Investigation On The Detection Of Salbutamol Based On Competitive Immunoassay And Surface Enhanced Raman Spectroscopy

Due to the lackness of enough binding sites of small molecular antigen and hapten, itlimited the application of traditional detection by sandwiched structures of “antibody-antigen-antibody”. Instead, competitive immunoassay was appropriate to detect smallmolecular antigen. Surface-enhanced Raman spectroscopy (SERS) exhibited extremelyhigh sensitivity and provided rich information for probing the surface structure and processat molecular level. Moreover, it also opened new approach for the direct/indirect detectionof biomedical subject. Combining the competitive immunoassay with SERS, magneticcore-shell nanoparticles and the microfluidic techniques together, a new kind ofimmunoassay based on SERS has been developed to achieve the specific detection ofsalbutamol with high sensitivity. This paper was focused on the following issues:(1) A novel approach based on competitive immunoassay and surface enhancedRaman spectroscopy has been developed to detect salbutamol. The competitive interactionwith labelled immunogold between free salbutamol molecule and its coated antigenresulted in the change of the amount of the immoblized immunogold on solid substrates.Thus, the intensities of SERS were dependent on the competitive interaction. The highconcentration of free salbutamol was, the low intensity of the SERS signal was. The resultsrevealed that this approach possessed high specificity and sensitivity and the limit ofdetection was about100fg/mL. It provided an effective and convenient way to achieve thetrace detection of salbutamol.(2) The SERS based magnetic immunoassay was constructed and it was combinedwith microfluidic chip to realize the on-line detection. Based on the hyphenated technology,salbutamol has been detected rapidly with high sensitivity. Firstly, the functionalizedFe3O4@Au immunonanoparticles were prepared to perform the liquid competitivemagnetic immunoassay. The sensitivity of detection was about10ng/mL based on theon-line magnetic enrichment by microfluidic chip. It was benifical to establish an effective method for highly sensitive detection based on SERS and competitive magneticimmunoassay.(3) The laser-induced surface catalytic reaction of para-mercaptobenzoic acid (PMBA)transfering to thiophenol (TP) has been explored. By associating with the dual function ofsurface plasmon involving catalysis and surface optical enhancement, SERS has beendeveloped to in-situ monitor the surface catalysis reaction. A systematical investigation onthe influence of the solution pH values, substrates, laser power and wavelength has beenperformed. The results indicated that the decarboxylation reaction was catalyzed favorablyby surface plasmon in the alkaline solution. The preliminary mechanism of thedecarboxylation reaction was proposed. It opened a facile routine for the decarboxylationand the corresponding construction of new carbon frameworks and complex organicmolecules for the practical application.