Novel Modification of Collagen: Realizing Desired Water Solubility and Thermostability in a Conflict-Free Way

Assembled collagen films modified using polyacrylic acid with improved mechanical properties via mineralization

The imperative task of enforcing collagen materials holds paramount significance in the field of hard tissue repair. We hereby present mineralized collagen fiber films via mineralization with improved mechanical properties. Self-extracted collagen was assembled into an array with an aligned fibrous pattern and then modified with polyacrylic acid (PAA) followed by mineralization in cationic polyacrylamide (CPAM)-SBF. Biomineralization occurred at the inner and outer surface of the assembled collagen fiber films. A tensile strength of up to 40.38 ± 3.08 MPa of mineralized collagen was obtained, for the first time, which may be attributed to the synergistic effect of polyanion and polycation on the mineralization process of assembled intrafibrillar collagen fibers. It was argued that PAA may facilitate the intra-fiber interaction of collagen, which extends the elongation at break of collagen fibers. This study introduces a pioneering approach for the preparation of mineralized collagen materials with superior mechanical properties, which would be beneficial for hard tissue repair.

A highly biocompatible and bioactive transdermal nano collagen for enhanced healing of UV-damaged skin

Skin damage caused by excessive UV radiation has gradually become one of the most prevalent skin diseases. Collagen has gradually found applications in the treatment of UV-damaged skin; however, their high molecular weight greatly limits their capacity to permeate the skin barrier and repair the damaged skin. Nano collagen has garnered growing attentions in the mimicking of collagen; while the investigation of its skin permeability and wound-healing capability remains vacancies. Herein, we have for the first time created a highly biocompatible and bioactive transdermal nano collagen demonstrating remarkable transdermal capacity and repair efficacy for UV-damaged skin. The transdermal nano collagen exhibited a stable triple-helix structure, effectively promoting the adhesion and proliferation of fibroblasts. Notably, the transdermal nano collagen displayed exceptional penetration capabilities, permeating fibroblast and healthy skin. Combo evaluations revealed that the transdermal nano collagen contributed to recovering the intensity and TEWL values of UV-damaged skin to normal level. Histological analysis further indicated that transdermal nano collagen significantly accelerated the repair of damaged skin by promoting the collagen regeneration and fibroblasts activation. This highly biocompatible and bioactive transdermal nano collagen provides a novel substituted strategy for the transdermal absorption of collagen, indicating great potential applications in cosmetics and dermatology.

Collagen Biocomposites Derived from Fish Waste: Doped and Cross-Linked with Functionalized Fe3O4 Nanoparticles and Their Comparative Studies with a Green Approach

Collagen-based nanobiocomposites can reabsorb and are biodegradable. These properties are effectively controlled by the number of cross-links. This study demonstrates an effortless and proficient approach for the functionalization of Fe₃O₄ NPs for cross-linking collagen obtained from biowaste, viz., fish scales of Lates Calcarifer, a marine origin. The size of Fe₃O₄ NPs (10-40 nm) was confirmed using particle size analysis. The physico-chemical properties of the aminosilane-coated Fe₃O₄ NPs cross-linked via succinylated collagen (FFCSC) were characterized using different analytical techniques and compared with succinylated collagen doped with Fe₃O₄ NPs (FDSC). Thermogravimetric analysis indicates cross-linked product FFCSC to be more stable than the FDSC. Also, the antibacterial effect was more pronounced for FFCSC than for FDSC nanobiocomposites. FFCSC exhibited improved mechanical properties which are essential for materials used for wound dressing purposes. Moreover, the cell viability of fibroblasts (3T3-L1) and their morphology studied by SEM and fluorescence microscopy showed biocompatibility of both FDSC and FFCSC. Thus, the current investigation, involves a waste to wealth approach where the collagen-based nanobiocomposites present an easy way to recycle the biowaste to value-added products using simple and clean methods, which are suitable for use in biomedical and environmental applications.

