Rational design of aqueous conjugated polymer nanoparticles as potential theranostic agents of breast cancer

Abstract

Conjugated polymer nanoparticles (CPNs) have emerged as a new promising class of cancer theranostic agents due to their desirable optical features, such as high absorption coefficient and photoluminescence quantum yields, spanning from the ultraviolet to the near infrared, along with their photothermal and photodynamic properties. However, limited studies have been demonstrated up to now on the rational design of CPNs for specific biological purposes. In particular, it is not well understood how exactly the chemical structure of the conjugated polymer and the nanoparticle formulation approach (encapsulation versus nanoprecipitation) associates with the cytotoxicity, the intracellular uptake in vitro and the therapeutic behavior. For this reason, nanoprecipitated and encapsulated aqueous CPNs were formulated consisting of thiophene–quinoxaline type conjugated polymers varying as regards the number of the fluorine atoms (three versus four) on the repeat unit. The obtained CPNs were systematically examined in terms of cytotoxicity and intracellular uptake in vitro in three epithelial breast cell lines represented by one normal cell line, and two breast cancer cell lines composed of one luminal and one triple negative line. From the obtained results, it is presented that only the nanoprecipitated CPNs with the three fluorine atoms exhibited efficient intracellular uptake to all the epithelial cell lines tested, in addition to the visible fluorescence on the triple negative breast cancer cells. Moreover, evaluation of the comparison of the effect of the CPNs on cell proliferation and apoptosis of all cell lines with the corresponding antibiotic staurosporine was performed, indicating a putative therapeutic potential of nanoparticles under study.