Iron‐Single‐Atom Nanozyme with NIR Enhanced Catalytic Activities for Facilitating MRSA‐Infected Wound Therapy

Abstract Patients with methicillin‐resistant Staphylococcus aureus (MRSA) infections may have higher death rates than those with non‐drug‐resistant infections. Nanozymes offer a promising approach to eliminating bacteria by producing reactive oxygen species. However, most of the conventional nanozyme technologies encounter significant challenges with respect to size, composition, and a naturally low number of active sites. The present study synthesizes a iron‐single‐atom structure (Fe‐SAC) via nitrogen doped‐carbon, a Fe‐N5 catalyst (Fe‐SAC) with a high metal loading (4.3 wt.%). This catalyst permits the development of nanozymes consisting of single‐atom structures with active sites resembling enzymes, embedded within nanomaterials. Fe‐SAC displays peroxidase‐like activities upon exposure to H2O2. This structure facilitates the production of hydroxyl radicals, well‐known for their strong bactericidal effects. Furthermore, the photothermal properties augment the bactericidal efficacy of Fe‐SAC. The findings reveal that Fe‐SAC disrupts the bacterial cell membranes and the biofilms, contributing to their antibacterial effects. The bactericidal properties of Fe‐SAC are harnessed, which eradicates the MRSA infections in wounds and improves wound healing. Taken together, these findings suggest that single Fe atom nanozymes offer a novel perspective on the catalytic mechanism and design, holding immense potential as next‐generation nanozymes.


Figure S1 .
Figure S1.(A) TEM images of NP with a scale bar of 500 nm and (B) enlarged TEM image of (A) with a scale bar of 100 nm.

Figure S3 .
Figure S3.The XPS survey spectrum of Fe-SAC.

Figure S4 .
Figure S4.UV absorption spectrum of NP (A) and Fe-SAC (B) with different concentrations.

Figure S5 .
Figure S5.Comparison of UV absorption between NP and Fe-SAC at 808 nm.

Figure S6 .
Figure S6.Infrared thermal images of various concentrations of Fe-SAC upon an 808 nm laser irradiation.

Figure S7 .
Figure S7.Photothermal stability during five cycles of on/off NIR-I irradiation.

Figure S8 .
Figure S8.TMB absorption with NC in ddH2O and Relevant photographs of TMB color change.

Figure S9 .
Figure S9.TMB absorption at 652 nm with dispersed NC suspension under different pH phosphate buffers and Relevant photographs of TMB color change.

Figure S10 .
Figure S10.TMB absorption with Fe-SAC nanoparticles in ddH2O and Relevant photographs of TMB color change.

Figure S11 .
Figure S11.TMB absorption at 652 nm with dispersed Fe-SAC suspension under different pH phosphate buffers and Relevant photographs of TMB color change.

Figure S12 .
Figure S12.ESR spectrum of singlet oxygen trapped by DMPO under different pH conditions.

Figure S13 .
Figure S13.ESR spectrum of superoxide anion by DMPO under different pH conditions.

Figure S14 .
Figure S14.(A) Lineweaver-Burk plot for Fe-SAC with H2O2 as a substrate and (B) Michaelis-Menten kinetic analysis of Fe-SAC with H2O2 as a substrate at room temperature.Data of each of the three independent experiments (n = 3) are presented as mean ± standard deviation (SD).The following criteria were used to assess statistical significance: *P < 0.05, **P < 0.01, ***P < 0. 001.

Figure S20 .
Figure S20.Antibacterial performance of Fe-SAC in vitro.(A) Agar plate photographs of E.coli bacterial colonies by Fe-SAC under NIR-I irradiation, PBS as control.(B) Relative bacterial viability of E.coli.(C) Live/dead staining of MRSA.(D) SEM images of E.coli after different treatments.Data of each of the three independent experiments (n = 3) are presented as mean ± standard deviation (SD).The following criteria were used to assess statistical significance: *P < 0.05, **P < 0.01, ***P < 0. 001.

Table S1 .
Elemental composition of different samples measured by XPS.

Table S2 .
The catalytic activity for different single atom nanozymes.