A molecular imprinted polymer thin film for photoelectrochemical (PEC) sensing of chlorpyrifos molecules was first constructed by electropolymerizing the o-phenylenediamine (o-PD) monomer and chlorpyrifos template molecule on gold nanoparticles-modified titanium dioxide nanotubes. The resulting PEC sensors were characterized by scanning electron microscopy, ultraviolet (UV)-vis spectra and electrochemical impedance spectra. Clearly, the imprinted film showed high selectivity to chlorpyrifos in our case. Under visible light irradiation, poly(o-phenylenediamine) (PoPD) 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 conduction band (CB) of the titanium dioxide nanotubes (TiO(2) NTs). Simultaneously, it is believed that a positively charged hole (h(+)) of PoPD that took part in the oxidation process was consumed to promote the amplification of photocurrent response. Under the optimal experimental conditions, the photocurrents were proportional to the concentrations of chlorpyrifos ranging from 0.05 to 10 μmol L(-1) with the detection limit of 0.96 nmol L(-1). The PEC sensor had an excellent specificity and could be successfully applied to the detection of reduced chlorpyrifos in green vegetables, indicating a promising application in PEC sensing.

An ultrasensitive electrochemiluminescence (ECL) immunosensor was developed using PtAg@carbon nanocrystals (CNCs) as excellent labels based on carbon nanotubes-chitosan/AuNPs (CNT-CHIT/AuNPs) composite modified screen-printed carbon electrodes (SPCEs) for prostate protein antigen (PSA) detection. The CNCs were obtained simply by electro-oxidation of graphite with abundant carboxyl groups at their surfaces. The PtAg bimetallic nanocomposites with hierarchically hollow structures were fabricated through simple replacement reaction using dealloyed nanoporous silver (NPS) as both a template and reducing agent. Structure characterization was obtained by means of transmission electron microscope (TEM) and scanning electron microscope (SEM) images. The PtAg@CNCs composites exhibit a 6 times higher ECL intensity than the pure CNCs labeled anti-PSA. The as-prepared CNT-CHIT/AuNPs composite can attach more antibody than pure CNTs. Due to the dual-amplification techniques, the concentrations of PSA were obtained in the range from 1 pg mL(-1) to 50 ng mL(-1) with a detection limit of 0.6 pg mL(-1). Finally, the as-proposed ECL immunosensor has the advantages of high sensitivity, specificity and stability and could become a promising technique for tumor marker detection.

A low-cost, portable rechargeable battery was firstly used to fabricate a battery-triggered, screen-printed two-electrode electrochemiluminescent immunoassay on a 3D microfluidic origami electronic device.