Donor-acceptor squaraine-based theranostic platforms for combined type I photodynamic, photothermal and chemo...

A donor-acceptor-type squaraine dye is synthesized, and its phototherapeutic features are comprehensively evaluated for in vitro applications. It is noteworthy that squaraine shows both photodynamic and photothermal activity under illumination. More importantly, squaraine induces type I sensitization for photodynamic therapy and produces superoxide with a quantum yield of 0.356. The photothermal activity of squaraine is examined under a 635 nm laser, which increased the temperature gradually from 24.0 °C to 60.0 °C. The photothermal conversion efficiency is calculated to be 21.2%. Subsequently, in vitro studies are carried out with two different types of cancer cells (SK-MEL-30/An1 and MCF-7). The cell death is increased up to 90% in SK-MEL-30/An1 (ATCC® HTB-73™) and MCF-7 (ATCC® HTB-22™) cells. Furthermore, various amounts of squaraine are incorporated into polyacrylamide (PAAm) hydrogels that exhibit phototherapeutic effects. In addition, methotrexate (MTX) was loaded into these hydrogels. It is found that PAAm hydrogels are good candidates for multimodal therapy, including PDT, PTT, and chemotherapy against SK-MEL-30/An1 cells. The results indicate that 89% of SK-MEL-30/An1 cells are eliminated after a session of multitherapy.