Core-Shell Au@Pd Bimetallic Nanozyme Mediated Mild Photothermal Therapy through Reactive Oxygen Species-Regulating Tumor Thermoresistance.

Mild photothermal therapy (mPTT), which circumvents the limitations of conventional photothermal therapy, is emerging and exhibits remarkable potential in clinical applications. Nevertheless, mPTT is not able to efficiently eradicate tumors because its therapeutic efficacy is dramatically diminished by stress-induced heat shock proteins (HSP). Herein, a core-shell structured Au@Pd (AP) bimetallic nanozyme was fabricated for reactive oxygen species (ROS) augmentation-induced mPTT. The nanocatalytic AP nanozymes with photothermal conversion performance harbor multienzymatic (catalase, oxidase, and peroxidase) activities to induce ROS storm formation. The generated ROS could suppress the heat-defense response of tumor cells by cleaving HSP. Overall, our work highlights a ROS-regulating strategy to counteract hyperthermia-associated resistance in mPTT.

Low-Temperature Photothermal Therapy Platform Based on Pd Nanozyme-Modified Hydrogenated TiO2.

In photothermal treatments (PTTs), normal tissues around cancerous tumors get injured by excessive heat, whereas damaged cancer cells are easily restored by stress-induced heat shock proteins (HSPs) at low temperatures. Therefore, to achieve a unique tumor microenvironment (TME), it is imperative to increase PTT efficiency and reduce normal tissue injury by adopting appropriate reactive oxygen species (ROS) and lipid peroxides (LPO) cross-linked with HSPs. In the present research, a potential strategy for mild photothermal treatments (mPTTs) was proposed by initiating localized catalytic chemical reactions in TME based on Pd nanozyme-modified hydrogenated TiO2 (H-TiO2@Pd). In vitro and in vivo evaluations demonstrated that H-TiO2@Pd had good peroxidase-like activities (POD), glutathione oxidase-like activities (GSHOx), and photodynamic properties and also satisfactory biocompatibility for 4T1 cells. Localized catalytic chemical reactions in H-TiO2@Pd significantly depleted GSH to downregulate the protein expression of GPX4 and promoted the accumulation of LPO and ROS, which consumed HSP70 or inhibited its function in 4T1 cells. Hence, the as-constructed low-temperature photothermal therapeutic platform based on Pd nanozyme-modified H-TiO2 can be a promising candidate to develop a safe and effective mPTT for cancer treatments.

Mo2C-MoO2 Heterostructure Quantum Dots for Enhanced Electrocatalytic Nitrogen Reduction to Ammonia.

The electrocatalytic nitrogen reduction reaction (NRR) has been regarded as a promising strategy for producing ammonia (NH3) at ambient conditions. However, the development of the NRR is severely hindered by the difficult adsorption and activation of N2 on the catalyst surface and the competitive hydrogen evolution reaction (HER) due to the lack of efficient NRR electrocatalysts. Herein, Mo2C-MoO2 heterostructure quantum dots embedded in reduced graphene oxide (RGO) are proposed as efficient catalysts for the electrocatalytic NRR. The ultrasmall size of the quantum dot is beneficial for exposing the active sites for the NRR, and the synergetic effect of Mo2C and MoO2 can promote N2 adsorption and activation and suppress the competitive HER simultaneously. As a result, a well-balanced NRR performance is achieved with a high NH3 yield rate of 13.94 ± 0.39 µg h-1 mg-1 at -0.15 V vs RHE and a high Faradaic efficiency of 12.72 ± 0.58% at -0.1 V vs RHE. Density functional theory (DFT) calculations reveal that the Mo2C (001) surface has a strong N2 adsorption energy of -1.47 eV with the side-on configuration, and the N≡N bond length is elongated to 1.254 Å, indicating the enhanced N2 adsorption and activation on the Mo2C surface. On the other hand, the low ΔGH* for HER over the MoO2 (-111) surface demonstrates the impeded HER process for MoO2. This work may provide effective catalyst-design strategies for enhancing the electrocatalytic NRR performance of Mo-based materials.