Origin of critical nature and stability enhancement in collagen matrix based biomaterials: Comprehensive modification technologies

Engineered protein-based materials for tissue repair: A review

The human body may suffer multiple injuries and losses due to various external factors, such as tumors, diseases, traffic accidents, and war conflicts. Under such circumstances, engineered protein-based materials, as an innovative adjunctive material, can not only effectively promote the natural repair process of tissues, but also greatly circumvent the negative effects and complications that may be associated with conventional surgery. In this review, we first trace the definition and development of engineered protein-based materials and explain in detail their mechanism of action in promoting tissue repair. Subsequently, the advantages and disadvantages of various engineered protein-based materials in tissue repair are analyzed by comparison. In addition, the present review reveals in depth how material properties can be optimized by scientific means to meet different tissue repair needs. In addition, we present in detail specific application cases of engineered protein-based materials in the field of tissue repair. Finally, we summarize current challenges in engineered protein-based materials and provide an outlook for the future. This review not only provides theoretical support for the further exploration and development of engineered protein-based materials in the field of tissue repair, but also provides valuable references and inspiration for research in related fields.

Unraveling the role of integrating signal peptides into natural collagen on modulating cancer cell adhesion

The signal peptides GVMGFO and GFOGER exhibit differential binding affinities towards Michigan Cancer Foundation-7 (MCF-7) breast cancer cells and HT-1080 human fibrosarcoma cells, respectively, which in turn modulate the cell adhesion properties of natural collagen. GVMGFO demonstrates a more potent interaction with discoidin domain receptor 1(DDR1)-expressing MCF-7 cells, whereas GFOGER preferentially binds to the integrin α2β1 present on HT-1080 cells. The integration of GVMGFO into natural collagen through direct doping or crosslinking markedly enhances its association with MCF-7 cells, especially when optimal peptide concentrations and blending ratios are utilized, indicating a synergistic effect. This augmented adhesion is attributed to specific binding at the DDR1-collagen interface, facilitated by a constellation of amino acids within the collagen scaffold engaging with the DDR1 discoidin (DS) domain through polar interactions and hydrogen bonding. Conversely, the incorporation of GFOGER into natural collagen through co-assembling or crosslinking leads to a progressive increase in adherence to HT-1080 cells, as evidenced by the peptide's affinity for integrin α2β1. These findings advance the design of collagen-based biomaterials for targeted cellular interactions in the medical, pharmaceutical, and enhance our understanding of the molecular mechanisms governing peptide-collagen mediated cell adhesion processes.

Flexible high electrochemical collagen/lignin composite hydrogel for sensing and supercapacitor applications

Synthesis of polymer-based highly conductive hydrogels from natural and renewable sources with robust mechanical performances in flexible electronics remains a great challenge. In this research, a dynamic redox system is designed by using collagen (CL), sulfonate lignin (SL), acrylic acid (AA), and Al3+ to synthesize CL/PAA/SL/Al hydrogels. The formation of effective complexes of Al3+ with the abundant functional groups of CL, SL and PAA, the prepared hydrogel delivers various specific properties, for example, excellent ionic conductivity (4.61 S·m-1), stretchability and antimicrobial performance. The CL/PAA/SL/Al hydrogel demonstrates good mechanical strength, while the maximum tensile strength of the hydrogels is ∼604 kPa at a stretching of 1254 %, and the maximum compressive strength is ∼0.45 MPa, with the maximum stretching of 59.6 %. The CL/PAA/SL/Al hydrogel acts as a flexible strain sensor with high sensitivity. Enough hydroxyl and carboxyl groups in the hydrogels are essential for delivering the maximum 191 mV of open circuit voltage (Voc) rendered during moisture spraying. The supercapacitor assembled from CL/PAA/SL/Al hydrogel manifests specific capacitance (Cs), maximum energy density (Ed) and power density (Pd) of 268.75 F·g-1, 23.89 Wh·kg-1 and 2.4 kW·kg-1, respectively. The supercapacitor can retain its capacitance of 95.8 % after 5000 consecutive charge-discharge cycles.

