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. An electrochemical bio‐barcode assay allows protein biomarkers to be analyzed in undiluted and unprocessed human plasma samples. The dynamic DNA/protein complexes, composed of antibody‐labelled DNA motifs (TB and B*C) and redox‐labelled DNA (CR*), eliminate the need for multistep processing and allow sample‐in‐answer‐out analysis.