Synthesis of surfactant-free starch-based microspheres indifferent size ranges and factors affecting the synthesisprocess

Microspheres with controlled size and morphology are preferred in various applications, especially in the medical field as drug delivery systems. Emulsion polymerization technique is commonly used for the synthesis of microspheres. In this study, the aim was to synthesize biocompatible and biodegradable microspheres with narrow size distribution as drug carriers. Starch, a natural polymer with low cytotoxicity, was chosen for the production of microspheres using the surfactant-free emulsion polymerization (SFEP) method. The increase in the ratio of dispersed phase to continuous phase (21% - 100%) was observed to increase the diameter of the microspheres and with increasing polymer concentration (3% - 10% by weight), pH (7 - 10), temperature (30 - 70°C), cross-linker amount (1% - 20% by volume), and emulsion stirring speeds (500 – 1000 RPM) were perceived to decrease the diameter of the microspheres. Microspheres produced with narrow size distribution above 400µm were examined by scanning electron microscopy (SEM) for their topography. Weight and size changes were evaluated with respect to temperature conditions. Additionally, drug loading of the particles was analyzed using UV-Vis Spectrophotometry. The highest drug loading efficiency (99.81%) was observed in microspheres synthesized with 500 RPM stirring speed, with a degradation time of 55±2.33 days. The cytotoxic effect of particles on the L-929 cell line was evaluated through viability tests, and the highest viability (113.53 ± 5.54%) was observed in microspheres synthesized with 10% polymer concentration by weight. The results of this thesis study demonstrate that stable microspheres produced from starch using the SFEP method exhibit low cytotoxicity and high drug loading efficiency, making them suitable for various medical and cosmetic applications. Keywords: Polymeric microsphere, Starch, Crosslinker, Surfactant-free emulsion polymerization