Mussel-Inspired Magnetic Nanoflowers as an Effective Nanozyme and Antimicrobial Agent for Biosensing and Catalytic Reduction of Organic Dyes

Mussel-inspired chemistry has been embodied as a method for acquiring multifunctional nanostructures. In this research, a novel mussel-inspired magnetic nanoflower was prepared through a mussel-inspired approach. Herein, magnetic PDA-Cu nanoflowers (NFs) were assembled via incorporating magnetic Fe 3 O 4 @SiO 2 -NH 2 core/shell nanoparticles (NPs) into mussel-inspired polydopamine (PDA) and copper phosphate as the organic and inorganic portions, respectively. Accordingly, the flower-like morphology of MNPs PDA-Cu NFs was characterized by scanning electron microscopy (SEM) images. X-ray diffraction (XRD) analysis confirmed the crystalline structure of magnetic nanoparticles (MNPs) and copper phosphate. Vibrating sample magnetometer (VSM) data revealed the superparamagnetic behavior of MNPs (40.5 emu/g) and MNPs PDA-Cu NFs (35.4 emu/g). Catalytic reduction of MNPs PDA-Cu NFs was evaluated through degradation of methylene blue (MB). The reduction of MB pursued the Langmuir-Hinshelwood mechanism and first-order kinetics, in which the apparent reduction rate K app of MB was higher than 1.44 min -1 and the dye degradation ability was 100%. MNPs PDA-Cu NFs also showed outstanding recyclability and reduction efficiency, for at least six cycles. Furthermore, the prepared MNPs PDA-Cu NFs demonstrated a peroxidase-like catalytic activity for catalyzing 3,3',5,5'-tetramethylbenzidine (TMB) to a blue oxidized TMB (oxTMB) solution in the presence of H 2 O 2 . Antimicrobial assays for MNPs PDA-Cu and PDA-Cu NFs were conducted on both Gram-negative and Gram-positive bacteria. Moreover, we demonstrated how the existence of magnetic nanoparticles in PDA-Cu NFs influences the inhibition of an increasing zone. Based on the results, mussel-inspired magnetic nanoflowers appear to have great potential applications, including those relevant to biological, catalysis, and environmental research.