Natural Thermoresponsive Rice Granules as Biocompatible Drug Carriers

Through thermal gravimetric, X-ray diffraction, infrared spectroscopy, and scanning electron microscopic analyses, here we reveal that the 4-5 μm diameter pentagonal shaped rice granules are surprisingly stable against α-amylase, trypsin, lipase, diluted acids, and diluted bases. Some papain-sensitive proteins play an important role in the granular shape stabilization. We employ the reversible thermoresponsive expansion/shrinking character in aqueous medium of this biopolymeric pentagonal granular assembly to encapsulate the antibiotic vancomycin into the granule at the drug loading content of 80% drug mass with only 20% rice granule mass. The obtained drug-loaded granules display no-burst but steady sustained release of the water-soluble vancomycin in an aqueous environment for more than 24 h.