The Study Of High Sensitive Quantitative Immunochromatographic Assay Based On Surface Enhanced Raman Spectroscopy

In the last years,surface-enhanced Raman scattering based immunochromatographic assay(SERS-ICA)has been getting great attention and been applied for the detection of different target analytes.The development of novel SERS active substrate materials is the key to improve the sensitivity of SERS-ICA.In view of this,three highly active SERS substrates were successfully prepared for the detection of prohibited additives in food(such as Sudan I,salbutamol)and drug residues in water environment(such as diclofenac).The content of this thesis includes following parts:Firstly,an immunochromatographic assay(ICA)based on surface-enhanced Raman scattering(SERS)for ultrasensitive determination of Sudan I in food samples was established.Gold-silver core-shell bimetallic nanorods(Au@Ag NRs)were synthesized,characterized and used as the substrate for preparation of the ICA.Polyclonal antibody against Sudan I was immobilized on the surface of the Au@Ag NRs carrying the Raman reporter 5,5'-dithiobis(2-nitrobenzoic acid).The Raman scattering intensity on the test line was used for quantitation of Sudan I.The assay was completed in 15 min.The half maximal inhibitory concentration(IC50)and limit of detection(LOD)were 30pg mL-1 and 0.2 pg mL-1,respectively.There was no cross-reactivity(CR)of the assay with Sunset Yellow,Lemon Yellow and Brilliant blue FCF,but only 3.53%-9.74%CR with Sudan ?,? and ?.The recoveries of Sudan I from spiked food samples were in the range of 88.9?107.6%with relative standard deviation of 3.7?8.7%(n=3).Secondly,a novel SERS-ICA using AgMBA@SiO2-Ab as an immunoprobe has been developed for rapid,quantitative and ultrasensitive detection of a pharmaceutical diclofenac(DCF)residue in water samples.Ag,Ag@SiO2 and AgMBA@SiO2 nanoparticles(NPs)were synthesized and characterized.The immunoprobe was prepared by sandwiching the Raman reporter mercaptobenzoic acid(MBA)between the core-shell layers and immobilizing the monoclonal antibody(mAb)against DCF on the surface of the Ag@SiO2 NPs.Under optimal conditions,the sensitivity and limit of detection(LOD)of the SERS-ICA for DCF were found to be 9 pg mL-1 and 0.07 pg mL-1,respectively.AgMBA@SiO2-Ab was stable within four months without significant loss of SERS intensity.The key to success of the SERS-ICA was the employment of the Ag@SiO2 NPs as the SERS substrate,which possessed gorgeous SERS enhancement capability,predominant bipcompatibility and excellent stability.Thirdly,a novel indirect competitive immunochromatographic assay(ic-ICA)integrated with surface-enhanced Raman scattering(SERS)using gold triangular nanoplates(AuTNPs)as substrate earring Raman reporter(MBA)and antibody(AuMBATNPs-Ab)has been established,which could be applied for rapid quantitative screening of a broad concentration range of salbutamol in real samples.The half maximal inhibitory concentration(IC50)and limit of detection(LOD)values of the SERS-ICA for salbutamol were 0.016ng mL-1 and of 0.14pg mL-1,respectively.The AuTNPs with high SERS performance due to its sharp vertexes and predominant SPR property have been synthesized through a rapid one-pot seedless growth method.The edge length of AuTNPs can be easily modulated by varying the experimental parameters.The above three SERS-ICAs based on different atctive substrates display the merits such as low cost,portability,short operation time and high sensitivity,endowing the SERS-ICA with infinite potential to rapid and ultrasensitive screening in point-of-care testing,clinical diagnosis,food inspecting and environmental monitoring.