VS 4 Nanodendrites with Narrow Bandgaps in Activating Dissolved Oxygen for Boosted Chemiluminescence and Hemin Detection by Unexpected Quenching.

Chemiluminescence (CL)-based analytical methods utilize luminophores that need to be activated with an oxidizing agent to trigger CL emission. Despite its susceptibility to decomposition when exposed to external light or trace metals, hydrogen peroxide (H 2 O 2 ) has been widely used to develop chemiluminescent methods due to the limited number of suitable alternatives for activating chemiluminescent luminophores. Also, analytical methods based on the well-known luminol/H 2 O 2 CL system have low sensitivity. Dissolved oxygen (DO) is a naturally abundant and environmentally benign alternative oxidant for luminol and other CL luminophores. However, DO alone is inactive and needs an efficient catalyst or a coreaction accelerator for its activation. Because of the narrow bandgap of VS 4 ( ca. 1.12 eV), it can facilitate fast electron-transfer kinetics with an acceptor molecule such as DO. Here, we introduce vanadium tetrasulfide (VS 4 ) to boost CL for the first time. Under the optimized conditions, VS 4 nanodendrite catalyzes the generation of reactive oxygen species by activating DO which subsequently reacts with luminol to generate intense CL. It enhances the CL intensity of luminol/DO by about 10,000 times. Surprisingly, hemin remarkably quenches the generated CL of luminol/DO/VS 4 nanodendrites, which is completely opposite to its typical enhancement of luminol CL. Based on the remarkable concentration-dependent quenching of the luminol/DO/VS 4 nanodendrite CL by hemin, we have developed a sensitive CL method that can selectively detect hemin in the linear concentration range of 1-250 nM and achieved a limit of detection of 0.11 nM. The practical utility of the developed method was demonstrated by the determination of hemin in a pharmaceutical drug for the treatment of acute intermittent porphyria and in human serum. This study demonstrates that VS 4 holds great promise in analytical method development.