Collagen Fiber Matrix Research Articles

Poster 367: Nano-Semiconductor Fibers in a Commercial Compression Sleeve Accelerates Healing of Achilles Tendon Injury in a Rat Model

Objectives: Commercial compression sleeves have been promoted to ameliorate pain secondary to arthritis and tendinopathy. The fabric of one particular sleeve is embedded with nano-semiconductor fibers that reflect thermal energy produced by the body at a photonic wavelength mimicking low-level laser therapy. The device is theorized to accelerate the inflammatory stage of tissue healing to reach the proliferation and remodeling stages at faster rates. Previous clinical studies have shown a significant improvement in patient-reported outcomes between patients who did and did not use this sleeve to treat osteoarthritis. The objective of this investigation was to determine if compression sleeves embedded with nano-semiconductor fibers can accelerate Achilles tendon healing in a rabbit model. Methods: Twelve New Zealand White rabbits—under IACUC approval—were administered intratendinous injections of 0.2% collagenase into the right Achilles tendon to simulate an acute tendon injury. Rabbits were divided into three groups: group I received the commercial compression sleeve without nano-semiconductors (n = 4), group II received the sleeve with nano-semiconductors (n = 4), and group III received an alternate sleeve design also with nano-semiconductors (n = 4). Calf circumference measurements and thermal radiation imaging of the right lower leg of each rabbit were collected days 7, 14, 21, and 28 post-injection. Two rabbits from each group were sacrificed at the 14-day and 28-day marks and the right Achilles tendons were harvested. Histological analysis using picrosirius red staining was performed to evaluate tissue organization. A custom MATLAB program (MathWorks, Natick, MA) was used to quantify the collagen fiber dispersion within the Achilles tendon samples. Results: A statistically significant difference in calf circumference was found at the 28-day mark between group I versus groups II and III: group I had an average calf circumference of 5.2 cm while groups II and III had an average calf circumference of 4.85 cm (p = 0.036) and 4.60 cm (p = 0.021) respectively. Additionally, after 28 days, group I demonstrated an average pixel density intensity on thermal radiation imaging of 1,531,192 while groups II and III yielded average pixel density intensities of 1,363,515 (p = 0.008) and 1,335,456 (p = 0.003) respectively. Histological staining showed observable alterations in collagen architecture, with group I displaying widespread disorganization and degradation of type I and type III collagen fibers near the injection site. Groups II and III displayed greater organization at the 28-day mark in comparison to group I, with signs of tissue proliferation and remodeling evident. No statistically significant differences were found between group I versus groups II and III regarding collagen fiber dispersion at both the 2-week mark (p = 0.145, p = 0.236) and the 4-week mark (p = 0.113, p = 0.268), respectively. Conclusions: The nano-semiconductor fibers embedded within a commercial sleeve significantly decreased swelling and temperature of the lower leg 28 days following acute Achilles tendon injury in a rabbit model. Furthermore, histologic analysis demonstrated greater collagen fiber and extracellular matrix organization as well as greater proliferation of type III collagen suggesting a faster transition to the proliferation stage of tissue healing.

Characterization of lamina propria remodeling in pediatric eosinophilic esophagitis using second harmonic generation microscopy

Eosinophilic esophagitis (EoE) is a chronic inflammatory condition characterized by an intense infiltration of eosinophils into the esophageal epithelium. When not adequately controlled, eosinophilic inflammation can lead to changes in components of the extracellular matrix (ECM) of the lamina propria. Particularly, alterations to the collagen fiber matrix can lead to lamina propria fibrosis (LPF), which plays an important role in the fibrostenotic complications of EoE. Current approaches to assess LPF in EoE are prone to inter-observer inconsistencies and provide limited insight into the structural remodeling of the ECM. An objective approach to quantify LPF can eliminate inter-observer inconsistencies and provide novel insights into the fibrotic transformation of the lamina propria in EoE. Second harmonic generation (SHG) microscopy is a powerful modality for objectively quantifying disease associated alterations in ECM collagen structure that is finding increasing use for clinical research. We used SHG with morphometric analysis (SHG-MA) to characterize lamina propria collagen fibers and ECM porosity in esophageal biopsies collected from children with active EoE (n = 11), inactive EoE (n = 11), and non-EoE (n = 11). The collagen fiber width quantified by SHG-MA correlated positively with peak eosinophil count (r = 0.65, p < 0.005) and histopathologist scoring of LPF (r = 0.52, p < 0.005) in the esophageal biopsies. Patients with active EoE had a significant enlargement of ECM pores compared to inactive EoE and non-EoE (p < 0.005), with the mean pore area correlating positively with EoE activity (r = 0.76, p < 0.005) and LPF severity (r = 0.65, p < 0.005). These results indicate that SHG-MA can be utilized to objectively characterize and provide novel insights into lamina propria ECM structural remodeling in children with EoE, which could aid in monitoring disease progression.

