Acridine orange tethered chitosan reduced gold nanoparticles: a dual functional probe for combined photodynamic and photothermal therapy

Abstract

Plasmonic nanoparticles have been widely used in photomedicine owing to their unique photophysical properties including surface plasmon resonance, high optical extinction and extensive thermal stability, which makes metal nanoparticles more suitable for application in cancer phototherapy. Here, we exploit the appropriateness of chitosan reduced gold nanoparticles (AuNPs) as a photothermal converter, photodynamic carrier and contrast agent in the applications of bioimaging, photothermal (PTT) and photodynamic therapy (PDT), concurrently to destroy the human breast cancer cells (MCF-7). AuNPs were successfully conjugated by non-covalent interaction with hydrophilic photosensitizer, acridine orange (AO) through glutathione (GSH) to achieve improved PDT and PTT therapy. This could be attributed to the high loading efficiency with enhanced cellular uptake and excellent photothermal stability of the nanoconjugate (AO@GSH–AuNPs). In addition, the anticancer activity of the nanoconjugate in combination with blue light irradiation (λ = 492 nm) demonstrated a pronounced effect compared to the free AO or light irradiation. Thus results of our studies represent the dual mode action of both AO and AuNPs showing photodynamic and photothermal ablation, respectively. Our findings suggest that the AO@GSH–AuNPs nanoconjugate could be used as a multifunctional probe for anticancer therapy.