Application of Epigallocatechin-3-gallate (EGCG) Modified 1-Ethyl-3-(3-dimethylaminopropylcarbodiimide hydrochloride/N-hydroxy-succinimide (EDC/NHS) Cross-Linked Collagen Membrane to Promote Macrophage Adhesion

Preparation of fibre-reinforced PLA-collagen@PLA-PCL@PCL-gelatin three-layer vascular graft by EDC/NHS cross-linking and its performance study

In this study, a three-layer small diameter artificial vascular graft with a structure similar to that of natural blood vessels was first constructed by triple-step electrospinning technology, in which polylactic acid (PLA) and collagen (COL) were used for the inner layer, polylactic acid and polycaprolactone (PCL) was used for the middle layer and polycaprolactone and gelatin was used for the outer layer. The properties of the artificial vascular graft were adjusted by the EDC/NHS cross-linking agent through the reaction between the collagen or gelatine and EDC/NHS. The mechanical and hydrophilic properties of the cross-linked artificial vessels were substantially enhanced, with a maximum stress of 9.56 MPa in the axial direction and 9.31 MPa in the radial direction for the P/C (4:1) vascular graft, which exceeded that of many textile-based and natural vascular grafts. The increased hydrophilicity of the inner layer of the vessel before crosslinking was due to the addition of COL, and the inner layer of the artificial vessel after crosslinking had a substantial increase in hydrophilicity due to the production of a more hydrophilic urea derivative. The increased hydrophilicity led to easier cell adhesion to the inner layer of the artificial vessel, especially for the P/C (2:1) vascular graft, where the cell proliferation rate and adhesion were high due to COL incorporation and cross-linking. The three-layer vascular grafts studied did not lead to haemolysis. Therefore, the EDC/NHS cross-linked three-layer vascular graft had good mechanical properties, hydrophilicity, anticoagulation and could enhance cell adhesion and proliferation.

Polyphenols-based intelligent oral barrier membranes for periodontal bone defect reconstruction

Periodontitis-induced periodontal bone defects significantly impact patients' daily lives. The guided tissue regeneration and guided bone regeneration techniques, which are based on barrier membranes, have brought hope for the regeneration of periodontal bone defects. However, traditional barrier membranes lack antimicrobial properties and cannot effectively regulate the complex oxidative stress microenvironment in periodontal bone defect areas, leading to unsatisfactory outcomes in promoting periodontal bone regeneration. To address these issues, our study selected the collagen barrier membrane as the substrate material and synthesized a novel barrier membrane (PO/4-BPBA/Mino@COL, PBMC) with an intelligent antimicrobial coating through a simple layer-by-layer assembly method, incorporating reactive oxygen species (ROS)-scavenging components, commercial dual-functional linkers and antimicrobial building blocks. Experimental results indicated that PBMC exhibited good degradability, hydrophilicity and ROS-responsiveness, allowing for the slow and controlled release of antimicrobial drugs. The outstanding antibacterial, antioxidant and biocompatibility properties of PBMC contributed to resistance to periodontal pathogen infection and regulation of the oxidative balance, while enhancing the migration and osteogenic differentiation of human periodontal ligament stem cells. Finally, using a rat periodontal bone defect model, the therapeutic effect of PBMC in promoting periodontal bone regeneration under infection conditions was confirmed. In summary, the novel barrier membranes designed in this study have significant potential for clinical application and provide a reference for the design of future periodontal regenerative functional materials.

Cyanophycin modifications for applications in tissue scaffolding

Cyanophycin (CGP) is a polypeptide consisting of amino acids-aspartic acid in the backbone and arginine in the side chain. Owing to its resemblance to cell adhesive motifs in the body, it can be considered suitable for use in biomedical applications as a novel component to facilitate cell attachment and tissue regeneration. Although it has vast potential applications, starting with nutrition, through drug delivery and tissue engineering to the production of value-added chemicals and biomaterials, CGP has not been brought to the industry yet. To develop scaffolds using CGP powder produced by bacteria, its properties (e.g., biocompatibility, morphology, biodegradability, and mechanical strength) should be tailored in terms of the requirements of the targeted tissue. Crosslinking commonly stands for a primary modification method for renovating biomaterial features to these extents. Herein, we aimed to crosslink CGP for the first time and present a comparative study of different methods of CGP crosslinking including chemical, physical, and enzymatic methods by utilizing glutaraldehyde (GTA), UV exposure, genipin, 1-ethyl-3-[3-dimethylaminopropyl] carbodiimide hydrochloride/N-hydroxysuccinimide (EDC/NHS), and monoamine oxidase (MAO). Crosslinking efficacy varied among the samples crosslinked via the different crosslinking methods. All crosslinked CGP were non-cytotoxic to L929 cells, except for the groups with higher GTA concentrations. We conclude that CGP is a promising candidate for scaffolding purposes to be used as part of a composite with other biomaterials to maintain the integrity of scaffolds. The initiative study demonstrated the unknown characteristics of crosslinked CGP, even though its feasibility for biomedical applications should be confirmed by further examinations. KEY POINTS: • Cyanophycin was crosslinked by 5 different methods • Crosslinked cyanophycin is non-cytotoxic to L929 cells • Crosslinked cyanophycin is a promising new material for scaffolding purposes.

Novel biodegradable hydrogel scaffold based on hydroxyapatite eggshell, collagen, and epigallocatechin-3-gallate

Background

Biodegradable hydrogel scaffold is one of the crucial characteristics that determine the success of pulp regeneration. The degradation should be suitable for the growth of new tissue establishment. The aim of this study is to synthesize and compare the novel biodegradable hydrogel scaffold based on hydroxyapatite (HAp) eggshell, collagen, and epigallocatechin-3-gallate (HAp-Col-EGCG) with different HAp concentrations in vitro.

Materials and Methods

This study is original research. HAp-Col-EGCG hydrogel scaffolds were prepared using 1:1, 1:2, and 1:4 ratios of collagen and HAp with 10 μmol/L EGCG. The samples were freeze-dried and immersed in phosphate buffer saline containing lysozyme enzyme. The dried samples were weighed to determine the percentage of biodegradation value (P < 0.05).

Results

The result showed HAp-Col-EGCG was biodegradable but it has not been concluded that it can be completely eliminated. The data were analyzed by one-way analysis of variance and it indicated significant differences in percentage values.

Conclusion

Hydrogel scaffold based on HAp-Col-EGCG can be degraded and have the potential to be used as a biodegradable scaffold in supporting tissue regeneration.

Barrier Membranes for Guided Bone Regeneration (GBR): A Focus on Recent Advances in Collagen Membranes

Guided bone regeneration (GBR) has become a clinically standard modality for the treatment of localized jawbone defects. Barrier membranes play an important role in this process by preventing soft tissue invasion outgoing from the mucosa and creating an underlying space to support bone growth. Different membrane types provide different biological mechanisms due to their different origins, preparation methods and structures. Among them, collagen membranes have attracted great interest due to their excellent biological properties and desired bone regeneration results to non-absorbable membranes even without a second surgery for removal. This work provides a comparative summary of common barrier membranes used in GBR, focusing on recent advances in collagen membranes and their biological mechanisms. In conclusion, the review article highlights the biological and regenerative properties of currently available barrier membranes with a particular focus on bioresorbable collagen-based materials. In addition, the advantages and disadvantages of these biomaterials are highlighted, and possible improvements for future material developments are summarized.