1
|
Alharbi N, Guthold M. Mechanical properties of hydrated electrospun polycaprolactone (PCL) nanofibers. J Mech Behav Biomed Mater 2024; 155:106564. [PMID: 38749267 DOI: 10.1016/j.jmbbm.2024.106564] [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] [Received: 07/11/2023] [Revised: 04/18/2024] [Accepted: 04/26/2024] [Indexed: 05/28/2024]
Abstract
Polycaprolactone (PCL) nanofibers are a promising material for biomedical applications due to their biocompatibility, slow degradation rate, and thermal stability. We electrospun PCL fibers onto a striated substrate with 12 μm wide ridges and grooves and determined their mechanical properties in an aqueous solution with a combined atomic force/inverted optical microscopy technique. Fiber diameters, D, ranged from 27 to 280 nm. The hydrated PCL fibers had an extensibility (breaking strain), εmax, of 137%. The Young's modulus, E, and tensile strength, σT, showed a strong dependence on fiber diameter, D; decreasing steeply with increasing diameter, following empirical equations E(D)=(4.3∙103∙e-D51nm+1.1∙102) MPa and σT(D)=(2.6∙103∙e-D55nm+0.6∙102) MPa. Incremental stress-strain measurements were employed to investigate the viscoelastic behavior of these fibers. The fibers exhibited stress relaxation with a fast and slow relaxation time of 3.7 ± 1.2 s and 23 ± 8 s and these experiments also allowed the determination of the elastic and viscous moduli. Cyclic stress-strain curves were used to determine that the elastic limit of the fibers, εelastic, is between 19% and 36%. These curves were also used to determine that these fibers showed small energy losses (<20%) at small strains (ε < 10%), and over 50% energy loss at large strains (ε > 50%), asymptotically approaching 61%, as Eloss=61%·(1-e-0.04*ε). Our work is the first mechanical characterization of hydrated electrospun PCL nanofibers; all previous experiments were performed on dry PCL fibers, to which we will compare our data.
Collapse
Affiliation(s)
- Nouf Alharbi
- Department of Physics, Wake Forest University, Winston-Salem, NC, 27109, USA
| | - Martin Guthold
- Department of Physics, Wake Forest University, Winston-Salem, NC, 27109, USA; Center for Functional Materials, Wake Forest University, Winston-Salem, NC, 27109, USA.
| |
Collapse
|
2
|
Rajeev M, Helms CC. A Study of the Relationship between Polymer Solution Entanglement and Electrospun PCL Fiber Mechanics. Polymers (Basel) 2023; 15:4555. [PMID: 38231998 PMCID: PMC10707761 DOI: 10.3390/polym15234555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 11/21/2023] [Accepted: 11/23/2023] [Indexed: 01/19/2024] Open
Abstract
Electrospun fibers range in size from nanometers to micrometers and have a multitude of potential applications that depend upon their morphology and mechanics. In this paper, we investigate the effect of polymer solution entanglement on the mechanical properties of individual electrospun polycaprolactone (PCL) fibers. Multiple concentrations of PCL, a biocompatible polymer, were dissolved in a minimum toxicity solvent composed of acetic acid and formic acid. The number of entanglements per polymer (ne) in solution was calculated using the polymer volume fraction, and the resultant electrospun fiber morphology and mechanics were measured. Consistent electrospinning of smooth fibers was achieved for solutions with ne ranging from 3.8 to 4.9, and the corresponding concentration of 13 g/dL to 17 g/dL PCL. The initial modulus of the resultant fibers did not depend upon polymer entanglement. However, the examination of fiber mechanics at higher strains, performed via lateral force atomic force microscopy (AFM), revealed differences among the fibers formed at various concentrations. Average fiber extensibility increased by 35% as the polymer entanglement number increased from a 3.8 ne solution to a 4.9 ne solution. All PCL fibers displayed strain-hardening behavior. On average, the stress increased with strain to the second power. Therefore, the larger extensibilities at higher ne also led to a more than double increase in fiber strength. Our results support the role of polymer entanglement in the mechanical properties of electrospun fiber at large strains.
