Temperature and magnetic field responsive hyaluronic acid particles with tunable physical and chemical properties

We report the preparation and characterization of thiolated-temperature-responsive hyaluronic acid–cysteamine–N-isopropyl acrylamide (HA–CYs–NIPAm) particles and thiolated-magnetic-responsive hyaluronic acid (HA–Fe–CYs) particles. Linear hyaluronic acid (HA) crosslinked with divinyl sulfone as HA particles was prepared using a water-in-oil micro emulsion system which were then oxidized HA–O with NaIO4 to develop aldehyde groups on the particle surface. HA–O hydrogel particles were then reacted with cysteamine (CYs) which interacted with aldehydes on the HA surface to form HA particles with cysteamine (HA–CYs) functionality on the surface. HA–CYs particles were further exposed to radical polymerization with NIPAm to obtain temperature responsive HA–CYs–NIPAm hydrogel particles. To acquire magnetic field responsive HA composites, magnetic iron particles were included in HA to form HA–Fe during HA particle preparation. HA–Fe hydrogel particles were also chemically modified. The prepared HA–CYs–NIPAm demonstrated temperature dependent size variations and phase transition temperature. HA–CYs–NIPAm and HA–Fe–CYs particles can be used as drug delivery vehicles. Sulfamethoxazole (SMZ), an antibacterial drug, was used as a model drug for temperature-induced release studies from these particles.