Photoelectrochemical lab-on-paper device equipped with a porous Au-paper electrode and fluidic delay-switch for sensitive detection of DNA hybridization.

The sequence-specific detection of DNA hybridization has attracted considerable interest in numerous fields. Although traditional DNA biosensors have been widely explored due to their high sensitivity, it is still challenging to develop a low-cost, portable, disposable, fast, and easy-to-use DNA detection method for public use at home or in the field. To address these challenges, herein, we report a novel microfluidic photoelectrochemical (PEC) paper-based analytical platform, integrated with an internal chemiluminescent light source, a novel paper supercapacitor (PS) amplifier, and a terminal digital multi-meter (DMM) detector, for sensitive DNA detection using a graphene-modified porous Au-paper electrode as the working electrode to obtain enhanced PEC responses. The quantification mechanism of this strategy is based on the charging of this PS, which was constructed on a paper-based analytical platform through a simple "drawing and soaking" method, by the generated photocurrent. After a fixed period, the PS was automatically shorted under the control of a novel built-in fluidic delay-switch to output an instantaneously amplified current, which could be sensitively detected by the DMM. At optimal conditions, this paper-based analytical platform can detect DNA at concentrations at femtomolar level. This approach also shows excellent specificity toward single nucleotide mismatches.