Optical Characteristics of Indocyanine Green J-Aggregates Induced by Cisplatin for Phototheranostic Applications.

The development of an optical system for combinatorial theranostics is of significant interest. Clinical translation of such theranostic agents need to cross several barriers. Herein, we have developed a facile method for the preparation of J-aggregates using FDA approved agents, namely, NIR fluorophore indocyanine green (ICG) and a chemotherapeutic drug, cisplatin (CDDP), which induces ICG to form indocyanine green J-aggregates (IJAs). The formation of IJAs has been characterized by the formation of a new absorption peak centered at ∼896 nm. The existing methods to synthesize IJAs have used several harsh reaction conditions, such as elevated temperatures, for a prolonged time duration (∼60 days). To the best of our knowledge, for the first time, we have reported the formation of IJAs assisted by CDDP at 37 °C temperature within 12 h. The presence of CDDP in ICG favors IJA formation and thereby reduces the harshness of the reaction conditions in the conventionally followed protocols. Moreover, the presence of CDDP can facilitate photoactivated combinatorial therapy. The as synthesized IJA optical system has superior properties to those of free ICG, in terms of diagnostic and therapeutic capabilities (being activatable at ∼896 nm wavelength, which can achieve deeper tissue penetration) and excellent optical and storage stability. The facile synthesis proposed along with CDDP incorporation makes the optical system a clinically relevant one-component theranostic agent.