confluence between regenerative medicine, where materials remodel and integrate in the biological milieu, and technology, through the use of recently developed material platforms based on biomaterials and bioresorbable technologies such as optics and electronics. The union of materials and technology in this context enables a class of biomedical devices that can be optically or electronically functional and yet harmlessly degrade once their use is complete. We present here a fully degradable, remotely controlled, implantable therapeutic device operating in vivo to counter a Staphylococcus aureus infection that disappears once its function is complete. This class of device provides fully resorbable packaging and electronics that can be turned on remotely, after implantation, to provide the necessary thermal therapy or trigger drug delivery. Such externally controllable, resorbable devices not only obviate the need for secondary surgeries and retrieval, but also have extended utility as therapeutic devices that can be left behind at a surgical or suturing site, following intervention, and can be externally controlled to allow for infection management by either thermal treatment or by remote triggering of drug release when there is retardation of antibiotic diffusion, deep infections are present, or when systemic antibiotic treatment alone is insufficient due to the emergence of antibiotic-resistant strains. After completion of function, the device is safely resorbed into the body, within a programmable period.
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64
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65
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Silk fibroin rods for sustained delivery of breast cancer therapeutics. Biomaterials 2014; 35:8613-20. [DOI: 10.1016/j.biomaterials.2014.06.030] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Accepted: 06/15/2014] [Indexed: 01/06/2023]
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66
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Schweizer D, Serno T, Goepferich A. Controlled release of therapeutic antibody formats. Eur J Pharm Biopharm 2014; 88:291-309. [DOI: 10.1016/j.ejpb.2014.08.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Revised: 06/30/2014] [Accepted: 08/03/2014] [Indexed: 10/24/2022]
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67
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Yucel T, Lovett ML, Kaplan DL. Silk-based biomaterials for sustained drug delivery. J Control Release 2014; 190:381-97. [PMID: 24910193 PMCID: PMC4142080 DOI: 10.1016/j.jconrel.2014.05.059] [Citation(s) in RCA: 212] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Revised: 05/24/2014] [Accepted: 05/28/2014] [Indexed: 10/25/2022]
Abstract
Silk presents a rare combination of desirable properties for sustained drug delivery, including aqueous-based purification and processing options without chemical cross-linkers, compatibility with common sterilization methods, controllable and surface-mediated biodegradation into non-inflammatory by-products, biocompatibility, utility in drug stabilization, and robust mechanical properties. A versatile silk-based toolkit is currently available for sustained drug delivery formulations of small molecule through macromolecular drugs, with a promise to mitigate several drawbacks associated with other degradable sustained delivery technologies in the market. Silk-based formulations utilize silk's well-defined nano- through microscale structural hierarchy, stimuli-responsive self-assembly pathways and crystal polymorphism, as well as sequence and genetic modification options towards targeted pharmaceutical outcomes. Furthermore, by manipulating the interactions between silk and drug molecules, near-zero order sustained release may be achieved through diffusion- and degradation-based release mechanisms. Because of these desirable properties, there has been increasing industrial interest in silk-based drug delivery systems currently at various stages of the developmental pipeline from pre-clinical to FDA-approved products. Here, we discuss the unique aspects of silk technology as a sustained drug delivery platform and highlight the current state of the art in silk-based drug delivery. We also offer a potential early development pathway for silk-based sustained delivery products.
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Affiliation(s)
- Tuna Yucel
- Tufts University, Department of Biomedical Engineering, Medford, MA 02155, USA; Ekteino Laboratories, New York, NY 10022, USA
| | - Michael L Lovett
- Tufts University, Department of Biomedical Engineering, Medford, MA 02155, USA; Ekteino Laboratories, New York, NY 10022, USA
| | - David L Kaplan
- Tufts University, Department of Biomedical Engineering, Medford, MA 02155, USA
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68
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Tang S, Liao X, Shi B, Qu Y, Huang Z, Lin Q, Guo X, Pei F. The effects of controlled release of neurotrophin-3 from PCLA scaffolds on the survival and neuronal differentiation of transplanted neural stem cells in a rat spinal cord injury model. PLoS One 2014; 9:e107517. [PMID: 25215612 PMCID: PMC4162607 DOI: 10.1371/journal.pone.0107517] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Accepted: 08/18/2014] [Indexed: 02/05/2023] Open
Abstract
Neural stem cells (NSCs) have emerged as a potential source for cell replacement therapy following spinal cord injury (SCI). However, poor survival and low neuronal differentiation remain major obstacles to the use of NSCs. Biomaterials with neurotrophic factors are promising strategies for promoting the proliferation and differentiation of NSCs. Silk fibroin (SF) matrices were demonstrated to successfully deliver growth factors and preserve their potency. In this study, by incorporating NT-3 into a SF coating, we successfully developed NT-3-immobilized scaffolds (membranes and conduits). Sustained release of bioactive NT-3 from the conduits for up to 8 weeks was achieved. Cell viability was confirmed using live/dead staining after 14 days in culture. The efficacy of the immobilized NT-3 was confirmed by assessing NSC neuronal differentiation in vitro. NSC neuronal differentiation was 55.2 ± 4.1% on the NT-3-immobilized membranes, which was significantly higher than that on the NT-3 free membrane. Furthermore, 8 weeks after the NSCs were seeded into conduits and implanted in rats with a transected SCI, the conduit+NT-3+NSCs group achieved higher NSC survival (75.8 ± 15.1%) and neuronal differentiation (21.5 ± 5.2%) compared with the conduit+NSCs group. The animals that received the conduit+NT-3+NSCs treatment also showed improved functional outcomes, as well as increased axonal regeneration. These results indicate the feasibility of fabricating NT-3-immobilized scaffolds using the adsorption of NT-3/SF coating method, as well as the potential of these scaffolds to induce SCI repair by promoting survival and neuronal differentiation of transplanted NSCs.
