A Plasmonic method for the determination of serotonin

Thesis Type: Postgraduate

Institution Of The Thesis: Middle East Technical University, Faculty of Arts and Sciences, Department of Chemistry, Turkey

Approval Date: 2019

Student: Begüm Avcı



Serotonin is an important neurotransmitter for regulating many cognitive and behavioral functions. Its abnormal levels have been related with various diseases hence the determination of the serotonin is very important. Sialic acid is mostly found in acidic glycan chains, glycolipids and glycoproteins and it is known to have a specific affinity for serotonin. In this study, determination of serotonin by using plasmonic property of gold nanoparticles was aimed. After synthesizing gold nanoparticles through sialic acid reduction, the method was simply based on the red shift in absorbance peak of gold nanoparticles at 520 nm upon aggregation of gold nanoparticles which was induced by the reaction between serotonin and sialic acid. This shift was seen only for serotonin among serotonin, dopamine, l-cysteine, l-aspartic acid and l-glutamic acid and it has shown that the determination of serotonin can be performed in a simple and selective way by measuring the absorbance with an Ultraviolet-Visible (UV-VIS) spectrophotometer. The method successfully worked for serotonin concentration between 10 and 500 µM. To be able to work with serotonin levels in blood between 0.5 and 1.7 µM some modifications on gold nanoparticles were performed. Making selective side of sialic acid available for serotonin binding was aimed by attaching carboxyl group of sialic acid onto amine group containing gold nanoparticles so that an enhancement in aggregation can be achieved. The studies on binding sialic acid to gold nanoparticles from its nonselective side for serotonin are in progress.