Oxidized sodium alginate crosslinked silk fibroin composite scaffold for skin tissue engineering

Abstract

Engineering skin substitutes represent a prospective source of advanced therapy in repairing severe traumatic wounds. Sodium alginate (SA) and silk fibroin (SF) are natural biomaterials, which are widely used in tissue engineering and other fields because of their low price, high safety, and good biocompatibility. However, SA itself degrades slowly, its degradation mode is difficult to control, and the degradation products are difficult to remove from the body because of its high molecular weight.Therefore, the composite scaffolds were prepared by freeze-drying composite technology by using the Schiff base reaction between biocompatible SF and permeable oxidized sodium alginate (OSA). Sodium periodate was used as oxidant to modify SA. The results showed that higher oxidation degree of OSA could be obtained by increasing the proportion of oxidant, and the relative molecular weight of the oxidized products could also be reduced. The composite scaffolds were prepared by using sodium tetraborate as a crosslinking accelerator of the Schiff base reaction between OSA and SF. FT-IR confirmed that the Schiff base group appeared in the material. In vitro biodegradation experiments showed that the biodegradation of the composite scaffolds was controllable, and the cytocompatibility experiment showed that the composite scaffolds had good biocompatibility.

Genipin-Cross-Linked Silk Fibroin/Alginate Dialdehyde Hydrogel with Tunable Gelation Kinetics, Degradability, and Mechanical Properties: A Potential Candidate for Tissue Regeneration

“…The formation of β-glycosidic linkage due to the Alg oxidation leads to its higher susceptibility to hydrolysis. 10 As it was expected, the rate of degradation of all samples gradually decreased over 14 days. After 14 days of incubation in SBF, 100ADA showed the lowest weight retention percentage (34.16%).…”

“…The in vitro degradation (weight loss) behavior of all hydrogels was monitored in a simulated body fluid (SBF) solution (pH 7.4), as illustrated in Figure c. The formation of β-glycosidic linkage due to the Alg oxidation leads to its higher susceptibility to hydrolysis . As it was expected, the rate of degradation of all samples gradually decreased over 14 days.…”

“…24 The crosslinking mechanism of ADA with different oxidation degrees and SF has been studied using sodium tetraborate as an accelerator agent for facile Schiff-base reaction. 10 Despite a faster gelation process in the presence of sodium tetraborate, its cytotoxicity has been previously noted. 25 In a recent study, it was reported that while the gelation process and the mechanical performance of ADA/SF composite hydrogels were accelerated considerably when combined at higher concentrations, the denser network might negatively affect cell function.…”

“…The amino acid sequence of SF, containing repetitive glycine–alanine–glycine–alanine–glycine–serine (GAGAGS), can self-assemble into an antiparallel β-sheet structure . To overcome the brittleness of pristine SF hydrogels, previous studies have suggested exploiting chemically derived cross-linking agents like glutaraldehyde, carbodiimide coupling, sodium tetraborate, horseradish peroxidase (HRP)-H 2 O 2 , riboflavin, and 1,4-butanediol diglycidyl ether (BDDE) . The potential of hybrid materials, including other proteins (gelatin and collagen), polysaccharides (alginate, hyaluronic acid, chitosan, and cellulose), and their derivatives, have also been investigated to benefit from the synergistic effects of various hybrid biomaterials to be able to improve the ECM biomimicry and mechanical strength by tuning the properties. − In this regard, genipin, a naturally derived cross-linking agent obtained from geniposide, is an effective and low-cytotoxic agent.…”

“…ADA-based hydrogels can offer tunable biodegradability and reactive binding site provision for Schiff-base reaction when amine groups are available . The cross-linking mechanism of ADA with different oxidation degrees and SF has been studied using sodium tetraborate as an accelerator agent for facile Schiff-base reaction . Despite a faster gelation process in the presence of sodium tetraborate, its cytotoxicity has been previously noted .…”