Recent Advances in Implantable 3D-Printed Scaffolds for Repair of Spinal Cord Injury

Spinal cord injury (SCI) is an important factor in sensory and motor disorders that affects thousands of people every year. Currently, despite successes in basic science and clinical research, there are few effective methods in the treatment of chronic and acute spinal cord injuries. In the last decade, the use of 3D printed scaffolds in the treatment of SCI had satisfactory and promising results. By providing a microenvironment around the injury site and in combination with growth factors or cells, 3D printed scaffolds help in axon regeneration as well as neural recovery after SCI. Here, we provide an overview of tissue engineering, 3D printing scaffolds, the different polymers used and their characterization methods. This review highlights the recent encouraging applications of 3D printing scaffolds in developing the novel SCI therapy.

Environment-Friendly Preparation and Characterization of Multilayered Conductive PVP/Col/CS Composite Doped with Nanoparticles as Potential Nerve Guide Conduits

Tissue engineering constitutes the most promising method of severe peripheral nerve injuries treatment and is considered as an alternative to autografts. To provide appropriate conditions during recovery special biomaterials called nerve guide conduits are required. An ideal candidate for this purpose should not only be biocompatible and protect newly forming tissue but also promote the recovery process. In this article a novel, multilayered biomaterial based on polyvinylpyrrolidone, collagen and chitosan of gradient structure modified with conductive nanoparticles is presented. Products were obtained by the combination of electrospinning and electrospraying techniques. Nerve guide conduits were subjected to FT-IR analysis, morphology and elemental composition study using SEM/EDS as well as biodegradation. Furthermore, their effect on 1321N1 human cell line was investigated by long-term cell culture. Lack of cytotoxicity was confirmed by XTT assay and morphology study. Obtained results confirmed a high potential of newly developed biomaterials in the field of nerve tissue regeneration with a special focus on injured nerves recovery.

Patterned collagen films loaded with miR-133b@MBG-NH2for potential applications in corneal stromal injury repair

Corneal stromal injury is a common surgical disease. With the development of tissue engineering materials, many artificial corneal scaffolds have been developed to replace allograft corneal transplantation and solve the problem of corneal donor shortage. However, few researchers have paid attention to corneal stromal wound healing. Herein, a nanocomposite of amino modified mesoporous bioactive glass (MBG-NH2) and microRNA-133b (miR-133b) was introduced into the patterned collagen films to achieve corneal stromal injury repair. MBG-NH2nanoparticles as a nano delivery carrier could efficiently load miR-133b and achieve the slow release of miR-133b. The physicochemical properties of collagen films were characterized and found the microgrooved collagen films loaded with miR-133b@MBG-NH2nanoparticles possessed similar swelling properties, optical clarity, and biodegradability to the natural cornea.In vitrocell experiments were also conducted and proved that the patterned collagen films with miR-133b@MBG-NH2possessed good biocompatibility, and miR-133b@MBG-NH2nanoparticles could be significantly uptake by rabbit corneal stromal cells (RCSCs) and have a significant impact on the orientation, proliferation, migration, and gene expression of RCSCs. More importantly, the patterned collagen films with miR-133b@MBG-NH2could effectively promote the migration of RCSCs and accelerate wound healing process, and down-regulate the expression levels ofα-SMA, COL-I, and CTGF genes associated with myofibroblast differentiation of corneal stromal cells, which has a potential application prospect in the repair of corneal stromal injury.

Balanced chemical reactivity, antimicrobial properties and biocompatibility of decellularized dermal matrices for wound healing