Collapse
|
3
|
Alharbi N, Brigham A, Guthold M. The Mechanical Properties of Blended Fibrinogen:Polycaprolactone (PCL) Nanofibers. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:1359. [PMID: 37110944 PMCID: PMC10145448 DOI: 10.3390/nano13081359] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 04/10/2023] [Accepted: 04/11/2023] [Indexed: 06/19/2023]
Abstract
Electrospinning is a process to produce versatile nanoscale fibers. In this process, synthetic and natural polymers can be combined to produce novel, blended materials with a range of physical, chemical, and biological properties. We electrospun biocompatible, blended fibrinogen:polycaprolactone (PCL) nanofibers with diameters ranging from 40 nm to 600 nm, at 25:75 and 75:25 blend ratios and determined their mechanical properties using a combined atomic force/optical microscopy technique. Fiber extensibility (breaking strain), elastic limit, and stress relaxation times depended on blend ratios but not fiber diameter. As the fibrinogen:PCL ratio increased from 25:75 to 75:25, extensibility decreased from 120% to 63% and elastic limit decreased from a range between 18% and 40% to a range between 12% and 27%. Stiffness-related properties, including the Young's modulus, rupture stress, and the total and relaxed, elastic moduli (Kelvin model), strongly depended on fiber diameter. For diameters less than 150 nm, these stiffness-related quantities varied approximately as D-2; above 300 nm the diameter dependence leveled off. 50 nm fibers were five-ten times stiffer than 300 nm fibers. These findings indicate that fiber diameter, in addition to fiber material, critically affects nanofiber properties. Drawing on previously published data, a summary of the mechanical properties for fibrinogen:PCL nanofibers with ratios of 100:0, 75:25, 50:50, 25:75 and 0:100 is provided.
Collapse
|
4
|
Jung SH, Jang BH, Kwon S, Park SJ, Park TE, Kang JH. Nematic Fibrin Fibers Enabling Vascularized Thrombus Implants Facilitate Scarless Cutaneous Wound Healing. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023:e2211149. [PMID: 37052392 DOI: 10.1002/adma.202211149] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 03/15/2023] [Indexed: 06/19/2023]
Abstract
Autologous implantable scaffolds that induce vasculogenesis have shown great potential in tissue regeneration; however, previous attempts mainly relied on cell-laden hydrogel patches using fat tissues or platelet-rich plasma, which are insufficient for generating a uniform vasculature in a scalable manner. Here, implantable vascularized engineered thrombi (IVETs) are presented using autologous whole blood, which potentiate effective skin wound healing by constructing robust microcapillary vessel networks at the wound site. Microfluidic shear stresses enable the alignment of bundled fibrin fibers along the direction of the blood flow streamlines and the activation of platelets, both of which offer moderate stiffness of the microenvironment optimal for facilitating endothelial cell maturation and vascularization. Rodent dorsal skin wounds patched with IVET present superior wound closure rates (96.08 ± 1.58%), epidermis thickness, collagen deposition, hair follicle numbers, and neutrophil infiltration, which are permitted by enhanced microvascular circulation. Moreover, IVET treatment accelerates wound healing by recruiting M2 phenotype macrophages.
Collapse
Affiliation(s)
- Su Hyun Jung
- Department of Biomedical Engineering, Ulsan National Institute of Science and Technology (UNIST), UNIST gil 50, Ulsan, 44919, Republic of Korea
| | - Bong Hwan Jang
- Department of Biomedical Engineering, Ulsan National Institute of Science and Technology (UNIST), UNIST gil 50, Ulsan, 44919, Republic of Korea
| | - Seyong Kwon
- Department of Biomedical Engineering, Ulsan National Institute of Science and Technology (UNIST), UNIST gil 50, Ulsan, 44919, Republic of Korea
| | - Sung Jin Park
- Department of Biomedical Engineering, Ulsan National Institute of Science and Technology (UNIST), UNIST gil 50, Ulsan, 44919, Republic of Korea
| | - Tae-Eun Park
- Department of Biomedical Engineering, Ulsan National Institute of Science and Technology (UNIST), UNIST gil 50, Ulsan, 44919, Republic of Korea
| | - Joo H Kang
- Department of Biomedical Engineering, Ulsan National Institute of Science and Technology (UNIST), UNIST gil 50, Ulsan, 44919, Republic of Korea
| |
Collapse
|
5
|
Vargas-Molinero HY, Serrano-Medina A, Palomino-Vizcaino K, López-Maldonado EA, Villarreal-Gómez LJ, Pérez-González GL, Cornejo-Bravo JM. Hybrid Systems of Nanofibers and Polymeric Nanoparticles for Biological Application and Delivery Systems. MICROMACHINES 2023; 14:208. [PMID: 36677269 PMCID: PMC9864385 DOI: 10.3390/mi14010208] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 01/09/2023] [Accepted: 01/10/2023] [Indexed: 06/17/2023]
