A needle-like Cu<inf>2</inf>CdSnS<inf>4</inf> alloy nanostructure-based integrated electrochemical biosensor for detecting the DNA of Dengue serotype 2

The authors describe an integrated biosensor for amperometric DNA detection of Dengue virus in real time. Cu2CdSnS4 (CCTS) quaternary alloy nanostructures were successfully synthesized, deposited on an oxygen-etched silicon substrate (O2/Si) via spin coating, and annealed at 400 °C. The nanostructures were investigated by using UV-vis spectroscopy, X-ray diffraction, atomic force microscopy and scanning electron microscopy. Interdigitated electrodes were fabricated using silver as a metal contact deposited on the CCTS/O2/Si substrate using a thermal evaporator vacuum coater and a hard mask. The quaternary alloy acts as a support for immobilization of a Dengue-specific DNA probe that is employed as the recognition element. Single-stranded DNA in concentrations from 100 f. to 10 nM were successfully recognized via amperometry, typically at a working voltage of 1.5 V. The lower detection limit is 17 nM. Sensitivity is found to be 24.2 μA nM−1 cm−2. The biosensor is inexpensive, fast, highly sensitive, and has low power consumption.