pH-responsive onion-structured hydrogel beads based on chitosan-spider silk-graphene quantum dots for controlled drug...

Cancer therapy often faces challenges related to poor drug targeting, side effects, and burst release of drug. To overcome these challenges, pH-responsive multilayer hydrogel beads were developed using chitosan (Cs) and natural spider silk (SS) for controlled delivery of doxorubicin (DOX), incorporating graphene quantum dots (GQDs) for fluorescent properties. The hydrogel beads were developed by using chitosan for pH-responsiveness and spider silk for mechanical reinforcing as bio polymers. Chitosan was ionically crosslinked using sodium citrate (S.Cit). Native spider silk was successfully extracted from domestic spider webs using formic acid/calcium chloride while preserving the β-sheet structures. GQDs synthesized via direct pyrolysis of citric acid. Ionically crosslinked monolayer hydrogel beads showed pH dependent swelling, with maximum swelling (550%) at acidic media, and minimal swelling (90-110%) at basic media. In vitro DOX release profile of monolayer beads properly aligns with the swelling behavior. Release percentage at pH 4 was 84% and at pH 7 was 21%, ensures tumor microenvironment target releasing. Multilayer beads successfully avoid the burst release (40% release of total loaded drug from multilayer hydrogel beads and 80% of total loaded drug from monolayer hydrogel beads in 5 h), achieving controlled delivery. Mechanical testing confirmed spider silk reinforcement increased compressive strength. The porous monolayer structures and layered architectures in multilayer beads were analyzed by SEM analysis. Antibacterial assays showed improved antibacterial activity in hydrogel beads against S.aureus and E.Coli antimicrobial properties of chitosan, spider silk, and GQD.