A Photomodulable Bacteriophage-Spike Nanozyme Enables Dually Enhanced Biofilm Penetration and Bacterial Capture for Photothermal-Boosted Catalytic Therapy of MRSA Infections

Abstract

Nanozymes, featuring intrinsic biocatalytic effects and broad-spectrum antimicrobial properties, are emerging as a novel antibiotic class. However, prevailing bactericidal nanozymes face a challenging dilemma between biofilm penetration and bacterial capture capacity, significantly impeding their antibacterial efficacy. Here, this work introduces a photomodulable bactericidal nanozyme (ICG@hMnO_x ), composed of a hollow virus-spiky MnO_x nanozyme integrated with indocyanine green, for dually enhanced biofilm penetration and bacterial capture for photothermal-boosted catalytic therapy of bacterial infections. ICG@hMnO_x demonstrates an exceptional capability to deeply penetrate biofilms, owing to its pronounced photothermal effect that disrupts the compact structure of biofilms. Simultaneously, the virus-spiky surface significantly enhances the bacterial capture capacity of ICG@hMnO_x . This surface acts as a membrane-anchored generator of reactive oxygen species and a glutathione scavenger, facilitating localized photothermal-boosted catalytic bacterial disinfection. Effective treatment of methicillin-resistant Staphylococcus aureus-associated biofilm infections is achieved using ICG@hMnO_x , offering an appealing strategy to overcome the longstanding trade-off between biofilm penetration and bacterial capture capacity in antibacterial nanozymes. This work presents a significant advancement in the development of nanozyme-based therapies for combating biofilm-related bacterial infections.

Keywords: antibacterial therapy; bacterial capture; biofilm penetration; nanozyme; nature-inspired nanostructures.

Scheme 1

Schematic illustration of the photomodulable bacteriophage‐spike nanozyme for photothermal‐boosted catalytic therapy against MRSA biofilm infection. The ICG integrated hollow virus‐spiky MnO _x nanozyme exhibits both photothermal and catalytic activities. The biofilm disruption facilitated by the photothermal effect allows for deep penetration of ICG@hMnO _x , which can then act as a bacteriophage‐mimetic membrane‐anchored ROS generator. The ICG@hMnO _x enables dually enhanced biofilm penetration and bacterial capture to treat MRSA biofilm‐associated infections.

Figure 1

Fabrication and characterization of the photomodulable bacteriophage‐spike ICG@hMnO _x . A) Schematic illustration of the synthetic procedure of ICG@hMnO _x . TEM images of the B) SSN, C) SSN@MnO _x , and D) ICG@hMnO _x . E) The HRTEM image of a single ICG@hMnO _x . F) The SEM image of the ICG@hMnO _x . G) Dark‐field STEM and the corresponding EDX mapping (Mn, O, S) images of the ICG@hMnO _x . H) Elemental line scanning profile of the ICG@hMnO _x . I) UV–vis absorption spectra of indicated samples. J) Nitrogen absorption‐desorption isotherm with the corresponding pore‐size distribution of the ICG@hMnO _x . K) DLS characterization of ICG@hMnO _x and hMnO _x . L) High‐resolution XPS spectra of Mn 2p in ICG@hMnO _x .

Figure 2

Laser‐enhanced POD‐like activity of the photomodulable bacteriophage‐spike ICG@hMnO _x . A) Time‐dependent infrared thermal images and B) heating curves of aqueous dispersions of indicated samples under the irradiation with an 808 nm laser (1.0 W cm⁻²). C) Temperature elevation curves of ICG@hMnO _x at different concentrations under irradiation with an 808 nm laser (1.0 W cm⁻²). D) Heating curves of ICG@hMnO _x under 808 nm laser irradiation with different power densities. E) Temperature evolutions of ICG and ICG@hMnO _x solutions subjected to laser on‐off cycles under 808 nm laser irradiation (1.0 W cm⁻²). F) UV–vis absorption spectra of 3,3′,5,5′‐tetramethylbenzidine (TMB) solution containing different samples with or without NIR‐808 nm laser irradiation (1.0 W cm⁻²). G) UV–vis absorption spectra of TMB solution with ICG@hMnO _x upon 808 nm laser irradiation at different power densities (0–1.5 W cm⁻²). H) Schematic illustration of the laser‐augmented POD‐like activities of the ICG@hMnO _x nanozyme.

Figure 3

Anti‐bacterial and anti‐biofilm performance of the photomodulable bacteriophage‐spike ICG@hMnO _x . A) Representative plates of MRSA colonies after different treatments. B) SEM images of MRSA under different treatments. C) Confocal laser scanning microscope (CLSM) images of live/dead staining, in which green fluorescence indicates the live bacteria while red fluorescence indicates dead bacteria. D) MRSA viability determined by the live/dead ratio (n = 4). E) Biomass of MRSA biofilm after indicated treatments (n = 4). F) 3D CLSM images of live/dead stained MRSA biofilm after different treatments. G) Schematic illustration of the highly efficient bactericidal effect by ICG@hMnO _x . Data are presented as mean ± s.d. *p < 0.05.

Figure 4

Concurrent biofilm penetration and bacterial capture capacity of the photomodulable bacteriophage‐spike ICG@hMnO _x . A) Crystal violet‐stained biofilm with or without 808 nm laser (1.0 W cm⁻²) irradiation. B) 3D CLSM images of the ICG@hMnO _x incubated MRSA biofilms with or without 808 nm laser (1.0 W cm⁻²) irradiation. Purple: ICG@hMnO _x ; green: MRSA biofilm. C) CLSM images, and D) the corresponding line profiles of fluorescence intensity across the white lines, suggesting the tight interaction between FITC‐stained MRSA and ICG@hMnO _x . E) Membrane potential of MRSA upon indicated treatments was assessed by the DiOC₂(3) staining. F) Fluorescence images of ROS marker DCFH‐DA stained MRSA upon indicated treatments. G) Schematic illustration of the highly efficient biofilm penetration, bacterial capture, and GSH depletion induced by ICG@hMnO _x for photothermal‐boosted NCT against MRSA biofilm.

Figure 5

In vivo wound disinfection and healing by using the photomodulable bacteriophage‐spike ICG@hMnO _x . A) Schematic illustration of the full‐thickness MRSA wound model and the in vivo antimicrobial activity of ICG@hMnO _x . B) Real‐time thermal photographs of PBS‐ or ICG@hMnO _x ‐treated wound under irradiation with an 808 nm laser (1.5 W cm⁻²). C) Representative photographs and closing traces of the MRSA‐infected wound at 0, 4, 8, and 12 days post‐wounding after different treatments. D) MRSA colonies at 4 days post‐wounding with indicated treatments. E) Wound healing kinetics of different groups (n = 5). F) Relative bacterial burden of wound tissues harvested from different groups at 4 days post‐wounding (n = 4). G) Representative IL6 immunofluorescence staining images, and H) corresponding quantification of IL6 level in wound tissues harvested from different groups at 4 days post‐wounding (n = 4). I) Representative immunofluorescence images of MPO in wound tissues harvested from different groups at 4 days post‐wounding, where the red fluorescence indicates the expressed MPO in wound tissues. J) Quantitative analysis for immunofluorescence staining of MPO (n = 4). K) Immunofluorescence images of CD31 positive blood vasculature in wound tissues harvested from different groups at 14 days post‐wounding. L) Quantification of oxygen saturation (sO₂) level in wound tissues at 14 days post‐wounding (n = 4). M) Photoacoustic maps of sO₂ in wound tissues at 14 days post‐wounding. Data are presented as mean ± s.d. *p < 0.05.