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Fink TD, Funnell JL, Gilbert RJ, Zha RH. One-Pot Assembly of Drug-Eluting Silk Coatings with Applications for Nerve Regeneration. ACS Biomater Sci Eng 2024; 10:482-496. [PMID: 38109315 DOI: 10.1021/acsbiomaterials.3c01042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2023]
Abstract
Clinical use of polymeric scaffolds for tissue engineering often suffers from their inability to promote strong cellular interactions. Functionalization with biomolecules may improve outcomes; however, current functionalization approaches using covalent chemistry or physical adsorption can lead to loss of biomolecule bioactivity. Here, we demonstrate a novel bottom-up approach for enhancing the bioactivity of poly(l-lactic acid) electrospun scaffolds though interfacial coassembly of protein payloads with silk fibroin into nanothin coatings. In our approach, protein payloads are first added into an aqueous solution with Bombyx mori-derived silk fibroin. Phosphate anions are then added to trigger coassembly of the payload and silk fibroin, as well as noncovalent formation of a payload-silk fibroin coating at poly(l-lactic) acid fiber surfaces. Importantly, the coassembly process results in homogeneous distribution of protein payloads, with the loading quantity depending on payload concentration in solution and coating time. This coassembly process yields greater loading capacity than physical adsorption methods, and the payloads can be released over time in physiologically relevant conditions. We also demonstrate that the coating coassembly process can incorporate nerve growth factor and that coassembled coatings lead to significantly more neurite extension than loading via adsorption in a rat dorsal root ganglia explant culture model.
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Affiliation(s)
- Tanner D Fink
- Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
- Shirley Ann Jackson, Ph. D. Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
- Department of Chemistry and International Institute for Nanotechnology, Northwestern University, Evanston, Illinois 60208, United States
| | - Jessica L Funnell
- Department of Biomedical Engineering, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180, United States
- Shirley Ann Jackson, Ph. D. Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
| | - Ryan J Gilbert
- Department of Biomedical Engineering, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180, United States
- Shirley Ann Jackson, Ph. D. Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
| | - R Helen Zha
- Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
- Shirley Ann Jackson, Ph. D. Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
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Hofmaier M, Heger JE, Lentz S, Schwarz S, Müller-Buschbaum P, Scheibel T, Fery A, Müller M. Influence of the Sequence Motive Repeating Number on Protein Folding in Spider Silk Protein Films. Biomacromolecules 2023; 24:5707-5721. [PMID: 37934893 DOI: 10.1021/acs.biomac.3c00688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2023]
Abstract
Like multiblock copolymers, spider silk proteins are built of repetitive sequence motives. One prominent repetitive motif is based on the consensus sequence of spidroin 4 of the spider Araneus diadematus ADF4. The number x of the repeating sequence motives (C) determines the molecular weight of the recombinant ADF4-based, engineered spider silk protein denoted as eADF4(Cx). eADF4(Cx) can be used as a model for intrinsically disordered proteins (IDP) and to elucidate their folding. Herein, the influence of the variation of the sequence motive repeating number x (x = 1, 2, 4, 8, 16) on the protein folding within eADF4(Cx) films was investigated. eADF4(Cx) films were cast from 1,1,1,3,3,3-hexafluoropropan-2-ol (HFIP) solutions onto planar silicon model substrates, revealing mainly helical or random coil structure. Upon treatment with methanol vapor (ptm), the formation of crystalline β-sheets was triggered. Dichroic Fourier-transform infrared (FTIR) spectroscopy, circular dichroism, spectroscopic ellipsometry, atomic force microscopy, grazing-incidence small-angle X-ray scattering (GISAXS), grazing-incidence wide-angle X-ray scattering (GIWAXS), and electrokinetic and contact angle measurements were used to get information concerning the secondary structure and folding kinetics, orientation of β-sheets, the ratio of parallel/antiparallel β-sheets, domain sizes and distributions, surface topography, surface potential, hydrophobicity and the film integrity under water. Significant differences in the final β-sheet content, the share of antiparallel β-sheet structures, film integrity, surface potential, and isoelectric points between eADF4(Cx) with x = 1, 2 and eADF4(Cx) with x = 4, 8, 16 gave new insights in the molecular weight-dependent structure formation and film properties of IDP systems. GISAXS and kinetic measurements confirmed a relation between β-sheet crystal growth rate and final β-sheet crystal size. Further, competing effects of reduced diffusibility hindering accelerated crystal growth and enhanced backfolding promoting accelerated crystal growth with increasing molecular weight were discussed.
