Study On The Detection Of Cr(Ⅵ) In Water By Gold Nanoparticles-based Optical Probes

Since the beginning of twenty-first century,human society has faced various difficulties and challenges,including chromium pollution caused by industrialization and urbanization.Hexavalent chromium is rated as one of the most dangerous seventeen chemical contaminants to human health by the US Environmental Protection Agency(US-EPA).Trace amounts of Cr(Ⅵ)absorbed by the body may cause hemolysis,respiratory injury,DNA damage and even leading to various types of cancer.The establishment and development of timely,simple,accurate and highly sensitive detection methods for Cr(Ⅵ)is the basis,prerequisite and even key point of the prevention,control and treatment of Cr(Ⅵ)pollution.At present,the detection methods of Cr(Ⅵ)mainly depend on large-scale instruments,although showing high sensitivity and accuracy in detecting processes.However,unavoidable disadvantages such as high cost,sophisticated pretreatment and requirement of professional operation render them applied to real-time field monitoring on a lager scale.In view of the above problems,The optical detection strategies provide a potential and effective method for real-time detection of Cr(Ⅵ).Our research took full advantages of the excellent optical properties of gold nanoparticles and constructed three different optical probes,providing a new detection method for Cr(Ⅵ)detection in different environmental water samples.The specific research work carried out in this paper is as follows:(1)The nanoparticles with average particle size of 14 nm were synthesized through chitosan as the "green" reducing agent,and the macromolecule bovine serum protein was modified as a stabilizer on the surface of gold nanoparticles,constructing a bovine serum albumin stabilized gold nanoparticles colorimetric probe(BSA-Au NPs)successfully.The results suggested that the BSA-Au NPs probe has a good perfermances in detecting Cr(Ⅵ),showing a good linear relationship when the concentration of Cr(Ⅵ)ranged between 0.15 μM and 50 μM(R2 = 0.9925)and with a minimum detection limit of 0.12 μM(S/N=3).In addition,the BSA-Au NPs probe showed strong anti-interference ability and excellent reproducibility(RSD <5%)in the actual detection process,and achieved good recovery in the actual river water samples(102.34%-107.87%),indicating that the constructed BSA-Au NPs probe has a great prospect in the actual water sample detection of Cr(Ⅵ).(2)Functional modifications of ordinary cellulose filter paper were carried out and the BSA-Au NPs were anchored to the surface of modified filter pape through chemical interactions,realizinge the immobilization of BSA-Au NPs.Thus,a functionalized cellulose filter paper based on gold nanoparticles solid phase colorimetric probe was successfully constructed(BSA-Au NPs/STCP).The results showed a good linear relationship when the concentration of Cr(Ⅵ)ranged between 0.15 μM and 50 μM(R2 = 0.9928)and with a minimum detection limit of 0.28 μM(S/N=3).In addition,the BSA-Au NPs/STCP probe showed strong anti-interference ability and excellent reproducibility(RSD <5%)in the actual detection process,and achieved good recovery in the actual river water as well as drilling wastewater samples(100.96%-103.33%).Compared with the common liquid phase detection probes,the constructed BSA-Au NPs/STCP solid-phase colorimetric probe is more selectivity,practicability and convenience for Cr(Ⅵ)detection in complex environmental water samples.(3)A novel fluorescence nanoparticle with an average particle size of 3.4 nm was prepared by using natural macromolecular bovine serum albumin as a reducing agent and a stabilizer.A strong fluorescent probe with strong stability and high selectivity was successfully constructed(BSA-Au NCs).The results showed that the as-prepared fluorescent probe has a strong sensitivity to the low concentration of Cr(Ⅵ)in solution,and has a good linear relationship when the concentration range of Cr(Ⅵ)is between 0.001 μM-2.5 μM(R2 = 0.9953),the lowest detection limit as low as 0.6 nM(S/N = 3).Besides,the BSA-Au NCs probe has a strong anti-interference ability and excellent reproducibility(RSD <5%),and in the actual river water samples and tap water in the spikes of the experiment achieved a good recovery(93.92%-106.51%).Compared with the colorimetric detection probe,the constructed BSA-Au NCs fluorescent probe achieved better detection effect for low concentration Cr(Ⅵ)detection in environmental water samples.