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Affiliation(s)
- Shuo Tang
- Department of Orthopaedics, West China Hospital, Sichuan University, Chengdu, China
| | - Xiang Liao
- Department of Pain Medicine, Shenzhen Nanshan Hospital, Shenzhen, China
| | - Bo Shi
- Department of Orthopaedics, Mianyang Center Hospital, Mianyang, China
| | - Yanzhen Qu
- Department of Orthopaedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Zeyu Huang
- Department of Orthopaedics, West China Hospital, Sichuan University, Chengdu, China
| | - Qiang Lin
- Department of Orthopaedics, Guangdong hospital of traditional Chinese medicine, Guangzhou, China
- * E-mail: (QL); (XDG); (FXP)
| | - Xiaodong Guo
- Department of Orthopaedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- * E-mail: (QL); (XDG); (FXP)
| | - Fuxing Pei
- Department of Orthopaedics, West China Hospital, Sichuan University, Chengdu, China
- * E-mail: (QL); (XDG); (FXP)
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69
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Silk fibroin layer-by-layer microcapsules for localized gene delivery. Biomaterials 2014; 35:7929-39. [DOI: 10.1016/j.biomaterials.2014.05.062] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Accepted: 05/21/2014] [Indexed: 12/23/2022]
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70
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Kim S, Marelli B, Brenckle MA, Mitropoulos AN, Gil ES, Tsioris K, Tao H, Kaplan DL, Omenetto FG. All-water-based electron-beam lithography using silk as a resist. NATURE NANOTECHNOLOGY 2014; 9:306-10. [PMID: 24658173 DOI: 10.1038/nnano.2014.47] [Citation(s) in RCA: 149] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2013] [Accepted: 02/11/2014] [Indexed: 05/11/2023]
Abstract
Traditional nanofabrication techniques often require complex lithographic steps and the use of toxic chemicals. To move from the laboratory scale to large scales, nanofabrication should be carried out using alternative procedures that are simple, inexpensive and use non-toxic solvents. Recent efforts have focused on nanoimprinting and the use of organic resists (such as quantum dot-polymer hybrids, DNA and poly(ethylene glycol)), which still require, for the most part, noxious chemicals for processing. Significant advances have been achieved using 'green' resists that can be developed with water, but so far these approaches have suffered from low electron sensitivity, line edge roughness and scalability constraints. Here, we present the use of silk as a natural and biofunctional resist for electron-beam lithography. The process is entirely water-based, starting with the silk aqueous solution and ending with simple development of the exposed silk film in water. Because of its polymorphic crystalline structure, silk can be used either as a positive or negative resist through interactions with an electron beam. Moreover, silk can be easily modified, thereby enabling a variety of 'functional resists', including biologically active versions. As a proof of principle of the viability of all-water-based silk electron-beam lithography (EBL), we fabricate nanoscale photonic lattices using both neat silk and silk doped with quantum dots, green fluorescent proteins (GFPs) or horseradish peroxidase (HRP).
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Affiliation(s)
- Sunghwan Kim
- 1] Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, Massachusetts 02155, USA [2] [3]
| | - Benedetto Marelli
- 1] Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, Massachusetts 02155, USA [2]
| | - Mark A Brenckle
- Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, Massachusetts 02155, USA
| | - Alexander N Mitropoulos
- Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, Massachusetts 02155, USA
| | - Eun-Seok Gil
- Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, Massachusetts 02155, USA
| | - Konstantinos Tsioris
- 1] Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, Massachusetts 02155, USA [2]
| | - Hu Tao
- Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, Massachusetts 02155, USA
| | - David L Kaplan
- Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, Massachusetts 02155, USA
| | - Fiorenzo G Omenetto
- 1] Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, Massachusetts 02155, USA [2] Department of Physics, Tufts University, 4 Colby Street, Medford, Massachusetts 02155, USA
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71
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Perrone GS, Leisk GG, Lo TJ, Moreau JE, Haas DS, Papenburg BJ, Golden EB, Partlow BP, Fox SE, Ibrahim AMS, Lin SJ, Kaplan DL. The use of silk-based devices for fracture fixation. Nat Commun 2014; 5:3385. [PMID: 24594992 DOI: 10.1038/ncomms4385] [Citation(s) in RCA: 112] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Accepted: 02/05/2014] [Indexed: 12/21/2022] Open
Abstract
Metallic fixation systems are currently the gold standard for fracture fixation but have problems including stress shielding, palpability and temperature sensitivity. Recently, resorbable systems have gained interest because they avoid removal and may improve bone remodelling due to the lack of stress shielding. However, their use is limited to paediatric craniofacial procedures mainly due to the laborious implantation requirements. Here we prepare and characterize a new family of resorbable screws prepared from silk fibroin for craniofacial fracture repair. In vivo assessment in rat femurs shows the screws to be self-tapping, remain fixed in the bone for 4 and 8 weeks, exhibit biocompatibility and promote bone remodelling. The silk-based devices compare favourably with current poly-lactic-co-glycolic acid fixation systems, however, silk-based devices offer numerous advantages including ease of implantation, conformal fit to the repair site, sterilization by autoclaving and minimal inflammatory response.
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Affiliation(s)
- Gabriel S Perrone
- 1] Department of Biomedical Engineering, Tufts University, Medford, Massachusetts 02155, USA [2] Department of Mechanical Engineering, Tufts University, Medford, Massachusetts 02155, USA
| | - Gary G Leisk
- Department of Mechanical Engineering, Tufts University, Medford, Massachusetts 02155, USA
| | - Tim J Lo
- Department of Biomedical Engineering, Tufts University, Medford, Massachusetts 02155, USA
| | - Jodie E Moreau
- Department of Biomedical Engineering, Tufts University, Medford, Massachusetts 02155, USA
| | - Dylan S Haas
- Department of Biomedical Engineering, Tufts University, Medford, Massachusetts 02155, USA
| | - Bernke J Papenburg
- Department of Biomedical Engineering, Tufts University, Medford, Massachusetts 02155, USA
| | - Ethan B Golden
- Department of Biomedical Engineering, Tufts University, Medford, Massachusetts 02155, USA
| | - Benjamin P Partlow
- Department of Biomedical Engineering, Tufts University, Medford, Massachusetts 02155, USA
| | - Sharon E Fox
- Beth Israel Deaconess Medical Center, Department of Pathology, Harvard Medical School, Boston, Massachusetts 02215, USA
| | - Ahmed M S Ibrahim
- Divisions of Plastic Surgery and Otolaryngology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA
| | - Samuel J Lin
- Divisions of Plastic Surgery and Otolaryngology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA
| | - David L Kaplan
- Department of Biomedical Engineering, Tufts University, Medford, Massachusetts 02155, USA
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72
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Raja WK, Maccorkle S, Diwan IM, Abdurrob A, Lu J, Omenetto FG, Kaplan DL. Transdermal delivery devices: fabrication, mechanics and drug release from silk. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2013; 9:3704-13. [PMID: 23653252 PMCID: PMC3883884 DOI: 10.1002/smll.201202075] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Revised: 01/18/2013] [Indexed: 05/22/2023]
Abstract
Microneedles are a relatively simple, minimally invasive and painless approach to deliver drugs across the skin. However, there remain limitations with this approach because of the materials most commonly utilized for such systems. Silk protein, with tunable and biocompatibility properties, is a useful biomaterial to overcome the current limitations with microneedles. Silk devices preserve drug activity, offer superior mechanical properties and biocompatibility, can be tuned for biodegradability, and can be processed under aqueous, benign conditions. In the present work, the fabrication of dense microneedle arrays from silk with different drug release kinetics is reported. The mechanical properties of the microneedle patches are tuned by post-fabrication treatments or by loading the needles with silk microparticles, to increase capacity and mechanical strength. Drug release is further enhanced by the encapsulation of the drugs in the silk matrix and coating with a thin dissolvable drug layer. The microneedles are used on human cadaver skin and drugs are delivered successfully. The various attributes demonstrated suggest that silk-based microneedle devices can provide significant benefit as a platform material for transdermal drug delivery.