Modeling of Chitosan modified PLGA atorvastatin-curcumin conjugate (AT-CU) nanoparticles, overcoming the barriers associated with PLGA: an approach for better management of atherosclerosis

Conjugate drugs are evolving into potent techniques in the drug development process for enhancing the biopharmaceutical, physicochemical, and pharmacokinetic properties. Atorvastatin (AT) is the first line of treatment for coronary atherosclerosis; however its therapeutic efficacy is limited because of its poor solubility and fast pass metabolism. Curcumin (CU) is evidenced in several crucial signaling pathways linked to lipid regulation and inflammation. To enhance the therapeutic efficacy and physical properties of AT and CU, a new conjugate derivative (AT-CU) was synthesized and assessed by in silico, in vitro characterizations, and in vivo efficacy through mice model. Although the biocompatibility and biodegradability of Polylactic-co-Glycolic Acid (PLGA) in nanoparticles are well documented, burst release is a common issue with this polymer. Hence the current work used chitosan as a drug release modifier to the PLGA nanoparticles. The chitosan-modified PLGA AT-CU nanoparticles were prepaid by single emulsion and solvent evaporation technique. With raising the concentration of chitosan the particle size grew from 139.2 nm to 197.7 nm, the zeta potential rose from -20.57 mV to 28.32 mV, and the drug encapsulation efficiency improved from 71.81 % to 90.57 %. At 18 hours, the burst release of AT-CU from PLGA nanoparticles was seen, hitting abruptly 70.8%. For chitosan-modified PLGA nanoparticles, the burst release pattern was significantly reduced which could be due to the adsorption of the drug on the surface of chitosan. The efficiency of the ideal formulation i.e F4 (chitosan/PLGA= 0.4) in treating atherosclerosis was further strongly evidenced by in vivo investigation.

Adhesive hydrogels in osteoarthritis: from design to application

Osteoarthritis (OA) is the most common type of degenerative joint disease which affects 7% of the global population and more than 500 million people worldwide. One research frontier is the development of hydrogels for OA treatment, which operate either as functional scaffolds of tissue engineering or as delivery vehicles of functional additives. Both approaches address the big challenge: establishing stable integration of such delivery systems or implants. Adhesive hydrogels provide possible solutions to this challenge. However, few studies have described the current advances in using adhesive hydrogel for OA treatment. This review summarizes the commonly used hydrogels with their adhesion mechanisms and components. Additionally, recognizing that OA is a complex disease involving different biological mechanisms, the bioactive therapeutic strategies are also presented. By presenting the adhesive hydrogels in an interdisciplinary way, including both the fields of chemistry and biology, this review will attempt to provide a comprehensive insight for designing novel bioadhesive systems for OA therapy.

Screening of Self-Assembling of Collagen IV Fragments into Stable Structures Potentially Useful in Regenerative Medicine

The aim of the research was to check whether it is possible to use fragments of type IV collagen to obtain, as a result of self-assembling, stable spatial structures that could be used to prepare new materials useful in regenerative medicine. Collagen IV fragments were obtained by using DMT/NMM/TosO- as a coupling reagent. The ability to self-organize and form stable spatial structures was tested by the CD method and microscopic techniques. Biological studies covered: resazurin assay (cytotoxicity assessment) on BJ, BJ-5TA and C2C12 cell lines; an alkaline version of the comet assay (genotoxicity), Biolegend Legendplex human inflammation panel 1 assay (SC cell lines, assessment of the inflammation activity) and MTT test to determine the cytotoxicity of the porous materials based on collagen IV fragments. It was found that out of the pool of 37 fragments (peptides 1-33 and 2.1-2.4) reconstructing the outer sphere of collagen IV, nine fragments (peptides: 2, 4, 5, 6, 14, 15, 25, 26 and 30), as a result of self-assembling, form structures mimicking the structure of the triple helix of native collagens. The stability of spatial structures formed as a result of self-organization at temperatures of 4 °C, 20 °C, and 40 °C was found. The application of the MST method allowed us to determine the Kd of binding of selected fragments of collagen IV to ITGα1β1. The stability of the spatial structures of selected peptides made it possible to obtain porous materials based on their equimolar mixture. The formation of the porous materials was found for cross-linked structures and the material stabilized only by weak interactions. All tested peptides are non-cytotoxic against all tested cell lines. Selected peptides also showed no genotoxicity and no induction of immune system responses. Research on the use of porous materials based on fragments of type IV collagen, able to form stable spatial structures as scaffolds useful in regenerative medicine, will be continued.

