SERS analysis of biological analytes using an azo tether

The link between the concentration of neurotransmitters and mental diseases can potentially be used to monitor ones psychological health. The importance of this connection has led to the development of many analytical techniques. The detection of neurotransmitters in biological samples requires very sensitive detection methods. Surface enhanced Raman scattering (SERS) techniques provide the requisite sensitivity for the monitoring of biological analytes in real time.; Surface enhanced Raman scattering in combination with the creation of an azo-analyte complex is used for the detection of bilirubin and neurotransmitters. The dye will be used to enhance the SERS spectrum of the complex to obtain the required sensitivity through the attachment of the complex via a thiol to the silver surface and the resonance Raman effect.; Our approach for the detection of bilirubin involves the use of 3-methoxybenzothialazone hydrazone hydrochloride (MBTH) to creat an azo dye with aromatic amines and heterocyclic amines as a model for bilirubin. We have identified the unique spectral features for 10 different amines reacted with MBTH and the detection limits for each of the complexes. The model led to the determination of the detection limits for the bilirubin/MBTH complex in a buffered solution.; Our approach for the detection of neurotransmitters utilizes a diazonium modified with a thiol linkage to creat an analyte responsive coating (ARC). The detection limits for different ARC/neurotransmitter complexes were determined for dopamine, serotonin, 5-hydroxindole-3-acetic acid, and homovanillic acid individually and in binary mixtures. Extracellular fluid samples were obtained from Vanderbilt University for the analysis of serotonin using the developed ARC method.; An long shelf-life ARC method for bilirubin was also developed. For long term stability, lyophilized ARCs and lyophilized silver nanoparticles were utilized in blood collecting tubes. We demonstrate the quantification of bilirubin in the blood collecting tubes. Detection limits of 5.7x10-9 M for bilirubin in the tubes were obtained.