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Affiliation(s)
- Waseem K Raja
- Biomedical Engineering, Science and Technology Center, Tufts University, 4 Colby Street, Medford, MA 02155, USA
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73
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Pritchard EM, Normand V, Hu X, Budijono S, Benczédi D, Omenetto F, Kaplan DL. Encapsulation of oil in silk fibroin biomaterials. J Appl Polym Sci 2013. [DOI: 10.1002/app.39990] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Affiliation(s)
- Eleanor M. Pritchard
- Department of Biomedical Engineering; Tufts University; Medford Massachusetts 02155
| | | | - Xiao Hu
- Department of Physics & Astronomy; Rowan University; Glassboro NJ 08028
| | | | - Daniel Benczédi
- Firmenich SA; 1, Route des Jeunes, 1211 Geneva 8 Switzerland
| | - Fiorenzo Omenetto
- Department of Biomedical Engineering; Tufts University; Medford Massachusetts 02155
| | - David L. Kaplan
- Department of Biomedical Engineering; Tufts University; Medford Massachusetts 02155
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74
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Guziewicz NA, Massetti AJ, Perez-Ramirez BJ, Kaplan DL. Mechanisms of monoclonal antibody stabilization and release from silk biomaterials. Biomaterials 2013; 34:7766-75. [PMID: 23859659 DOI: 10.1016/j.biomaterials.2013.06.039] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Accepted: 06/23/2013] [Indexed: 11/30/2022]
Abstract
The availability of stabilization and sustained delivery systems for antibody therapeutics remains a major clinical challenge, despite the growing development of antibodies for a wide range of therapeutic applications due to their specificity and efficacy. A mechanistic understanding of protein-matrix interactions is critical for the development of such systems and is currently lacking as a mode to guide the field. We report mechanistic insight to address this need by using well-defined matrices based on silk gels, in combination with a monoclonal antibody. Variables including antibody loading, matrix density, charge interactions, hydrophobicity and water access were assessed to clarify mechanisms involved in the release of antibody from the biomaterial matrix. The results indicate that antibody release is primarily governed by hydrophobic interactions and hydration resistance, which are controlled by silk matrix chemistry, peptide domain distribution and protein density. Secondary ionic repulsions are also critical in antibody stabilization and release. Matrix modification by free methionine incorporation was found to be an effective strategy for mitigating encapsulation induced antibody oxidation. Additionally, these studies highlight a characterization approach to improve the understanding and development of other protein sustained delivery systems, with broad applicability to the rapidly developing monoclonal antibody field.
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Affiliation(s)
- Nicholas A Guziewicz
- BioFormulations Development, Genzyme, A Sanofi Company, Framingham, MA 01701-9322, USA
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75
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Pritchard EM, Hu X, Finley V, Kuo CK, Kaplan DL. Effect of silk protein processing on drug delivery from silk films. Macromol Biosci 2013; 13:311-20. [PMID: 23349062 PMCID: PMC3761156 DOI: 10.1002/mabi.201200323] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Revised: 10/29/2012] [Indexed: 11/06/2022]
Abstract
Sericin removal from the core fibroin protein of silkworm silk is a critical first step in the use of silk for biomaterial-related applications, but degumming can affect silk biomaterial properties, including molecular weight, viscosity, diffusivity and degradation behavior. Increasing the degumming time (10, 30, 60, and 90 min) decreases the average molecular weight of silk protein in solution, silk solution viscosity, and silk film glass-transition temperature, and increases the rate of degradation of a silk film by protease. Model compounds spanning a range of physical-chemical properties generally show an inverse relationship between degumming time and release rate through a varied degumming time silk coating. Degumming provides a useful control point to manipulate silk's material properties.
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Affiliation(s)
- Eleanor M. Pritchard
- Department of Biomedical Engineering, Tufts University, Medford, Massachusetts 02155
| | - Xiao Hu
- Department of Physics and Astronomy, Rowan University, Glassboro, NJ
| | - Violet Finley
- Department of Biomedical Engineering, Tufts University, Medford, Massachusetts 02155
| | - Catherine K. Kuo
- Department of Biomedical Engineering, Tufts University, Medford, Massachusetts 02155
| | - David L. Kaplan
- Department of Biomedical Engineering, Tufts University, Medford, Massachusetts 02155
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76
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Pritchard EM, Valentin T, Panilaitis B, Omenetto F, Kaplan DL. Antibiotic-Releasing Silk Biomaterials for Infection Prevention and Treatment. ADVANCED FUNCTIONAL MATERIALS 2013; 23:854-861. [PMID: 23483738 PMCID: PMC3589549 DOI: 10.1002/adfm.201201636] [Citation(s) in RCA: 140] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Effective treatment of infections in avascular and necrotic tissues can be challenging due to limited penetration into the target tissue and systemic toxicities. Controlled release polymer implants have the potential to achieve the high local concentrations needed while also minimizing systemic exposure. Silk biomaterials possess unique characteristics for antibiotic delivery including biocompatibility, tunable biodegradation, stabilizing effects, water-based processing and diverse material formats. We report on functional release of antibiotics spanning a range of chemical properties from different material formats of silk (films, microspheres, hydrogels, coatings). The release of penicillin and ampicillin from bulk-loaded silk films, drug-loaded silk microspheres suspended in silk hydrogels and bulk-loaded silk hydrogels was investigated and in vivo efficacy of ampicillin-releasing silk hydrogels was demonstrated in a murine infected wound model. Silk sponges with nanofilm coatings were loaded with gentamicin and cefazolin and release was sustained for 5 and 3 days, respectively. The capability of silk antibiotic carriers to sequester, stabilize and then release bioactive antibiotics represents a major advantage over implants and pumps based on liquid drug reservoirs where instability at room or body temperature is limiting. The present studies demonstrate that silk biomaterials represent a novel, customizable antibiotic platform for focal delivery of antibiotics using a range of material formats (injectable to implantable).
