A photoresponsive multifunctional carbon-based nanozymes for synergistic detecting and depleting GSH in cancer therapy

Nanozymes have served as the desired substitute for natural enzymes in biosensing and tumor therapy. However, the low catalytic efficiency and poor sensitivity restrict their comprehensive performance. Herein, a facile dual-doped carbon-based hybrid of rich graphitic nitrogen (N) and phosphorous-carbon (P-C) species is synthesized via an annealing process by altering the calcination temperature with the assistance of the hydrogel based on the aniline, phytic acid, and graphene (Gr). The optimal NPCG-900 possesses abundant defect active sites and photothermal-enhanced multienzyme-like catalytic activities of peroxidase (POD), catalase (CAT), and oxidase (OXD), which promote the production of reactive oxygen species (ROS) and depleting glutathione (GSH) levels in the tumor microenvironment (TME), simultaneously. Based on its intrinsic POD-like properties, a simple, highly sensitive, and selectively colorimetric biosensor for the measurement of GSH is established in a wide range. The limit of detection (LOD) was calculated as low as 0.36 μM in aqueous solution. Moreover, the redox mechanism of endogenic GSH in TME is illustrated by using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Surprisingly, the multifunctional NPCG-900 nanozymes can also simultaneously produce abundant ROS and consume intracellular GSH to induce cell apoptosis and necrosis for anticancer treatment in vitro. Therefore, this work demonstrated that satisfactory synergistic biosensor and antitumor therapy based on NPGC-900 hybrid of multi-enzymes activity have been successfully accomplished. Such multifunctional carbon-based nanoplatforms will open a new avenue for exploring various biological applications.