Preparation And Characterization Of Chitosan-based Functional Microcapsules

Over the past few decades,smart drug delivery systems have attracted great attention in the biomedical field.Smart drug delivery systems have been widely used for delivering and releasing of drug,gene,cells and enzymes.Smart drug delivery systems are not only non-toxic,non-immunogenic,biocompatible and biodegradable,but also possess the properties of stimuli-responsive targeted drug delivery and triggered drug release?e.g.,p H,redox gradient,temperature and enzyme?to efficiently improve the chemotherapy efficiency and avoid the severe side effects in healthy tissues.In this paper,the research focuses on the fabrication of multi-stimuli responsive smart chitosan-based microcapsules?MSRS-CS-MCs?via sonochemical method and their performances.The designed multi-stimuli responsive smart chitosan-based microcapsules?MSRS-CS-MCs?have been fabricated successfully from folic acid?FA?functionalized thiolated chitosan via a facile sonochemical method.Targeting moiety FA and red fluorescent dye?Rhodamine B isothiocyanate,RITC?were immobilized onto the shells of microcapsules.Meanwhile,oleic acid?OA?modified Fe₃O₄ magnetic nanoparticles?OA-Fe₃O₄ MNPs?and a model hydrophobic drug,green fluorescent dye?Coumarin 6,C6?,were encapsulated into the microcapsules.Furthermore,the influences of ultrasonic power,ultrasonic time and concentration of CS aqueous solution on the morphologies and sizes of MSRS-CS-MCs were investigated in detail.Moreover,the magnetic responsive ability,cellar selectivity and reduction-responsive controlled release ability for hydrophobic drugs have been studied.It is indicated that the obtained spherical MSRS-CS-MCs showed excellent molecular and magnetic targeting ability due to the FA molecules fixed on the shell of microcapsules and the OA-Fe₃O₄ NPs loaded into the microcapsules.Furthermore,the shell of MSRS-CS-MCs could protect the drugs to be delivery to the targeted point and avoid leaking drugs during transportation.MSRS-CS-MCs showed attractive reduction-responsive release ability for hydrophobic drugs due to cross-linking of the shell by disulfide bonds and can effectively control the release of the hydrophobic drugs under the reduction of GSH.