Eco-Friendly synthesis,characterization,and biocompatibility of zirconium dioxide nanoparticles using Calendula officinalis extract:a possible agent against uropathogenic bacteriaOA

Background:Urinary tract infections(UTIs)are a challenge in the healthcare sector globally,exacerbated by increasing antibiotic resistance.Methods:Photophysical characterization of CO-ZrO_(2)-NPs was done using UV-vis spectroscopy,XRD,FTIR,SEM,EDX,TEM,and zeta potential measurements.Biocompatibility assessment was performed in vitro and in vivo using MTT assay,haemolysis assay,and zebrafish embryo toxicity assay,followed by antimicrobial activity estimation using the disc diffusion method.Results:The results demonstrated the absorption peak at 300 nm,a hydrodynamic diameter of 156 nm,and a zeta potential of -21 mV,showing moderate stability.The particle size ranged from 163 nm to 224 nm with spherical morphology in SEM,and 50-80 nm in TEM image,with an average particle size of 66 nm.The nanoparticles showed that above 95% cells were alive,lower than 5% haemolysis,and no developmental toxicity in zebrafish embryos,indicating a good biocompatibility up to a dose of 50μg/mL.The antimicrobial activity showed zones of inhibition(ZOIs)of 16±0.14 and 16±0.15,respectively,for E.coli and S.aureus post-treatment with 100μg/mL of CO-ZrO_(2)-NPs.Anti-biofilm activity was quantified using a crystal violet staining method,which showed a decline in biofilm mass when compared with the untreated control.Antioxidant capacity was determined using the DPPH assay,showing that the CO-ZrO_(2)-NPs possessed antioxidant activity,however,lower than that of ascorbic acid at the respective dose.Conclusion:Results demonstrate the successful green synthesis of stable CO-ZrO_(2)-NPs with significant antimicrobial,moderate antioxidant properties,and moderate anti-biofilm activity against key uropathogens.This study highlights the potential of green-synthesized CO-ZrO_(2)-NPs as one of the therapeutic approaches to kill UTI-causing pathogens.