Jianqiu Chen,Juan Shu,Jiao Chen,Zhiran Cao,An Xiao,Zhengyu Yan
S,N co-doped carbon quantum dots (N,S-CQDs) with super high quantum yield (79%) were prepared by the hydrothermal method and characterized by transmission electron microscopy, photoluminescence, UV–Vis spectroscopy and Fourier transformed infrared spectroscopy. N,S-CQDs can enhance the chemiluminescence intensity of a luminol–H 2 O 2 system. The possible mechanism of the luminol–H 2 O 2 –(N,S-CQDs) was illustrated by using chemiluminescence, photoluminescence and ultraviolet analysis. Ranitidine can quench the chemiluminescence intensity of a luminol–H 2 O 2 –N,S-CQDs system. So, a novel flow-injection chemiluminescence method was designed to determine ranitidine within a linear range of 0.5–50 μg ml −1 and a detection limit of 0.12 μg ml −1 . The method shows promising application prospects.
Yonghong Wang,Zeyang Fang,Ge Ning,Shaoming Mao,Yaohui Wu,Shun Wu,Gao-Qiang Liu
After successively introducing elements of a triple-helix aptamer probe (TAP) and a luminol–hydrogen peroxide (H 2 O 2 ) solution, we proposed a brand-new chemiluminescence (CL)-based biosensor for the assay of ochratoxin A (OTA). Primarily, the TAP contains an aptamer loop, two DNA segment stems, and a triplex-forming oligonucleotide (signal probe). In the presence of a target, the aptamer sequence binds to the target with an impressive affinity. This association leads to a conformational change in the TAP, thus releasing the signal probe. Sequentially, with the participation of hemin and potassium ions, the dissociated probe forms into a G-quadruplex structure that is capable of catalyzing luminol to produce CL mediated by H 2 O 2 . In contrast, in the absence of the target, a low background signal remains. Using this approach of combining a novel TAP switch with a G-quadruplex-catalyzed luminol-H 2 O 2 system, we presented a label-free and signal-on CL strategy for the measurement of OTA. Under optimal conditions, the gradually strengthened signal maintained a linear dependence on target concentrations ranging from 0.1 ng/mL to 2.0 ng/mL, and the detection limit was as low as 0.07 ng/mL. This newly designed, simple, and cost-effective protocol affords high sensitivity, specificity, suitability, and efficacy for biosensing. Thus, this protocol is attractive for a range of target quantifications, with only the matched aptamer requiring replacement (no redesign of signal probes).
Highly ordered structure of catalysts could spring up unique properties in catalytic activities. There is apparently no good reason to disregard the structurally ordered catalyst-amplified chemiluminescence (CL) signals. Herein, we have fabricated the structurally ordered ionic liquid-layered double hydroxide (LDH) assembly through the hydrogen bonding interactions between abundant hydroxyl groups on the surfaces of LDHs and the amino groups in 1-(3-aminopropyl)-3-methyl-imidazolium tetrafluoroborate ([apmim]BF4). Interestingly, we found that the CL signals of luminol–H2O2 system in the presence of structurally ordered [apmim]BF4 ionic liquid-LDH assembly were extraordinarily enhanced, in comparison with those in the presence of the disordered 1-aminoethyl-3-methyl imidazolium tetrafluoroborate ([aemim]BF4) ionic liquid-LDH assembly. The improved CL performances of the structurally ordered [apmim]BF4 ionic liquid-LDH assembly were attributed to the increasing amounts of superoxide anion radicals (O2•–) and hydroxide radicals (•OH) by accelerating of the mass transport from the solution to the surface of ionic liquid–LDH assembly. In addition, such a highly orderly arrangement could increase the emission of the luminol oxidation products by facilitating the electron transfer. Our findings open up new possibilities in the structurally ordered catalyst-enhanced CL emissions, which can be expected to provide a novel and sensitive platform for the CL amplified detection.
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