Microstructured cystine dendrites-based impedimetric sensor for nucleic acid detection.

We report results of the studies relating to the fabrication and characterization of novel biosensing electrode by covalent immobilization of DNA onto microstructural cystine (Cys) prepared by acoustic cavitation method. The TEM investigations of these structures reveal transformation of microstructured Cys from nanorods to dendritic structure under optimum conditions. The Cys dendrites (denCys) have been investigated by XRD, FT-IR, and SEM studies. These biosensing electrodes have been fabricated by immobilization of Escherichia coli (E. coli)-specific DNA probe onto the dendritic cystine. The results of the electrochemical impedance spectroscopy studies reveal that this nucleic acid sensor exhibits linear response to cDNA in the concentration range of 10(-6) to 10(-14) M with response time of 30 min. The biosensing characteristics show that the fabricated E. coli sensor can be reused about 4 times and is stable for ∼4 weeks. The studies on cross-reactivity of the sensor for other water-borne pathogens like Salmonella typhimurium, Neisseria meningitides, and Klebsiella pneumonia reveal specificity of the bioelectrode for E. coli detection.