Table of Contents Chemicals and Methods S3 Characterisation of nanoparticles S4 POPG hydrolysis by MALDI-Mass Analysis S7 Phosphatidylcholine hydrolysis UV-Vis assay scheme S8 UV-Visible analysis of p-Nitrophenylphosphatidyl choline (NPPC) hydrolysis S9 Kinetic parameters of NPPC hydrolysis S10 31 P NMR analysis of NPPC hydrolysis S11 XPS and HRTEM analysis of nanoparticles S12 Phosphatidylcholine hydrolysis by nanoceria S13 Confocal study of bacterial cell membrane disruption S13 CFU analysis of Salmonella growth and death curve S15 Confocal microscopy analysis of antibacterial activity S17 Study of pre-attachment phase of biofilm formation S18 Synthesis and characterization of FITC-tagged PAA-Cnp S18 Localization of PAA-Cnp inside biofilm S21 Dispersibility of nanozymes in solution S21 SEM images of biofilm formation/disruption S22 Comparison of biofilm inhibition using oxidase-mimetic S22 Antibacterial activity on various pathogenic bacteria S23 Antibiofouling studies on urinary catheters S28 MIC quantification and comparison S29 Cytotoxicity study against HeLa cells S30 S3 1. Chemicals Cerium chloride heptahydrate (CeCl3.7H2O) was purchased from Avra synthesis Pvt. Ltd. Cerric ammonium nitrate ((NH4)2Ce(NO3)6), ethylenediamine, hydrazine hydrate and ammonium hydroxide, 3-aminopropyltriethoxysilane used for various synthesis were purchased from Sisco Research Laboratories. Sodium polyacrylate and flouresceine isothiocynate used for preparing PAA-Cnp and FITC-tagged PAA-Cnp nanoparticles respectively were purchased from Sigma Aldrich. Trizma base and phosphotidyl choline (lecithin) used for hydrolysis assays were also purchased from Sigma Aldrich. 1-Palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol and pnitrophenyl phosphorylcholine used for other hydrolysis assays were purchased from TCI Co. Ltd. and Alfa Aesar Fischer Scientific respectively. 2. Characterization Methods Scanning electron microscopy (SEM) and EDX spectrawere performed on a Carl-Zeiss Ultra 55, FEI Sirion UHR SEM and ESEM-Quanta instruments,respectively. Transmission electron microscopy (TEM), high resolution TEM (HRTEM), electron diffraction X-Ray (EDX) analysis and selected area electron diffraction (SAED) were recorded on JEOL transmission electron microscope operating at 200 kV after casting a drop of nanoparticle dispersion in acetone over Cu grid. Powder XRDwas recordedon Philips PANalytical X-ray diffractometer by using a Cu-Kα (1.5406 Å)radiation. X-ray photoelectron spectroscopy (XPS) was acquired on AXIS ULTRA, KRATOS ANALYTICAL, SHIMADAZU. Raman spectroscopy was performed on HORIBA JOBIN YVON LabRAM HR Raman spectrometer (532 nm laser. FT-IR spectra were recorded on aPerkinElmer FT-IR spectrometer. Zeta potential was measured usingMalvern Zetasizer Nano UK.UV-Vis absorption spectra were acquired onSHIMADAZU UV-2600 spectrophotometer. Fluorescence spectroscopy was measured by using HORIBA JOBIN YVON (Fluoromax-4 Spectrofluorometer) instrument. All the 31 P NMR spectra were recorded using AV400 and AV500 MHz Avance Bruker High Resolution...

Organophosphate‐based nerve agents irreversibly inhibit acetylcholinesterase enzyme, leading to respiratory failure, paralysis and death. Several organophosphorus hydrolases are capable of degrading nerve agents including pesticides and insecticides. Development of stable artificial enzymes capable of hydrolysing nerve agents is important for the degradation of environmentally toxic organophosphates. Herein, we describe a Zr‐incorporated CeO2 nanocatalyst that can be used for an efficient capture and hydrolysis of nerve agents such as methyl paraoxon to less toxic monoesters. This unusual sequential degradation pathway involves a covalently linked nanocatalyst‐phosphodiester intermediate.

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