Can the Sterilization Protocol Be Improved to Enhance the Healing of Allograft Tendons? An In Vivo Study in Rabbit Tendons.

Peracetic acid and irradiation are common sterilization methods for allograft tendons; however, under some conditions, both methods adversely affect the fiber arrangement and ultimate load of the tendon. An in vitro study showed that low-dose peracetic acid combined with irradiation may be less detrimental to allograft tendon structure and properties, possibly because the breakdown of peracetic acid can lead to an enlargement of the interstitial spaces and an increase in porosity. Using a rabbit Achilles tendon model, we asked: What is the effect of peracetic acid-ethanol combined irradiation on (1) the histopathology and fiber diameter of the allograft tendon, (2) tensile creep and load-to-failure biomechanical properties of allograft tendons, and (3) healing of the treated tendon in vivo compared with fresh-frozen allograft and peracetic acid-ethanol sterilization at 4 and 8 weeks? The Achilles tendons used in this study were sourced from euthanized 10-week-old male New Zealand White rabbits previously used for ophthalmic experiments. All allografts were divided into three groups: fresh-frozen group (control group, n = 20), peracetic acid-ethanol sterilization group (n =20), and peracetic acid-ethanol combined irradiation group (n = 20). The sterilization protocols were performed per a predetermined plan. In the peracetic acid-ethanol sterilization group, the tendon tissues were covered with the peracetic acid-ethanol sterilization solution (1% peracetic acid for 30 minutes). In the peracetic acid-ethanol combined irradiation group, the tendon tissues were covered with the peracetic acid-ethanol sterilization solution (0.2% peracetic acid for 30 minutes) and were subjected to 15 kGy gamma irradiation. Thirty 10-week-old male New Zealand White rabbits received bilateral Achilles tendon allografts surgically. Tendon samples from each group were harvested at 4 weeks (n = 30) and 8 weeks (n = 30) postoperatively. For each timepoint, eight tissues were used for histologic staining and electron microscopy, 15 tissues were used for biomechanical testing, and seven tissues were used for hydroxyproline assay and quantitative polymerase chain reaction. Histopathology was determined qualitatively by hematoxylin and eosin and Masson staining, while fiber diameter was measured quantitatively by transmission electron microscopy. Biomechanical properties were measured using cyclic loading tests and load-to-failure tests. The healing outcome was quantitatively judged through healing-related genes and proteins. At 4 weeks and 8 weeks postoperatively, the peracetic acid-ethanol combined irradiation group visually demonstrated the best continuity and minimal peripheral adhesions. Histologic staining showed that tendon fibers in the peracetic acid-ethanol combined irradiation group maintained consistent alignment without notable disruptions or discontinuities, and there was a qualitatively observed increase in the number of infiltrating cells compared with the control group at the 4-week timepoint (444 ± 49 /mm 2 versus 256 ± 43 /mm 2 , mean difference 188 /mm 2 [95% confidence interval 96 to 281]; p < 0.001). At 8 weeks postoperatively, the tendon fiber diameter in the peracetic acid-ethanol combined irradiation groups was similar to that of the control group (0.23 ± 0.04 µm versus 0.21 ± 0.03 µm, mean difference 0.02 µm [95% CI -0.04 to 0.08]; p = 0.56). At 8 weeks postoperatively, the peracetic acid-ethanol combined irradiation group exhibited better properties in terms of both ultimate load (129 ± 15 N versus 89 ± 20 N, mean difference 40 N [95% CI 7 to 73]; p = 0.02) and energy absorption density (17 ± 6 kJ/m 2 versus 8 ± 4 kJ/m 2 , mean difference 8 kJ/m 2 [95% CI 0.7 to 16]; p = 0.004) compared with the control group. Gene expression analysis revealed higher expression levels of COL1A1 (2.1 ± 0.8 versus 1.0 ± 0, mean difference 1.1 [95% CI 0.1 to 2.1]; p = 0.003) and MMP13 (2.0 ± 0.8 versus 1.0 ± 0, mean difference 1.0 [95% CI 0.4 to 1.6]; p = 0.03) in the peracetic acid-ethanol combined irradiation group than in the control group. There was a higher amount of collagen Type I in tendons treated with peracetic acid-ethanol combined irradiation than in the control group (0.36 ± 0.03 versus 0.31 ± 0.04, mean difference 0.05 [95% CI 0.01 to 0.09]; p = 0.02). Treatment with peracetic acid-ethanol combined irradiation did not have any discernible adverse effect on the histology, fiber diameter, enzymatic resistance, collagen content, or biomechanical strength of the allograft tendons compared with the control group. Peracetic acid-ethanol combined irradiation treatment had a positive impact on remodeling of the extracellular matrix and realignment of collagen fibers. This sterilization method could be helpful to expand the scope and frequency with which allogeneic materials are applied. The long-term healing effect and strength of allograft tendons must be tested before clinical use, and it is necessary to conduct comparative studies on autografts and synthetic materials that are currently widely used clinically.

