Near-infrared stimulated hydrogel patch for photothermal therapeutics and thermoresponsive drug delivery.

Nanotechnology driven cancer theranostics hold potential as promising future clinical modalities. Currently, there is a strong emphasis on the development of combinational modalities, especially for cancer treatment. In this study, we present a topical hydrogel patch for nanomaterial-assisted photothermal therapeutics as well as for on-demand drug delivery application. The patch was derived from interpenetrating networks (IPNs) of alginate (Alg) and polyacrylamide (PAAm) in weight ratio 8:1 by free radical polymerization. The patch interiors were composed of hybrid nanostructures derived from gold nanorods (AuNRs) anchored onto polyvinylpyrrolidone (PVP) functionalized graphene oxide (PVP-nGO) to form PVP-nGO@AuNRs hybrids. Field emission scanning electron microscopy (FE-SEM) images revealed the porous nature of the hybrid hydrogel patch with an average pore size of ~28.60 ± 3.10 μm. Besides, functional characteristics of the hybrid patch, such as mechanical strength, viscoelastic and swelling behavior, were investigated. Under near-infrared (NIR) radiation exposure, the hybrid patch exhibited photothermal properties such as surface temperature rise to 75.16 ± 0.32 °C, sufficient to ablate cancer cells thermally. Besides, the heat generated in the hybrid patch could be transmitted to an underlying hydrogel (mimicking skin tissue) when stacked together without much loss. Under cyclic photothermal heating, the patch could retain its photothermal stability for four cycles. Furthermore, the hybrid patch demonstrated NIR stimulated drug release, which was evaluated using methotrexate (MTX, water-insoluble anticancer drug) and rhodamine B (RhB, water-soluble dye). Taken together, this work provides a new dimension towards the development of externally placed hydrogel patches for thermal destruction of localized solid tumors and tunable delivery of chemotherapeutic drugs at the target site.