The prevention of bacterial infection and prompt wound repair are crucial considerations when local skin tissue is compromised by burns, cuts, or similar injuries. Porcine acellular dermal matrix (pADM) is a commonly employed biological material in wound repair due to its inherent natural properties. Nonetheless, the pADM's primary constituent, collagen fibers, lacks antimicrobial properties and is vulnerable to bacterial infection when used in the treatment of incompletely debrided wounds. Meanwhile, conventional antimicrobial agents primarily consist of chemical compounds that exhibit inadequate biocompatibility and biological hazards. This research endeavors to create an antimicrobial collagen scaffold dressing utilizing the Schiff base reaction through the incorporation of oxidized chitosan diquaternary (ODHTCC) salt into the pADM. Compared with the unmodified pADM, ODHTCC-pADM (OD-pA) still retained the three-stranded helical structure of natural collagen. At an ODHTCC cross-linker concentration of 4%, the thermal denaturation temperature of OD-pA was 85 °C. According to the enzymatic degradation resistance test in vitro, the degradation resistance of OD-pA to type I collagenase was significantly improved compared with that of the uncross-linked pADM. In addition, OD-pA exhibited good antibacterial properties, with inhibition rates of 95.6% and 99.9% for E. coli and Staphylococcus aureus, respectively, and a cytotoxicity level 1, meeting the in vitro requirements of national biomedical materials. In vivo experiments showed that the OD-pA scaffold could better promote wound healing and more effectively promote the positive expression of bFGF, PDGF and VEGF. In conclusion, OD-pA has struck a balance between antibacterial properties, chemical reaction properties and biocompatibility, ultimately achieving controllability, and has broad application prospects in the field of antibacterial biomedical materials.

Oxidized Xanthan Gum Crosslinked NOCC: Hydrogel System and Their Biological Stability from Oxidation Levels of the Polymer

Dynamic hydrogel systems from N,O-carboxymethyl chitosan (NOCC) are investigated in the past years, which has facilitated their widespread use in many biomedical engineering applications. However, the influence of the polymer's oxidation levels on the hydrogel biological properties is not fully investigated. In this study, chitosan is converted into NOCC and introduced to react spontaneously with oxidized xanthan gum (OXG) to form several injectable hydrogels with controlled degradability. Different oxidation levels of xanthan gum, as well as NOCC/OXG volume ratios, are trialed. The infrared spectroscopy spectra verify chemical modification on OXG and successful crosslinking. With increasing oxidation levels, more dialdehyde groups are introduced into the OXG, resulting in changes in physical properties including gelation, swelling, and self-healing efficiency. Under different volume ratios, the hydrogel shows a stable structure and rigidity with higher mechanical properties, and a slower degradation rate. The shear-thinning and self-healing properties of the hydrogels are confirmed. In vitro assays with L929 cells show the biocompatibility of all formulations although the use of a high amount of OXG15 and OXG25 limited the cell proliferation capacity. Findings in this study suggested a suitable amount of OXG at different oxidation levels in NOCC hydrogel systems for tissue engineering applications.

Evolution of biomimetic ECM scaffolds from decellularized tissue matrix for tissue engineering: A comprehensive review

Tissue engineering is essentially a technique for imitating nature. Natural tissues are made up of three parts: extracellular matrix (ECM), signaling systems, and cells. Therefore, biomimetic ECM scaffold is one of the best candidates for tissue engineering scaffolds. Among the many scaffold materials of biomimetic ECM structure, decellularized ECM scaffolds (dECMs) obtained from natural ECM after acellular treatment stand out because of their inherent natural components and microenvironment. First, an overview of the family of dECMs is provided. The principle, mechanism, advances, and shortfalls of various decellularization technologies, including physical, chemical, and biochemical methods are then critically discussed. Subsequently, a comprehensive review is provided on recent advances in the versatile applications of dECMs including but not limited to decellularized small intestinal submucosa, dermal matrix, amniotic matrix, tendon, vessel, bladder, heart valves. And detailed examples are also drawn from scientific research and practical work. Furthermore, we outline the underlying development directions of dECMs from the perspective that tissue engineering scaffolds play an important role as an important foothold and fulcrum at the intersection of materials and medicine. As scaffolds that have already found diverse applications, dECMs will continue to present both challenges and exciting opportunities for regenerative medicine and tissue engineering.