Celastrol as a candidate drug for silicosis: From bioinformatics and network pharmacology to experimental validation

Silicosis, a highly lethal occupational respiratory disease characterized by irreversible pulmonary fibrosis, remains challenging to treat due to its unclear pathogenesis. In this study, bioinformatics, network pharmacology, and experimental validation were combined to explore potential mechanisms and therapeutic drugs for silicosis. First, the differentially expressed genes（DEGs）and pathway enrichment in pulmonary fibrosis were identified by GO and KEGG analysis. Next, the differential genes were submitted to cMap database for drug prediction and celastrol stood out as the most promising candidate drug. Then, network pharmacology analysis identified pharmacological targets of celastrol and demonstrated that celastrol could regulate JAK-STAT, MAPK, and Toll-like receptor signaling pathways. Finally, we verified the therapeutic role and mechanism of celastrol on silicosis. In vivo, celastrol significantly ameliorated CS-induced inflammation and fibrosis in silicosis mice, including inflammatory cell infiltration, collagen fiber and extracellular matrix deposition, fibroblast activation and related factor expression. Moreover, it dramatically improved lung respiratory function of silicosis mice. In vitro, celastrol suppressed CS-induced cytokine expression, apoptosis of macrophages and activation of Stat3 and Erk1/2 signals. Overall, our research identified and verified celastrol as a novel and promising candidate drug for silicosis.

Covalently surface-grafting α‑zirconium phosphate nanoplatelets enables collagen fiber matrix with ultraviolet barrier, antibacterial, and flame-retardant properties

Manipulating the dispersibility and reactivity of two-dimensional nanomaterials in collagen fibers (CFs) matrix has aroused attention in the fabrication of multifunctional collagen-based nanocomposites. Here, α‑zirconium phosphate nanoplatelets (ZrP NPs) were surface-functionalized with gallic acid (GA) to afford ZrP–GA NPs for engineering CFs matrix. The influence of ZrP–GA NPs on the ultraviolet barrier, antibacterial, and flame-retardant properties of resultant CFs matrix were investigated. Microstructural analysis revealed that ZrP–GA NPs were dispersed and bound within the collagen fibrils and onto the collagen strands in the CFs matrix. The resultant CFs matrix also maintained typical D-periodic structures of collagen fibrils and native branching and interwoven structures of CFs networks with increased porosity and enhanced ultraviolet barrier properties. Inhibition zone testing presented excellent antibacterial activities of the CFs matrix owing to surface grafting of antibacterial GA. Thanks to enhanced dispersion and binding of ZrP NPs with the CFs matrix by surface-functionalization with GA, the resultant CFs matrix reduced the peak heat release rate and the total heat release by 42.9 % and 39.0 %, respectively, highlighting improved flame-retardant properties. We envision that two-dimensional nanomaterials possess great potential in developing reasonable collagen-based nanocomposites towards the manufacture of emergent multifunctional collagen fibers-based wearable electronics.

