LAUSR

Multi-compartmentalized nanostructures are of interest because they can provide unique physicochemical properties and multi-functionalities in each compartment. Furthermore, stimuli-responsive anisotropic nanostructures (ANPs) with distinct opposite charges would be useful for drug delivery systems because different drug release kinetics could be achieved from each compartment in response to both charge and stimuli. In this study, stimuli-responsive ANPs with oppositely charged compartments composed of two kinds of thermally responsive poly(N-isopropylacrylamide) copolymers were prepared via electrohydrodynamic co-jetting. The positively charged compartment was composed of poly(N-isopropylacylamide-co-stearyl acrylate-co-allylamine) (i.e., poly(NIPAM-co-SA-co-AAm)), while the negatively charged compartment consisted of poly(N-isopropylacylamide-co-stearyl acrylate-co-acrylic acid) (i.e., poly(NIPAM-co-SA-co-AAc)). The two distinct compartments of ANPs were physically crosslinked through hydrophobic interactions among long alkyl chains of SA moieties of both poly(NIPAM-co-SA-co-AAm) and poly(NIPAM-co-SA-co-AAc). Oppositely charged, small molecule model drugs (fluorescein sodium salt and rhodamine 6G) were alternately loaded into each compartment and released based on changes in noncovalent interactions and temperature. Furthermore, two different biomacromolecule drugs with opposite charges, BSA and lysozyme (which were complexed with polysaccharides by hydrophobic ion pairing), were separately encapsulated within the ANPs. Electrostatic interactions between the encapsulated drugs and each ANP compartment controlled the rate of drug release from the ANPs. In addition, these ANPs showed a thermally-induced actuation, leading to drug release at different rates due to the collapse of poly(NIPAM) copolymers under aqueous conditions. This work may be useful for decoupled drug release kinetics.