Sulfur-Doped NiFe Hydroxide Nanobowls with Wrinkling Patterns for Photothermal Cancer Therapy

Hierarchical multiscale wrinkling nanostructures have shown great promise for many biomedical applications, such as cancer diagnosis and therapy. However, synthesizing these materials with precise control remains challenging. Here, we report a sulfur doping strategy to synthesize sub-1 nm NiFe hydroxide ultrathin nanosheets (S-NiFe HUNs). The introduction of sulfur affects the reduction of the band gap and the adjustment of the electronic structure, thereby improving the light absorption ability of the S-NiFe HUNs. Additionally, S-NiFe HUNs show a multilayered nanobowl-like structure that enables multiple reflections of incident light inside the nanostructure, which improved the utilization of incident light and achieved high photothermal conversion. As a result, the as-prepared product with hydrophilic modification (dS-NiFe HUNs) demonstrated enhanced tumor-killing ability in vitro. In a mouse model of breast cancer, dS-NiFe HUNs combined with near-infrared light irradiation greatly inhibited tumor growth and prolonged the mice survival. Altogether, our study demonstrates the great potential of dS-NiFe HUNs for cancer photothermal therapy applications.