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Affiliation(s)
| | | | | | | | - David L. Kaplan
- Corresponding author: David L. Kaplan, Tufts University, Department of Biomedical Engineering, 4 Colby St. Medford, Massachusetts 02155 U.S.A. Tel: 617-627-3251, Fax: 617-627-3231,
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77
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Hronik-Tupaj M, Raja WK, Tang-Schomer M, Omenetto FG, Kaplan DL. Neural responses to electrical stimulation on patterned silk films. J Biomed Mater Res A 2013; 101:2559-72. [PMID: 23401351 DOI: 10.1002/jbm.a.34565] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2012] [Revised: 12/15/2012] [Accepted: 12/18/2012] [Indexed: 12/21/2022]
Abstract
Peripheral nerve injury is a critical issue for patients with trauma. Following injury, incomplete axon regeneration or misguided axon innervation into tissue will result in loss of sensory and motor functions. The objective of this study was to examine axon outgrowth and axon alignment in response to surface patterning and electrical stimulation. To accomplish our objective, metal electrodes with dimensions of 1.5 mm × 4 cm, were sputter coated onto micropatterned silk protein films, with surface grooves 3.5 μm wide × 500 nm deep. P19 neurons were seeded on the patterned electronic silk films and stimulated at 120 mV, 1 kHz, for 45 min each day for 7 days. Responses were compared with neurons on flat electronic silk films, patterned silk films without stimulation, and flat silk films without stimulation. Significant alignment was found on the patterned film groups compared with the flat film groups. Axon outgrowth was greater (p < 0.05) on electronic films on days 5 and 7 compared with the unstimulated groups. In conclusion, electrical stimulation, at 120 mV, 1 kHz, for 45 min daily, in addition to surface patterning, of 3.5 μm wide × 500 nm deep grooves, offered control of nerve axon outgrowth and alignment.
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Affiliation(s)
- Marie Hronik-Tupaj
- Department of Biomedical Engineering, Science & Technology Center, Tufts University, Medford, Massachusetts 02155, USA
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78
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Abstract
Silk protein-biomaterial wound dressings with epidermal growth factor (EGF) and silver sulfadiazine were studied with a cutaneous excisional mouse wound model. Three different material designs and two different drug incorporation techniques were studied to compare wound healing responses. Material formats included silk films, lamellar porous silk films and electrospun silk nanofibers, each studied with the silk matrix alone and with drug loading or drug coatings on the silk matrices. Changes in wound size and histological assessments of wound tissues showed that the functionalized silk biomaterial wound dressings increased wound healing rate, including reepithelialization, dermis proliferation, collagen synthesis and reduced scar formation, when compared to air-permeable Tegaderm tape (3M) (- control) and a commercial wound dressing, Tegaderm Hydrocolloid dressing (3M) (+ control). All silk biomaterials were effective for wound healing, while the lamellar porous films and electrospun nanofibers and the incorporation of EGF/silver sulfadiazine, via drug loading or coating, provided the most rapid wound healing responses. This systematic approach to evaluating functionalized silk biomaterial wound dressings demonstrates a useful strategy to select formulations for further study towards new treatment options for chronic wounds.
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Affiliation(s)
- Eun Seok Gil
- Department of Biomedical Engineering, St. Tufts University Medford, MA, USA
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79
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Wray LS, Rnjak-Kovacina J, Mandal BB, Schmidt DF, Gil ES, Kaplan DL. A silk-based scaffold platform with tunable architecture for engineering critically-sized tissue constructs. Biomaterials 2012; 33:9214-24. [PMID: 23036961 DOI: 10.1016/j.biomaterials.2012.09.017] [Citation(s) in RCA: 102] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2012] [Accepted: 09/11/2012] [Indexed: 11/25/2022]
Abstract
In the field of tissue engineering and regenerative medicine there is significant unmet need for critically-sized, fully degradable biomaterial scaffold systems with tunable properties for optimizing tissue formation in vitro and tissue regeneration in vivo. To address this need, we have developed a silk-based scaffold platform that has tunable material properties, including localized and bioactive functionalization, degradation rate, and mechanical properties and that provides arrays of linear hollow channels for delivery of oxygen and nutrients throughout the scaffold bulk. The scaffolds can be assembled with dimensions that range from millimeters to centimeters, addressing the need for a critically-sized platform for tissue formation. We demonstrate that the hollow channel arrays support localized and confluent endothelialization. This new platform offers a unique and versatile tool for engineering 'tailored' scaffolds for a range of tissue engineering and regenerative medicine needs.
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Affiliation(s)
- Lindsay S Wray
- Department of Biomedical Engineering, Tufts University, Medford, MA 02155, USA
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80
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Seib FP, Kaplan DL. Doxorubicin-loaded silk films: drug-silk interactions and in vivo performance in human orthotopic breast cancer. Biomaterials 2012; 33:8442-50. [PMID: 22922025 DOI: 10.1016/j.biomaterials.2012.08.004] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2012] [Accepted: 08/01/2012] [Indexed: 10/28/2022]
Abstract
Breast cancer is the most common of all malignant diseases in women. Systemic chemotherapy provides low clinical benefit for locoregional control of the disease, while localised chemotherapy may provide a therapeutic advantage. In this study, doxorubicin-loaded silk films were directly applied to tumours. Affinity binding studies demonstrated that the adsorption of doxorubicin onto silk was partially dependent on crystallinity. By manipulating silk crystallinity, or β-sheet content, the doxorubicin release rate could be controlled ranging from immediate release to prolonged release over >4 weeks. The therapeutic impact of doxorubicin-loaded silk films on primary tumour growth and metastasis was assessed in mice using a humanised orthotopic breast cancer model (adenocarcinoma). Both soluble and stabilised silk films loaded with doxorubicin had a significantly greater primary tumour response than the equivalent dose of doxorubicin administered intravenously in the absence of the silk film carrier. In addition to reducing primary tumour growth, stabilised silk films loaded with doxorubicin also reduced metastatic spread and autopsy indicated that these films were not associated with any local or systemic toxicities. Collectively, these results suggest that the future use of this approach for localised chemotherapy is promising.
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Affiliation(s)
- F Philipp Seib
- Tufts University, Department of Biomedical Engineering, 4 Colby Street, Medford, MA 02155, USA
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81
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Zhang J, Pritchard E, Hu X, Valentin T, Panilaitis B, Omenetto FG, Kaplan DL. Stabilization of vaccines and antibiotics in silk and eliminating the cold chain. Proc Natl Acad Sci U S A 2012; 109:11981-6. [PMID: 22778443 PMCID: PMC3409735 DOI: 10.1073/pnas.1206210109] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Sensitive biological compounds, such as vaccines and antibiotics, traditionally require a time-dependent "cold chain" to maximize therapeutic activity. This flawed process results in billions of dollars worth of viable drug loss during shipping and storage, and severely limits distribution to developing nations with limited infrastructure. To address these major limitations, we demonstrate self-standing silk protein biomaterial matrices capable of stabilizing labile vaccines and antibiotics, even at temperatures up to 60 °C over more than 6 months. Initial insight into the mechanistic basis for these findings is provided. Importantly, these findings suggest a transformative approach to the cold chain to revolutionize the way many labile therapeutic drugs are stored and utilized throughout the world.
