Near-Infrared Mediated Photothermal Ablation of Cancer Cells using Low Band Gap Polymer Nanoparticles

C.M. MacNeill, R.C. Coffin, D.L. Carroll, N.H. Levi-Polyachenko
Wake Forest University Health Sciences, US

Keywords: cancer, conjugated polymer, photothermal therapy

Summary:

Near-infrared (NIR) photothermal therapy using nanomaterials, such as carbon or metal nanoparticles, has garnered much attention as a minimally invasive and efficient treatment for cancer. Under NIR stimulation, excitation of vibrational resonances in the nanomaterial allow for heat generation, which destroys surrounding cancer cells. We have recently developed donor-acceptor (D-A) electrically conducting polymer (ECP) based nanoparticles that can be used for NIR photothermal therapy. Through judicious choice of co-monomers used, D-A ECPs can be tuned to have excellent absorption properties in the NIR window from 700-900 nm, where body tissue is most transparent. We have utilized low band gap D-A ECPNs along with NIR light to photothermally destroy cancer cells in-vitro. The D-A ECPs chosen for this study are based on cyclopentadithiophene with 2,1,3-benzothiadiazole (PCPDTBT) and 2,1,3-benzoselenadiazole (PCPDTBSe) because both of the copolymers absorb around 800 nm (Eg = 1.46 and 1.37 eV). We have employed a facile technique to disperse the D-A ECPs in aqueous media to form D-A electrically conducting polymer nanoparticles (ECPNs). We have characterized these nanoparticles using TEM, DLS, UV-Vis, FT-IR and Raman spectroscopies. We have also tested the heating efficacy, cytotoxicity and photothermal ablation efficiency of these polymer nanoparticles in vitro.