Qing Tian

Development of Amperometric Lactate Biosensor Modified with Pt-black Nanoparticles for Rapid Assay

For point-of-care determination, a disposable biosensor for the analysis of L-lactate in athletes serum samples was developed and optimized. The planar electrochemical biosensor was fabricated with gold thin-film two-electrode system and was modified with platinum-black nanoparticles and ferricyanide mediator. Platinum-black nanoparticles were deposited on the electrodes to improve the sensitivity and stability. Lactate oxidase (LOD, E.C.1.1.3.2) was immobilized on working electrodes with ferricyanide as mediator to improve the electron transfer ability by lowering the work potential to +0.2 V. The optimizations of the deposition of platinum-black nanoparticles, concentration of LOD, and concentration of ferricyanide in this article have resulted in the development of a lactate electrode with a wide linear range of 1–20 mM lactate, a high sensitivity of 1.43 µA mM−1, a fast detection time of 50 s, and a coefficient variation (CV) of 0.0549. The activity of biosensor held above 90% after one year storage at room temperature. The biosensor was successfully applied to the determination of L-lactate in serum samples without dilution. This disposable biosensor combined with portable meter is promising for rapid determination of point-of-care lactate.

Detection of Bacillus Anthracis Using Fluorescence Immunoassay with Quantum Dots Labels

Abstract A method for detecting Bacillus anthracis ( B. anthracis ) was developed using indirect immunofluorescence technique with quantum dots (QDs) as fluorescent probes. B. anthracis could be selectively labeled with QDs, which was demonstrated by fluorescence microscope and F4500 spectrofluorometer. A laboratory-made system including biosensor and device was used as detection apparatus. A linear relationship of the fluorescence intensity and log total count of B. anthracis was obtained with correlation coefficient of 0.9554 from 1 × 10 2 CFU mL −1 to 1 × 10 6 CFU mL −1 and a low relative standard deviation (RSD) of 2.19%. By comparing the fluorescence intensity of B. anthracis and other bacillus, this method showed good specificity. Because of simple operation and less detection time (1 h) than traditional methods and quantitative detection, this method has potential prospect in monitoring B. anthracis and other biowarfare agents.

Key Electrochemical Problems in Transdermal Noninvasive Glucose Monitoring

Abstract Several key problems were analyzed for the transdermal noninvasive glucose monitoring. A modified calibration equation was proposed for the high-sensitivity glucose biosensor due to its narrow linear range. The new equation has increased the sensors linear range by 20 times. A new diffuse model was constructed for the electrode system of the glucose sensor in view of the unique “finite space” electrochemical problem in transdermal technique. In addition, electrode masks were utilized to solve the problem of electrode loss in long-time glucose monitoring. In animal in-vivo experiments, 70.1% of the noninvasive glucose data points are clinically accurate, whereas the remains are clinically acceptable. All the solutions mentioned above are based on both theoretical analysis and experimental validation, promoting the realization and optimization of transdermal noninvasive glucose monitoring techniques.