Molecular aggregates for enhanced photothermal effect

Abstract

Photothermal therapy (PTT) is emerging as a promising non-invasive cancer treatment which utilizes localized heat generation by near-infrared (NIR) light to cause tumor ablation. Indocyanine green (ICG) is an FDA approved NIR dye which has been widely used as a photothermal agent (PTA). The therapeutic potential of ICG is hindered by rapid degradation, rapid clearance from circulation and poor photostability. To address these limitations, recent studies are going on in J-aggregates which are the molecular assemblies of ICG arranged in a head to tail manner with a red shifted absorption spectrum. Our study explores the photophysical characteristics of J-aggregates. It also focuses on the formation and application of J-aggregates, which exhibit enhanced optical stability, improved heat generation, and superior photothermal conversion efficiency. A new approach has been followed to enhance the photothermal conversion efficiency by utilizing a dual-laser irradiation set up orchestrated using some optical tools. This report highlights the optimal concentration, temperature, incubation time for the formation of J-aggregates and its stability across different solvents and pH systems. In addition, the photothermal studies revealed a substantial increase in temperature elevation for J-aggregates under dual laser irradiation. Preliminary in-vitro cytotoxicity studies have shown high biocompatibility of J-aggregates in normal and cancer cells. However, In-vitro PTT study and life-dead assays also shown that J-aggregates are efficient photothermal agent for the killing of cancerous cells under dual laser irradiation. Thus, these findings bring that J-aggregates can be a promising photothermal agent for effective cancer treatment.