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Affiliation(s)
- Mirjam Hofmaier
- Institute of Physical Chemistry and Polymer Physics, Leibniz Institute of Polymer Research Dresden (IPF), Dresden 01069, Germany
- Chair of Physical Chemistry of Polymeric Materials, Technical University Dresden (TUD), Dresden 01069, Germany
| | - Julian E Heger
- TUM School of Natural Sciences, Department of Physics, Chair for Functional Materials, Technical University of Munich, Garching 85748, Germany
| | - Sarah Lentz
- Functional Polymer Interfaces Group, University of Bayreuth, Bayreuth 95447, Germany
| | - Simona Schwarz
- Institute of Physical Chemistry and Polymer Physics, Leibniz Institute of Polymer Research Dresden (IPF), Dresden 01069, Germany
| | - Peter Müller-Buschbaum
- TUM School of Natural Sciences, Department of Physics, Chair for Functional Materials, Technical University of Munich, Garching 85748, Germany
- Heinz Maier-Leibnitz Zentrum (MLZ), Technical University of Munich, Garching 85748, Germany
| | - Thomas Scheibel
- Chair of Biomaterials, University of Bayreuth, Bayreuth 95447, Germany
- Bayreuth Center of Colloids and Interfaces (BZKG), University of Bayreuth, Bayreuth 95440, Germany
- Bayreuth Center for Molecular Bioscience (BZMB), University of Bayreuth, Bayreuth 95440, Germany
- Bayreuth Center for Material Science and Engineering (BayMAT), Universität Bayreuth, Bayreuth 95440, Germany
- Bavarian Polymer Institute (BPI), University of Bayreuth, Bayreuth 95440, Germany
| | - Andreas Fery
- Institute of Physical Chemistry and Polymer Physics, Leibniz Institute of Polymer Research Dresden (IPF), Dresden 01069, Germany
- Chair of Physical Chemistry of Polymeric Materials, Technical University Dresden (TUD), Dresden 01069, Germany
| | - Martin Müller
- Institute of Physical Chemistry and Polymer Physics, Leibniz Institute of Polymer Research Dresden (IPF), Dresden 01069, Germany
- Chair of Macromolecular Chemistry, Technical University of Dresden (TUD), Dresden 01062, Germany
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3
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Bargel H, Trossmann VT, Sommer C, Scheibel T. Bioselectivity of silk protein-based materials and their bio-inspired applications. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2022; 13:902-921. [PMID: 36127898 PMCID: PMC9475208 DOI: 10.3762/bjnano.13.81] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 08/23/2022] [Indexed: 06/15/2023]
Abstract
Adhesion to material surfaces is crucial for almost all organisms regarding subsequent biological responses. Mammalian cell attachment to a surrounding biological matrix is essential for maintaining their survival and function concerning tissue formation. Conversely, the adhesion and presence of microbes interferes with important multicellular processes of tissue development. Therefore, tailoring bioselective, biologically active, and multifunctional materials for biomedical applications is a modern focus of biomaterial research. Engineering biomaterials that stimulate and interact with cell receptors to support binding and subsequent physiological responses of multicellular systems attracted much interest in the last years. Further to this, the increasing threat of multidrug resistance of pathogens against antibiotics to human health urgently requires new material concepts for preventing microbial infestation and biofilm formation. Thus, materials exhibiting microbial repellence or antimicrobial behaviour to reduce inflammation, while selectively enhancing regeneration in host tissues are of utmost interest. In this context, protein-based materials are interesting candidates due to their natural origin, biological activity, and structural properties. Silk materials, in particular those made of spider silk proteins and their recombinant counterparts, are characterized by extraordinary properties including excellent biocompatibility, slow biodegradation, low immunogenicity, and non-toxicity, making them ideally suited for tissue engineering and biomedical applications. Furthermore, recombinant production technologies allow for application-specific modification to develop adjustable, bioactive materials. The present review focusses on biological processes and surface interactions involved in the bioselective adhesion of mammalian cells and repellence of microbes on protein-based material surfaces. In addition, it highlights the importance of materials made of recombinant spider silk proteins, focussing on the progress regarding bioselectivity.
