The hydroxethyl starch (HES) is very trending biopolymer in biomedical field.In recent research we have successfully synthesized a novel ester of HES, i.e., HES-acetate by acetylation of HES followed by investigation of its thermal behavior. The successful acetylation of HES was confirmed by Fourier Transform Infrared (FTIR) and Proton-Nuclear Magnetic Resonance (1H NMR) spectroscopic techniques. Thermal stability and thermal degradation kinetics of HES-acetate were investigated by thermo-gravimetric analysis. Flynn-Waal-Ozawa model was fitted to the thermal data to find the values of thermodynamic triplet (𝚫S, 𝚫G and 𝚫E). Energy of activation (Ea) values of the major thermal degradation steps were found to be 242.85 and 287.17 kJ mol -1 for HES and HES-acetate, respectively. The order of degradation, integral procedural decomposition temperature (IPDT) and index of intrinsic thermal stability (ITS) were also taken into account. The results of the thermal analysis reveal that the HES-acetate gained significant thermal stability as compared to that of HES. This benign polysaccharide-based material was investigated for its potential in drug release studies by taking caffeine as a model drug. HES-acetate-based matrix tablets showed sustained release behavior of the drug indicating its potential for the development of oral delivery systems for sustained drug release.

This study reports cross-linking of hydroxyethyl starch (HES) using citric acid to from cross-linked HES-citrate. The HES-citrate as obtained is characterized using FTIR and 1 H NMR. The cross-linked product HES-citrate shows remarkable swelling in different media simulated to the physiological systems of human body, i.e., deionized water (DW), pH 6.8 and 7.4, and followed second order swelling kinetics. The HES-citrate exhibits reversible swelling/deswelling in different combinations of stimuli, i.e., at pH 7.4 and 1.2, in DW and normal saline and in DW and ethanol which makes it a potential candidate for intelligent drug delivery. Therefore, cross-linked product shows extraordinary stimuli-responsiveness under different physiological conditions such as in presence electrolytes and solvents and at different temperatures. HES-citrate-based aceclofenac tablet is formulated that demonstrates sustained-release under conditions mimicked to gastrointestinal tract (GIT) in terms of pH and transit time.