Multisine impedimetric probing of biocatalytic reactions for label-free detection of DEFB1 gene: How to verify that your dog is not human?

Abstract

Albert is a dog (Canis familiaris), but he does not realize this. Albert loves human food (and beer), watching movies on the internet, sleeping in bed, and more. But he should not do all these things. To convince him that, we have desinged a test procedure. The DEFB1 gene is unique to human species. Detecting its presence from saliva and in short periods may offer an advantage in the field of forensic medicine, and influence Albert’s bad habits.This study reveals novel utilization of the multisine impedance spectroscopy carried out during potentiodynamic polarization (pDEIS) of the electrode. We have utilized pDEIS to detect DEFB1 gene in collected saliva samples. The detection process was conducted at the boron-doped diamond surfaces functionalized with DEFB1-complimentary oligonucleotide sequence, anchored at the electrode surface. Next, a short-term electrode incubation in presence of target DNA sample allows for achieving DNA hybridization when exposed to human DNA material. The dsDNA orientation vs electrode surface is affected by polarization, and tracked by changes in the electrode kinetics preceded by subtle capacitance dispersion effects. The optimized measurement conditions range between +0.5 and +0.9 V vs Ag|AgCl due to nonspecific DNA adsorption, affecting heterogeneous charge transfer. The DNA hybridization is not achieved in the case of non-complimentary ssDNA originated from any other species subjected to this test. The discussed differences obtained during electrode incubation are supported by the XPS analyses.