Synthesis and Characterization of Carboxymethyl Starch for Drug Delivery Applications

In this study, carboxymethyl starch (CMS) was synthesized by reacting native sago starch with sodium monochloroacetate through single-step etherification reaction. Synthesis conditions such as reaction temperature, concentration of sodium hydroxide, amount of etherifying agent such as sodium monochloroacetate and reaction time of carboxymethylation were used to achieve the highest degree of substitution (DS) value of CMS. The preparation of CMS was carried out in the form of nanoparticles and hydrogel membrane while their physicochemical characteristics were studied for the potential application as drug delivery carrier. The fabrication of CMS nanoparticles was carried out by using simple nanoprecipitation and microemulsion techniques with the aid of sonication process. CMS nanoparticles with the mean particle size of 137 nm were directly obtained using sonication aided nano-precipitation technique. CMS nanoparticles showed to exhibit a lower swell ability characteristic in simulated gastric fluid at pH 1.4 which can be explained by longer paracetamol release rate within 28 hours. In comparison, drug release rate of paracetamol was observed to be faster in higher pH value of pH 8.6 which also governed by the deionization activity that encourage matrix swelling of the nanoparticles, while a fair proliferation of paracetamol release rate was observed within 23 hours in simulated blood and saliva fluid at pH 7.4 . In addition, the role of CMS / PVA hydrogel as a potential drug carrier membrane was elucidated in this study. The physical entrapment of penicillin G onto hydrogel matrix was achieved at 16 mg/g and the mechanism of drug release was described. It was revealed that the controlled release of drug penicillin G from the CMS hydrogel undergoes Zero Order and Hixson – Crowell kinetics which prevailed by the erosion of mesoporous hydrogel occurred progressively with time. Besides, this biodegradable hydrogel characteristic can be further utilized as the potential application in green transdermal drug delivery without the usage of any harsh chemicals. This study also demonstrated that the fabrication of CMS materials can be achieved in the facile and environmentally friendly system. Keywords: pH-responsive, carboxymethyl starch nanoparticles, carboxymethyl starch hydrogel, drug deliver