Quercetin-Derived\nPlatinum Nanomaterials Influence\nParticle Stability, Catalytic, and Antimicrobial Performance

Quercetin possesses\nhigh biological properties but low\nbioavailability,\npoor solubility, and rapid body clearance. Its structural modification\nis imperative for enhanced applications. Herein, we demonstrate the\ncatalytic and antimicrobial characteristics of shape-dependent (cuboidal\nand peanuts) platinum nanoparticles. Modified quercetin, 4<sup>'</sup>-QP, was employed as the reducing and stabilizing agent for the aqueous\nsynthesis of PtNPs without extraneous reagents. Monodispersed platinum\nnanocubes (C-PtNPs) and nanopeanuts (P-PtNPs) were produced by reacting\n4<sup>'</sup>-QP and Pt ions in the ratios of 3:1 and 1:1, respectively.\nTEM characterization confirmed the formation of Pt nanocubes and Pt\nnanopeanuts, with their corresponding sizes of 39.1 ± 0.20 and\n45.1 ± 0.24 nm. The shape-dependency of PtNPs on the nosocomial-causing\nbacteria, Citrobacter freundii ATCC\n8090 (C. freundii) was determined by\nthe Agar well-diffusion assay. Under the same particle size and dose\ntreatments, C-PtNPs and P-PtNPs exhibited 16.28 ± 0.10 and 4.50\n± 0.15 mm zones of inhibition with minimum inhibitory concentrations\nof 25 and 45 μg/mL, respectively. SEM analysis of C-PtNPs treated C. freundii showed a damaged cell membrane and confirmed\ncontact-killing as the antibacterial mechanism. The catalytic conversion\nof 4-nitrophenol (4-NP) to 4-amino phenol (4-AP) was tested using\na shape-dependent PtNPs catalyst in the presence of sodium borohydride.\nThe conversion rates (<i>k</i>) of C-PtNPs and P-PtNPs in\nwastewater samples from New Jersey were 0.0108 and 0.00607 s<sup>–1</sup>, respectively.