Dynamic Bio‐Barcode Assay Enables Electrochemical Detection of a Cancer Biomarker in Undiluted Human Plasma: A Sample‐In‐Answer‐Out Approach

There is a need for biosensing systems that can be operated at the point-of-care (POC) for disease screening and diagnostics and health monitoring. In spite of this, simple to operate systems with the required analytical sensitivity and specificity in clinical samples, using a sample-in-answer-out approach, remain elusive. Reported here is an electrochemical bio-barcode assay (e-biobarcode assay) that integrates biorecognition with signal transduction using molecular (DNA/protein) machines and signal readout using nanostructured electrodes. The e-biobarcode assay eliminates multistep processing and uses a single step for analysis following sample collection into the reagent tube. A clinically relevant performance for the analysis of prostate specific antigen (PSA) in undiluted and unprocessed human plasma: a log-linear range of 1 ng mL^-1 -200 ng mL^-1 and a LOD of 0.4 ng mL^-1 , was achieved. The e-biobarcode assay offers a realistic solution for biomarker analysis at the POC.