OBJECTIVE:To establish a method for the content determination of isoniazid in Isoniazid tablet. METHODS:Mi-crofluidic chip with contactless conductivity detection was adopted. The effects of electrophoresis parameters,such as the variety, concentration,pH,additive types and dosage,injection time and separation voltage on the separation detection were explored. RE-SULTS:The optimized buffer system was 1.86 mmol/L citrate-0.14 mmol/L sodium citrate buffer solution (pH3.0),no additive , the injection time was 20 s and the separation voltage was 2.5 kV. In the optimal conditions,the linear range of isoniazid was 10-200 μg/mL(r=0.9993);the limits of quantification and detection were 8.0 μg/mL and 2.4 μg/mL;RSDs of precision,stability and reproducibility tests were lower than 2.0%;recovery was 97.8%-102.9%(RSD=1.9%,n=9). CONCLUSIONS:The method is rapid and simple,and suitable for the content determination of isoniazid in Isoniazid tablet.

With the continuous development in microfluidic fabrication technology, microfluidic analysis has evolved from a concept to one of research frontiers in last twenty years. The research of enzymes and enzyme inhibitors based on microfluidic devices has also made great progress. Microfluidic technology improved greatly the analytical performance of the research of enzymes and enzyme inhibitors by reducing the consumption of reagents, decreasing the analysis time, and developing automation. This review focuses on the development and classification of enzymes and enzyme inhibitors research based on microfluidic devices.

A new on-column conductivity detection for microchip capillary based on the accessional solution conductor between separation channel and electrodes was designed. In this detection, the carrier electrolyte solution was chosen as conductor to eliminate large drifts of the detection signals, that because different composition or concentration can lead to transport processes(diffusion and electromigration) between the carrier electrolyte solution and mediator. The separation channel incorporated a dual-T and a crux-channel, dual-T was used for sample introduction, and the crux-channel was used for detection. The sensing electrodes connected to separation channel through the crux-channel and obtained the potential different of conductivity. This method avoids integrating the sensing electrodes directly within the separation channel and prevents any direct contact of the electrodes with the sample. It not only avoids electrode reactions but also is convenient for washing and replacing electrodes. In addition, the signals, contrary to contactless conductivity detection, can be detected in the low excitation voltage(2.5-4.0 V) and frequency(700-1700 Hz) range. In the buffer solution of 15 mmol/L MES-His(pH 5.8), the detection limits was 0.5 and 0.1 μmol/L for K+ and Na+.

Liquid biopsy is a technology that exhibits potential to detect cancer early,monitor therapies,and predict cancer prognosis due to its unique characteristics,including noninvasive sampling and real-time analysis.Circulating tumor cells(CTCs)and extracellular vesicles(EVs)are two important components of circu-lating targets,carrying substantial disease-related molecular information and playing a key role in liquid biopsy.Aptamers are single-stranded oligonucleotides with superior affinity and specificity,and they can bind to targets by folding into unique tertiary structures.Aptamer-based microfluidic platforms offer new ways to enhance the purity and capture efficiency of CTCs and EVs by combining the advantages of microfluidic chips as isolation platforms and aptamers as recognition tools.In this review,we first briefly introduce some new strategies for aptamer discovery based on traditional and aptamer-based micro-fluidic approaches.Then,we subsequently summarize the progress of aptamer-based microfluidics for CTC and EV detection.Finally,we offer an outlook on the future directional challenges of aptamer-based microfluidics for circulating targets in clinical applications.