A bifunctional biomineralized polyoxometalate enabling efficient Non-Inflammatory NIR-II photothermal tumor therapy

•We synthesized a novel bifunctional biomineralized Mo-polyoxometalate (B-POM) via a facile self-assembled method for non-inflammatory near-infrared (NIR)-II PTT for the first time.•The obtained B-POM NPs show excellent biocompatibility and high NIR-II photothermal conversion efficiency up to 57.2%.•More importantly, the B-POM NPs are also endowed with scavenging many kinds of ROS, including H2O2, •OH, and O2– etc. significantly reduce inflammation after NIR-II PTT in vivo. Conventional NIR-I photothermal therapy (PTT) has insufficient penetration depth, and the local tissue damage caused by it often concomitants inflammation. Herein, a bifunctional nanoagent based on bovine serum albumin (BSA) and Mo-polyoxometalate (named as B-POM NPs), was developed via a facile self-assembled method for non-inflammatory near-infrared (NIR)-II PTT of triple-negative breast cancer. Thanks for the BSA modification, the obtained B-POM NPs show excellent biocompatibility with high NIR-II photothermal conversion efficiency of 57.2%. In vivo tumor inhibition efficiency under NIR-II PTT reached up to 87 %. More importantly, it is found that the prepared B-POM NPs also have excellent reactive oxygen species scavenging ability. The inflammatory-related factors, such as TNF-α, IL-6 and IL-1β, are significantly down-regulated, which is much beneficial to reduce side effects of PTT. In brief, this work provides a novel protein-based bifunctional nanoagent to effectively inhibit tumor growth meanwhile alleviate inflammatory post NIR-II PTT, showing good promising in clinical.