No abstract

Electrogenerated chemiluminescence (also called electrochemiluminescence and abbreviated ECL) involves the generation of species at electrode surfaces that then undergo electron-transfer reactions to form excited states that emit light. ECL biosensor, combining advantages offered by the selectivity of the biological recognition elements and the sensitivity of ECL technique, is a powerful device for ultrasensitive biomolecule detection and quantification. Nanomaterials are of considerable interest in the biosensor field owing to their unique physical and chemical properties, which have led to novel biosensors that have exhibited high sensitivity and stability. Nanomaterials including nanoparticles and nanotubes, prepared from metals, semiconductor, carbon or polymeric species, have been widely investigated for their ability to enhance the efficiencies of ECL biosensors, such as taking as modification electrode materials, or as carrier of ECL labels and ECL-emitting species. Particularly useful application of nanomaterials in ECL biosensors with emphasis on the years 2004-2008 is reviewed. Remarks on application of nanomaterials in ECL biosensors are also surveyed.

No abstract

No abstract

No abstract

Four kinds of platelike mesocrystalline nanocomposites of TiO 2 polymorphs were successfully synthesized for the first time based on a topochemical mesocrystal conversion mechanism. In this conversion process, a [010]-oriented titanate H 1.07 Ti 1.73 □ 0.27 O 4 (□: vacancy of Ti) single crystal with lepidocrocite-like structure and platelike morphology was successively transformed into [001]-and [102]-oriented TiO 2 (B) phases including a {010}-faceted TiO 2 (B) twinning, [010]-oriented anatase phase, and [110]-oriented rutile phase. The platelike particle morphology is retained in the topochemical conversion process. The platelike particles are constructed from nanocrystals which wellaligned in the same orientation for the same phase, resulting in the formations of HTO/TiO 2 (B), HTO/TiO 2 (B)/anatase, TiO 2 (B)/anatase, and anatase/rutile mesocrystalline nanocomposites. The reaction mechanism and the crystallographic topological correspondences between the precursor, intermediates, and the final product were given on the basis of the nanostructural analysis results. The mesocrystalline nanocomposite of anatase/rutile polymorphs exhibits unexpectedly high surface photocatalytic activity, which can be explained by the superior electron−hole separation effect and the high activity of {010}-faceted anatase surface in the mesocrystalline nanocomposite. Such mesocrystalline anatase/rutile nanocomposite is an ideal photocatalytic system.

It remains a great challenge to develop effective strategies for improving the weak cathodic electrogenerated chemiluminescence (ECL) of the luminol-dissolved O 2 system. Interface modulation between metal and supports is an attractive strategy to improve oxygen reduction reaction (ORR) activity. Therefore, the design of electrocatalysts via interface modulation would provide new opportunities for the ECL amplification involving reactive oxygen species (ROSs). Herein, we have fabricated an Ag single-atom catalyst with an oxygen-bridged interface (Ag−O−Co) through the electrodeposition of Ag on a CoAl layered double hydroxide (LDH) modified indium tin oxide (ITO) electrode (Ag s /LDH/ITO). Interestingly, it was found that the cathodic ECL intensity of the luminol-dissolved O 2 system at the Ag s /LDH/ITO electrode was extraordinarily enhanced in comparison with those at bare ITO and other Ag nanoparticle-based electrodes. The enhanced ECL performances of the Ag s /LDH/ITO electrode were attributed to the increasing amounts of ROSs by electrocatalytic ORR in the Ag−O−Co interface. The electron redistribution of Ag and Co bimetallic sites could accelerate electron transfer, promote the adsorption of O 2 , and sufficiently activate O 2 through a four-electron reaction pathway. Finally, the luminol cathodic ECL intensity was greatly improved. Our findings can provide inspiration for revealing the interface effects between metal and supports, and open up a new avenue to improve the luminol cathodic ECL.

Iron can enter the electron-rich cavities of graphitic carbon nitride (g-C3N4). On account of this phenomenon, Fe-doped g-C3N4 (Fe-g-C3N4) was prepared as a peroxidase mimetic by using one-step pyrolysis of urea and FeCl3·6H2O. Compared to g-C3N4, Fe-g-C3N4 has a large specific surface area due to the presence of mesopores and cracks, a smaller band gap, and a high loading of Fe in its structure. Thus, Fe-g-C3N4 exhibits greater peroxidase activity with a more obvious color change when using 3,3′,5,5′-tetramethylbenzidine (TMB) as a substrate in the presence of hydrogen peroxide (H2O2). The color of a mixture of TMB and Fe-g-C3N4 gradually deepens with increasing concentrations of H2O2. Accordingly, a rapid, sensitive, and low-cost colorimetric assay for the detection of H2O2 was developed. After optimization, this method boasts a wide linear dynamic range for H2O2 detection from 0.005 to 400 μM (r 2 = 0.9971) with a detection limit of 0.005 μM. Because H2O2 is a main product of glucose oxidation by glucose oxidase (GOx), a colorimetric assay for glucose detection was also realized, with a linear dynamic range of 1–1000 μM (r 2 = 0.9996) and a detection limit of 0.5 μM. These assays were applied to the quantitative detection of H2O2 in milk and glucose in human serum, respectively.