| As the most representative chemical warfare agents(CWA),sulfur mustard(SM)is often used by terrorist organizations and large-scale wars and has attracted widespread attention.Patients with SM poisoning often have skin erosions,eye injuries,blindness and other symptoms,and even lead to death due to exhaustion of respiratory system.Due to it is extremely stable,hard to decompose,lack of antidote and easy synthesis characteristics,it seriously threatens people’s safety of health and life.A certain amount of relatively stable,low volatility and low toxicity metabolite thiodiglycol(TDG)will be produced in the blood,urine and subcutaneous tissue of SM victims,and there will also be a certain amount of metabolites in non-poisoned humans.Although a small amount of TDG exists,its concentration in the urine of normal people ranges from 0-1ng/m L while the concentration of TDG in the urine of patients with SM poisoning usually exceeds 10 ng/m L,so TDG is both the main hydrolysate of SM and metabolic markers in the body of poisoned persons.At present,the detection of TDG has been determined as one of the clinical diagnostic methods for SM poisoning,which provides a basis for clinical testing.The existing detection methods for TDG are mainly based on chromatographic analysis methods and the required instruments which are limited to laboratories.Therefore,designing a fast,simple and practical POCT method of TDG is of great significance in the fields of medicine,environment and national security.This paper uses molecular imprinting technology to synthesize molecularly imprinted polymers(MIPs)with high selectivity to TDG,and uses gold nanoparticles(AuNPs)as signal reporting units to construct TDG point-of-care detection(Point-of-care testing,POCT)method,which has the advantages of simple operation,low cost,and does not require the use of large-scale equipment.It is expected to be used for rapid diagnosis of SM poisoning and provide a basis for clinical treatment.The specific research content includes the following two aspects:(1)A kind of MIPs using water as the pore-forming agent was synthesized to capture the target TDG with high specificity.The template molecule TDG and the functional monomer α-methacrylic acid formed a pre-assembled solution in an aqueous solution.Under the action of the initiator,a regularly dispersed network structure was formed on the surface of the nitrocellulose membrane.Subsequently,the template molecules were removed under the interaction of a suitable eluent,leaving corresponding binding sites on the surface of the polymer membrane,and molecularly imprinted test strips were obtained.Because TDG has a sulfur atom,it can form a strong covalent Au-S bond with AuNPs.Therefore,they would adsorb a large number of AuNPs to produce a color change when molecularly imprinted test strips(MITS)with a large number of cavities specifically adsorbed TDG molecules,and the red color of AuNPs was visible to the naked eye which realized the visual detection of TDG.A free color analysis software Image-Pro Plus was used for subsequent analysis.The experimental results confirmed that a good non-covalent bond could be formed when the ratio of TDG to MAA concentration was 1:2.Chloroform was the best eluent and the best elution effect could be obtained when the elution time was 50 min.50 min was selected as the optimal interaction time between TDG and gold nanoparticles.The effect of adsorption time between MIP and TDG on the detection was 15 min.In addition,30℃ was the best incubation temperature between TDG and gold nanoparticles.There was a good linear relationship between the color change of MITS and the TDG concentration from 1.0 ng/m L to 100.0 μg/m L,and the detection limit was 0.23 ng/m L.The diagnosis of SM poisoning can be realized because the method has excellent selectivity and anti-interference ability,and has been used for detection in urine.(2)The above methods may cause the loss of MIPs or poor dispersion during the elution process.Electrospun nanofibers have the advantages of large specific surface area,high porosity,good uniformity and three-dimensional network structure.So we further designed and constructed a new type of molecularly imprinted electrospun nanofiber membrane.In this work,we used electrostatic interaction as a driving force to assemble the negatively charged MIPs with template molecules removed on the surface of the positively charged PEI/PVA electrospun nanofibers,and cut them neatly to obtain MIPs/PEI/PVA nanofiber membrane.TDG was also captured by MIPs,and the concentrated AuNPs were used as the signal reporting units to produce a red color visible to the naked eye.In order to further reduce the detection limit and improve sensitivity,the silver enhanced solutions was used to deepen the wine red color of AuNPs and the software Image J was used to read the gray value for subsequent analysis.Experimental results indicated that the optimal electrospinning time was 100 min.The optimal concentration of MIPs was 80 mg/m L.The best interaction time between TDG and AuNPs was 2h.There was a good linear relationship between the color change of MIPs/PEI/PVA nanofiber membranes and the TDG concentration from0.1 ng/m L to 1.0 μg/m L,and the detection limit was 38 pg/m L.Finally,this method has been applied for the determination of TDG in the urine samples. |
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