Synthesis and characterization of a chitosan/gelatin transparent film crosslinked with a combination of EDC/NHS for corneal epithelial cell culture scaffold with potential application in cornea implantation

Effect of different crosslinking agents on hybrid chitosan/collagen hydrogels for potential tissue engineering applications

Tissue engineering (TE) demands scaffolds that have the necessary resistance to withstand the mechanical stresses once implanted in our body, as well as excellent biocompatibility. Hydrogels are postulated as interesting materials for this purpose, especially those made from biopolymers. In this study, the microstructure and rheological performance, as well as functional and biological properties of chitosan and collagen hydrogels (CH/CG) crosslinked with different coupling agents, both natural such as d-Fructose (F), genipin (G) and transglutaminase (T) and synthetic, using a combination of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride with N-hydroxysuccinimide (EDC/NHS) will be assessed. FTIR tests were carried out to determine if the proposed crosslinking reactions for each crosslinking agent occurred as expected, obtaining positive results in this aspect. Regarding the characterization of the properties of each system, two main trends were observed, from which it could be established that crosslinking with G and EDC-NHS turned out to be more effective and beneficial than with the other two crosslinking agents, producing significant improvements with respect to the base CH/CG hydrogel. In addition, in vitro tests demonstrated the potential application in TE of these systems, especially for those crosslinked with G, T and EDC-NHS.

Diatom-guided bone healing via a hybrid natural scaffold

Bone tissue engineering (BTE) involves the design of three-dimensional (3D) scaffolds that aim to address current challenges of bone defect healing, such as limited donor availability, disease transmission risks, and the necessity for multiple invasive surgeries. Scaffolds can mimic natural bone structure to accelerate the mechanisms involved in the healing process. Herein, a crosslinked combination of biopolymers, including gelatin (GEL), chitosan (CS), and hyaluronic acid (HA), loaded with diatom (Di) and β-sitosterol (BS), is used to produce GCH-Di-S scaffold by freeze-drying method. The GCH scaffold possesses a uniform structure, is biodegradable and biocompatible, and exhibits high porosity and interconnected pores, all required for effective bone repair. The incorporation of Di within the scaffold contributes to the adjustment of porosity and degradation, as well as effectively enhancing the mechanical property and biomineralization. In vivo studies have confirmed the safety of the scaffold and its potential to stimulate the creation of new bone tissue. This is achieved by providing an osteoconductive platform for cell attachment, prompting calcification, and augmenting the proliferation of osteoblasts, which further contributes to angiogenesis and anti-inflammatory effects of BS.

Ca-AlN MOFs-loaded chitosan/gelatin scaffolds; a dual-delivery system for bone tissue engineering applications

Creating a scaffold for bone tissue engineering that is bioactive and capable of acting as a local-dual delivery system, releasing bioactive molecules and regulating the bone remodeling process to achieve balanced bone resorption and formation, is a significant challenge. The objective of this research is to create a composite scaffold using chitosan/gelatin (CHS/Gel) and the calcium (Ca)-alendronate (ALN) metal-organic frameworks (MOFs). The scaffold will act as a dual-delivery system, releasing Ca ions and ALN to regulate bone formation. Ca-ALN MOF nanoparticles (NPs) were prepared in mild conditions and studied by FTIR, XRD, FESEM, and TGA. Ca-ALN NPs-loaded CHS/Gel scaffolds were opportunely fabricated through freeze-drying approach. Physicochemical features of the scaffolds after incorporating NPs equated by CHS/Gel scaffold changed, therefore, the attendance of NPs caused a decreasing porosity, decreased swelling, and low rate of degradation. The release profile results showed that the NPs-loaded CHS/Gel scaffolds were able to simultaneously release ALN and Ca ions due to the decomposition of NPs. Additionally, the loading of NPs in the CHS/Gel scaffold led to an increment in alkaline phosphatase (ALP) activity and the quantity of deposited Ca along with osteogenesis gene markers. These findings suggest that the NPs-loaded CHS/Gel scaffold has the potential to enhance the differentiation of human adipose tissue-derived mesenchymal stem cells, making it a promising approach for bone repair.

