The Pimpled Gold Nanosphere: a Superior Candidate for Plasmonic Photothermal Therapy

Abstract

Background: The development of highly efficient nanoparticles to convert light to heat for anti-cancer applications is quite a challenging field of research. Methods: In this study, we synthesized unique pimpled gold nanospheres (PGNSs) for plasmonic photothermal therapy (PPTT). The light-to-heat conversion capability of PGNSs and PPTT damage at the cellular level were investigated using a tissue phantom model. The ability of PGNSs to induce robust cellular damage was studied during cytotoxicity tests on colorectal adenocarcinoma (DLD-1) and fibroblast cell lines. Further, a numerical model of plasmonic (COMSOL Multiphysics) properties was used with the PPTT experimental assays. Results: A low cytotoxic effect of thiolated polyethylene glycol (SH-PEG400-SH-) was observed which improved the biocompatibility of PGNSs to maintain 89.4% cell viability during cytometry assays (in terms of fibroblast cells for 24 hrs at a concentration of 300 mu g/mL). The heat generated from the nanoparticle-mediated phantom models resulted in Delta T=30 degrees C, Delta T=23.1 degrees C and Delta T=21 degrees C for the PGNSs, AuNRs, and AuNPs, respectively (at a 300 mu g/mL concentration and for 325 sec). For the in vitro assays of PPTT on cancer cells, the PGNS group induced a 68.78% lethality (apoptosis) on DLD-1 cells. Fluorescence microscopy results showed the destruction of cell membranes and nuclei for the PPTT group. Experiments further revealed a penetration depth of sufficient PPTT damage in a physical tumor model after hematoxylin and eosin (H&E) staining through pathological studies (at depths of 2, 3 and 4 cm). Severe structural damages were observed in the tissue model through an 808-nm laser exposed to the PGNSs. Conclusion: Collectively, such results show much promise for the use of the present PGNSs and photothermal therapy for numerous anti-cancer applications.