DNA biosensor as a confirmatory test: Studies of household cleaners effects of onto electrochemical DNA detection

The detection and identification of human body fluids at crime scenes is usually performed using colorimetric and crystallographic tests. However, these assays may limit the samples detection during the washing steps. Currently, biosensors are emerging as alternative devices in molecular biology, combining the specificity and sensitivity of biological systems with the computing power of microprocessors. Herein, we report a preliminary study of an electrochemical biosensor able to detect DNA sequences in solutions mixed with household cleaners, aiming to simulate the effects of these chemicals on sample detection. The device was made using pencil graphite, acting as a working electrode (PGE) and an Ag/AgCl pin as a reference electrode. Single-strand DNA probes (ssDNA) were immobilized on PGE surface and the hybridization assay was performed by immersing the ssDNA–PGE electrode in a buffer solution with the target sequence under specific annealing temperature for 10min. Samples contamination was stimulated by household cleaners by immersing dsDNA–PGE immersed in solutions containing sodium hypochlorite, alcohol and SDS for 30min. The current peaks obtained with ssDNA–PGE and dsDNA–PGE were highly distinguishable (118.6nA and 24.435nA, respectively), even when dsDNA–PGE was mixed with sodium hypochloride, alcohol and detergent (17.12nA, 35.81nA and 69.44nA, respectively). These findings suggest that DNA biosensors have a great potential to be used as a confirmatory test to detect human body fluids in crime scenes.