Synthesis, Characterization, and In Vitro Evaluation of Near-Infrared Absorbing Conductive Polymer Nanoparticles as Agents for Photothermal Ablation of Breast Cancer Cells
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In recent years, photothermal therapy (PTT) has emerged as a viable alternative for cancer treatment. Much effort has been devoted to finding various types of PTT agents with excellent heat generation, photothermal efficiency, biocompatibility, and biodegradability. In this work, polymeric nanoparticles (NPs) composed of poly(1,4-bis(3,4-ethylenedioxythienyl)-2,5-dialkoxybenzenes) (PBEDOT-B(OR)2) and poly(3,4-ethylenedioxythiophene) (PEDOT) were synthesized using microemulsion polymerization. The NPs were characterized using dynamic light scattering, UV-Vis-NIR spectroscopy, and electron microscopy. The microemulsion polymerization yielded sub–100 nm NPs and the colloidal suspensions exhibited a strong absorbance in the near infrared region. The photothermal transduction and efficiency of these materials were determined and compared to those of commonly used PTT agents. When irradiated with NIR light, the suspensions showed a temperature change of ca. 30 °C with a photothermal efficiency of ca. 35%. In vitro cytocompatibility studies were also performed on the conductive polymeric NPs in an effort to determine the concentration limits that could be used without causing toxicity to cells. Cytocompatibility studies for the colloid suspensions were conducted at 24 h and exposure times, and the NPs were found to be non-toxic at a dose of 50 μg/mL. Photothermal in vitro studies also demonstrated that cell death can be achieved after 5 min of irradiation at concentrations as low as 0.5 μg/mL. These results suggest that these materials could be good candidates for use as photothermal therapy (PTT) agents.