Tin oxide quantum dot based DNA sensor for pathogen detection.

We report the application of nano crystalline tin oxide quantum dots (SnO2-QDs) for electrochemical detection of Vibrio cholerae based on DNA hybridization technique. SnO2-QDs (- 1-5 nm) have been synthesized by laser ablation technique in liquid (LAL) and electrophoretically deposited onto hydrolyzed surface of indium tin oxide (ITO) coated glass electrode. A single stranded oligonucleotide probe (23 bases) have been designed form the virulent gene sequence of V. cholerae and has been immobilized onto SnO2-QDs/ITO surface for the fabrication of ssDNA/SnO2-QDs/ITO bioelectrode and these bioelectrode have been further used for DNA hybridization (dsDNA/SnO2-QDs/ITO). The electrochemical response studies have been carried out with different concentration genomic DNA (100-500 ng/microL), which indicated that SnO2 provides an effective surface to bind with the phosphate group of DNA, thus resulting in an enhanced electron transport. The hybridized electrode exhibits linear response with regression coefficient (R) 0.974, high sensitivity 35.20 nA/ng/cm2, low detection limit (31.5 ng/microL), faster response time (3 s) and high stability of 0-120 days when stored under refrigerated conditions.