Scheme 1.

Schematic illustration of the synthetic process of 2D composite nanosheets Nb₂C–MSNs–SNO and photonic thermogaseous therapy against cancer with potential PA‐imaging (PAI) guidance and monitoring. a) Scheme of the fabrication process of ultrathin Nb₂C nanosheets by HF etching and TPAOH intercalation. b) Schematic diagram for the fabrication of Nb₂C–MSNs–SNO, including CTAC absorption, mesoporous silica coating, PEGylation, and NO donor conjugation. c) Schematic illustration of theranostic functions of Nb₂C–MSNs–SNO, including free delivery within blood vessel after intravenous injection, photothermal‐triggered NO release, photonic thermogaseous therapy toward oncotherapy, and PAI guidance and monitoring.