Recent advances on stimuli-responsive biopolymer-based nanocomposites for drug delivery

Drug delivery plays a crucial part in medical therapy, where stimuli-responsive nanocarriers exhibit high delivery efficacy through changing their physicochemical properties in response to in vivo or external stimuli. In particular, biopolymer-based nanocomposites have attracted great attention as drug carriers due to their good biocompatibility, biodegradation, easy modification, low immunogenicity, and so on. They can be designed to transform size, charge and/or stability to prolong the blood circulation, accumulate at the diseased site, penetrate in tissues, internalize to target cells, and finally deliver and control drug release on demand under endogenous stimuli (e.g., acidic pH, enzymes and GSH), exogenous stimuli (e.g., temperature, light, magnetic field, and ultrasound), and both endogenous and exogenous stimuli. Different from the reviews on stimuliresponsive nanocomposites based on single biopolymer or general ideas of biopolymer-based nanocomposites, this paper summarizes strategies and recent progress of stimuli-responsive nanocomposites based on biopolymers such as polysaccharides (chitosan, hyaluronic acid, alginate, cyclodextrin, starch and cellulose) and proteins (gelatin, silk fibroin and collagen), and details their fabrication and application in drug delivery. Furthermore, this review provides evidence and ideas for designing stimuli-responsive nanocomposites for drug delivery.