A rapid quantitative determination method of Luteinizing hormone with gold immunochromatographic strip.

Measurement of Luteinizing hormone (LH) levels is of great importance in guidance for pregnancy, diagnosis of ovarian diseases and evaluation of clinical effect. Gold immunochromatographic strip(GICS) assay is a rapid, simple, low-costs, and on-site technology. Quantitative detection of GICS has advantage over the traditional qualitative or semi-quantitative strip assay. In this paper, we developed a novel quantitative detection method for GICS based on smart-phone. First, smart-phone was used to acquire GICS image. Then, we applied the canny edge detection operator to extract the reading window from GICS image, and the fuzzy c-means (FCM) clustering algorithm to locate the test and control lines in the reading window. In order to reduce environmental interference, luminance compensation based on color constancy algorithms was applied. Finally, the property of the developed quantitative method is demonstrated by the detection of LH sample and clinical serum sample. Experimental results revealed that this method could achieve a low detection limit of 1.0 mIU/mL in a linear range from 1.0 to 125.0 mIU/mL. Furthermore, the proposed method could be used for the determination of clinical serum samples and its corresponding correlation coefficients were 0.964. Results showed that this novel method could be an effective tool for the rapid quantitative determination of LH.

Research on the synchronous detection of neuronal signals under a nerve stimulation system control.

Deep brain stimulation (DBS) provides a recognized research intervention for neurological disease currently. However, there is a lack of traditional electrical stimulator to observe neuronal firing activity synchronously. The aim of the present study was to realize concurrent detection of neuronal signals better under a nerve stimulation system control. Herein, we designed an integrated software, which could control not only neuro-stimulator but also detection instrument at the same time. Moreover, the actual stimulation signals applied to the experiment object could be collected back to data acquisition card and in consistent with the electrophysiological signals. As to basic performance of self-building stimulator, the accuracy of output square signal was verified to be greater than 99.05 % with the change of voltage amplitude. Practicably, combined with homemade microelectrode array (MEA) detecting device, medial forebrain bundle (MFB) DBS effects were observed significantly through the changes of electrophysiological signals in caudate putamen (CPu) of Sprague-Dawley (SD) rat, and the signal-to-noise ratio (SNR) was 5:1 after stimulation. Therefore, the comprehensive nerve stimulation system, which consists of neuro-stimulator and integrated software, could be widely used in the field of neuroscience research with high precision and synchronization.

Application of Micro-Electro-Mechanical-System Probe and Low-power & Low-noise Single Chip Integration System in Neural Loop Researching / 分析化学

A 8-channel neural signal′s simultaneous transducer detection micro system was developed to research the neural loop located at the brain hippocampus zone. The components of the system contained the neural probe manufactured with the Micro-electro-mechanical-systems (MEMS) technique based on silicon-on-insulator (SOI) substrate, biological low noise chopper-stabilization amplifier, low noise and intermediate speed SAR-ADC converter, reduced and low power ASK/FSK modulation radio transmitter. The micro system was applicable with the characters of small volume, interferences free, neural electrophysiology and neurotransmitter simultaneous detection, high sensitivity, high linearity, etc. The electrode resistance was optimized to 35.0 kΩ after depositing nanometer platinum black on the 4 electrophysiological sites on the Pt electrode. With the modification enzyme technique, nanomaterial enzyme membrane (Pt-mPD-GluOx) was directly fixed on the glutamate detection locus for selectively detecting special neural neurotransmitter matter. In addition, the electrochemistry measurement results indicated that the linear range of glutamate was 6-35 μmol/L with correlation coefficient of 0.97, the sensitivity was 0.0069 pA/(μmol/L). The current response error was less than 3.0 pA, which showed that the neural needle satisfied differential selection. Also, the logic/analog mixed signal 180-nm Application specific integrated circuit (ASIC ) technique (SmicRF180 nm 1Poly6M) was used to manufacture the transducer back-end disposing IC chip, and the test results provided some key parameters such as chopper-stabilization amplifier (equivalent in putting noise voltage ≤0.7 μV rms@1 kHz, gain of 71-82 dB, CMRR/PSRR>100 dB), SAR-ADC (ENOB is 12 bits, power consumption is 1.2 mW when maxmium conversion speed is 1 Msps, signal-noise-ratio is 60.9 dB, etc), and ASK/FSK modulation radio transmitter (the PA′s outputting power of 4-5 dBm, the radiation range of 10 meters). The micro neural transducer integrated system was convenient and wireless wearable for the research of brain hippocampus region.

