Browsing by Author "Kashish"

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Genosensor based on a nanostructured, platinum-modified glassy carbon electrode for Listeria detection
(Royal Society of Chemistry, 2015) Kashish; Sandeep Gupta; Suresh Kumar Dubey; Rajiv Prakash
In this article, we describe the development of a simple and cost-effective genosensor probe based on a glassy carbon electrode modified with platinum nanomaterials dispersed in a chitosan matrix. Further, this probe was explored for the label-free detection of Listeria monocytogenes obtained from milk samples. DNA-based interfacial interaction between target DNA and platinum nanomaterials (PtNPs) immobilized with 24 mer ssDNA was investigated using impedance spectroscopy. As-prepared nanomaterials (for electrode fabrication) were characterized by UV-vis, FT-IR, TEM and cyclic voltammetry before fabricating the impedimetric sensor platform. The interfacial interaction between PtNPs and DNA results in the increase of charge transfer resistance (RCT) on hybridization with consecutive increasing concentrations of target DNA. This user-friendly and simple platform was used for the detection of target DNA and shows excellent response and specificity (even for 1-bp mismatch of target DNA). Also, this sensing platform was utilized for the detection of Listeria monocytogenes in real samples (milk beverage) and had a wide range of detection from 1 × 10-12 M to 1 × 10-4 M. In general, our simple and user-friendly sensor probe shows potential for detection of Listeria monocytogenes in food samples with high specificity. © The Royal Society of Chemistry 2015.
Label-free impedimetric detection of Listeria monocytogenes based on poly-5-carboxy indole modified ssDNA probe
(Elsevier, 2015) Kashish; Dharmendra Kumar Soni; Sunil Kumar Mishra; Rajiv Prakash; Suresh Kumar Dubey
Listeria monocytogenes is a life threatening pathogenic bacteria concerned with human health. The accurate and rapid detection of L. monocytogenes is required for preventing of listeriosis. In this study, DNA sensing probe based on conducting polymer poly-5-carboxy indole (5C Pin) was developed for the detection of L. monocytogenes hlyA gene responsible for pathogenicity. The probe sequences (24 mer ssDNA) were covalently immobilized on 5C Pin via N-(3-dimethylaminopropyl)-N'-ethylcarbodiimidehydrochloride (EDC) and N-hydroxysuccinimide (NHS). The probe having ssDNA was further hybridized with the target DNA sequence. Electrochemical impedance spectroscopic study was carried out to determine the extent of DNA hybridization over the probe. Significant change was observed in the impedance spectra before and after hybridization of ssDNA immobilized over the probe with the target DNA. RCT (charge transfer resistance) was estimated from the Nyquist plot (impedance plot) for target DNA (hlyA gene) in the solution. RCT vs. logarithmic concentrations of the target (genomic) DNA plot showed a linear range (1×10-4 to 1×10-12M) in case hybridization was performed under optimized conditions. The method proposed, is simple, free from any label, and highly sensitive for the detection of L. monocytogenes in environmental and clinical samples. © 2015 Elsevier B.V.