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Affiliation(s)
- Hendrik Bargel
- Department of Biomaterials, University of Bayreuth, Prof.-Rüdiger-Bormann-Str. 1, 95447 Bayreuth, Germany
| | - Vanessa T Trossmann
- Department of Biomaterials, University of Bayreuth, Prof.-Rüdiger-Bormann-Str. 1, 95447 Bayreuth, Germany
| | - Christoph Sommer
- Department of Biomaterials, University of Bayreuth, Prof.-Rüdiger-Bormann-Str. 1, 95447 Bayreuth, Germany
| | - Thomas Scheibel
- Department of Biomaterials, University of Bayreuth, Prof.-Rüdiger-Bormann-Str. 1, 95447 Bayreuth, Germany
- Bayreuth Center of Material Science and Engineering (BayMat), University of Bayreuth, Universitätsstr. 30, 95440 Bayreuth, Germany
- Bavarian Polymer Institute (BPI), University of Bayreuth, Universitätsstr. 30, 95440 Bayreuth, Germany
- Bayreuth Center of Colloids and Interfaces (BZKG), University of Bayreuth, Universitätsstr. 30, 95440 Bayreuth, Germany
- Bayreuth Center for Molecular Biosciences (BZMB), University of Bayreuth, Universitätsstr. 30, 95440 Bayreuth, Germany
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General Methods to Produce and Assemble Recombinant Spider Silk Proteins. Methods Mol Biol 2021. [PMID: 34472055 DOI: 10.1007/978-1-0716-1574-4_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Orb-weaving spiders are known to spin up to seven types of silks/glues from different silk glands. The inherent mechanical variety of these silks makes them attractive models for a variety of biomaterial design, from superglues to extremely strong and/or extendible fibers. Spider silk spinning is a process in which spinning dope stored in specific glands assembles into fibrils upon chemical and mechanical stimuli. The exploration of silk protein assembly into controllable filaments is vital for both uncovering biological functions and molecular structure relationship, as well as fabricating new biomaterials. This chapter describes the methods for biosynthesis and assembly of recombinant spider silk proteins, which will provide insights into the mechanism exploration of fiber formation and spider silk-based material manufacture.
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Liu Y, Huang W, Meng M, Chen M, Cao C. Progress in the application of spider silk protein in medicine. J Biomater Appl 2021; 36:859-871. [PMID: 33853426 DOI: 10.1177/08853282211003850] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Spider silk protein has attracted much attention on account of its excellent mechanical properties, biodegradability, and biocompatibility. As the main protein component of spider silk, spidroin plays important role in spider spinning under natural circumstances and biomaterial application in medicine as well. Compare to the native spidroin which has a large molecular weight (>300 kDa) with highly repeat glycine and polyalanine regions, the recombinant spidroin was maintained the core amino motifs and much easier to collect. Here, we reviewed the application of recombinant spider silk protein eADF4(C16), major ampullate spidroin (MaSp), minor ampullate spidroin (MiSp), and the derivatives of recombinant spider silk protein in drug delivery system. Moreover, we also reviewed the application of spider silk protein in the field of alternative materials, repairing materials, wound dressing, surgical sutures along with advances in recombinant spider silk protein.
