Photoelectrochemical lab-on-paper device based on molecularly imprinted polymer and porous Au-paper electrode

In this work, microfluidic paper-based analytical device (μ-PAD) was applied in a photoelectrochemical (PEC) method and thus a truly low-cost, simple, portable, and disposable microfluidic PEC origami device (μ-PECOD) was demonstrated. The molecular imprinting technique was introduced into microfluidic paper-based analytical devices (μ-PADs) through electropolymerization of molecular imprinted polyaniline (MPANI) in a novel Au nanoparticle (AuNP)-modified paper working electrode (Au-PWE). This is fabricated through the growth of an AuNP layer on the surfaces of cellulose fibers in the PWE. Under visible light irradiation, MPANI can generate the photoelectric transition from the highest occupied molecular orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO), delivering the excited electrons to the AuNPs, and then to the carbon working electrode. Simultaneously, it is believed that a positively charged hole of MPANI that took part in the oxidation process was consumed by ascorbic acid (AA) to promote the amplifying photocurrent response. On the basis of this novel MPANI-Au-PWE and the principle of origami, a microfluidic molecular imprinted polymer (MIP)-based photoelectrochemical analytical origami device (μ-MPECOD), comprised of an auxiliary tab and a sample tab, is developed for the detection of heptachlor in the linear range from 0.03 nmol L−1 to 10.0 nmol L−1 with a low detection limit of 8.0 pmol L−1. The selectivity, reproducibility, and stability of this μ-MPECOD are investigated. This μ-MPECOD would provide a new platform for high-throughput, sensitive, specific, and multiplex assay in public health, environmental monitoring, and the developing world.