Colorimetric And Electrochemical Sensing Assay Based On Nanoporous Metal Materials

Due to their unique three-dimensional continuous ligament-hole structure,nanoporous?NP?metal materials are considered as one of the most important new materials in the future.In many research fields,nanoporous metal materials have achieved remarkable results in electrochemical sensing.Since the discovery of magnetic Fe₃O₄ nanoparticles with peroxidase activity for the first time in 2007,the group of precious metals,metal oxides,and carbon-based materials have been found to have mimetic activity.Compared with natural enzymes,mimetic enzymes have these abilities of strong tolerance,high catalytic activity and easy to preparation.In this paper,NP-CeO₂,NP-PtFe,and NP-PtY were prepared by arc-melting and dealloying method.On the one hand,NP-Ce O₂ and NP-PtFe were investigated to detect small molecules as mimetic enzyme.On the other hand,NP-PtY as a modified material of glassy carbon electrode?GCE?to construct electrochemical sensors.The main contents are as follows:?1?The uniform needle-like nanostructure of NP-CeO₂ was prepared by arc-melting and dealloying method.Organophosphorus pesticide was indirectly detected by enzyme inhibition colorimetric analysis,where NP-CeO₂ plays a memetic role.NP-CeO₂ was measured by X-ray photoelectron spectroscopy?XPS?,the result displays that Ce³⁺/Ce⁴⁺ratio is higher than 1,thus oxidase activity has been occurred.In order to investigate the relationship between acetylcholinesterase?AChE?as well as malathion concentration and absorbance,NP-CeO₂+TMB?3,3?,5,5?-tetramethylbenzidine?colorimetric system as the detection platform.A good linear relationship of the AChE concentration and absorbance was in the range of 0.1 to 12 mU mL^-1with a detection limit?LOD?0.048 mU mL^-1?S/N=3?.Malathion concentration in the 0.1⁸ nM and 8⁴5 nM also have good linearity with the detection limit of 0.056 nM(18.5 ng L^-1).This colorimetric assay has a wide linear range,low detection limit,high sensitivity for AChE and malathion detection.The standard addition recovery experiment proves that this method can be used for real samples detection.The recovery is between 96.5%and 101.3%,which has proved that a precision and accuracy result in recovery experiment.?2?NP-PtFe was prepared by melting-dealloying method and followed by the investigation of the relationship between sulfite concentration and absorbance.NP-PtFe acts as peroxidase in the double-substrate?H₂O₂ and TMB?catalytic system.Kinetics experiments of NP-PtFe and HRP give a Michaelis-Menten constant?K_m?,which show a good affinity to H₂O₂ and TMB.There is a good linear relationship between sulfite concentration?0.08⁷?M?and the absorbance and the detection limit is 24 nM.?3?NP-PtY was fabricated by dealloying ribbons of a PtYAl alloy.Owing to the high porosity and the synergistic effect of Y in the Pt backbone as well as the good biocompatibility with small biological molecules,the NP-PtY exhibits superior structural stability,reproducibility and electrocatalytic activity.An electrochemical sensor was developed for highly sensitive and selective detection of dopamine?DA?based on the use of a glass carbon electrode?GCE?modified with NP-PtY alloy and graphene?GR?.The sensor,best operated at 0.16 V vs.SCE,has a linear range that covers the 0.9 to 82?M concentration range,a 0.36?M detection limit,and good selectivity over tyramine,tryptamine,phenethylamine,uric acid?UA?,and ascorbic?AA?.