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Affiliation(s)
- Yi Liu
- 1Key Laboratories of Fine Chemicals and Surfactants in Sichuan Provincial Universities, School of Chemical Engineering, Sichuan University of Science & Engineering, Zigong, China
| | - Wei Huang
- 1Key Laboratories of Fine Chemicals and Surfactants in Sichuan Provincial Universities, School of Chemical Engineering, Sichuan University of Science & Engineering, Zigong, China
| | - Minsi Meng
- 1Key Laboratories of Fine Chemicals and Surfactants in Sichuan Provincial Universities, School of Chemical Engineering, Sichuan University of Science & Engineering, Zigong, China
| | - Minhui Chen
- 2Department of Neurosurgery, Zigong Fourth People's Hospital, Zigong, China
| | - Chengjian Cao
- 3Department of Clinical Laboratory, Zigong First People's Hospital, Zigong, China
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Zhang D, Xu X, Long X, Cheng K, Li J. Advances in biomolecule inspired polymeric material decorated interfaces for biological applications. Biomater Sci 2020; 7:3984-3999. [PMID: 31429424 DOI: 10.1039/c9bm00746f] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
With the development of surface modification technology, interface properties have great effects on the interaction between biomedical materials and cells and biomolecules, which significantly affects the biocompatibility and functionality of materials. As an orderly and perfect system, biological organisms in nature effectively integrate all kinds of bio-interfaces with physiological functions, which shed light on the importance of biomolecules in organisms. It gives birth to a bio-inspiration strategy to design and fabricate smart materials with specific functionalities, e.g. osteogenic and chondrocytic induced materials inspired by bone sialoprotein and chondroitin sulfate. Through this mimicking approach, various functional materials were utilized to decorate the interfaces and further optimize the performance of biomedical materials, which would widely expand their applications. In this review, followed by a summary and brief introduction of surface modification methods, we highlight recent advances in the fabrication of functional polymeric materials inspired by a range of biomolecules for decorating interfaces. Then, the other applications of biomolecule inspired materials including tissue engineering, diagnosis and treatment of diseases and physiological function regulation are presented and the future outlook is discussed as well.
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Affiliation(s)
- Dongyue Zhang
- College of Polymer Science and Engineering, Sichuan University, Chengdu, 610065, P. R. China.
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Ziemba AM, Fink TD, Crochiere MC, Puhl DL, Sapkota S, Gilbert RJ, Zha RH. Coating Topologically Complex Electrospun Fibers with Nanothin Silk Fibroin Enhances Neurite Outgrowth in Vitro. ACS Biomater Sci Eng 2020; 6:1321-1332. [PMID: 33455379 PMCID: PMC8275559 DOI: 10.1021/acsbiomaterials.9b01487] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Electrospun poly-l-lactic acid (PLLA) fibers are commonly used for tissue engineering applications because of their uniform morphology, and their efficacy can be further enhanced via surface modification. In this study, we aimed to increase neurite outgrowth along electrospun fibers by coating with silk fibroin (SF), a bioinert protein derived from Bombyx mori cocoon threads, shown to be neurocompatible. Aligned PLLA fibers were electrospun with smooth, pitted, and divoted surface nanotopographies and coated with SF by immersion in coating solution for either 12 or 24 h. Specifically, thin-film coatings of SF were generated by leveraging the controlled self-assembly of SF in aqueous conditions that promote β-sheet assembly. For both 12- and 24-h coatings, Congo Red staining for β-sheet structures confirmed the presence of SF coatings on PLLA fibers. Confocal imaging of fluorescein-labeled SF further demonstrated a homogeneous coating formation on PLLA fibers. No change in the water contact angle of the surfaces was observed after coating; however, an increase in the isoelectric point (pI) to values comparable with the theoretical pI of SF was seen. Notably, there was a significant trend of increased dorsal root ganglia (DRG) adhesion on scaffolds coated with SF, as well as greater neurite outgrowth on pitted and divoted fibers that had been coated with SF. Ultimately, this work demonstrated that thin-film SF coatings formed by self-assembly uniformly coat electrospun fibers, providing a new strategy to increase the neuroregenerative capacity of electrospun scaffolds. To our knowledge, this is the first instance of biomedical modification of topologically complex substrates using noncovalent methods.
