Da Ha

A novel microphysiometer based on high sensitivity LAPS and microfluidic system for cellular metabolism study and rapid drug screening

This study presents a novel microphysiometer for studying the mechanism of cellular metabolism and drug effect. Based on the photocurrent amplification of light-addressable potentiometric sensor (LAPS), the constant voltage detection mode was introduced to enhance the detection sensitivity to replace the conventional constant current mode with the slow feedback rate. The photocurrent amplification of LAPS was improved by developing the sensor structure and fabrication processes. The sensor unit with microfluidic system was designed to detect the concentration change of cellular acidic metabolites in the extracellular microenvironment rapidly. Characteristic test experiments and cellular metabolism experiments were carried out to determine the performance of microphysiometer. The result showed that sensitivity of microphysiometer is significantly enhanced to sense the fluctuation of cellular metabolism rapidly and sensitively in real-time detection of living cells under physiological condition. With these improvements, the novel microphysiometer holds promise as a utility platform for studying cellular metabolism and evaluating drug effect.

Smart voltammetric procedure in an automatic trace metal monitoring system for expanding the measurement range of a gold-band microelectrode array

A smart voltammetric procedure in an original automatic trace metal monitoring system is presented in this study. Its aim is to expand the measurement range of a gold-band microelectrode array (MEA) for monitoring heavy metal ions such as Zn2+, Pb2+?and Cu2+. A?voltammetric controller to execute a smart voltammetric procedure and a homemade mercury-free gold-band MEA are introduced. Three particular features are included in the smart procedure, which are self-calibration, multi-standard solution fluidics control and automatic adjustment of deposition time. The measurement range of a gold-band MEA is investigated by a traditional voltammetric set-up. Experiments show good linearity from 10 to 50??g?L?1?for Zn2+, Pb2+?and Cu2+; the MEA detection limit for Zn2+, Pb2+?and Cu2+?is about 0.4, 1 and 0.4??g?L?1, respectively. Moreover, self-calibration, multi-standard solution fluidics control and automatic adjustment of deposition time are introduced in smart voltammetric measurement with the method of standard additions. The upper concentration limit can be increased to twice that of conventional measurements; the detection limit for Zn2+, Pb2+?and Cu2+?can reach 0.1, 0.2 and 0.1??g?L?1, respectively. In addition, this design has been validated by monitoring natural concentrations of Zn2+, Pb2+?and Cu2+?(West Lake, China) and comparing with atomic absorption spectrometry.

THE STUDY ON NOVEL MICROELECTRODE ARRAY CHIPS FOR THE DETECTION OF HEAVY METALS IN WATER POLLUTION

Qualitative and quantitative analysis of trace heavy metals in aqueous environment are rapidly assuming significance along with the rapid development of industry. In this paper, gold microelectrode array (MEA) plated with mercury film was used for simultaneous voltammetric detection of zinc, cadmium, lead and copper ions in water. The electrochemical behavior and the actual surface area of the MEA were investigated by cyclic voltammetry in K3[Fe(CN)6]. Electrochemical impedance spectrum (EIS) was utilized to examine the deposition of mercury on the electrode surface. Based on anodic stripping voltammetry, mercury film–Au MEA was applied to the detection of heavy metals in artificial analyte, where good calibrate linearity was obtained for cadmium, lead and copper ions, but with zinc exhibiting poor linearity.

DESIGN OF MICROPHYSIOMETER BASED ON MULTIPARAMETER CELL-BASED BIOSENSORS FOR QUICK DRUG ANALYSIS

Cellular metabolism arouses the changes of substance in extracellular physiological micro-environment, and the metabolic level reflects the physiological state of cells. This paper developed a novel microphysiometer automatic analysis instrument based on multiparameter cell-based biosensors for quick drug analysis. This study included the multiparameter cell-based biosensors, cell culture chamber, drug auto-injection detection and analysis. The analysis instrument was capable of real-time detection for the acidic product and other chemical parameters generated by the cellular metabolism in the micro-volume. Finally, the paper employs human breast cancer cell line MCF-7 and drug experiments to verify the performance of microphysiometer, and study effects of different drugs on cell metabolism. Further, the research explores drug analysis method of the multiparameter microphysiometer. The results showed that the cell-based microphysiometer system provides a utility platform for rapid, long-term and automatic cell physiological environment detection and drug analysis.

Electronic Nose and Electronic Tongue

The sensations of smell and taste resulting from a series of specific and nonspecific molecular recognition can be used as an analytical tool in many industries to measure the quality of food, drinks, and chemical products. In a few cases, there are olfactory receptor s or gustatory receptors which are specific for individual chemical molecules. However, most tastes and odorants are identified through a synthesis of the global chemical information from nonspecific interactions. Taking mammalian gustation as an example, the combination of “gustatory buds” which respond to five taste categories : sour , sweet , bitter , salty , and umami creates a distinct pattern for each taste.

Biomimetic Gustatory Membrane-Based Taste Sensors

Electronic tongue is the classical tool for taste evaluation in different applications such as food evaluation [1], water [2], and process monitoring [3]; biomimetic membrane-based taste biosensor is another important approach for taste evaluation.

8.2.2 A High Spatial Resolution MEA for Voltammetric Analysis of Trace Metals in Water Pollution Based on Partial Least Squares Regression

Estimation of heavy metals in water has been paid significant attention because of the toxicity of such metals on the whole ecological system. A microelectrode array (MEA) of individually addressable microelectrodes was fabricated for cadmium, lead and copper analysis in water pollution. The ratio of interelectrode distance to the electrode diameter of the MEA was sufficient enough to get a collective current response while maintaining the excellent features of single microelectrodes. Cyclic voltammograms made in various scan rates confirmed that a high spatial resolution MEA was constructed with no diffusion layers overlapping. Then the mercury film Au-MEA was utilized to detect cadmium, lead and copper ions using differential pulse anodic stripping voltammetry (DPASV). The sensitivity of 130nA/μg, 52nA/μg and 46nA/μg for Cd 2+ , Pb 2+ and Cu 2+ ions, separately, were achieved using this microsensing chip. Calibrations were made via partial least-squares regression (PLSR) modeling. Well correlation was found between the lab-determined values and the values predicted from PLSR calibration.

Design of precision light intensity modulation for light-addressable potentiometric sensor

In this study, we present a novel design of precision light intensity modulation for LAPS measurement, aim to ameliorating the stability and precision of light source. A superluminescence LED (SLED) module, with a specialized designed SLED driver, is proposed as the light source. This design provides precision sine light intensity output. Furthermore, this design is immune from variation of ambient temperature. Contrast experiments were given between two conditions, with design of precision light intensity modulation and with traditional light source. From contrast experiments, it can be deduced that LAPS system with design of precision light intensity modulation has better linearity and accuracy than the latter one.

Design of wireless sensor node based on a novel hybrid chemical sensor for heavy metal monitoring

A wireless sensor node based on a novel hybrid chemical sensor was designed for heavy metal monitoring. The node consisted of four units that were the transducer unit, the processor unit, the communication unit and the power unit. The hybrid chemical sensor combining microelectrode arrays (MEA) and light-addressable potentiometric sensors (LAPS) on the same silicon chip was used to get redundant data about the concentrations of heavy metal and hydrogen ions in water environment. Multiple linear regression (MLR) with peak currents of Zn²⁺, Pb²⁺ and Cu²⁺ from MEA and equilibrium potentials of Zn²⁺, Pb²⁺, Cu²⁺ and H+ from LAPS as the explanatory variables and the concentrations of Zn²⁺, Pb²⁺ and Cu²⁺ as the response variables was modeled to improve the anti-interference ability.