Metal-organic framework-modulated Fe3O4 composite au nanoparticles for antibacterial wound healing via synergistic peroxidase-like nanozymatic catalysis.

Bacterial wound infections are a serious threat due to the emergence of antibiotic resistance. Herein, we report an innovative hybrid nanozyme independent of antibiotics for antimicrobial wound healing. The hybrid nanozymes are fabricated from ultra-small Au NPs via in-situ growth on metal-organic framework (MOF)-stabilised Fe3O4 NPs (Fe3O4@MOF@Au NPs, FMA NPs). The fabricated hybrid nanozymes displayed synergistic peroxidase (POD)-like activities. It showed a remarkable level of hydroxyl radicals (·OH) in the presence of a low dose of H2O2 (0.97 mM). Further, the hybrid FMA nanozymes exhibited excellent biocompatibility and favourable antibacterial effects against both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria. The animal experiments indicated that the hybrid nanozymes promoted wound repair with adequate biosafety. Thus, the well-designed hybrid nanozymes represent a potential strategy for healing bacterial wound infections, without any toxic side effects, suggesting possible applications in antimicrobial therapy.

Anti-CD44 antibodies grafted immunoaffinity Fe3O4@MnO2 nanozymes with highly oxidase-like catalytic activity for specific detection of triple-negative breast cancer MDA-MB-231 cells.

Cell-enzyme-linked immunosorbent assay (CELISA) is extensively applied for cancer diagnosis and screening because of its simple operation, high sensitivity, and intuitive color change. However, the unstable horseradish peroxidase (HRP), hydrogen peroxide (H2O2) and non-specificity have led to a high false negative rate, which limits its application. In this study, we have developed an innovative immunoaffinity nanozyme aided CELISA based on anti-CD44 monoclonal antibodies (mAbs) bioconjugated manganese dioxide-modified magnetite nanoparticles (Fe3O4@MnO2 NPs) for the specific detection of triple-negative breast cancer MDA-MB-231 cells. The CD44FM nanozymes were fabricated to replace unstable HRP and H2O2 to counteract possible negative effects in conventional CELISA. Results suggested that CD44FM nanozymes displayed remarkable oxidase-like activities over an extensive pH and temperature range. The bioconjugation of CD44 mAbs enabled CD44FM nanozymes to enter MDA-MB-231 cells selectively via over-expressed CD44 antigens on the membrane surface of these cells, and then catalyzed oxidation of the chromogenic substrate TMB, further achieving specific detection of these cells. Additionally, this study exhibited high sensitivity and low detection limit for MDA-MB-231 cells with a quantitation range of just 186 cells. To sum up, this report developed a simple, specific and sensitive assay platform based on CD44FM nanozymes, which could provide a promising strategy for targeted diagnosis and screening of breast cancer.

Synergistic Pro-Apoptotic Effect of a Cyclic RGD Peptide-Conjugated Magnetic Mesoporous Therapeutic Nanosystem on Hepatocellular Carcinoma HepG2 Cells.

Numerous nanocarriers have been developed to deliver drugs for the treatment of hepatocellular carcinoma. However, the lack of specific targeting ability, the low administration efficiency, and insufficient absorption by hepatocellular carcinoma cells, severely limits the therapeutic effect of the current drugs. Therefore, it is still of great clinical significance to develop highly efficient therapies with few side effects for the treatment of hepatocellular carcinoma. Herein, we developed a highly effective nanocarrier, cyclic RGD peptide-conjugated magnetic mesoporous nanoparticles (RGDSPIO@MSN NPs), to deliver the chemotherapeutic drug doxorubicin (DOX) to human hepatocellular carcinoma HepG2 cells, and further explored their synergistic apoptosis-promoting effects. The results showed that the prepared RGDSPIO@MSN NPs had good stability, biosafety and drug-loading capacity, and significantly improved the absorption of DOX by HepG2 cells, and that the RGDSPIO@MSN@DOX NPs could synergistically promote the apoptosis of HepG2 cells. Thus, this cyclic RGD peptide-modified magnetic mesoporous silicon therapeutic nanosystem can be regarded as a potentially effective strategy for the targeted treatment of hepatocellular carcinoma.

A flexible visual detection of calcium peroxide in flour employing enhanced catalytic activity of heterogeneous catalysts binary copper trapped silica-layered magnetite nanozyme.

Herein, a novel heterogeneous nanozyme with peroxidase (POD)-like activity was conducted to achieve ultrasensitive visual detection of calcium peroxide (CaO2) in flour by the assembly of binary copper-trapped mesoporous silica layer coated magnetite nanoparticles (Fe3O4 @SiO2 @CuO NPs). The prepared nanozymes were characterized using HRTEM, SEM, FT-IR, XRD, DLS, and EIS, which displayed a dispersed core-shell structure with a uniform diameter of approximately 100 nm. The nanozymes exhibited remarkable and stable POD-like activity in a wide range of pH values, incubation temperature, and reaction time, and the optimum catalytic activity was obtained at pH 3.6, 37 °C, and 10 min. The quantification range of CaO2 of this method is 0.1-5 mM with a limit as low as 5.6 × 10-3 mM, and it is not affected by multiple interferences. In conclusion, this detection method is sensitive, stable, low-cost, and simple to operate, so it has broad application prospects in the detection of food additives such as CaO2.