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Affiliation(s)
- Alexis M. Ziemba
- Department of Biomedical Engineering and Center for Biotechnology and Interdisciplinary Sciences, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
| | - Tanner D. Fink
- Department of Chemical and Biological Engineering and Center for Biotechnology and Interdisciplinary Sciences, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
| | - Mary Clare Crochiere
- Department of Biomedical Engineering and Center for Biotechnology and Interdisciplinary Sciences, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
| | - Devan L. Puhl
- Department of Biomedical Engineering and Center for Biotechnology and Interdisciplinary Sciences, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
| | - Samichya Sapkota
- Department of Biomedical Engineering and Center for Biotechnology and Interdisciplinary Sciences, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
| | - Ryan J. Gilbert
- Department of Biomedical Engineering and Center for Biotechnology and Interdisciplinary Sciences, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
| | - R. Helen Zha
- Department of Chemical and Biological Engineering and Center for Biotechnology and Interdisciplinary Sciences, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
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8
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Humenik M, Preiß T, Gödrich S, Papastavrou G, Scheibel T. Functionalized DNA-spider silk nanohydrogels for controlled protein binding and release. Mater Today Bio 2020; 6:100045. [PMID: 32259099 PMCID: PMC7096766 DOI: 10.1016/j.mtbio.2020.100045] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 02/06/2020] [Accepted: 02/07/2020] [Indexed: 12/19/2022] Open
Abstract
Hydrogels are excellent scaffolds to accommodate sensitive enzymes in a protective environment. However, the lack of suitable immobilization techniques on substrates and the lack of selectivity to anchor a biocatalyst are major drawbacks preventing the use of hydrogels in bioanalytical devices. Here, nanofilm coatings on surfaces were made of a recombinant spider silk protein (rssp) to induce rssp self-assembly and thus the formation of fibril-based nanohydrogels. To functionalize spider silk nanohydrogels for bioselective binding of proteins, two different antithrombin aptamers were chemically conjugated with the rssp, thereby integrating the target-binding function into the nanohydrogel network. Human thrombin was selected as a sensitive model target, in which the structural integrity determines its activity. The chosen aptamers, which bind various exosites of thrombin, enabled selective and cooperative embedding of the protein into the nanohydrogels. The change of the aptamer secondary structure using complementary DNA sequences led to the release of active thrombin and confirmed the addressable functionalization of spider silk nanohydrogels.
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Affiliation(s)
- Martin Humenik
- Department of Biomaterials, Faculty of Engineering Science, Universität Bayreuth, Prof.-Rüdiger-Bormann.Str. 1, 95447 Bayreuth, Germany
| | - Tamara Preiß
- Department of Biomaterials, Faculty of Engineering Science, Universität Bayreuth, Prof.-Rüdiger-Bormann.Str. 1, 95447 Bayreuth, Germany
| | - Sebastian Gödrich
- Department of Physical Chemistry II, Faculty of Biology, Chemistry & Earth Sciences, Universität Bayreuth, Universitätsstraße 30, 95440 Bayreuth, Germany
| | - Georg Papastavrou
- Department of Physical Chemistry II, Faculty of Biology, Chemistry & Earth Sciences, Universität Bayreuth, Universitätsstraße 30, 95440 Bayreuth, Germany
- Bayreuth Center for Colloids and Interfaces (BZKG), Universität Bayreuth, Universitätsstraße 30, 95440 Bayreuth, Germany
- Bavarian Polymer Institute (BPI), Universität Bayreuth, Universitätsstraße 30, 95440 Bayreuth, Germany
| | - Thomas Scheibel
- Department of Biomaterials, Faculty of Engineering Science, Universität Bayreuth, Prof.-Rüdiger-Bormann.Str. 1, 95447 Bayreuth, Germany
- Bayreuth Center for Colloids and Interfaces (BZKG), Universität Bayreuth, Universitätsstraße 30, 95440 Bayreuth, Germany