Abstract
Nanomedicine is a new discipline resulting from the combination of nanotechnology and biomedicine. Nanomedicine has contributed to the development of new and improved treatments, diagnoses, and therapies. In this field, nanoparticles have notable importance due to their unique properties and characteristics, which are useful in different applications, including tissue engineering, biomarkers, and drug delivery systems. Electrospinning is a versatile technique used to produce fibrous mats. The high surface area of the electrospun mats makes them suitable for applications in fields using nanoparticles. Electrospun mats are used for tissue engineering, wound dressing, water-treatment filters, biosensors, nanocomposites, medical implants, protective clothing materials, cosmetics, and drug delivery systems. The combination of nanoparticles with nanofibers creates hybrid systems that acquire properties that differ from their components' characteristics. By utilizing nanoparticles and nanofibers composed of dissimilar polymers, the two synergize to improve the overall performance of electrospinning mats and nanoparticles. This review summarizes the hybrid systems of polymeric nanoparticles and polymeric nanofibers, critically analyzing how the combination improves the properties of the materials and contributes to the reduction of some disadvantages found in nanometric devices and systems.
Collapse
Affiliation(s)
| | - Aracely Serrano-Medina
- Facultad de Ciencias Químicas e Ingeniería, Universidad Autónoma de Baja California, Tijuana 22390, Mexico
- Facultad de Medicina y Psicología, Universidad Autónoma de Baja California, Tijuana 22390, Mexico
| | - Kenia Palomino-Vizcaino
- Facultad de Ciencias Químicas e Ingeniería, Universidad Autónoma de Baja California, Tijuana 22390, Mexico
| | | | - Luis Jesús Villarreal-Gómez
- Facultad de Ciencias Químicas e Ingeniería, Universidad Autónoma de Baja California, Tijuana 22390, Mexico
- Facultad de Ciencias de la Ingeniería y Tecnología, Universidad Autónoma de Baja California, Tijuana 22427, Mexico
| | | | - José Manuel Cornejo-Bravo
- Facultad de Ciencias Químicas e Ingeniería, Universidad Autónoma de Baja California, Tijuana 22390, Mexico
| |
Collapse
|
6
|
Liu J, Wu S, Ma J, Liu C, Dai T, Wu X, Zhao H, Zhou D. Polycaprolactone/Gelatin/Hydroxyapatite Electrospun Nanomembrane Materials Incorporated with Different Proportions of Attapulgite Synergistically Promote Bone Formation. Int J Nanomedicine 2022; 17:4087-4103. [PMID: 36105619 PMCID: PMC9467850 DOI: 10.2147/ijn.s372247] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Accepted: 08/31/2022] [Indexed: 12/28/2022] Open
Abstract
Purpose To enhance the osteoinductive effect of Hydroxyapatite (HA) in bone tissue engineering, this study manufactured polycaprolactone (PCL)/gelatin (GEL)/HA nanofibrous scaffolds incorporated with different ratios of attapulgite (ATP): HA (0:3, 0:0, 1:1, 2:1 and 3:0) by high-voltage electrospinning. The synergistic effect exerted by ATP and HA on bone formation was explored both in vivo and in vitro. Methods and Results First, we determined the group composition and crystal structure of the nanosheets by Fourier transform infrared (FTIR) and X-ray diffraction (XRD) analyses. Then, the physical properties of the scaffolds, including the modulus of elasticity, porosity and water absorption were evaluated. Moreover, the surface microstructure of the nanofibrous scaffolds was captured by Scanning electron microscopy (SEM) and Transmission Electron Microscope (TEM). The biocompatibility of the fabricated scaffolds represented by cell counting kit 8 (CCK-8) and phalloidin staining was also assessed. Next, in vitro osteogenesis was evaluated. Real-time PCR, alkaline phosphatase (ALP) staining and Alizarin red S (ARS) staining results showed that the materials incorporated with HA and ATP at a ratio of 2:1 synergistically promoted more osteoblastic differentiation and extracellular mineralization than scaffolds doped with HA and ATP alone. Last, in vivo, Hematoxylin-Eosin staining (HE staining) and Masson staining showed that groups treated with HA and ATP acquired optimal patterns of bone regeneration. Conclusion This study clarified for the first time that the combination of HA and ATP orchestrated biomaterial-induced osseointegration, and the synergistic effect was more significant when the ratio of ATP/HA was 2:1. This conclusion also provides new ideas and a scientific basis for the development of functionalized nanomaterials in bone tissue engineering.
