Self-powered and sensitive DNA detection in a three-dimensional origami-based biofuel cell based on a porous Pt-paper cathode.

In this work, a mediator-less and compartment-less glucose/air enzymatic biofuel cell (BFC) was introduced into microfluidic paper-based analytical devices (μ-PADs) with gold nanoparticles (AuNPs) and platinum nanoparticles (PtNPs)-modified paper electrode as the anodic and cathodic substrate, respectively, to implement self-powered, sensitive, low-cost and simple DNA detection. As a further development of the analytical equipment, an all-solid-state paper supercapacitor (PS) was designed and integrated into the BFC for current amplification, and a terminal digital multi-meter detector (DMM) was introduced for the current detection. A highly sensitive DNA sensor was fabricated by covalently immobilizing the capture DNA in the AuNPs-modified anode. The nanoporous gold conjugated with bienzymes, glucose oxidase and horseradish peroxidase, which were used as electrochemical labels. The electrons generated at the anode flow through an external circuit to the PtNPs-modified cathode that catalyzed the reduction of oxygen with the participation of protons. In addition, the generated current could be collected and stored by the PS. After that, the PS was automatically shorted under the control of a switch to output an instantaneously amplified current, which could be sensitively detected by the terminal DMM. At the optimal conditions, the paper-based analytical platform can detect DNA at the femtomole level. This approach also shows excellent specificity toward single nucleotide mismatches.