- Bayreuth Center for Molecular Biosciences (BZMB), Universität Bayreuth, Universitätsstraße 30, 95440 Bayreuth, Germany
- Bayreuth Center for Material Science (BayMAT), Universität Bayreuth, Universitätsstraße 30, 95440 Bayreuth, Germany
- Bavarian Polymer Institute (BPI), Universität Bayreuth, Universitätsstraße 30, 95440 Bayreuth, Germany
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Aqueous electrospinning of recombinant spider silk proteins. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2020; 106:110145. [DOI: 10.1016/j.msec.2019.110145] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Revised: 08/28/2019] [Accepted: 08/28/2019] [Indexed: 11/19/2022]
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Malollari KG, Delparastan P, Sobek C, Vachhani SJ, Fink TD, Zha RH, Messersmith PB. Mechanical Enhancement of Bioinspired Polydopamine Nanocoatings. ACS APPLIED MATERIALS & INTERFACES 2019; 11:43599-43607. [PMID: 31644269 DOI: 10.1021/acsami.9b15740] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Inspired by the catechol and amine-rich adhesive proteins of mussels, polydopamine (pDA) has become one of the most widely employed methods for functionalizing material surfaces, powered in part by the versatility and simplicity of pDA film deposition that takes place spontaneously on objects immersed in an alkaline aqueous solution of dopamine monomer. Despite the widespread adoption of pDA as a multifunctional coating for surface modification, it exhibits poor mechanical performance. Attempts to modify the physical properties of pDA by incorporation of oxidizing agents, cross-linkers, or carbonization of the films at ultrahigh temperatures have been reported; however, improving mechanical properties with mild post-treatments without sacrificing the functionality and versatility of pDA remains a challenge. Here, we demonstrate thermal annealing at a moderate temperature (130 °C) as a facile route to enhance mechanical robustness of pDA coatings. Chemical spectroscopy, X-ray scattering, molecular force spectroscopy, and bulk mechanical analyses indicate that monomeric and oligomeric species undergo further polymerization during thermal annealing, leading to fundamental changes in molecular and bulk mechanical behavior of pDA. Considerable improvements in scratch resistance were noted in terms of both penetration depth (32% decrease) and residual depth (74% decrease) for the annealed pDA coating, indicating the enhanced ability of the annealed coating to resist mechanical deformations. Thermal annealing resulted in significant enhancement in the intermolecular and cohesive interactions between the chains in the pDA structure, attributed to cross-linking and increased entanglements, preventing desorption and detachment of the chains from the coating. Importantly, improvements in pDA mechanical performance through thermal annealing did not compromise the ability of pDA to support secondary coating reactions as evidenced by electroless deposition of a metal film adlayer on annealed pDA.
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Affiliation(s)
- Katerina G Malollari
- Department of Mechanical Engineering , University of California , Berkeley , California 94720 , United States
| | - Peyman Delparastan
- Department of Materials Science and Engineering , University of California , Berkeley , California 94720 , United States
| | - Caroline Sobek
- College of Chemistry , University of California , Berkeley , California 94720 , United States
| | | | - Tanner D Fink
- Department of Chemical & Biological Engineering , Rensselaer Polytechnic Institute , Troy , New York 12180 , United States
| | - R Helen Zha
- Department of Chemical & Biological Engineering , Rensselaer Polytechnic Institute , Troy , New York 12180 , United States
| | - Phillip B Messersmith
- Department of Materials Science and Engineering , University of California , Berkeley , California 94720 , United States
- Department of Bioengineering , University of California , Berkeley , California 94720 , United States
- Materials Sciences Division , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
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