Poly(2-ethyl-2-oxazoline)–IR780 conjugate nanoparticles for breast cancer phototherapy

To address the limitations of IR780 by preparing hydrophilic polymer–IR780 conjugates and to employ these conjugates in the assembly of nanoparticles (NPs) intended for cancer photothermal therapy. The cyclohexenyl ring of IR780 was conjugated for the first time with thiol-terminated poly(2-ethyl-2-oxazoline) (PEtOx). This novel poly(2-ethyl-2-oxazoline)-IR780 (PEtOx-IR) conjugate was combined with D-α-tocopheryl succinate (TOS), leading to the assembly of mixed NPs (PEtOx-IR/TOS NPs). PEtOx-IR/TOS NPs displayed optimal colloidal stability as well as cytocompatibility in healthy cells at doses within the therapeutic range. In turn, the combination of PEtOx-IR/TOS NPs and near-infrared light reduced heterotypic breast cancer spheroid viability to just 15%. PEtOx-IR/TOS NPs are promising agents for breast cancer photothermal therapy. Conventional anticancer approaches are often associated with severe side effects. Herein, the authors assembled a novel nanoparticle whose therapeutic effect is triggered by laser light. In assays, the produced nanomaterial was able to, after interacting with laser light, reduce the viability of classic and advanced cancer models. In these conditions, but in the absence of laser light, no cytotoxicity was observed. In this way, the on-demand effect (triggered by laser light) may contribute to reduced side effects. Moreover, the produced nanoparticle revealed good stability, which is important for its future translation.