Tendon-inspired fibers from liquid crystalline collagen as the pre-oriented bioink

Nature provides rich bionic resources for the construction of advanced materials with excellent mechanical properties. In this work, inspired by animal tendons, a bionic collagen fiber was developed using collagen liquid crystals as the pre-oriented bioink. The texture of liquid crystalline collagen observed from polarized optical microscopy (POM) showed the specific molecular pre-orientation. Meanwhile, the collagen spinning liquids exhibited a minimal rise in viscosity upon increasing concentration from 60 to 120 mg/mL, indicating the feasible processability. The collagen fiber, which was prepared via wet spinning without being denatured, exhibited the favorable orientation of fibrils along its axis as observed with FESEM and AFM. Thanks to the synergistic effects between pre-orientation and shearing orientation, the maximum tensile strength and Young's modulus of collagen fibers reached 9.98 cN/tex (219.29 ± 22.92 MPa) and 43.95 ± 1.11 cN/tex (966.20 ± 24.30 MPa), respectively, which were also analogous to those of tendon. In addition, the collagen fiber possessed a desirable wet strength. Benefiting from the natural tissue affinity of collagen, the as-prepared bionic collagen fiber possessed excellent wound suture performance and biodegradability in vivo, which offers a new perspective for the potential of widespread applications of collagen fibers in biomedical fields.

Mimicking the Hierarchical Organization of Natural Collagen: Toward the Development of Ideal Scaffolding Material for Tissue Regeneration

Biological materials found in living organisms, many of which are proteins, feature a complex hierarchical organization. Type I collagen, a fibrous structural protein ubiquitous in the mammalian body, provides a striking example of such a hierarchical material, with peculiar architectural features ranging from the amino acid sequence at the nanoscale (primary structure) up to the assembly of fibrils (quaternary structure) and fibers, with lengths of the order of microns. Collagen plays a dominant role in maintaining the biological and structural integrity of various tissues and organs, such as bone, skin, tendons, blood vessels, and cartilage. Thus, "artificial" collagen-based fibrous assemblies, endowed with appropriate structural properties, represent ideal substrates for the development of devices for tissue engineering applications. In recent years, with the ultimate goal of developing three-dimensional scaffolds with optimal bioactivity able to promote both regeneration and functional recovery of a damaged tissue, numerous studies focused on the capability to finely modulate the scaffold architecture at the microscale and the nanoscale in order to closely mimic the hierarchical features of the extracellular matrix and, in particular, the natural patterning of collagen. All of these studies clearly show that the accurate characterization of the collagen structure at the submolecular and supramolecular levels is pivotal to the understanding of the relationships between the nanostructural/microstructural properties of the fabricated scaffold and its macroscopic performance. Several studies also demonstrate that the selected processing, including any crosslinking and/or sterilization treatments, can strongly affect the architecture of collagen at various length scales. The aim of this review is to highlight the most recent findings on the development of collagen-based scaffolds with optimized properties for tissue engineering. The optimization of the scaffolds is particularly related to the modulation of the collagen architecture, which, in turn, impacts on the achieved bioactivity.

Bioactive Polymeric Materials for the Advancement of Regenerative Medicine

Biopolymers are widely accepted natural materials in regenerative medicine, and further development of their bioactivities and discoveries on their composition/function relationships could greatly advance the field. However, a concise insight on commonly investigated biopolymers, their current applications and outlook of their modifications for multibioactivity are scarce. This review bridges this gap for professionals and especially freshmen in the field who are also interested in modification methods not yet in commercial use. A series of polymeric materials in research and development uses are presented as well as challenges that limit their efficacy in tissue regeneration are discussed. Finally, their roles in the regeneration of select tissues including the skin, bone, cartilage, and tendon are highlighted along with modifiable biopolymer moieties for different bioactivities.