Journal of Vaccines & Vaccination

Application of electrochemically deposited gold nanoaggregates based DNA biosensor for early detection of typhoid

International Conference & Exhibition on Vaccines & Vaccination

22-24 Nov 2011 Philadelphia Airport Marriott, USA

Anu Singh, Yuvraj Joshi, Manoj Pratap Singh, Varsha Sharma, H. N. Verma and Kavita Arora

Accepted Abstracts: J Vaccines Vaccin

Abstract:

Nanostructured gold has improved prospects for interfacing biological recognition events with electronic signal transduction to design a new generation of bio-molecular electronic devices. Th is work shows a recent and promising utilization of gold nano particles for biological applications like deoxyribonucleic acid (DNA) biosensor for Typhoid detection. Bio- molecular electronics based DNA biosensors due to their inherent physicochemical stability and suitability to discriminate diff erent organism strains appear to be promising tool for early detection of typhoid as S. typhi can be isolated from blood at early stages of infection. A novel approach of electrochemical deposition of gold nano particles in form of aggregates (GNA) onto planar gold (Au) surface has been employed for fabrication of DNA biosensor. Fabricated nano pyramids electrode has been characterized using Scanning Electron Microscopy (SEM), UV-VIS spectroscopy, Atomic Force Microscopy (AFM), X-Ray diff raction (XRD) and electrochemical methods. It has been found that upon deposition of nano pyramids the performance was improved in terms of surface area and roughness (AFM studies), electron transport (cyclic Voltammetry), and surface stability (XRD studies). Th is nano pyramid based Au electrode was then used for fabrication of DNA biosensor by immobilizing specifi c single stranded DNA probe sequences identifi ed from conserved region of Vi capsular antigen gene, part of S. enteric serovars typhi through self assembled monolayer of 11-Mercaptoundecanoic acid (MUA). Prepared DNA electrode was effi ciently able to distinguish one base mismatch and non-complementary target and shows limit of detection for complementary targets upto 150 ottomol by monitoring guanine oxidation and upto 4 ottomol using Methylene blue as hybridization indicator using diff erential pulse Voltammetry (DPV) at 25�C in phosphate buff er with in 60 s hybridization time. Th is DNA electrode has implications towards detection of other pathogens like M. tuberculosis, Campylobacter, H. Pylori, E. coli etc for clinical diagnostics, food quality control and environmental monitoring.