Assessing the roles of collagen fiber morphology and matrix stiffness on ovarian cancer cell migration dynamics using multiphoton fabricated orthogonal image-based models

Ovarian cancer remains the deadliest of the gynecological cancers, where this arises from poor screening and imaging tools that can detect early disease, and also limited understanding of the structural and functional aspects of the tumor microenvironment. To gain insight into the underlying cellular dynamics, we have used multiphoton excited fabrication to create Second Harmonic Generation (SHG) image-based orthogonal models from collagen/GelMA that represent both the collagen matrix morphology and stiffness (∼2–8 kPa) of normal ovarian stroma and high grade serous ovarian cancers (HGSOC). These scaffolds are used to study migration/cytoskeletal dynamics of normal (IOSE) and ovarian cancer (OVCA433) cell lines. We found that the highly aligned fiber morphology of HGSOC promotes aspects of motility (motility coefficient, motility, and focal adhesion expression) through a contact guidance mechanism and that stiffer matrix further promotes these same processes through a mechanosensitive mechanism, where these trends were similar for both normal and cancer cells. However, cell specific differences were found on these orthogonal models relative to those providing only morphology, showing the importance of presenting both morphology and stiffness cues. Moreover, we found increased cadherin expression and decreased cell alignment only for cancer cells on scaffolds of intermediate modulus suggesting different stiffness-dependent mechanotransduction mechanisms are engaged. This overall approach affords decoupling the roles of matrix morphology, stiffness and cell genotype and affords hypothesis testing of the factors giving rise to disease progression and metastasis. Further, more established fabrication techniques cannot simultaneously reproduce both the 3D collagen fiber morphology and stiffness. Statement of significanceOvarian cancer metastasizes when lesions are small, where cells exfoliate from the surface of the ovary and reattach at distal sites in the peritoneum. The adhesion/migration dynamics are not well understood and there is a need for new 3D in vitro models of the extracellular matrix to study the biology. Here we use multiphoton excited crosslinking to fabricate ECM orthogonal models that represent the collagen morphology and stiffness in human ovarian tissues. These are then used to study ovarian cancer cell migration dynamics and we found that contact guidance and a mechanosensitive response and cell genotype all combine to affect the behavior. These models provide insight into disease etiology and progression not readily possible by other fabrication methods.

Superhydrophobic tough hierarchical porous thermal insulation composites prepared by in situ formation of silica aerogel in collagen fiber matrix

AbstractThe serious problem of energy consumption and the requirement for sustainable development has attracted people's extensive attention. The application of high‐efficiency thermal insulation materials can reduce consumption and waste in the process of energy transfer, and is the most effective way to save energy and protect the environment. Among many thermal insulation materials, silica aerogel, especially biomass fiber‐reinforced silica aerogel with good mechanical strength, shows great practical application potential. In this article, the collagen fiber‐silica aerogel composite (MCFF@SiO2) was successfully prepared by in situ sol–gel method and freeze‐drying method, innovatively using skin collagen fiber matrix with natural porous skeleton as reinforcing template. MCFF@SiO2 has good thermal stability, and has a hierarchical porous structure formed by filling nanoscale mesopores of silica aerogel in the macropores of collagen fiber matrix, thus delaying the spread of heat. Particularly, MCFF@SiO2 exhibits good thermal insulation performance, and its thermal conductivity is 0.068 W/(m K), which is lower than that of MCFF. In addition, MCFF@SiO2 shows superhydrophobicity, good mechanical properties, excellent flame retardancy, and self‐extinguishing performance. The prepared composite aerogels have potential application value in the field of thermal management, and this work is expected to provide inspiration for the preparation of biomass‐based porous functional materials.

Investigation of wear characteristics of collagen fiber reinforced polymer matrix composites used for orthopaedic implants

Composites have been found to be the most promising and discerning material available in everywhere in the world. The important requirement of biomaterial to be used as orthopaedic implant is their resistance to wear against the interacting part. In the present investigation, polymer matrix composites are produced from collagen fiber and epoxy matrix with varying volume fraction of fibers namely 10%, 20%, 30% and 40%. Test specimens prepared from the produced composite and subjected to pin on disc wear test to determine the wear rate for the collagen fiber reinforced polymer matrix composites to find the material’s use as a bio-implant. The wear test was performed using a normal load of 5 to 20 N, a manually selected track diameter, and a fixture that can take discs up to 165 mm in diameter and 8 mm thick. Here, their usage in orthopaedics as an implantable material in bone surgery was considered and studied. Bone fixation plates, hip joint replacement, bone cement, and bone transplant are just a few of the applications for these composite materials in orthopaedics.

