Chemiluminescence excited photoelectrochemical competitive immunosensing lab-on-paper device using an integrated paper supercapacitor for signal amplication

• Paper-based chemiluminescent excited photoelectrochemical competitive immunoassay was developed.
• Gold nanoparticles modified paper working electrode was prepared.
• CdS/TiO2 hybrid was prepared and used to modify Au-paper working electrode.
• A paper supercapacitor was constructed for photocurrent amplification.

A chemiluminescent (CL) excited photoelectrochemical (PEC) immunosensor for detection of carcinoembryonic antigen (CEA) was introduced into microfluidic paper-based analytical devices (μ-PADs) integrated with a paper supercapacitor (PS) amplifier, and a terminal digital multi-meter (DMM) detector, based on CdS/TiO2 hybrid modified porous Au-paper electrode. The effective matching of energy levels between the conduction bands of CdS and TiO2 allowed for fast electron injection from excited CdS to TiO2 upon irradiation, which inhibited the recombination process of electron–hole pairs and prompted PEC performance. Using CEA/ABEI-AuNPs-GOx bioconjugates as signal labels which featured CEA, N-(aminobutyl)-N-(ethylisoluminol) (ABEI) and glucose oxidase (GOx) linked to Au nanoparticles for signal amplification could greatly enhance the sensitivity. GOx could catalyze glucose to produce H2O2, which acted as a co-reactant in the ABEI-AuNPs-H2O2-p-iodophenol (PIP) CL system as well as sacrificial electron donor to scavenge the photogenerated holes in the valence band of CdS QDs, further causing an enhanced photocurrent. The quantification mechanism of this strategy is based on the charging of this PS by the photocurrent. The generated photocurrent could be stored by the PS and released instantaneously through a low cost, portable, and simple DMM to obtain an amplified current for the quantification of CEA. Under the optimal conditions, this analytical platform could detect CEA at concentrations at picomole level. This work offers a new route to highly selective and sensitive detection of biologically important small molecules.