Pop-up paper electrochemical device for label -free hepatitis B virus DNA detection

Hepatitis B virus (HBV) is a chronic viral infection, causing significant health concerns worldwide. For point-ofcare testing, a simple, rapid, and disposable sensor is required. In this work, a pop-up DNA device as an alternative 3D microfluidic paper-based analytical device (mu PAD) platform was firstly proposed for label-free HBV DNA detection. The pop-up design was created to allow control of the fluidic path, incubation time, and electrical connectivity by simple folding. The proposed platform enabled a multi-step operation to be performed within a single device. Moreover, this architecture allows facile sample introduction, avoiding contamination and minimizing the exposure of biofluids. A pyrrolidinyl peptide nucleic acid, acpcPNA, which exhibits high affinity and selectivity, was covalently immobilized onto the modified cellulose on a working electrode for capturing the target DNA. Differential pulse voltammetry was employed with a signal-off system. The presence of HBV DNA resulted in a decrease of the electrochemical signal of hexacyanoferrate (III)/(II) in a concentration-dependent fashion. Under optimal conditions, a linear range of 50 pM-100 nM with the detection limit of 1.45 pM was achieved. Moreover, good selectivity of proposed device was demonstrated. The pop-up DNA sensor was successfully applied for the detection of HBV DNA extracted from plasmid constructs.