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Affiliation(s)
- Jeney Zhang
- Tufts University, Department of Biomedical Engineering, Medford, MA 02155; and
- Tufts University, Department of Chemical & Biological Engineering, Medford, MA 02155
| | - Eleanor Pritchard
- Tufts University, Department of Biomedical Engineering, Medford, MA 02155; and
| | - Xiao Hu
- Tufts University, Department of Biomedical Engineering, Medford, MA 02155; and
| | - Thomas Valentin
- Tufts University, Department of Biomedical Engineering, Medford, MA 02155; and
| | - Bruce Panilaitis
- Tufts University, Department of Biomedical Engineering, Medford, MA 02155; and
| | | | - David L. Kaplan
- Tufts University, Department of Biomedical Engineering, Medford, MA 02155; and
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82
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Dennis PB, Walker AY, Dickerson MB, Kaplan DL, Naik RR. Stabilization of organophosphorus hydrolase by entrapment in silk fibroin: formation of a robust enzymatic material suitable for surface coatings. Biomacromolecules 2012; 13:2037-45. [PMID: 22651251 DOI: 10.1021/bm300358g] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Organophosphates are some of the most acutely toxic compounds synthesized on an industrial scale, and organophosphorus hydrolase (OPH) has the ability to hydrolyze and inactivate a number of these chemicals. However, OPH activity is vulnerable to harsh environmental conditions that would accompany its practical utility in the field; a limitation that can also be extended to conditions required for incorporation of OPH into useful materials. Here we present evidence that entrapment of OPH in silk fibroin leads to stabilization of OPH activity under a variety of conditions that would otherwise reduce free enzyme activity, such as elevated temperature, UV light exposure and the presence of detergent. Silk fibroin entrapment of OPH also allowed for its dispersal into a polyurethane-based coating that retained organophosphate hydrolysis activity after formulation, application and drying. Together, the data presented here demonstrate the utility of silk fibroin entrapment for the protection of OPH activity under a variety of environmental conditions.
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Affiliation(s)
- Patrick B Dennis
- Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson AFB, Ohio 45433, United States
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83
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Tao H, Kaplan DL, Omenetto FG. Silk materials--a road to sustainable high technology. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2012; 24:2824-37. [PMID: 22553118 DOI: 10.1002/adma.201104477] [Citation(s) in RCA: 191] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Revised: 01/21/2012] [Indexed: 05/18/2023]
Abstract
This review addresses the use of silk protein as a sustainable material in optics and photonics, electronics and optoelectronic applications. These options represent additional developments for this technology platform that compound the broad utility and impact of this material for medical needs that have been recently described in the literature. The favorable properties of the material certainly make a favorable case for the use of silk, yet serve as a broad inspiration to further develop biological foundries for both the synthesis and processing of Nature's materials for technological applications.
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Affiliation(s)
- Hu Tao
- Department of Biomedical Engineering, Tufts University, Medford, MA 02155, USA
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84
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Tansil NC, Koh LD, Han MY. Functional silk: colored and luminescent. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2012; 24:1388-97. [PMID: 22302383 DOI: 10.1002/adma.201104118] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2011] [Indexed: 05/04/2023]
Abstract
Silkworm silk is among the most widely used natural fibers for textile and biomedical applications due to its extraordinary mechanical properties and superior biocompatibility. A number of physical and chemical processes have also been developed to reconstruct silk into various forms or to artificially produce silk-like materials. In addition to the direct use and the delicate replication of silk's natural structure and properties, there is a growing interest to introduce more new functionalities into silk while maintaining its advantageous intrinsic properties. In this review we assess various methods and their merits to produce functional silk, specifically those with color and luminescence, through post-processing steps as well as biological approaches. There is a highlight on intrinsically colored and luminescent silk produced directly from silkworms for a wide range of applications, and a discussion on the suitable molecular properties for being incorporated effectively into silk while it is being produced in the silk gland. With these understanding, a new generation of silk containing various functional materials (e.g., drugs, antibiotics and stimuli-sensitive dyes) would be produced for novel applications such as cancer therapy with controlled release feature, wound dressing with monitoring/sensing feature, tissue engineering scaffolds with antibacterial, anticoagulant or anti-inflammatory feature, and many others.
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85
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Thakur G, Mitra A, Basak A, Sheet D. Characterization and scanning electron microscopic investigation of crosslinked freeze dried gelatin matrices for study of drug diffusivity and release kinetics. Micron 2012; 43:311-20. [DOI: 10.1016/j.micron.2011.09.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2010] [Revised: 07/30/2011] [Accepted: 09/09/2011] [Indexed: 01/15/2023]
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86
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Pritchard EM, Dennis PB, Omenetto F, Naik RR, Kaplan DL. Review physical and chemical aspects of stabilization of compounds in silk. Biopolymers 2012; 97:479-98. [PMID: 22270942 DOI: 10.1002/bip.22026] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2011] [Accepted: 12/14/2011] [Indexed: 12/13/2022]
Abstract
The challenge of stabilization of small molecules and proteins has received considerable interest. The biological activity of small molecules can be lost as a consequence of chemical modifications, while protein activity may be lost due to chemical or structural degradation, such as a change in macromolecular conformation or aggregation. In these cases, stabilization is required to preserve therapeutic and bioactivity efficacy and safety. In addition to use in therapeutic applications, strategies to stabilize small molecules and proteins also have applications in industrial processes, diagnostics, and consumer products like food and cosmetics. Traditionally, therapeutic drug formulation efforts have focused on maintaining stability during product preparation and storage. However, with growing interest in the fields of encapsulation, tissue engineering, and controlled release drug delivery systems, new stabilization challenges are being addressed; the compounds or protein of interest must be stabilized during: (1) fabrication of the protein or small molecule-loaded carrier, (2) device storage, and (3) for the duration of intended release needs in vitro or in vivo. We review common mechanisms of compound degradation for small molecules and proteins during biomaterial preparation (including tissue engineering scaffolds and drug delivery systems), storage, and in vivo implantation. We also review the physical and chemical aspects of polymer-based stabilization approaches, with a particular focus on the stabilizing properties of silk fibroin biomaterials.