A reusable, biomass-derived, and pH-responsive collagen fiber based oil absorbent material for effective separation of oil-in-water emulsions

Absorbent material plays an increasingly important role in oil-water separation due to its high-efficiency, cost-effective and environment-friendly. Herein, amino-functionalized biomass-derived collagen fiber matrix (defined as A-CFM) with dodecyl hydrocarbon chains was prepared as oil-water separation adsorbent material by in-situ graft copolymerization of 2-(dimethylamino)ethyl methacrylate (DMAEMA) and glycidyl methacrylate (GMA). The A-CFM possesses favorable porosity, appropriate pore size and excellent hydrophobicity, which exhibits high separation efficiency (~99.90%) for whether surfactant-free emulsions or surfactant stabilized emulsions, even after three cycles. In addition, the tunable wettability of A-CFM can be achieved by altering the pH value, which not only imparts outstanding recycling performance, but also improves the antifouling performance to A-CFM absorbent material. Furthermore, the analysis of oil-water separation mechanism indicates that hydrophobicity and capillary force, especially electrostatic interaction (electrostatic attraction/repulsion), play a key role in separating emulsions stabilized by ionic surfactant. Our findings expend the knowledge of oil-in-water emulsion separation, as well as pave a new way for developing high-performance adsorbent materials with good application prospects in oil-water emulsion separation.

Biomimetic Mechanically Strong One-Dimensional Hydroxyapatite/Poly(d,l-lactide) Composite Inducing Formation of Anisotropic Collagen Matrix.

Natural bone is a complex composite, consisting predominantly of collagen and hydroxyapatite (HA), which form a highly organized, hierarchical structure from the nano- to the macroscale. Because of its biphasic, anisotropic, ultrafine structural design, bone tissue possesses excellent mechanical properties. Herein, inspired by the composition and microstructure of natural bone, a biphasic composite consisting of highly aligned strontium/copper-doped one-dimensional hydroxyapatite (Sr/Cu-doped 1D HA) and poly(d,l-lactide) (PDLA) was developed. The presence and alignment of Sr/Cu-doped 1D HA crystals resulted in mechanical reinforcement of the polymer matrix, including compressive and tensile strength and modulus, fracture toughness, swelling resistance, and long-term structural stability. The compressive strength, tensile strength, and Young’s modulus of the biomimetic composite were comparable to that of cortical bone. Biologically, the biomimetic composite showed a sustained release of the incorporated Sr and Cu ions, facilitated mineral deposition from simulated body fluid, and supported attachment, proliferation, and alkaline phosphatase activity of human mesenchymal stromal cells (hMSCs). Moreover, the highly aligned Sr/Cu-doped 1D HA crystals in the 3D porous scaffolds induced the alignment of hMSCs and secretion of an anisotropic collagen fiber matrix in 3D. The biomimetic Sr/Cu-doped 1D HA/PDLA composite presented here contributes to the current efforts aiming at the design and development of load-bearing bioactive synthetic bone graft substitutes. Moreover, the biomimetic composite may serve as a 3D platform for studying cell–extracellular matrix interactions in bone tissue.

Precise Tuning of Polymeric Fiber Dimensions to Enhance the Mechanical Properties of Alginate Hydrogel Matrices.

Hydrogels based on biopolymers, such as alginate, are commonly used as scaffolds in tissue engineering applications as they mimic the features of the native extracellular matrix (ECM). However, in their native state, they suffer from drawbacks including poor mechanical performance and a lack of biological functionalities. Herein, we have exploited a crystallization-driven self-assembly (CDSA) methodology to prepare well-defined one-dimensional micellar structures with controlled lengths to act as a mimic of fibrillar collagen in native ECM and improve the mechanical strength of alginate-based hydrogels. Poly(ε-caprolactone)-b-poly(methyl methacrylate)-b-poly(N, N-dimethyl acrylamide) triblock copolymers were self-assembled into 1D cylindrical micelles with precise lengths using CDSA epitaxial growth and subsequently combined with calcium alginate hydrogel networks to obtain nanocomposites. Rheological characterization determined that the inclusion of the cylindrical structures within the hydrogel network increased the strength of the hydrogel under shear. Furthermore, the strain at flow point of the alginate-based hydrogel was found to increase with nanoparticle content, reaching an improvement of 37% when loaded with 500 nm cylindrical micelles. Overall, this study has demonstrated that one-dimensional cylindrical nanoparticles with controlled lengths formed through CDSA are promising fibrillar collagen mimics to build ECM scaffold models, allowing exploration of the relationship between collagen fiber size and matrix mechanical properties.