Monitoring of Subthalamic Nucleus Stimulation-induced DopamineFlux and Spike Firing Change of Striatum Neuronswith a Micro-Nano Electrode Array / 分析化学

Subthalamic nucleus (STN) deep brain stimulation (DBS) has become an important surgical treatment of Parkinson disease, but its exact mechanism is still unclear.In this study, a 16-channel implantable microelectrode array (MEA) was prepared by micro-electromechanical system (MEMS) technique and later modified with platinum black/reduced Graphene Oxide/Nafion (Pt/RGO/Nafion) nanocomposites.Extracellular dopamine (DA) content and spike of dorsal striatum neurons were synchronously recorded before and after STN stimulation.The results showed that the dopamine content began to increase within 20 s after electrical stimulation and dropped to normal level after about 50 s, with the highest rising concentration of 1.72 μmol/L.At the same time, there was an increased spike activity of interneurons in the dopamine ascending phase, and the spike firing rate of medium spiny projection neurons (MSNs) was high when the concentration of DA was higher than the normal level.The MEA sensor can simultaneously record dopamine flux and physiological signals in situ, thus providing an ideal tool for neural information detection.

An implantable microelectrode array for dopamine and electrophysiological recordings in response to L-dopa therapy for Parkinson's disease.

Dual-mode multielectrode recordings have become routine in rodent neuroscience research. However, robust and reliable application of acute, multielectrode recording methods in brain especially for in vivo research remains a challenge. In patients with Parkinson's disease (PD), the efficacy of L-dopa therapy depends on its ability to restore Dopamine (DA) neurotransmission in the striatum. In this paper, We describe a low cost thin film 16 sites implantable microelectrode array (MEA) chip fabricated by standard lithography technology for in vivo test. In urethane anesthetized rats, the MEA probes were implanted acutely for simultaneous recording of local field potentials, spikes, and L-dopa therapy evoked dopamine overflow on the same spatiotemporal scale. We present a detailed protocol for array fabrication, then show that the device can record Spikes, LFPs and dopamine variation in real time. Across any given microelectrode, spike amplitudes ranged from 80 to 300 µν peak to peak, with a mean signal-tonoise ratio of better than 5:1. Calibration results showed the MEA probe had high sensitivity and good selectivity for DA. Comparison with existing methods allow single mode recording, our neural probes would be useful for examining specific spatiotemporal relationships between electrical and chemical signaling in the brain.

A model-based method to measure baroreflex sensitivity.

This paper proposes a model-based method to quantitatively measure baroreflex sensitivity in autonomic nervous regulation of cardiovascular system. The method measures the continuous blood pressure and heart rate in orthostatic scenario, models dynamics of the baroreflex firing rate, solves parameters by optimization of measured blood pressure and heart rate variations. With this model, we can get the baroreflx sensitivity (BRS) inner indicators to evaluate the status of the autonomic nervous regulation system. Experimental results have shown the validation of the quantitative measures and the effectiveness of the method.

Research on neural information detecting system measuring neuroelectricity in hippocampus in vivo and dopamine in vitro based on microelectrode array.

