In Vitro Biodegradation, Drug Absorption, and Physical Properties of Gelatin-Fucoidan Microspheres Made of Subcritical-Water-Modified Fish Gelatin.

This study aimed to prepare gelatin-fucoidan microspheres with enhanced doxorubicin binding efficiency and controllable biodegradation using fish gelatin combined with low molecular weight (LMW) gelatin and fucoidan at fixed ratios. The MW of gelatin was modified by subcritical water (SW), which is known as a safe solvent, at 120 °C, 140 °C, and 160 °C. In addition, gelatin-fucoidan microspheres were prepared using a solvent exchange technique. Our findings revealed that particle size decreased, the surface was rougher, the swelling ratio increased, and particle shape was irregular in microspheres composed of SW-modified gelatin. Doxorubicin binding efficiency was improved by fucoidan and SW-modified gelatin at 120 °C but not at 140 °C and 160 °C. Interestingly, an increase in in vitro enzymatic degradation was observed in the microspheres consisting of SW-modified fish gelatin, although the cross-linking degree between them was not significantly different. This is because LMW gelatin could form more cross-linked bonds, which might be weaker than the intramolecular bonds of gelatin molecules. Gelatin-fucoidan microspheres consisting of SW-modified fish gelatin with controlled biodegradation rates could be a candidate for a short-term transient embolization agent. In addition, SW would be a promising method to modify the MW of gelatin for medical applications.

Influences of Molecular Weights on Physicochemical and Biological Properties of Collagen-Alginate Scaffolds.

For tissue engineering applications, biodegradable scaffolds containing high molecular weights (MW) of collagen and sodium alginate have been developed and characterized. However, the properties of low MW collagen-based scaffolds have not been studied in previous research. This work examined the distinctive properties of low MW collagen-based scaffolds with alginate unmodified and modified by subcritical water. Besides, we developed a facile method to cross-link water-soluble scaffolds using glutaraldehyde in an aqueous ethanol solution. The prepared cross-linked scaffolds showed good structural properties with high porosity (~93%) and high cross-linking degree (50-60%). Compared with collagen (6000 Da)-based scaffolds, collagen (25,000 Da)-based scaffolds exhibited higher stability against collagenase degradation and lower weight loss in phosphate buffer pH 7.4. Collagen (25,000 Da)-based scaffolds with modified alginate tended to improve antioxidant capacity compared with scaffolds containing unmodified alginate. Interestingly, in vitro coagulant activity assay demonstrated that collagen (25,000 Da)-based scaffolds with modified alginate (C25-A63 and C25-A21) significantly reduced the clotting time of human plasma compared with scaffolds consisting of unmodified alginate. Although some further investigations need to be done, collagen (25,000 Da)-based scaffolds with modified alginate should be considered as a potential candidate for tissue engineering applications.