The treatment response of barrier membrane with amoxicillin-loaded nanofibers in experimental periodontitis.

Infection control is a major determinant of guided tissue regeneration (GTR). This study aims to develop an antibiotic-loaded membrane to assist periodontal repair. Poly(D,L-lactic acid) (PDLLA) nanofibers encapsulating amoxicillin (PDLLA-AMX) were fabricated using the electrospinning technique, and their structures, drug encapsulation efficiency, and release characteristics were assessed. The viability and behaviors of periodontal ligament (PDL) cells on nanofibers, and antibacterial capabilities of nanofibers were evaluated in vitro. Early therapeutic efficiency of the antibiotic-loaded membranes was investigated in rats with ligature-induced experimental periodontitis, and the outcomes were evaluated by gene expression, microcomputed tomography imaging, and histology within 7 days of membrane placement. AMX was successfully encapsulated in the PDLLA nanofibers and released in a sustained manner. After initial attachment was achieved, cells stretched out along with the directions of nanofibers. The viability and expression of migration-associated gene of PDL cells were significantly improved, and the growth of Streptococcus sanguinis and Porphyromonas gingivalis was significantly reduced in the PDLLA-AMX group compared with the controls. On PDLLA-AMX-treated sites, wound dehiscence and sulcular inflammation were reduced. Collagen fiber matrix deposition was accelerated with upregulated type I collagen and interleukin-1β, and downregulated matrix metalloproteinase-8, whereas periodontal bone level and the expressions of vascular endothelial growth factor and core-binding factor subunit alpha-1 were equivalent to conventional membrane treatment. PDLLA-AMX nanofibers inhibited bacterial growth and promoted the viability and mobility of PDL cells after initial cell attachment. Membranes with PDLLA-AMX nanofibers reduced inflammation and accelerated periodontal repair at an early stage, providing good prospects for the further development of GTR membranes.

More Bone with Less Minerals? The Effects of Dietary Phosphorus on the Post-Cranial Skeleton in Zebrafish.

Dietary phosphorus (P) is essential for bone mineralisation in vertebrates. P deficiency can cause growth retardation, osteomalacia and bone deformities, both in teleosts and in mammals. Conversely, excess P supply can trigger soft tissue calcification and bone hypermineralisation. This study uses a wide range of complementary techniques (X-rays, histology, TEM, synchrotron X-ray tomographic microscopy, nanoindentation) to describe in detail the effects of dietary P on the zebrafish skeleton, after two months of administering three different diets: 0.5% (low P, LP), 1.0% (regular P, RP), and 1.5% (high P, HP) total P content. LP zebrafish display growth retardation and hypomineralised bones, albeit without deformities. LP zebrafish increase production of non-mineralised bone matrix, and osteoblasts have enlarged endoplasmic reticulum cisternae, indicative for increased collagen synthesis. The HP diet promotes growth, high mineralisation, and stiffness but causes vertebral centra fusions. Structure and arrangement of bone matrix collagen fibres are not influenced by dietary P in all three groups. In conclusion, low dietary P content stimulates the formation of non-mineralised bone without inducing malformations. This indicates that bone formation and mineralisation are uncoupled. In contrast, high dietary P content promotes mineralisation and vertebral body fusions. This new zebrafish model is a useful tool to understand the mechanisms underlying osteomalacia and abnormal mineralisation, due to underlying variations in dietary P levels.

