Synthesis,Characterization And Application In The Bioimaging Of Conjugated Polymer Nanomaterials Based On 2,1,3-benzothiadiazole

In recent years,conjugated polymers(CPs) nanoparticles had been widely used as biological fluorescence probe,drug carrier and optical physical therapy in cancer as CPs have excellent optical properties and well biocompatibility. Conjugated polyelectrolytes(CPEs) which have the same main chain structure while have ionization groups are another kind of emerging biological functional materials. CPEs can bring different charges which make it more easily and flexible for CPEs to use in the field of biomedical research. In this paper, we synthesized two kinds of conjugated polyelectrolytes based on 2,1,3-benzothiadiazole and then used them all in the field of bioimaging aiming to investigate the differences between them.PFBT fluorescent conjugated polymer has high fluorescence quantum efficiency,good optical stability and biocompatibility characteristics,and been widely used in biomedical research. Based on the Suzuki coupling reaction method we synthesized a cationic polyelectrolyte and an anionic polyelectrolyte,named PFBD and PFSBT respectively. Then we prepared PFBT,PFBD and PFSBT into nanoparticles,respectively. From the dynamic light scattering(DLS) it is well known that the size of the PFBT,PFBD and PFSBT nanoparticles are 18 nm,20 nm and 24 nm, respectively. From transmission electron microscopy(TEM) it is well known that all the three kinds of nanoparticles show spherical morphology. For the conjugated polyelectrolytes nanoparticle,the very low degree of aggregation in the TEM can be observed, which might be caused from the surface charges of the two kinds of nanoparticles. From the fluorescent spectra the absorption peak and the emission peak of these nanoparticles are very close,respectively. The emission spectrum of PFBD and PFSBT shows a bit redshift compared with PFBT, which might be caused from the different charges on the side chains.The biological experimental resμLts of three kinds of nanoparticles show that,in PFBD and PFSBT polyelectrolyte nanoparticles cytotoxicity is lower than PFBT nanoparticles. Even though the PFBD and PFSBT concentration reaches 80 ppm,they still can maintain the normal growth of cells can still be maintained. Cell imaging shows that PFBT and PFSBT nanoparticles have high effect of swallowing inside the cell,and the majority of these nanoparticles distribute in the cytoplasm. For the cationic conjugated polyelectrolyte PFBD nanoparticles,the intracellular distribution is more focused on the surface of the nucleus, which indicates that PFBD nanoparticles have potential on labeling nucleus specificity. By flow cytometry instrument testing,PFBD and PFSBT shows higher endocytosis brightness and efficiency of endocytosis. Moreover, after PFBT nanoparticles coupling peptide(R8) with a certain amount,it’s brightness is able to compare with that of PFBD.