Thermoresponsive Nanogel-Encapsulated PEDOT and HSP70 Inhibitor for Improving the Depth of the Photothermal Therapeutic Effect

Photothermal therapy (PTT), a new, noninvasive treatment measure, has recently drawn much attention. However, due to the limited penetration depth of near-infrared (NIR) light, PTT is focused on treating superficial tumors. Improving the depth of the therapeutic effect is a bottleneck for successful PTT. To solve this problem, a new kind of nanoplatform (Nanogel+phenylethynesulfonamide (PES)) is fabricated by using a thermo-responsive polymer shell (poly(N-isopropylacrylamide-co-acrylic acid) to encapsulate 2-PES, an effective heat shock protein 70 (HSP70) inhibitor, and poly(3,4-ethylenedioxythiophene), a widely used photothermal coupling agent. Upon NIR irradiation, PES can be released from the Nanogel+PES when a thermo-responsive phase transition occurs, which could restrain the function of HSP70 and reduces the cells' endurance to heat. In this way, a better therapeutic effect on deeper tissues is achieved with a relatively small rise in temperature. Therefore, with the advantages of the thermo-responsive photothermal effect, coupled with the inhibition of HSP70, and minimal cytotoxicity, the Nanogel+PES appears to be a promising photothermal agent that can improve the depth of the PTT effect.