Conversion of skin collagen fibrous material waste to an oil sorbent with pH-responsive switchable wettability for high-efficiency separation of oil/water emulsions

Collagen fibrous material waste is an undervalued sustainable resource with many potential applications. Herein, a three-dimensional collagen fiber matrix (CFM), derived from skin collagen fiber waste generated in the leather industry, was modified by pH-responsive copolymer P(MAA-co-GMA) terminated with dodecyl hydrocarbon chains via an in situ free radical polymerization. The functionalized CFM possesses an appropriate porous structure, and shows switchable hydrophobicity/hydrophilicity for different pH values. It displayed high separation efficiency (∼99.93 ± 0.03%) for separating surfactant-free oil-in-water emulsion (10 cycles) as well as surfactant-stabilized oil-in-water emulsion (3 cycles). More importantly, the functionalized CFM displayed excellent self-cleaning performance. In other words, the absorbed oil was released after treatment in basic aqueous medium. The attractive properties of the functionalized smart collagen fiber matrix make it an excellent prospect for potential application in oily emulsion treatment from the reusable resource and environmentally friendly perspectives.

Extracellular matrix collagen fiber structures of the gastrointestinal connective tissues in mice after a 30 day orbital flight

Using histochemical methods the condition of collagen fibers of a specific tissue microenvironment of the membranes of stomach and intestines of C57BL/6N mice (58 males with an initial body weight of 27.1±0.7 g) after a 30-day space flight and the following 7-day land readaptation was studied as well as in the animals representing corresponding control groups. Laboratory animal presence on the biosatellite «BION-M» No. 1 has led to the fibrous reduction of extracellular matrix of connective tissue in the studied organs of digestive system structure except for the proper lamina of the gastric mucous membrane. Fibrillogenesis increase in the gastrointestinal tract in comparison with the indicators of space flight animal group has been found after 7 days of the biosatellite landing. The collagen fibers were not characterized by the significance change from the vivarium control group during the experiment with the land modelling of orbital flight conditions. The obtained results represent the evidence of fibrous structure gravity sensitivity of extracellular matrix of the connective tissue and show the relevance in the sphere of preventive measure improvement of the digestive system organs in the profession of astronauts in the orbital flight conditions.

Using carboxylated cellulose nanofibers to enhance mechanical and barrier properties of collagen fiber film by electrostatic interaction.

Collagen-based films including casings with a promising application in meat industry are still needed to improve its inferior performance. In the present study, the reinforcement of carboxylated cellulose nanofibers (CNF) for collagen film, based on inter-/intra- molecular electrostatic interaction between cationic acid-swollen collagen fiber and anionic carboxylated CNF, was investigated. Adding CNF decreased the zeta-potential but increased particle size of collagen fiber suspension, with little effect on pH. Furthermore, CNF addition led to a higher tensile strength but a lower elongation, and the water vapor and oxygen barrier properties were improved remarkably. Because the CNF content was 50 g kg-1 or lower, the films had a homogeneous interwoven network, and CNF homogeneously embedded into collagen fiber matrix according to the scanning electron microscopy and atomic force microscopy analysis. Additionally, CNF addition increased film thickness and opacity, as well as swelling rate. The incorporation of CNF endows collagen fiber films good mechanical and barrier properties over a proper concentration range (≤ 50 g kg-1 collagen fiber), which is closely associated with electrostatic reaction of collagen fiber and CNF and, subsequently, the form of the homogenous, compatible spatial network, indicating a potential applications of CNF in collagenous protein films, such as edible casings. © 2017 Society of Chemical Industry.

Biodegradable porous organosilicone‐modified collagen fiber matrix: Synthesis and high oil absorbency

ABSTRACTWe used hexadecyl trimethyl ammonium bromide as a phase transfer catalyst (PTC) to enhance the effectiveness of a heterogeneous reaction system composed of collagen fiber (CF) and organosilicone modifying agents including epoxy‐polydimethylsiloxane (ES) and/or γ‐glycidoxypropylthrimethoxysilane (GS), in order to improve oil sorption behaviors of the modified products as sorbents. The effects of PTC dosage, organosilicone species or its dosage on the degree of modification of CFs were studied, and the optimum conditions were determined. Subsequently, the surface chemistry and porous structure of the prepared sorbents were thoroughly characterized, and their oil sorption behaviors were also investigated. It was confirmed that both their hydrophobicity‐oleophilicity character and pore structures could be significantly improved by introducing PTC agent and modulating the species or amount of organosilicone, resulting in improved oil sorption behaviors. In addition, the organosilicone modified CF matrix possessed acceptable reusability and biodegradability, and can be implemented as an eco‐friendly sorbent for oil spill cleanup. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46264.

