Hollow Cavity CaO 2 @polydopamin Nanocomposites for Ph-Responsive Ca 2+ -enhanced Efficient Mild Hyperthermia in The Nir-Ii Region.

Second near-infrared (NIR-II) mild photothermal therapy (PTT) with higher tissue penetration depth and less damage to healthy tissues is emerging as an attractive antitumor modality, but its therapeutic efficiency is dramatically suppressed by the resistance of heat shock proteins (HSPs). As a widely explored photothermal agent, the application of polydopamine (PDA) in the NIR-II region is hampered by low photothermal conversion efficiency (PCE). Herein, we improve its PCE in the NIR-II region by developing a novel hollow cavity CaO 2 @PDA nanocomposites through chelation-induced diffusion of inner core Ca 2+ to the shell PDA to facilitate multiple reflections of laser in the cavity. Upon pH-responsive degradation of CaO 2 , its structure was transformed into a stacked "nano-mesh" with excellent light absorption and an enlarged effective irradiation area. Overloading of Ca 2+ ions not only induced downregulation of HSPs but also enhanced interference of light on membrane potential, which further aggravated mitochondrial dysfunction and reduced the thermotolerance of tumor cells, promoting efficient mild hyperthermia of PDA in the NIR-II region. This article is protected by copyright. All rights reserved.