Nanozyme-based catalytic theranostics

Abstract

Nanozymes, a type of nanomaterial with intrinsic enzyme-like activities, have emerged as a promising tool for disease theranostics. As a type of artificial enzyme mimic, nanozymes can overcome the shortcomings of natural enzymes, including high cost, low stability, and difficulty in storage when they are used in disease diagnosis. Moreover, the multi-enzymatic activity of nanozymes can regulate the level of reactive oxygen species (ROS) in various cells. For example, superoxide dismutase (SOD) and catalase (CAT) activity can be used to scavenge ROS, and peroxidase (POD) and oxidase (OXD) activity can be used to generate ROS. In this review, we summarize recent progress on the strategies and applications of nanozyme-based disease theranostics. In addition, we address the opportunities and challenges of nanozyme-based catalytic theranostics in the near future.

Fig. 1. Nanozymes for cancer cell detection. (A) Schematic representation of colorimetric direction of cancer cells by using folic acid functionalized PtNPs/GO (reprinted from ref. 22 with permission from Anal. Chem.). (B) Illustration of DNA aptamer accelerating the intrinsic peroxidase-like activity of g-C₃N₄ NSs for the detection of exosomes (reprinted from ref. 23 with permission from Anal. Chem.).

Fig. 2. Nanozymes for tumor diagnosis. (A) Cancer diagnosis in clinical specimens using M-HFn nanoparticles (reprinted from ref. 25 with permission from Nat. Nanotechnol.). (B) Schematic illustration of exosome-like nanozyme vesicles for catalytic photoacoustic imaging of NPC tumors (reprinted from ref. 26 with permission from Nano Lett.). (C) Schematic illustration of the SGC (SPIO@GCS/acryl/biotin-CAT/SOD-gel) nanogel (reprinted from ref. 28 with permission from ACS Nano).

Fig. 3. Nanozyme-strip for virus detection. (A) Standard colloidal gold strip. (B) Nanozyme-strip employing MNPs in place of colloidal gold to form a novel nanozyme probe. (C) Standard colloidal gold strip for EBOV-GP detection. (D) Nanozyme-strip for EBOV-GP detection (reprinted from ref. 32 with permission from Biosens. Bioelectron.).

Fig. 4. Nanozyme-based tumor catalytic therapy. (A) Schematic for N-PCNS-induced tumor cell destruction via ferritin-mediated specific delivery (reprinted from ref. 38 with permission from Nat. Commun.). (B) Schematic illustration of oxidative-stress-induced cytotoxicity to different cells using a combination of Fe₃O₄@C-FA NPs and AA (reprinted from ref. 39 with permission from ACS Appl. Mater. Interfaces). (C) Intracellular distribution of pH-sensitive SPION-micelles, iron ion release, subsequent Fenton reactions with NQO1-dependent H₂O₂ generated from β-lapachone (β-lap) futile redox cycle to amplify ROS stress levels for improved antitumor efficacy (reprinted from ref. 40 with permission from Theranostics). (D) Fabrication and catalytic-therapeutic schematics of sequential GFD NCs (reprinted from ref. 41 with permission from Nat. Commun.).

Fig. 5. Nanozymes for relieving hypoxia in tumor therapy. (A) Synthesis scheme of PHPBNs-S-S-HA-PEG@GOx and illustration of GOx-induced starvation for enhanced low-temperature photothermal therapy in a hypoxic tumor microenvironment (reprinted from ref. 42 with permission from ACS Nano). (B) PCN-Pt NPs enhanced PDT (reprinted from ref. 44 with permission from ACS Nano).

Fig. 6. Nanozymes as antioxidants. (A) TEM image of Mn₃O₄ NPs and in vivo fluorescence imaging of mice with PMA-induced ear inflammation after treatment with (a) PMA, (b) DCFH-DA, (c) PMA and DCFH-DA, (d) PMA and DCFH-DA with 0.5 mg kg⁻¹ Mn₃O₄ NPs, and (e) PMA and DCFH-DA with 1.25 mg kg⁻¹ Mn₃O₄ NPs (reprinted from ref. 52 with permission from Chem. Sci.). (B) CeO₂-loaded edaravone (a brain free radical scavenger), coupled with targeted peptides, can relieve stroke through BBB (reprinted from ref. 54 with permission from ACS Nano). (C) Fenozyme protects the integrity of the blood–brain barrier against experimental cerebral malaria (reprinted from ref. 55 with permission from Nano Lett.). (D) Fe₂O₃@DMSA NPs protected coronary artery ligature (CAL)-induced injury in rats (reprinted from ref. 46 with permission from Sci. Rep.).

Fig. 7. Antibacterial nanozymes. (A) Schematic illustration of the GQD-assisted antibacterial system (reprinted from ref. 56 with permission from Acc. Chem. Res.). (B) Scheme of polysulfane released from nFeS (reprinted from ref. 65 with permission from Nat. Commun.).