Label-Free Microsensor for Total DNA-Breast Cancer Based on Bioimpedance Spectroscopy

Resumen

Breast cancer remains one of the leading causes of cancer mortality in women worldwide. Electrochemical biosensors are technologies of interest due to their low production cost and ease of miniaturization. They have been used to detect analytes associated with breast cancer, showing high sensitivity and selectivity. These techniques provide quantitative information about DNA, taking advantage of the electronegative properties of the phosphate groups in its structure, which affect its polarity and electrical properties, including Electrical Bioimpedance Spectroscopy (EBiS). The present research was conducted to characterize total DNA concentration in breast cancer. The biosensor has been fabricated by gold micro-electrode array enbibed on a crystal surface. The total DNA was quantified by UV-Vis spectrophotometry, using an optical density between 260 and 280 nm to determine the total concentration of DNA and its purity ratio of 260/280. Subsequently, each sample was subjected to EBiS measurements using an impedance spectrometer in the frequency range of 100Hz to 10MHz. The findings show absolute reactance (Xc) values with significative statistic correlation to DNA concentration at 3.3 MHz (R=0.821, p<0.05) for concentrations from 0 to 100 ng/μl.  The bioimpedance of biological analytes in suspension at frequencies above 1 MHz can be affected by how dipolar water molecules interact with structural environments. Thus, DNA concentration could intensify this interaction as the amount of nucleotide double helix structures increases, which is reflected in the reactive response associated with their electrical properties.  The use of a label-free microsensor based on EBiSmeasurement is a feasible technique to estimate BC DNA concentrations, and future research to determine its potential use to detect genetic BC markers is warranted.