Use of Chitosan from Southern King Crab to Develop Films Functionalized with RGD Peptides for Potential Tissue Engineering Applications

Southern King Crab (SKC) represents an important fishery resource that has the potential to be a natural source of chitosan (CS) production. In tissue engineering, CS is very useful to generate biomaterials. However, CS has a lack of signaling molecules that facilitate cell-substrate interaction. Therefore, RGD (arginine-glycine-aspartic acid) peptides corresponding to the main integrin recognition site in extracellular matrix proteins have been used to improve the CS surface. The aim of this study was to evaluate in vitro cell adhesion and proliferation of CS films synthesized from SKC shell wastes functionalized with RGD peptides. The FTIR spectrum of CS isolated from SKC shells (SKC-CS) was comparable to commercial CS. Thermal properties of films showed similar endothermic peaks at 53.4 and 53.0 °C in commercial CS and SKC-CS, respectively. The purification and molecular masses of the synthesized RGD peptides were confirmed using HPLC and ESI-MS mass spectrometry, respectively. Mouse embryonic fibroblast cells showed higher adhesion on SKC-CS (1% w/v) film when it was functionalized with linear RGD peptides. In contrast, a cyclic RGD peptide showed similar adhesion to control peptide (RDG), but the highest cell proliferation was after 48 h of culture. This study shows that functionalization of SKC-CS films with linear or cyclic RGD peptides are useful to improve effects on cell adhesion or cell proliferation. Furthermore, our work contributes to knowledge of a new source of CS to synthesize constructs for tissue engineering applications.

Recent Advances of Chitosan Formulations in Biomedical Applications

Chitosan, a naturally abundant cationic polymer, is chemically composed of cellulose-based biopolymers derived by deacetylating chitin. It offers several attractive characteristics such as renewability, hydrophilicity, biodegradability, biocompatibility, non-toxicity, and a broad spectrum of antimicrobial activity towards gram-positive and gram-negative bacteria as well as fungi, etc., because of which it is receiving immense attention as a biopolymer for a plethora of applications including drug delivery, protective coating materials, food packaging films, wastewater treatment, and so on. Additionally, its structure carries reactive functional groups that enable several reactions and electrochemical interactions at the biomolecular level and improves the chitosan’s physicochemical properties and functionality. This review article highlights the extensive research about the properties, extraction techniques, and recent developments of chitosan-based composites for drug, gene, protein, and vaccine delivery applications. Its versatile applications in tissue engineering and wound healing are also discussed. Finally, the challenges and future perspectives for chitosan in biomedical applications are elucidated.

Crosslinked Chitosan-Gelatin Biocompatible Nanocomposite as a Neuro Drug Carrier

The polymers, chitosan, a polysaccharide, and gelatin, a protein, are crosslinked in different ratios without the aid of a crosslinking agent. Facile chemical reactions were followed to synthesize a chitosan/gelatin nanocomposite in three different ratios (1:1, 1:3, and 3:1). The solubility of chitosan and the stability of gelatin were improved due to the crosslinking. Both the polymers have excellent biodegradability, biocompatibility, adhesion, and absorption properties in a biological environment. The properties of the composite were favorable to be used in drug delivery applications, and the drug dopamine was encapsulated in the composite for all three ratios. The properties of the chitosan/gelatin nanocomposite and dopamine-loaded chitosan/gelatin nanocomposite were examined using XRD, FTIR, SEM, UV, TGA, TEM, and DLS techniques, and the crosslinking was confirmed. Higuchi kinetic release was seen with a cumulative release of 93% within 24 h for the 1:3 nanocomposite in a neutral medium. The peaks at 9 and 20° in the XRD spectrum confirmed the encapsulation of dopamine with the increase in the crystallinity of chitosan, which is also evident from the SAED image. The dopamine functional groups were confirmed from the IR peaks between 500 and 1500 cm^-1 and the wide UV absorption maxima between 250 and 290 nm. The particle size of the drug-loaded composite in the ratios 1:1, 1:3, and 3:1 were calculated to be 275, 405, and 355 nm, respectively. The nanocomposite also showed favorable DPPH antioxidant and antibacterial activity againstStaphylococcus aureus. Sustained release of dopamine in a neutral medium using crosslinked chitosan and gelatin without the presence of a crosslinker is the highlight of the work.