Converting Acellular Dermal Matrix into On-Demand Versatile Skin Scaffolds by a Balanceable Crosslinking Approach for Integrated Infected Wounds Therapy

Ideal tissue-engineered skin scaffolds should possess integrated therapeutic effects and multifunctionality, such as broad-spectrum antibacterial properties, adjustable mechanical properties, and bionic structure. Acellular dermal matrix (ADM) has been broadly used in many surgical applications as an alternative treatment to the "gold standard" tissue transplantation. However, insufficient broad-spectrum antibacterial and mechanical properties for therapeutic efficacy limit the practical clinical applications of ADM. Herein, a balanceable crosslinking approach based on oxidized 2-hydroxypropyltrimethyl ammonium chloride chitosan (OHTCC) was developed for converting ADM into on-demand versatile skin scaffolds for integrated infected wounds therapy. Comprehensive experiments show that different oxidation degrees of OHTCC have significative influences on the specific origins of OHTCC-crosslinked ADM scaffolds (OHTCC-ADM). OHTCC with an oxidation degree of about 13% could prosperously balance the physiochemical properties, antibacterial functionality, and cytocompatibility of the OHTCC-ADM scaffolds. Owing to the natural features and comprehensive crosslinking effects, the proposed OHTCC-ADM scaffolds possessed the desirable multifunctional properties, including adjustable mechanical, degradable characteristics, and thermal stability. In vitro/in vivo biostudies indicated that OHTCC-ADM scaffolds own well-pleasing broad-spectrum antibacterial performances and play effectively therapeutic roles in treating infection, inhibiting inflammation, promoting angiogenesis, and promoting collagen deposition to enhance the infected wound healing. This study proposes a facile balanceable crosslinking approach for the design of ADM-based versatile skin scaffolds for integrated infected wounds therapy.

Preparation, Characterization and ex vivo Skin Permeability Evaluation of Type I Collagen-Loaded Liposomes

Purpose

In the present study, we prepared collagen liposomes with the addition of polyol, which is expected to not only increase the solubility of collagen but also improve skin penetration.

Methods

Collagen liposomes were prepared by the film dispersion method, and their characteristics, integrity and biosafety were evaluated by Fourier transform infrared spectroscopy (FTIR), UV-VIS spectroscopy, polyacrylamide gel electrophoresis (SDS-PAGE), dynamic light scattering (DLS) and transmission electron microscope (TEM). The transdermal absorption of collagen and collagen liposomes were tested by an ex vivo horizontal Valia-Chien diffusion cell system.

Results

We first demonstrated that collagen extracted from bovine Achilles tendon was type I collagen. The results of DLS measurement and TEM observation showed that the collagen liposomes were spherical in shape with average diameter (75.34±0.93 nm) and maintained high stability at low temperature (4°C) for at least 42 days without toxicity. The encapsulation rate of collagen liposomes was 57.80 ± 0.51%, and SDS-PAGE analysis showed that collagen was intact in liposomes. Finally, permeability studies indicated that the collagen-loaded liposomes more easily penetrated the skin compared to collagen itself.

Conclusion

This study proposed a new method to improve the bioavailability and permeability of bovine type I collagen, which improves the applicability of collagen in biomedicine, cosmeceuticals and pharmaceutical industries.

Antibacterial Collagen-Based Nanocomposite Dressings for Promoting Infected Wound Healing

Pathogenic bacterial infection is the most frequent wound complication, which has become a major clinical and healthcare challenge in wound management worldwide, leading to impaired healing processes, the risk of amputation, and even death. Here, collagen-based nanocomposite dressings (APZC) with broad-spectrum antibacterial activity are developed to promote the infected full-thickness wound healing. Short rod-like shaped ZnO NPs are synthesized and then coated with polydopamine (PDA) to obtain PDA coated ZnO NPs (PDA@ZnO NPs). Afterward, PDA@ZnO NPs are conjugated on the backbone of a collagen chain, and the obtained collagen-PDA@ZnO NPs conjugate is crosslinked by dialdehyde sodium alginate to fabricate APZC dressings. PDA@ZnO NPs show well dispersibility and are uniformly incorporated into the collagen matrix. APZC dressings have interconnected microporous structure and great physicochemical properties, besides good blood coagulation performance and well cytocompatibility. APZC dressings demonstrate long-lasting and excellently broad-spectrum antimicrobial activity, which can relieve the inflammatory reaction by killing pathogenic bacteria and induce the generation of blood vessels and the orderly deposition of collagen in the wound site, thus promoting infected full-thickness wound healing without obvious scar formation. Overall, the functionalized collagen-based nanocomposite dressings have great potential in the clinical treatment against bacteria-associated wound infection.