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Black phosphorus quantum dots are useful oxidase mimics for colorimetric determination of biothiols
摘要： Black phosphorus quantum dots (BP QDs) with small size are synthesized using an easy to operate thermal method. It was found that BP QDs possess oxidase-mimicking activity. They can catalyze the oxidation of the substrate 3,3′,5,5′-tetramethylbenzidine to produce a blue-colored product even in the absence of hydrogen peroxide. Active oxygen species are proved to be involved in the reaction through the experiments of radical scavenging and electron spin resonance. Biothiols including reduced glutathione and cysteine inactivate the oxidase-mimicking activity of BP QDs, concomitant to the fading of the blue solution. This provides the base for a colorimetric method for the determination of glutathione and cysteine. The decreased absorbance at 652 nm displays linear response to the concentrations of glutathione ranging from 0.1 to 5.0 μmol L?1, and cysteine from 0.1 to 10.0 μmol L?1. The detection limits are 0.02 μmol L?1 and 0.03 μmol L?1 for glutathione and cysteine, respectively. Successive determinations of 1.0 μmol L?1 glutathione and 5.0 μmol L?1 cysteine solution give relative standard deviations of 0.8% and 1.7% (n = 11), respectively. As a preliminary application, the practicability of the method was evaluated by the determination of glutathione in pharmaceutical preparations. This work not only discovers a useful oxidase mimics but also sets up a reliable platform based on BP QDs in colorimetric detection.
关键词： Cysteine,Pharmaceutical,Nanoprobe,Reactive oxygen species,Black phosphorous quantum dots,Oxidase-mimicking activity,Glutathione,Biothiols,Colorimetric method
更新于2025-09-23 15:19:57
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Effect of Defects on Diffusion Behaviors of Lithium-ion Battery Electrodes: In Situ Optical Observation and Simulation
摘要： Lithium-ion batteries (LIBs) with high energy efficiency are urgeniltly needed in various fields. For the LIBs electrodes, defects would be generated during manufacture processes and mechanical degradation, and the defects significantly impact the stability and performance of LIBs. However, the effects of electrode defects on the electrochemical processes are still not clear. Herein, an in situ optical observation system is developed for monitoring the Li diffusion around the pre-introduced defects in the commercial graphite electrodes. The experiments show the gas-filled defects vertical to the direction of the Li diffusion would obviously decelerate Li diffusion, while the electrolyte-filled defects parallel to the direction of the Li diffusion would accelerate Li diffusion. In addition, finite element analysis (FEA) suggests consistent with the experiments, showing nonuniform distribution of local Li concentration around the defect. The equivalent diffusivity obtained by FEA is also dependent on the configuration of the defects. The diffusivities of electrolyte-filled parallel defect and gas-filled vertical defect are 12.6 % and 11.0 %, respectively. For the gas-filled defects, the size-effect calculation manifests that equivalent diffusivity would decrease with the enlarged defect size, and the shape of the defects would substantially impact the decrease rate. The results directly reveal the mechanisms of defect induced diffusion behavior change in the electrodes by the new equivalent 2D experiments, and the equivalent diffusivity would be useful for optimizing electrode designs in LIBs.
关键词： colorimetric method,defect,graphite anode,lithium-ion battery,diffusion
更新于2025-09-09 09:28:46
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Optical sensing platform for colorimetric determination of silver nanoprisms and its application for hydrogen peroxide and glucose detections using a mobile device camera
摘要： Silver nanoprisms (AgNPrs) have a unique localized surface plasmon resonance, resulting in strong absorption and scattering within the visible light region. In this work, we propose the image acquisition from colloidal solutions of AgNPrs using a combination of transmitted and scattering lights. The developed measurement technique could be carried out by separately recording transmitted and scattering images of the solutions, using a mobile device camera prior to calculation of empirical absorption value (IA). IA value of green for AgNPrs solutions was found in agreement with the absorption spectra obtained using a conventional spectroscopic technique. This technique was utilized for the quantifications of hydrogen peroxide and glucose. The good linearities between ΔIA and those typical analytes were observed. The limit of detection for typical biosensor of glucose was 19.8 μM. As such, we expect the methodology herein developed for hydrogen peroxide and glucose determinations by means of monitoring the color change of transmitted and scatting images from solutions, to contribute to the development of simple, rapid, and reliable detection systems to be further applied in biochemical analysis and clinical diagnosis, as well as in household biosensor applications.
关键词： silver nanoprisms,glucose sensor,hydrogen peroxide sensor,localized surface plasmon resonance,colorimetric method
更新于2025-09-09 09:28:46