Novel image analysis methods for quantification of in situ 3-D tendon cell and matrix strain

Macroscopic tendon loads modulate the cellular microenvironment leading to biological outcomes such as degeneration or repair. Previous studies have shown that damage accumulation and the phases of tendon healing are marked by significant changes in the extracellular matrix, but it remains unknown how mechanical forces of the extracellular matrix are translated to mechanotransduction pathways that ultimately drive the biological response. Our overarching hypothesis is that the unique relationship between extracellular matrix strain and cell deformation will dictate biological outcomes, prompting the need for quantitative methods to characterize the local strain environment. While 2-D methods have successfully calculated matrix strain and cell deformation, 3-D methods are necessary to capture the increased complexity that can arise due to high levels of anisotropy and out-of-plane motion, particularly in the disorganized, highly cellular, injured state. In this study, we validated the use of digital volume correlation methods to quantify 3-D matrix strain using images of naïve tendon cells, the collagen fiber matrix, and injured tendon cells. Additionally, naïve tendon cell images were used to develop novel methods for 3-D cell deformation and 3-D cell-matrix strain, which is defined as a quantitative measure of the relationship between matrix strain and cell deformation. The results support that these methods can be used to detect strains with high accuracy and can be further extended to an in vivo setting for observing temporal changes in cell and matrix mechanics during degeneration and healing.

Label-free imaging of brain and brain tumor specimens with combined two-photon excited fluorescence and second harmonic generation microscopy

Label-free imaging techniques are gaining acceptance within the medical imaging field, including brain imaging, because they have the potential to be applied to intraoperative in situ identifications of pathological conditions. In this paper, we describe the use of two-photon excited fluorescence (TPEF) and second harmonic generation (SHG) microscopy in combination for the label-free detection of brain and brain tumor specimens; gliomas. Two independently detecting channels were chosen to subsequently collect TPEF/SHG signals from the specimen to increase TPEF/SHG image contrasts. Our results indicate that the combined TPEF/SHG microscopic techniques can provide similar rat brain structural information and produce a similar resolution like conventional H&E staining in neuropathology; including meninges, cerebral cortex, white-matter structure corpus callosum, choroid plexus, hippocampus, striatum, and cerebellar cortex. It can simultaneously detect infiltrating human brain tumor cells, the extracellular matrix collagen fiber of connective stroma within brain vessels and collagen depostion in tumor microenvironments. The nuclear-to-cytoplasmic ratio and collagen content can be extracted as quantitative indicators for differentiating brain gliomas from healthy brain tissues. With the development of two-photon fiberscopes and microendoscope probes and their clinical applications, the combined TPEF and SHG microcopy may become an important multimodal, nonlinear optical imaging approach for real-time intraoperative histological diagnostics of residual brain tumors. These occur in various brain regions during ongoing surgeries through the method of simultaneously identifying tumor cells, and the change of tumor microenvironments, without the need for the removal biopsies and without the need for tissue labelling or fluorescent markers.

Thyroxine Exposure Effects on the Cranial Base.

Thyroid hormone is important for skull bone growth, which primarily occurs at the cranial sutures and synchondroses. Thyroid hormones regulate metabolism and act in all stages of cartilage and bone development and maintenance by interacting with growth hormone and regulating insulin-like growth factor. Aberrant thyroid hormone levels and exposure during development are exogenous factors that may exacerbate susceptibility to craniofacial abnormalities potentially through changes in growth at the synchondroses of the cranial base. To elucidate the direct effect of in utero therapeutic thyroxine exposure on the synchondroses in developing mice, we provided scaled doses of the thyroid replacement drug, levothyroxine, in drinking water to pregnant C57BL6 wild-type dams. The skulls of resulting pups were subjected to micro-computed tomography analysis revealing less bone volume relative to tissue volume in the synchondroses of mouse pups exposed in utero to levothyroxine. Histological assessment of the cranial base area indicated more active synchondroses as measured by metabolic factors including Igf1. The cranial base of the pups exposed to high levels of levothyroxine also contained more collagen fiber matrix and an increase in markers of bone formation. Such changes due to exposure to exogenous thyroid hormone may drive overall morphological changes. Thus, excess thyroid hormone exposure to the fetus during pregnancy may lead to altered craniofacial growth and increased risk of anomalies in offspring.