Synthesis and characterization of photoresponsive amphiphilic star copolymers as drug carriers

In recent years, drug delivery systems have come to the forefront because of the advantages of increasing drug efficacy, targeted transport and especially minimizing the side effects of cancer therapeutics and increasing the studies in this field. On the other hand, particularly micelles which are formed by amphiphilic block copolymers that respond to external stimuli gather attention. The development of star copolymers having advantageous properties compared to linear polymer analogs has gained importance. With the help of controlled radical polymerization techniques, it is provided to obtain the desired size and functionality of polymer structures and to improve the micelle structures. By forming photosensitive micelles, micelle stabilization, release mechanism and specific targeting properties are tried to be obtained. In this study, an amphiphilic star block copolymer bearing light dimerizable anthracene groups was synthesized by using controlled polymerization technique. Methyl methacrylate and anthracene methacrylate monomers were polymerized together by atom transfer radical polymerization (ATRP) to form hydrophobic arms of the star. The obtained polymer was used as a macroinitiator in the ATRP polymerization of poly (ethylene glycol) methyl ether methacrylate monomer and the amphiphilic star block copolymer was obtained. Polymers synthesized in the study were characterized by FT-IR, 1H NMR, UV-Vis and DSC. In the next step, micelles were formed with the amphiphilic copolymer using the dialysis membrane method and then loaded with doxorubicin (DOX) to determine drug delivery efficiency. The particle sizes of empty and drug loaded micelles were measured with DLS and compared with those obtained from TEM images. In the last stage, in vitro drug release profiles of DOX loaded micelles were examined in physiological pH.