Peroxidase memetic nanozymes with their free radical-mediated catalytic actions proved as efficacious antibacterial agents for combating bacterial resistance. Herein, nanocellulose (NC) extracted from Eragrostis teff straw was used to prepare NC/Fe₃O₄/Ag peroxidase nanozyme as an antibacterial and wound healing agent. Characterization of the nanozyme with XRD, FTIR, SEM-EDX, and XPS confirmed the presence of silver NPs and the magnetite phase of iron oxide dispersed on nanocellulose. The peroxidase activity of the prepared nanozyme was examined using TMB and H₂O₂ as substrates which turned blue in acidic pH (λ_max = 652 nm). With a lower K_m (0.387 mM), the nanozyme showed a comparable affinity for TMB with that reported for the HRP enzyme. Furthermore, the nanozyme remained efficient over a broader temperature range while maintaining 61.53% of its activity after the fourth cycle. In vitro, antibacterial tests against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) bacterial strains showed that NC/Fe₃O₄/Ag exhibits concentration-dependent and enhanced antibacterial effect for Escherichia coli compared to NC and NC-Fe₃O₄ and negative control. Furthermore, the wound-healing performance of the NC-Fe₃O₄-Ag nanozyme was investigated in vivo using an animal model (mice). The nanozyme showed 30% higher wound healing performance compared to the control base ointment and is comparable with the commercial nitrofurazone ointment. The results show the potential of the prepared nanozyme for wound-healing purposes.

An inexpensive flexible plasmonic substrate exploiting the intrinsic properties of paper and anisotropic Ag@SiO ₂ nanocubes with improved SERS activity is demonstrated.

Industrial effluents containing phenolic compounds are a major public health concern and thus require effective and robust remediation technologies. Although laccase-like nanozymes are generally recognized as being catalytically efficient in oxidizing phenols, their support materials often lack resilience in harsh environments. Herein, bacterial nanocellulose (BNC) was introduced as a sustainable, strong, biocompatible, and environmentally friendly biopolymer for the synthesis of a laccase-like nanozyme (BNC/Cu). A native bacterial strain that produces nanocellulose was isolated from black tea broth fermented for 1 month. The isolate that produced BNC was identified as Bacillus sp. strain T15, and it can metabolize hexoses, sucrose, and less expensive substrates, such as molasses. Further, BNC/Cu nanozyme was synthesized using the in situ reduction of copper on the BNC. Characterization of the nanozyme by scanning electron microscopy (SEM) and X-ray diffraction (XRD) confirmed the presence of the copper nanoparticles dispersed in the layered sheets of BNC. The laccase-mimetic activity was assessed using the chromogenic redox reaction between 2,4-dichlorophenol (2,4-DP) and 4-aminoantipyrine (4-AP) with characteristic absorption at 510 nm. Remarkably, BNC/Cu has 50.69% higher catalytic activity than the pristine Cu NPs, indicating that BNC served as an effective biomatrix to disperse Cu NPs. Also, the bionanozyme showed the highest specificity toward 2,4-DP with a K_m of 0.187 mM, which was lower than that of natural laccase. The bionanozyme retained catalytic activity across a wider temperature range with optimum activity at 85 °C, maintaining 38% laccase activity after 11 days and 46.77% activity after the fourth cycle. The BNC/Cu bionanozyme could efficiently oxidize more than 70% of 1,4-dichlorophenol and phenol in 5 h. Thereby, the BNC/Cu bionanozyme is described here as having an efficient ability to mimic laccase in the oxidation of phenolic compounds that are commonly released into the environment by industry.

Adsorption is alternative technique for recovery of nutrient resources with no/less secondary pollution. PNC adsorbents are effective for removal and recovery of nutrient resources, and reusing nutrients as fertilizer could prevent eutrophication.