Sewage Biosensor to Identify Potential Population Biomarker for Monitoring of Public Health

Wastewater-based epidemiology (WBE) has shown to be a powerful tool for the evaluation of human population’s drugs use. This approach is based on the analysis of specific urinary biomarkers such as drug residues in wastewater after being excreted by humans at treatment plants, and this approach can also be utilized for the evaluation of public health by assessing disease biomarkers. Here we describe a new label-free electrochemical DNA (E-DNA) biosensor using a synthesized ferrocenyl (Fc) redox marker which intercalates to double-stranded DNA (dsDNA to detect human-specific mitochondrial DNA (mtDNA) associated with cancer biomarkers. The Fc intercalator binding to dsDNA was characterized by differential pulse voltammetry. This new biosensor was optimized to allow the detection of single base pair mismatched sequences, able to detect as low as 10 pM DNA, and covering a dynamic range from 10 pM to 100 nM. To validate the biosensor, DNA was extracted from wastewater and human-specific mtDNA was amplified with quantitative polymerase chain reaction (qPCR). The E-DNA biosensor was employed to detect mtDNA after PCR amplification. Experimental results show that the peak current from Fc intercalator oxidation depends on the amount of target mtDNA. The biosensor is able to detect mtDNA in PCR products even with a 100-time dilution, but with low non-specific adsorption. Our results demonstrate that human biomarkers are detectable in wastewater, and this may open the door to identify potential population biomarkers for the monitoring of public health using WBE.