Collapse
Affiliation(s)
- Jun Liu
- Medical Research Centre, The Affiliated Changzhou No.2 People's Hospital of Nanjing Medical University, Changzhou, 213164, People's Republic of China.,Dalian Medical University, Dalian, 116044, People's Republic of China
| | - Siyu Wu
- Medical Research Centre, The Affiliated Changzhou No.2 People's Hospital of Nanjing Medical University, Changzhou, 213164, People's Republic of China.,Dalian Medical University, Dalian, 116044, People's Republic of China
| | - Jiayi Ma
- Medical Research Centre, The Affiliated Changzhou No.2 People's Hospital of Nanjing Medical University, Changzhou, 213164, People's Republic of China.,Dalian Medical University, Dalian, 116044, People's Republic of China
| | - Chun Liu
- Medical Research Centre, The Affiliated Changzhou No.2 People's Hospital of Nanjing Medical University, Changzhou, 213164, People's Republic of China
| | - Ting Dai
- Medical Research Centre, The Affiliated Changzhou No.2 People's Hospital of Nanjing Medical University, Changzhou, 213164, People's Republic of China
| | - Xiaoyu Wu
- Medical Research Centre, The Affiliated Changzhou No.2 People's Hospital of Nanjing Medical University, Changzhou, 213164, People's Republic of China
| | - Hongbin Zhao
- Medical Research Centre, The Affiliated Changzhou No.2 People's Hospital of Nanjing Medical University, Changzhou, 213164, People's Republic of China
| | - Dong Zhou
- Medical Research Centre, The Affiliated Changzhou No.2 People's Hospital of Nanjing Medical University, Changzhou, 213164, People's Republic of China
| |
Collapse
|
7
|
Nie J, Jin C, Liu Y, Du J, Chen S, Zheng Y, Lou B. PBAT/gelatin hybrid nanofibers based on post-double network bond processing as a promising vascular substitute. RSC Adv 2022; 12:21957-21967. [PMID: 36043079 PMCID: PMC9361720 DOI: 10.1039/d2ra02313j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2022] [Accepted: 07/27/2022] [Indexed: 11/21/2022] Open
Abstract
The development of injured vascular tissue substitutes with proangiogenic, anti-thrombus, and anti-hyperplasia activity still remains a major challenge in vascular tissue engineering. In this study, we have prepared a series of poly(butylene adipate-co-terephthalate)/gelatin hybrid nanofibers (P/G) through random electrospinning and post-double network bond crosslinking for process optimization according to physiochemical and mechanical properties as well as promoting enhanced vascular cell viability in vitro. The gelatin matrix was shown to be successfully contained in the bicomponent hybrid P/G nanofibers, and the formed P/G nanofibers exhibited a uniform and smooth morphology. Importantly, the bicomponent hybrid nanofibers showed a potentially reliable ability to promote the proliferation of human umbilical vein endothelial cells (HUVECs). In addition, all the results demonstrated the significantly stable microstructure, appropriate surface wettability, matched mechanical properties, and excellent blood compatibility, cellular compatibility, and histocompatibility of hybrid nanofibers containing 15 wt% gelation (P/G-15) compared to PG-0, P/G-5, and PG-25 groups, indicating their potential for vascular injury healing. A PBAT/gelatin hybrid nanofibers vascular graft containing 15 wt% gelation (P/G-15) exhibited matched mechanical properties, especially they demonstrate excellent blood compatibility, cellular compatibility, and histocompatibility in rabbit carotid artery model.![]()
Collapse
Affiliation(s)
- Jiakun Nie
- Fuzhou Medical College, Nanchang University 9 Donglin Rd. Fuzhou 344000 Jiangxi P. R. China
| | - Changjie Jin
- School of Chemistry and Chemical Engineering, Shanghai Engineering Research Center of Pharmaceutical Intelligent Equipment, Shanghai Frontiers Science Research Center for Druggability of Cardiovascular Non-coding RNA, Institute for Frontier Medical Technology, Shanghai University of Engineering Science 333 Longteng Rd. Shanghai 201620 P. R. China
| | - Yonghang Liu
- School of Chemistry and Chemical Engineering, Shanghai Engineering Research Center of Pharmaceutical Intelligent Equipment, Shanghai Frontiers Science Research Center for Druggability of Cardiovascular Non-coding RNA, Institute for Frontier Medical Technology, Shanghai University of Engineering Science 333 Longteng Rd. Shanghai 201620 P. R. China
| | - Juan Du
- School of Chemistry and Chemical Engineering, Shanghai Engineering Research Center of Pharmaceutical Intelligent Equipment, Shanghai Frontiers Science Research Center for Druggability of Cardiovascular Non-coding RNA, Institute for Frontier Medical Technology, Shanghai University of Engineering Science 333 Longteng Rd. Shanghai 201620 P. R. China