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Affiliation(s)
- Eleanor M Pritchard
- Department for Biomedical Engineering, Tufts University, Medford, MA 02155, USA
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87
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Effect of self-assembled nanofibrous silk/polycaprolactone layer on the osteoconductivity and mechanical properties of biphasic calcium phosphate scaffolds. Acta Biomater 2012; 8:302-12. [PMID: 22023750 DOI: 10.1016/j.actbio.2011.10.009] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2011] [Revised: 10/05/2011] [Accepted: 10/06/2011] [Indexed: 11/20/2022]
Abstract
We here present the first successful report on combining nanostructured silk and poly(ε-caprolactone) (PCL) with a ceramic scaffold to produce a composite scaffold that is highly porous (porosity ∼85%, pore size ∼500 μm, ∼100% interconnectivity), strong and non-brittle with a surface that resembles extracellular matrix (ECM). The ECM-like surface was developed by self-assembly of nanofibrous structured silk (20-80 nm diameter, similar to native collagen found in ECM) over a thin PCL layer which is coated on biphasic calcium phosphate (BCP) scaffolds. The effects of different concentrations of silk solution on the mechanical and physical properties of the scaffolds were also comprehensively examined. Our results showed that using silk only (irrespective of concentration) for the modification of ceramic scaffolds could drastically reduce the compressive strength of the modified scaffolds in aqueous media, and the modification made a limited contribution to improving scaffold toughness. Using PCL/nanostructured silk the compressive strength and modulus of the modified scaffolds reached 0.42 MPa (compared with 0.07 MPa for BCP) and ∼25 MPa (compared with 5 MPa for BCP), respectively. The failure strain of the modified scaffold increased more than 6% compared with a BCP scaffold (failure strain of less than 1%), indicating a transformation from brittle to elastic behavior. The cytocompatibility of ECM-like composite scaffolds was investigated by studying the attachment, morphology, proliferation and bone-related gene expression of primary human bone-derived cells. Cells cultured on the developed scaffolds for 7 days had significant up-regulation of cell proliferation (∼1.6-fold higher, P<0.001) and osteogenic gene expression levels (collagen type I, osteocalcin and bone sialoprotein) compared with the other groups tested.
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88
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Diab T, Pritchard EM, Uhrig BA, Boerckel JD, Kaplan DL, Guldberg RE. A silk hydrogel-based delivery system of bone morphogenetic protein for the treatment of large bone defects. J Mech Behav Biomed Mater 2011; 11:123-31. [PMID: 22658161 DOI: 10.1016/j.jmbbm.2011.11.007] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2011] [Revised: 11/10/2011] [Accepted: 11/16/2011] [Indexed: 01/26/2023]
Abstract
The use of tissue grafting for the repair of large bone defects has numerous limitations including donor site morbidity and the risk of disease transmission. These limitations have prompted research efforts to investigate the effects of combining biomaterial scaffolds with biochemical cues to augment bone repair. The goal of this study was to use a critically-sized rat femoral segmental defect model to investigate the efficacy of a delivery system consisting of an electrospun polycaprolactone (PCL) nanofiber mesh tube with a silk fibroin hydrogel for local recombinant bone morphogenetic protein 2 (BMP-2) delivery. Bilateral 8 mm segmental femoral defects were formed in 13-week-old Sprague Dawley rats. Perforated electrospun PCL nanofiber mesh tubes were fitted into the adjacent native bone such that the lumen of the tubes contained the defect (Kolambkar et al., 2011b). Silk hydrogels with or without BMP-2 were injected into the defect. Bone regeneration was longitudinally assessed using 2D X-ray radiography and 3D microcomputed topography (μCT). Following sacrifice at 12 weeks after surgery, the extracted femurs were either subjected to biomechanical testing or assigned for histology. The results demonstrated that silk was an effective carrier for BMP-2. Compared to the delivery system without BMP-2, the delivery system that contained BMP-2 resulted in more bone formation (p<0.05) at 4, 8, 12 weeks after surgery. Biomechanical properties were also significantly improved in the presence of BMP-2 (p<0.05) and were comparable to age-matched intact femurs. Histological evaluation of the defect region indicated that the silk hydrogel has been completely degraded by the end of the study. Based on these results, we conclude that a BMP-2 delivery system consisting of an electrospun PCL nanofiber mesh tube with a silk hydrogel presents an effective strategy for functional repair of large bone defects.
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Affiliation(s)
- Tamim Diab
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332-0363, USA.
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89
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Karve KA, Gil ES, McCarthy SP, Kaplan DL. Effect of β-sheet crystalline content on mass transfer in silk films. J Memb Sci 2011; 383:44-49. [PMID: 22135474 DOI: 10.1016/j.memsci.2011.08.032] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The material properties of silk are favorable for drug delivery due to the ability to control material structure and morphology under ambient, aqueous processing conditions. Mass transport of compounds with varying physical-chemical characteristics was studied in silk fibroin films with control of β-sheet crystalline content. Two compounds, vitamin B12 and fluorescein isothiocynate (FITC) labeled lysozyme were studied in a diffusion apparatus to determine transport through silk films. The films exhibited size exclusion phenomenon with permeability coefficients with contrasting trends with increases in β-sheet crystallinity. The size exclusion phenomenon observed with the two model compounds was characterized by contrasting trends in permeability coefficients of the films as a function of β-sheet crystallinity. The diffusivity of the compounds was examined in the context of free volume theory. Apart from the β-sheet crystallinity, size of the compound and its interactions with silk influenced mass transfer. Diffusivity of vitamin B12 was modeled to define a power law relationship with β-sheet crystallinity. The results of the study demonstrate that diffusion of therapeutic agents though silk fibroin films can be directed to match a desired rate by modulating secondary structure of the silk proteins.
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Affiliation(s)
- Kiran A Karve
- Biomedical Engineering and Biotechnology Program, University of Massachusetts at Lowell, Lowell MA 01854 USA
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90
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Hu X, Park SH, Gil ES, Xia XX, Weiss AS, Kaplan DL. The influence of elasticity and surface roughness on myogenic and osteogenic-differentiation of cells on silk-elastin biomaterials. Biomaterials 2011; 32:8979-89. [PMID: 21872326 DOI: 10.1016/j.biomaterials.2011.08.037] [Citation(s) in RCA: 154] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2011] [Accepted: 08/14/2011] [Indexed: 12/22/2022]
Abstract
The interactions of C2C12 myoblasts and human bone marrow stem cells (hMSCs) with silk-tropoelastin biomaterials, and the capacity of each to promote attachment, proliferation, and either myogenic- or osteogenic-differentiation were investigated. Temperature-controlled water vapor annealing was used to control beta-sheet crystal formation to generate insoluble silk-tropoelastin biomaterial matrices at defined ratios of the two proteins. These ratios controlled surface roughness and micro/nano-scale topological patterns, and elastic modulus, stiffness, yield stress, and tensile strength. A combination of low surface roughness and high stiffness in the silk-tropoelastin materials promoted proliferation and myogenic-differentiation of C2C12 cells. In contrast, high surface roughness with micro/nano-scale surface patterns was favored by hMSCs. Increasing the content of human tropoelastin in the silk-tropoelastin materials enhanced the proliferation and osteogenic-differentiation of hMSCs. We conclude that the silk-tropoelastin composition facilitates fine tuning of the growth and differentiation of these cells.
