Construction And Properties Of Colorimetric Sensor Based On Co₃S₄ And AgI Nanomaterials

Mimic enzyme nanomaterials have many advantages than traditional bio-enzyme,such as tolerance,stability and low cost.Colorimetric sensor based on nanomaterials has improved the sensitivity and reduced the detection limit.In this paper,the applications of colorimetric sensor in food additives,biotoxin,chemical toxin and other contaminants detection were summarized.On these basis,we constructed three kinds of colorimetric sensors based on Co₃S₄,AgI and AgI/TiO₂ nanomaterials.Furthermore,we analysed the build process and applied these colorimetric sensor in detecting harmful substances such as H₂O₂,melamine and chloramphenicol in food,which provides a new idea for the future practical application.The main contents are listed as follows:?1?The Co₃S₄ spherical nanoparticles with uniform size in the range of 4 nm to 7 nm were made from metal carbonyl cobalt by thermal reflux method.Furthermore,we construct AgI NPs-TMB-H₂O₂ colorimetric sensor and investigated it's sensitivity and stability.The kinetic studies show that Co₃S₄ NPs have high adsorption capacity and catalytic activity for H₂O₂ and TMB.Under optimal conditions,the detection for H₂O₂ exhibited a linear range from 0.1 mmol/L to 0.8 mmol/L with a detection limit of 0.1 mmol/L.This method can be used for the detection of H₂O₂ in real milk samples and the results suggested the recovery was varied in the range 90.42% to 120.57%,which revealed that this assay was reliable and practicable.?2?Silver iodide nanoparticles?Ag I NPs?were successfully synthesized by a typical precipitation method,and the average particle size is about 60 nm.We found AgI NPs possess peroxidase-like activity,and have higher thermal durance than HRP.The Steady-state kinetic analysis shows that the catalytic process of Ag I NPs conform to the typical Michaelis-Menten kinetics and has better affinity for H₂O₂ than HRP and other materials.Using AgI NPs,we constructed a highly sensitive and selective colorimetric sensor for H₂O₂ and melamine detection.The results show that linear range for H₂O₂ was 0.05 mmol/L to 0.4 mmol/L with a detection limit of 0.01 ?mol/L,and for melamine was 0.8 ?mol/L to 60 ?mol/L with a detection limit of 0.8 ?mol/L.Standard addition method was used in determining content of melamine in milk samples,results suggested the recovery was varied within the range 87.90% to 109.95%,which revealed this assay was reliable and practicable.?3?CS-Ag I/Ti O₂ with spherical structure about 25 nm was synthesized by deposition-precipitation method.The mechanism of the colorimetric assay is that photogenerated holes held primarily responsible for the oxidation of TMB.Then,by utilizing CS-AgI/TiO₂ heterojunction nanomaterials as enzymatic mimics by visible light-stimuli responsive,a novel competitive-type colorimetric immunoassay was constructed for detection of CAP,which exhibited linear in the range of 0.03 nmol/L to 12.53 nmol/L with a detection limit of 0.03 nmol/L.The selectivity,repeatability and stability were acceptable.Excitedly,no significant difference was observed for detection of the spiked CAP in the real food samples with the referenced values by commercialized enzyme-linked immunosorbent assay.