Meat species identification using DNA-redox electrostatic interactions and non-specific adsorption on graphene biochips

•High sensitive meat species detection using LAMP and new electrochemical sensor.•New sets of primers have been reported for porcine and chicken species identification.•New sensor strategy has been used for commercial processed foods.•Shows the true potential for on-site, reproducible and specific detection of foods.

This study describes the development of a novel electrochemical biosensor for meat species identification using DNA-redox electrostatic interactions and the nonspecific adsorption of these molecules on graphene biochips. The ruthenium hexamine molecule [Ru(NH3)6]3+, or RuHex, was observed to form complexes with free DNA in solution that adsorbed onto graphene surfaces, enabling the development of a rapid, high-sensitivity DNA biosensor. Reproducible cathodic current signals were generated from these low-cost graphene biochips, both in the presence and absence of dsDNA and loop-mediated isothermal amplification (LAMP) amplicons. The combination of the DNA-redox molecule complexes and the graphene surface therefore provided a novel detection strategy. This new biosensor was able to identify different meat species based on the isothermal amplification of target genes followed by electrochemical detection with square wave voltammetry. To optimize the specificity and sensitivity of the biosensor, the LAMP parameters were investigated under varying isothermal conditions using varying concentrations of reagents and target DNA, and with different combinations of newly designed loop primers. Using these novel biomarkers along with the new on-chip detection strategy, we observed limits of detection of target DNA of 1 pg/μL and 100 pg/μL for chicken and pork species, respectively.