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Affiliation(s)
- Xiao Hu
- Department of Biomedical Engineering, Tufts University, Medford, MA 02155, USA
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91
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Lu Q, Wang X, Zhu H, Kaplan DL. Surface immobilization of antibody on silk fibroin through conformational transition. Acta Biomater 2011; 7:2782-6. [PMID: 21382528 PMCID: PMC3104071 DOI: 10.1016/j.actbio.2011.03.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2010] [Revised: 02/24/2011] [Accepted: 03/02/2011] [Indexed: 11/30/2022]
Abstract
In recent studies silk fibroin has been explored as a new material platform for biosensors. Based on these developments, a procedure for the immobilization of antibodies on silk fibroin substrates was developed as a route to functionalizing these biosensor systems. By controlling the conformational transition of the silk fibroin, a primary antibody was immobilized and enriched at the surface of silk fibroin substrates under mild reaction conditions to maintain antibody function. Compared to chemical crosslinking, the immobilization efficiency in the present approach was increased significantly. This method, achieving high loading of antibody while retaining function, improves the feasibility of silk fibroin as a platform material for biosensor applications.
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Affiliation(s)
- Qiang Lu
- National Engineering Laboratory for Modern Silk, College of Textile and Clothing Engineering, Soochow University, Suzhou 215123, People's Republic of China.
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92
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Hu X, Shmelev K, Sun L, Gil ES, Park SH, Cebe P, Kaplan DL. Regulation of silk material structure by temperature-controlled water vapor annealing. Biomacromolecules 2011; 12:1686-96. [PMID: 21425769 PMCID: PMC3090511 DOI: 10.1021/bm200062a] [Citation(s) in RCA: 376] [Impact Index Per Article: 28.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
We present a simple and effective method to obtain refined control of the molecular structure of silk biomaterials through physical temperature-controlled water vapor annealing (TCWVA). The silk materials can be prepared with control of crystallinity, from a low content using conditions at 4 °C (α helix dominated silk I structure), to highest content of ∼60% crystallinity at 100 °C (β-sheet dominated silk II structure). This new physical approach covers the range of structures previously reported to govern crystallization during the fabrication of silk materials, yet offers a simpler, green chemistry, approach with tight control of reproducibility. The transition kinetics, thermal, mechanical, and biodegradation properties of the silk films prepared at different temperatures were investigated and compared by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), uniaxial tensile studies, and enzymatic degradation studies. The results revealed that this new physical processing method accurately controls structure, in turn providing control of mechanical properties, thermal stability, enzyme degradation rate, and human mesenchymal stem cell interactions. The mechanistic basis for the control is through the temperature-controlled regulation of water vapor to control crystallization. Control of silk structure via TCWVA represents a significant improvement in the fabrication of silk-based biomaterials, where control of structure-property relationships is key to regulating material properties. This new approach to control crystallization also provides an entirely new green approach, avoiding common methods that use organic solvents (methanol, ethanol) or organic acids. The method described here for silk proteins would also be universal for many other structural proteins (and likely other biopolymers), where water controls chain interactions related to material properties.
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Affiliation(s)
- Xiao Hu
- Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, MA 02155, USA
| | - Karen Shmelev
- Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, MA 02155, USA
| | - Lin Sun
- Department of Chemical and Biological Engineering, Tufts University, 4 Colby Street, Medford, MA 02155, USA
| | - Eun-Seok Gil
- Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, MA 02155, USA
| | - Sang-Hyug Park
- Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, MA 02155, USA
| | - Peggy Cebe
- Department of Physics and Astronomy, Tufts University, 4 Colby Street, Medford, MA 02155, USA
| | - David L. Kaplan
- Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, MA 02155, USA
- Department of Chemical and Biological Engineering, Tufts University, 4 Colby Street, Medford, MA 02155, USA
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93
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Pritchard EM, Kaplan DL. Silk fibroin biomaterials for controlled release drug delivery. Expert Opin Drug Deliv 2011; 8:797-811. [PMID: 21453189 DOI: 10.1517/17425247.2011.568936] [Citation(s) in RCA: 204] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION Given the benefits of polymer drug delivery implants over traditional periodic systemic administration, the development of biomaterial systems with the necessary properties (biocompatibility, degradation, stabilization, controllability) is paramount. Silk fibroin represents a promising, naturally derived polymer for local, controlled, sustained drug release from fully degrading implants and the polymer can be processed into a broad array of material formats. AREAS COVERED This review provides an overview of silk biomaterials for drug delivery, especially those that can function as long-term depots. Fundamentals of structure and assembly, processing options, control points and specific examples of implantable silk drug delivery systems (sponges, films) and injectable systems (microspheres, hydrogels) from the 1990s and onwards are reviewed. EXPERT OPINION Owing to its unique material properties, stabilization effects and tight controllability, silk fibroin is a promising biomaterial for implantable and injectable drug delivery applications. Many promising control points have been identified, and characterization of the relationships between silk processing and/or material properties and the resulting drug loading and release kinetics will ultimately enhance the overall utility of this unique biomaterial. The ever-expanding biomaterial 'tool kit' that silk provides will eventually allow the simultaneous optimization of implant structure, material properties and drug release behavior that is needed to maximize the cost-efficiency, convenience, efficacy and safety of many new and existing therapeutics, especially those that cannot be delivered by means of traditional administration approaches.
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Affiliation(s)
- Eleanor M Pritchard
- Tufts University, Department of Biomedical Engineering, Medford, MA 02155, USA
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94
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Van Vlierberghe S, Dubruel P, Schacht E. Biopolymer-based hydrogels as scaffolds for tissue engineering applications: a review. Biomacromolecules 2011; 12:1387-408. [PMID: 21388145 DOI: 10.1021/bm200083n] [Citation(s) in RCA: 1068] [Impact Index Per Article: 82.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Hydrogels are physically or chemically cross-linked polymer networks that are able to absorb large amounts of water. They can be classified into different categories depending on various parameters including the preparation method, the charge, and the mechanical and structural characteristics. The present review aims to give an overview of hydrogels based on natural polymers and their various applications in the field of tissue engineering. In a first part, relevant parameters describing different hydrogel properties and the strategies applied to finetune these characteristics will be described. In a second part, an important class of biopolymers that possess thermosensitive properties (UCST or LCST behavior) will be discussed. Another part of the review will be devoted to the application of cryogels. Finally, the most relevant biopolymer-based hydrogel systems, the different methods of preparation, as well as an in depth overview of the applications in the field of tissue engineering will be given.
