Konjuge polimer nanoparçacıkların ilaç taşınımı ve biyolojik görüntüleme içeren biyomedikal uygulamaları

In this study, the ability of fluorene-based conjugated polymer nanoparticles in the delivery of anticancer therapeutics and bioimaging was investigated through in vitro cytotoxicity assessments and fluorescence imaging. In order to prepare the nanoparticles, green light emitting polymer,poly[(9,9-bis{6-dimethylaminohexyl}fluorenyl-2,7-diyl)-co-(1,4-benzo-{2,1,3}-thiodiazole)] (PDAFBT),was synthesized via Suzuki coupling reaction and characterized by nuclear magnetic resonance (NMR), electrospray ionization mass spectroscopy (ESI-MS), matrix assisted laser desorption ionization mass spectroscopy (MALDI), fourier transform infrared spectroscopy (FT-IR), UV-visible absorption spectroscopy (UV-Vis) and fluorescence spectroscopies. PDAFBT nanoparticles were synthesized through reprecipitation method which is based on the injection of the polymer solution in a good solvent into a poor solvent for the polymer to enhance the collapse of polymer chains in the form of spherical nanoparticles. Anti-cancer drug, camptothecin (CPT), was entrapped into the PDAFBT nanoparticles via hydrophobic interaction during the nanoparticle formation. Size, surface charge, morphology and optical characterizations of blank and CPT loaded nanoparticles were investigated by dynamic light scattering (DLS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-Vis and fluorescence spectrocopies. In order to investigate the properties of nanoparticles as drug carrier, drug encapsulation efficiency (EE) and drug loading efficiency (LE) were determined and EE was found to be as 92% and 75% for the 1:35 and 1:25 polymer to drug ratios, respectively, while LE of PDAFBT nanoparticles was determined as 2.67±0.3 %. Preliminary drug release profile which needs to be strengthen statistically, of PDAFBT nanoparticles was analyzed and showed that almost 100% of the loaded CPT was released steadily during first 48h time period indicating that the release of CPT is not a burst process. Stability of blank and CPT loaded PDAFBT nanoparticles was examined in different biological media including cell culture medium, bovine serum albumine (BSA) andhuman serum. The precipitation in nanoparticle dispersion was observed due to adsorption of proteins onto the surface of polymers. In vitro dose dependent cytotoxicity of blank and CPT loaded PDAFBT nanoparticles was assessed through 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazoliumbromide (MTT) toxicology assay on human carcinoma breast cancer cell lines, namely,MDA-MB-231, MDA-MB-157 and MCF-7 cells. The blank PDAFBT nanoparticlesdo not exhibit significant toxicity to MDA-MB-231 and MDA-MB-157 cells up to 40 ?M, however, a linear decrease on the viability of MCF-7 cells was detected ata concentration higher than 2.5 ?M and nearly 40% of the cells were dead at 40 ?M.The half maximal inhibitory concentration (IC50 ) values of free CPT and CPT loaded PDAFBT NPs were calculated to be 4.50?M and 1.35?M for MDA-MB-157 cell line, respectively, and 1.97?M and 1.05?M for MDA-MB-231 cells, respectively. These results indicate clearly that the CT-loaded nanoparticles are more efficient than free CPT in destroying the cancer cells. Fluorescent microscope images show also the efficient internalization of blank and CPT-loaded nanoparticles by MDA-MB-157 and MDA-MB-213 cell lines. Preliminarily in vivo studies have been performed on embryonic zebra fish and C. Elegans animal models using these nanoparticles and the efficient uptake of nanoparticles by the tissues have been observed by fluorescent microscopy. This results indicate that CPNs are promising for imaging and delivery vehicles for time and dose dependent treatments.