Study On Semi-quantitative Detection Method Of SERS Combined With Immunochromatographic Technology

Surface-enhanced Raman spectroscopy(SERS)has the advantages of high sensitivity,fingerprint-type spectroscopy,low operating requirements for testers,and mild test conditions,while immunochromatography has the adventages of high specificity,rapid portability,etc.The combination of SERS and immunochromatography,mainly by optimizing the quality of SERS substrates and antibodies,not only overcomes the defects of poor signal reproducibility and low sensitivity of test strips in conventional SERS applications,but also expands the application of detection objects.Combined with deep learning artificial intelligence algorithms,semi-quantitative onsite inspection can be achieved,thereby promoting the application of this technology in on-site rapid inspection.The main research contents of this paper are as follows:(1)Au@Ag Nanoparticles SERS Physical Enhancement Mechanism Study.First,the effect of Ag shell thickness on the enhancement factor of Au-Ag core-shell nanoparticles and Au-Ag core-shell nanoparticles dimers with different spacings was studied by the finite difference time domain method.The results show that when the Ag shell thickness is 3 nm,the excitation wavelength At 532 nm,the enhancement effect is the best,and the theoretical enhancement effect is the best when the gold-silver coreshell nanoparticle dimer spacing is 1 nm;Secondly,considering that the aggregation methods of gold-silver core-shell nanoparticles are various in actual samples,the changes in the arrangement of "square","circular","triangular" and "pentagon" can be used to enhance the SERS enhancement effect.The results show that different arrangement forms have different enhancement effects,and among the four existing shapes,the "pentagon" arrangement theory has the best enhancement effect.(2)Application of SERS combined with immunochromatography(SERS-ICA)in the detection of trace bisphenol A in water.First,the Au@Ag modified Raman signaling molecule 5,5’-dithiobis(2-nitrobenzoic acid)(DTNB)was used as a SERS substrate to couple with bisphenol A(BPA)monoclonal antibody to prepare immunoprobes.Then,test the test strips with different concentrations of BPA standard solutions and actual samples to detect the SERS signal of the Raman signal molecule DTNB in the T-line region,so as to achieve rapid and high sensitivity to BPA.Highly specific detection.The minimum detection limit of this method for BPA is 0.1 pg/m L,which is several orders of magnitude lower than the existing market detection technology.This method is suitable for on-site,rapid and highly sensitive detection of small molecules with corresponding antigens and antibodies.(3)Realization of SERS-ICA Semi-quantitative Detection Based on Internal Standard Method.Firstly,three single-antigen test strips were constructed and their corresponding detection limits and RSDs were explored.It was found that the Raman spectrum signal of these test strips fluctuated greatly and the reproducibility was poor.In order to overcome the shortcomings of single-antigen SERS-ICA,a double-antigen was designed.SERS-ICA test strips,and the Raman data of the double-antigen SERSICA test strips were first normalized,and then processed by the internal standard algorithm combined with the deep learning method.The RSD before and after processing was reduced from 11.91% to 3.128%.Then,the RSD before and after the internal standard algorithm is compared for each concentration gradient Raman data,and there are different degrees of reduction.Studies have shown that the internal standard algorithm can effectively solve the problem of uneven hot spots on the test strip to a certain extent,thereby improving the semi-quantitative accuracy.