Title: Non- Enzymatic colorimetric sensor for cardiac troponin I (cTnI) based on self-assembly of gold nanorods on heparin

Biography:

Dr. Saji Alex works as an Assistant Professor at the Department of Chemistry, Government College for Women, Thiruvananthapuram, India. He obtained his Ph.D. Degree in Chemistry in 2006 from National Institute of Interdisciplinary Sciences and Technology (CSIR), Thiruvananthapuram (University of Kerala), India. He has done his postdoctoral Studies under the Indo-US, UGC Raman Fellowship-2013 in the Department of Materials Science and Engineering at the University of Utah. His current research interests include development of chemical and biological sensors based on nanostructured materials, and developing organic and inorganic based light harvesting systems.

Abstract

In this study we present a simple enzyme free colorimetric sensor for the detection of the cardiac marker, Troponin I (cTnI) based on the self-assembly of gold nanorods on heparin. The sensing system consist of a purple solution of cetyl trimethyl ammoniumbromide stabilized gold nano rods (AuNRs) self-assembled in the presence of heparin. Upon the addition of cTnI, the aggregated AuNRs are freely dispersed because of the stronger complex formation between heparin and cTnI, thereby retaining the native wine red colour of AuNRs. As the concentration of cTnI in the solution was increased the colour gradually changes from blue to red there by enabling the sensing of cTnI. The above mechanisms were confirmed by transmission electron microscopy. The AuNRs aggregation was found to be inversely proportional to the concentration of cTnI. The change in absorbance of AuNRs with different concentrations of cTnI was monitored by UV-Visible spectroscopy. Using this sensor system cTnI in the range of 0.5-15 ng/mL could be measured with a detection limit of 0.4 ng/mL. The system also showed good selectivity in the presence of different competing substances under the same experimental conditions. The method offers a simple, cost effective method for the detection and measurement of cTnI devoidng the use of antibodies.