| | - Sihao Chen
- School of Chemistry and Chemical Engineering, Shanghai Engineering Research Center of Pharmaceutical Intelligent Equipment, Shanghai Frontiers Science Research Center for Druggability of Cardiovascular Non-coding RNA, Institute for Frontier Medical Technology, Shanghai University of Engineering Science 333 Longteng Rd. Shanghai 201620 P. R. China
| | - Yujia Zheng
- Shanghai Institute of Measurement and Testing Technology 1500 Zhang Heng Rd. Shanghai 201203 P. R. China
| | - Binbin Lou
- School of Chemistry and Chemical Engineering, Shanghai Engineering Research Center of Pharmaceutical Intelligent Equipment, Shanghai Frontiers Science Research Center for Druggability of Cardiovascular Non-coding RNA, Institute for Frontier Medical Technology, Shanghai University of Engineering Science 333 Longteng Rd. Shanghai 201620 P. R. China .,Department of Stomatology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine 650 Xinsongjiang Rd., Songjiang District Shanghai 201600 P. R. China
| |
Collapse
|
8
|
Han W, Wang L, Li Q, Ma B, He C, Guo X, Nie J, Ma G. A Review: Current Status and Emerging Developments on Natural Polymer‐Based Electrospun Fibers. Macromol Rapid Commun 2022; 43:e2200456. [DOI: 10.1002/marc.202200456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2022] [Revised: 07/03/2022] [Indexed: 11/12/2022]
Affiliation(s)
- Weisen Han
- Beijing Laboratory of Biomedical Materials Beijing University of Chemical Technology Beijing 100029 P. R. China
| | - Liangyu Wang
- Beijing Laboratory of Biomedical Materials Beijing University of Chemical Technology Beijing 100029 P. R. China
| | - Qin Li
- Beijing Laboratory of Biomedical Materials Beijing University of Chemical Technology Beijing 100029 P. R. China
| | - Bomou Ma
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials Donghua University Shanghai 201620 P. R. China
| | - Chunju He
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials Donghua University Shanghai 201620 P. R. China
| | - Xuefeng Guo
- Changzhou Vocational Institute of Textile and Garment School of Textile 53 Gehu Middle Road Changzhou Jiangsu 213164 P.R. China
| | - Jun Nie
- Beijing Laboratory of Biomedical Materials Beijing University of Chemical Technology Beijing 100029 P. R. China
| | - Guiping Ma
- Beijing Laboratory of Biomedical Materials Beijing University of Chemical Technology Beijing 100029 P. R. China
| |
Collapse
|
9
|
Advances in Electrospun Hybrid Nanofibers for Biomedical Applications. NANOMATERIALS 2022; 12:nano12111829. [PMID: 35683685 PMCID: PMC9181850 DOI: 10.3390/nano12111829] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 05/18/2022] [Accepted: 05/24/2022] [Indexed: 02/04/2023]
Abstract
Electrospun hybrid nanofibers, based on functional agents immobilized in polymeric matrix, possess a unique combination of collective properties. These are beneficial for a wide range of applications, which include theranostics, filtration, catalysis, and tissue engineering, among others. The combination of functional agents in a nanofiber matrix offer accessibility to multifunctional nanocompartments with significantly improved mechanical, electrical, and chemical properties, along with better biocompatibility and biodegradability. This review summarizes recent work performed for the fabrication, characterization, and optimization of different hybrid nanofibers containing varieties of functional agents, such as laser ablated inorganic nanoparticles (NPs), which include, for instance, gold nanoparticles (Au NPs) and titanium nitride nanoparticles (TiNPs), perovskites, drugs, growth factors, and smart, inorganic polymers. Biocompatible and biodegradable polymers such as chitosan, cellulose, and polycaprolactone are very promising macromolecules as a nanofiber matrix for immobilizing such functional agents. The assimilation of such polymeric matrices with functional agents that possess wide varieties of characteristics require a modified approach towards electrospinning techniques such as coelectrospinning and template spinning. Additional focus within this review is devoted to the state of the art for the implementations of these approaches as viable options for the achievement of multifunctional hybrid nanofibers. Finally, recent advances and challenges, in particular, mass fabrication and prospects of hybrid nanofibers for tissue engineering and biomedical applications have been summarized.