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Affiliation(s)
- S Van Vlierberghe
- Polymer Chemistry & Biomaterials Research Group, Ghent University, Ghent, Belgium
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95
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Lu Q, Zhang B, Li M, Zuo B, Kaplan DL, Huang Y, Zhu H. Degradation mechanism and control of silk fibroin. Biomacromolecules 2011; 12:1080-6. [PMID: 21361368 DOI: 10.1021/bm101422j] [Citation(s) in RCA: 196] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Controlling the degradation process of silk is an important and interesting subject in the field of biomaterials. In the present study, silk fibroin films with different secondary conformations and nanostructures were used to study degradation behavior in buffered protease XIV solution. Different from previous studies, silk fibroin films with highest β-sheet content achieved the highest degradation rate in our research. A new degradation mechanism revealed that degradation behavior of silk fibroin was related to not only crystal content but also hydrophilic interaction and then crystal-noncrystal alternate nanostructures. First, hydrophilic blocks of silk fibroin were degraded. Then, hydrophobic crystal blocks that were formerly surrounded and immobilized by hydrophilic blocks became free particles and moved into solution. Therefore, on the basis of the mechanism, which enables the process to be more controllable and flexible, controlling the degradation behavior of silk fibroin without affecting other performances such as its mechanical or hydrophilic properties becomes feasible, and this would greatly expand the applications of silk as a biomedical material.
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Affiliation(s)
- Qiang Lu
- National Engineering Laboratory for Modern Silk, College of Textile and Clothing Engineering, Soochow University, Suzhou 215123, People's Republic of China.
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96
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Guziewicz N, Best A, Perez-Ramirez B, Kaplan DL. Lyophilized silk fibroin hydrogels for the sustained local delivery of therapeutic monoclonal antibodies. Biomaterials 2011; 32:2642-50. [PMID: 21216004 DOI: 10.1016/j.biomaterials.2010.12.023] [Citation(s) in RCA: 173] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2010] [Accepted: 12/14/2010] [Indexed: 01/09/2023]
Abstract
The development of sustained delivery systems compatible with protein therapeutics continues to be a significant unmet need. A lyophilized silk fibroin hydrogel matrix (lyogel) for the sustained release of pharmaceutically relevant monoclonal antibodies is described. Sonication of silk fibroin prior to antibody incorporation avoids exposing the antibody to the sol-gel transition inducing shear stress. Fourier Transform Infrared (FTIR) analysis showed no change in silk structural composition between hydrogel and lyogel or with increasing silk fibroin concentration. Antibody release from hydrogels occurred rapidly over 10 days regardless of silk concentration. Upon lyophilization, sustained antibody release was observed over 38 days from lyogels containing 6.2% (w/w) silk fibroin and above. In 3.2% (w/w) silk lyogels, antibody release was comparable to hydrogels. Swelling properties of lyogels followed a similar threshold behavior. Lyogels at 3.2% (w/w) silk recovered approximately 90% of their fluid mass upon rehydration, while approximately 50% fluid recovery was observed at 6.2% (w/w) silk and above. Antibody release was primarily governed by hydrophobic/hydrophilic silk-antibody interactions and secondarily altered by the hydration resistance of the lyogel. Hydration resistance was controlled by altering β-sheet (crystalline) density of the matrix. The antibody released from lyogels maintained biological activity. Silk lyogels offer an advantage as a delivery matrix over other hydrogel materials for the slow release of the loaded protein, making lyogels suitable for long-term sustained release applications.
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Affiliation(s)
- Nicholas Guziewicz
- BioFormulations Development, Genzyme Corporation, 1 Mountain Road, P.O. Box 9322, Framingham, MA 01701-9322, USA
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97
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Nanofibrous architecture of silk fibroin scaffolds prepared with a mild self-assembly process. Biomaterials 2010; 32:1059-67. [PMID: 20970185 DOI: 10.1016/j.biomaterials.2010.09.072] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2010] [Accepted: 09/30/2010] [Indexed: 12/20/2022]
Abstract
Besides excellent biocompatibility and biodegradability, a useful tissue engineering scaffold should provide suitable macropores and nanofibrous structure, similar to extracellular matrix (ECM), to induce desired cellular activities and to guide tissue regeneration. In the present study, a mild process to prepare porous and nanofibrous silk-based scaffolds from aqueous solution is described. Using collagen to control the self-assembly of silk, nanofibrous silk scaffolds were firstly achieved through lyophilization. Water annealing was used to generate insolubility in the silk-based scaffolds, thereby avoiding the use of organic solvents. The nano-fibrils formed in the silk-collagen scaffolds had diameters of 20-100 nm, similar with native collagen in ECM. The silk-collagen scaffolds dissolved slowly in PBS solution, with about a 28% mass lost after 4 weeks. Following the dissolution or degradation, the nanofibrous structure inside the macropore walls emerged and interacted with cells directly. During in vitro cell culture, the nanofibrous silk-collagen scaffolds containing 7.4% collagen demonstrated significantly improved cell compatibility when compared with salt-leached silk scaffolds and silk-collagen scaffolds containing 20% collagen that emerged less nano-fibrils. Therefore, this new process provides useful scaffolds for tissue engineering applications. Furthermore, the process involves all-aqueous, room temperature and pressure processing without the use of toxic chemicals or solvents, offering new green chemistry approaches, as well as options to load bioactive drugs or growth factors into process.
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98
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Hu X, Wang X, Rnjak J, Weiss AS, Kaplan DL. Biomaterials derived from silk-tropoelastin protein systems. Biomaterials 2010; 31:8121-31. [PMID: 20674969 DOI: 10.1016/j.biomaterials.2010.07.044] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2010] [Accepted: 07/07/2010] [Indexed: 01/03/2023]
Abstract
A structural protein blend system based on silkworm silk fibroin and recombinant human tropoelastin is described. Silk fibroin, a semicrystalline fibrous protein with beta-sheet crystals provides mechanical strength and controllable biodegradation, while tropoelastin, a noncrystallizable elastic protein provides elasticity. Differential scanning calorimetry (DSC) and temperature modulated DSC (TMDSC) indicated that silk becomes miscible with tropoelastin at different blend ratios, without macrophase separation. Fourier transform infrared spectroscopy (FTIR) revealed secondary structural changes of the blend system (beta-sheet content) before and after methanol treatment. Atomic Force Microscopy (AFM) nano-indentation demonstrated that blending silk and tropoelastin at different ratios resulted in modification of mechanical features, with resilience from approximately 68%- approximately 97%, and elastic modulus between 2 and 9 Mpa, depending on the ratio of the two polymers. Some of these values are close to those of native aortic elastin or elastin-like polypeptides. Significantly, during blending and drying silk-tropoelastin form micro- and nano-scale porous morphologies which promote human mesenchymal stem cell attachment and proliferation. These blends offer a new protein biomaterial system for cell support and tailored biomaterial properties to match mechanical needs.
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Affiliation(s)
- Xiao Hu
- Department of Biomedical Engineering, Tufts University, Medford, MA 02155, USA
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