An intense cathodic electrochemiluminescence from carbon-nanosheets in situ grown on glassy carbon electrode and application in immunoanalysis via biometallization strategy.

An intense cathodic electrochemiluminescence (ECL) is reported from a polarized glassy carbon electrode (GCE) in peroxydisulfate solution. After the polarization in 1 M Na2SO4 at the potential of - 3.7 V for 3 s, carbon nanosheets (C-NSs) were in situ grown on the surface of the GCE. Measured in 100 mM K2S2O8 solution, the ECL intensity of the GCE/C-NSs is 112-fold that of a bare GCE. The ECL spectrum revealed that the true ECL luminophore in the GCE/C-NSs-peroxydisulfate system is O2/S2O82- which is promoted by C-NSs. When Cu2+ was electrochemically enriched and reduced to Cu(0) on the catalytic sites of C-NSs, the ECL from GCE/C-NSs/Cu in K2S2O8 solution was decreased with increasing logarithmic concentration of Cu2+ in the range from 10 pM to 1 µM, with a limit of detection (LOD) of 3 pM. An immunoanalysis method is proposed via a biometallization strategy using CuS nanoparticles as the tags and carcinoembryonic antigen (CEA) as the model analyte. After the immune recognition in the microplate, the CuS tags in the immunocomplex were dissolved and the resultant Cu2+ was electrochemically enriched and reduced on the catalytic sites of C-NSs, quenching the ECL intensity of GCE/C-NSs-O2/S2O82- system. The proposed ECL immunoanalysis method was used to quantify CEA in actual serum samples with an LOD of 1.0 fg mL-1, possessing the advantages of simple electrode modification, high sensitivity and good reproducibility.

Wavelength-dependent photoelectrochemical response demonstrated by the determination of acetaminophen and rutin in differential molecularly imprinted polymers strategy.

Herein, the excitation wavelength-dependent responses of the molecularly imprinted polymer (MIP) photoelectrochemical (PEC) sensors were investigated, using acetaminophen (AP), rutin (RT) and perfluorooctanoate (PFOA) as the model templates, pyrrole as functional monomer, CuInS2@ZnS/TiO2 NTs as the basic photoelectrode. With wavelength λ > 240 nm, the photocurrent of MIPPFOA enhanced at higher concentrations of PFOA. With increasing AP concentration, the photocurrents of MIPAP could decline with λ < 271 nm, not change at λ = 270 nm, or increase with λ > 270 nm. As RT concentration increased, the photocurrents of MIPRT could decrease (λ < 431 nm), not change (λ = 431 nm) or increase (λ > 431 nm). The PEC responses depend on the comprehensive interaction of two contrary mechanisms from the template molecules within the MIP membrane. The photocurrent is enhanced by the role of the electron donor for photo-generated holes but attenuated due to the steric hindrance effect and the excitation light intensity loss via absorption or scattering. The apparent molar absorption coefficient of AP and RT within MIP membranes are 9.1-19.4 folds of those measured from dilute solutions. By using a routine UV lamp as the light source, the photocurrents of MIPRT at 254 nm and MIPAP at 365 nm were used to determine RT and AP, with the detection limits of 5.3 and 16 nM, respectively. The interference from the non-specific adsorption of interferents on the surfaces of MIPAP and MIPRT was reduced by one order of magnitude via a differential strategy.