Collapse
|
10
|
Maksudov F, Daraei A, Sesha A, Marx KA, Guthold M, Barsegov V. Strength, deformability and toughness of uncrosslinked fibrin fibers from theoretical reconstruction of stress-strain curves. Acta Biomater 2021; 136:327-342. [PMID: 34606991 PMCID: PMC8627496 DOI: 10.1016/j.actbio.2021.09.050] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 08/31/2021] [Accepted: 09/27/2021] [Indexed: 10/20/2022]
Abstract
Structural mechanisms underlying the mechanical properties of fibrin fibers are elusive. We combined tensile testing of uncrosslinked fibrin polymers in vitro and in silico to explore their material properties. The experimental stress (σ) - strain (ε) curves for fibrin fibers are characterized by elastic deformations with a weaker elastic response for ε<160% due to unraveling of αC tethers and straightening of fibrin protofibrils, and a stronger response for ε>160% owing to unfolding of the coiled coils and γ nodules in fibrin monomers. Fiber rupture for strains ε>212% is due to dissociation of the knob-hole bonds and rupture of D:D interfaces. We developed the Fluctuating Bilinear Spring model to interpret the σ-ε profiles in terms of the free energy for protofibril alignment ΔG0 = 10.1-11.5 kBT, Young's moduli for protofibril alignment Yu = 1.9-3.2 MPa and stretching Ya = 5.7-9.7 MPa, strain scale ε˜≈ 12-40% for fiber rupture, and protofibril cooperativity m= 3.6-8. We applied the model to characterize the fiber strength σcr≈ 12-13 MPa, deformability εcr≈ 222%, and rupture toughness U≈ 9 MJ/m3, and to resolve thermodynamic state functions, 96.9 GJ/mol entropy change for protofibril alignment (at room temperature) and 113.6 GJ/mol enthalpy change for protofibril stretching, which add up to 210.5 GJ/mol free-energy change. Fiber elongation is associated with protofibril dehydration and sliding mechanism to create an ordered protofibril array. Fibrin fibers behave like a hydrogel; protofibril dehydration and water expulsion account for ∼94-98% of the total free-energy changes for fiber elongation and rupture. STATEMENT OF SIGNIFICANCE: Structural mechanisms underlying the mechanical properties of fibrin fibers, major components of blood clots and obstructive thrombi, are elusive. We performed tensile testing of uncrosslinked fibrin polymers in vitro and in silico to explore their material properties. Fluctuating Bilinear Spring theory was developed to interpret the stress-strain profiles in terms of the energy for protofibril alignment, elastic moduli for protofibril alignment and stretching, and strain scale for fiber rupture, and to probe the limits of fiber strength, extensibility and toughness. Fibrin fibers behave like a hydrogel. Fiber elongation is defined by the protofibril dehydration and sliding. Structural rearrangements in water matrix control fiber elasticity. These results contribute to fundamental understanding of blood clot breakage that underlies thrombotic embolization.
Collapse
Affiliation(s)
- Farkhad Maksudov
- Department of Chemistry, University of Massachusetts, Lowell, MA 01854, United States
| | - Ali Daraei
- Department of Physics, Wake Forest University, Winston-Salem, NC 27109, United States
| | - Anuj Sesha
- Department of Chemistry, University of Massachusetts, Lowell, MA 01854, United States
| | - Kenneth A Marx
- Department of Chemistry, University of Massachusetts, Lowell, MA 01854, United States
| | - Martin Guthold
- Department of Physics, Wake Forest University, Winston-Salem, NC 27109, United States.
| | - Valeri Barsegov
- Department of Chemistry, University of Massachusetts, Lowell, MA 01854, United States.
| |
Collapse
|