Rapid Diethylstilbestrol Detection Methods Based On The Photothermal Effect Of Nanomaterials

Diethylstilbestrol（DES）is an estrogen that has been used as an animal growth promoter in livestock,poultry,and aquaculture.Meat products containing DES can disrupt the hormone balance in the human body,and in severe cases,can lead to the occurrence of cancer.Traditional DES detection methods that rely on large instruments can achieve trace detection,but the detection cycle is long,the cost is high,and the method is complex.Therefore,the development of fast and simple DES detection methods is of great significance.The lateral flow immunochromatographic strip detection method can achieve qualitative and semi quantitative detection of target substances through naked eye observation,and has the advantages of short cycle,low cost,and easy operation.However,the sensitivity of this method needs to be improved.The photothermal effect of nanomaterials can effectively improve the detection sensitivity.At present,colloidal gold,black phosphorus,graphite oxide and other nanomaterials have been used to improve the sensitivity of lateral flow immunochromatographic strip detection methods.However,the low photothermal conversion efficiency of these materials hinders their further development and application.Therefore,there is an urgent need to develop new photothermal materials with high photothermal conversion efficiency for lateral flow immunochromatographic strip detection methods.This article developed two new nanomaterials with high photothermal conversion efficiency,namely violet phosphorus and covalent organic framework（COF）.The DES lateral flow immunochromatographic test strip detection method was established using these two photothermal materials,and the testing conditions of the detection method were optimized and the detection performance was evaluated.The main content of this paper is as follows:Firstly,a violet phosphorus nanosheet was synthesized with a photothermal conversion efficiency of 31.1%,and its photothermal performance was investigated.A sensitive and fast detection method for DES based on the photothermal effect of violet phosphorus nanosheets was established,and the performance of the detection method was evaluated.Firstly,violet phosphorus crystals are prepared by ultrasonic treatment to form violet phosphorus nanosheets,which are then combined with DES antibodies to form photothermal detection probes.Then,DES complete antigen and sheep anti mouse secondary antibody were sprayed onto the detection area and quality control area of the test strip,respectively.The probe was incubated with the test substance,and then the test strip was tested.The paper systematically optimized detection conditions such as complete antigen coating concentration,sheep anti mouse secondary antibody coating concentration,composition and concentration of blocking solution,optimal p H value of material coupled antibody,coupling ratio of nanomaterials to antibodies,sample loading amount of photothermal detection probe,irradiation power,irradiation time,irradiation distance,and height of thermal imager.Under optimal conditions,a 808 nm laser is used to irradiate the detection area and quality control area respectively,and the photothermal effect of violet phosphorus nanosheets is utilized to achieve high sensitivity quantitative detection of DES.The paper establishes standard curves for the temperature change values and DES concentration of photothermal detection probes in the detection area and quality control area.When the DES concentration is between 3.0 and 50.0μg·L^-1,the linear relationship is good.Under the optimal experimental conditions,the minimum detection limit of the DES rapid detection method based on the photothermal effect of violet phosphorus nanosheets is 1.40μg·L^-1,the actual sample spiked recovery rate is 82.2%～115.2%,and the coefficient of variation is 2.0%～10.8%.In third part,P-P-COF nanosheets with better photothermal performance than violet phosphorus nanosheets were designed and synthesized,with a photothermal conversion efficiency of 51.17%.The photothermal performance of P-P-COF nanosheets was tested.A sensitive and rapid detection method for DES based on P-P-COF nanosheets was established,and the performance of this method was investigated.Firstly,5,10,15,20-tetrakis（4-aminophenyl）porphyrin and pyromellitic dianhydride were synthesized using amidation reaction at 120℃to synthesize P-P-COF crystal particles.Then,P-P-COF crystal particles were ultrasonically treated to form P-P-COF nanosheets,and they were electrostatically adsorbed with DES antibodies to form photothermal detection probes.Then,DES complete antigen and sheep anti mouse secondary antibody were sprayed onto the nitrocellulose membrane of the test strip to form a detection area and a quality control area,and then the test strip was tested.Finally,808 nm laser was used to irradiate the detection area and quality control area respectively,and the high sensitivity quantitative detection of DES was achieved using the photothermal effect of P-P-COF nanosheets.A standard curve was established between the temperature change value of the photothermal detection probe in the detection area and quality control area and the concentration of DES.When the DES concentration is between 0.25 and 50.0μg·L^-1,the linear relationship is good.Under the optimal experimental conditions,the minimum detection limit of the DES rapid detection method based on the photothermal effect of P-P-COF nanosheets is 0.24μg·L^-1,the actual sample spiked recovery range is 89.2%～118.7%,and the coefficient of variation is2.4%～12.0%.