Concurrently detecting the electrical activity of neurons and neurotransmitter release signals, will have a great significance in understanding the working mechanism of the brain. This paper describes a neural information detecting system based on microelectrode array(MEA) measuring neuroelectricity in hippocampus in vivo and dopamine(DA) in vitro. The detecting system contains of electrophysiological headstage, electrochemical headstage, microprocessor, electrophysiological signal amplifier, data acquisition module and neural signal analysis software. In electrophysiological test, the neural information detecting system was applied to detect neuroelectricity in hippocampus of SD rat with 16-channel microelectrode array in vivo. Active potentials were captured. The amplitude of the recorded neural spikes reached 182.90 µV, and signal to noise ratio was 7:1. For measure dopamine as neurotransmitter, there was a good linear relationship between response current and concentration of dopamine from 10nM to 18.88µ with correlation coefficient of 0.9974. Electrophysiological experiment and electrochemical experiment demonstrate the capability of the neural information detecting system to capture dual mode neural signal, which provides a convenient way to study dual mode operating mechanism of neural system.

Synchronous Detection of Rat Neural Spike Firing and Neurochemical Signals Based on Dual-mode Recording Instrument / 分析化学

A dual-mode recording system used for synchronous detection of neuroeletrical and neurochemical signals was developed, and a dual-mode synchronous detection experiment was carried out using the instrument. The device comprised 64-channel neuroelectricity recording module with voltage resolution of 0. 3 μV and 4-channel neurochemistry recording module with current resolution of 1 pA. The software had many basic features, including Spike separation and sort, chronoamperometry, cyclic voltammetry, etc. In particular, the software could observe and analyze the dual-mode neural signals synchronously. The performance of the system was demonstrated in the single mode detection experiments. In neuroeletrical experiments, 64-channel simulate neural signals were detected and the signal to noise ratio ( S/N) of Spike recorded from cortex of Sprague-Dawley ( SD ) rat was 6. In the K3 [ Fe ( CN )6 ] and ascorbic acid measurement experiments, the current response of K3 [ Fe ( CN)6 ] in the range of 0. 1-10 mmol/L was obtained by cyclic voltammetry, with a correlation coefficient of 0. 9889, and the current response of ascorbic acid ( concentration:10-800 μmol/L) by chronoamperometry increased linearly with a correlation coefficient of 0. 9841. Based on the rat model of global cerebral ischemia, a dual-mode detection experiment was carried out. In the experiment, the neuroelectrical and neurochemical signals were synchronously recorded in the SD rat primary visual cortex. According to the experimental results, we got the conclusion that the concentration of ascorbic acid negatively related to the Spike firing in the SD rat primary visual cortex.

A Wearable Wireless Electrochemical Instrument Used for In_vivo Neurotransmitter Detection / 分析化学

A wireless electrochemical recording device was designed for in_vivo neurotransmitters real_time detection. Low_power microcontroller MSP430 was chosen as main control unit in hardware system. Other modules were current detection module, waveform generator module and data transceiver module. This device had the merits of small size (2. 3 cm×1. 8 cm×0. 6 cm) and low power consumption. Firmware program design was based on uC/OS operating system. Combined with the PC software, the device could achieve online display and analysis of the recording data. For neurotransmitter detecting needs, the device implemented fast_scan cyclic voltammetry ( FSCV) and fixed_potential amperometry. By using fast_scan cyclic voltammetry method, a linear relationship ( R=0. 99 ) between the concentration of dopamine and response current was acquired in the range of 5. 0×10-7-7. 0×10-5 mol/L. In the in_vivo experiments, the electrically evoked dopamine was recorded in the caudate_putamen area of brain in rats. Experimental results showed that the system had high detection accuracy, which could realize qualitative and quantitative analysis of the brain neurotransmitter. This work would have a broad application prospect in the field of neuroscience research.

Study of Microelectrode Array Probe for Simultaneous Detection of Glutamate and Local Field Potential during Brain Death / 分析化学

High extracellular potassium can induce spreading depression-like depolarizations, elevations of extracellular glutamate and even neuronal death in normal brain. To investigate the contribution of high potassium in vivo, a microelectrode arrays ( MEAs ) probe integrated with recording sites for glutamate concentration (50í150 μm) and local field potential ( LFP) ( diameter=15 μm) was fabricated by Micro-electro-mechanical-systems ( MEMS) technologies. We implanted the MEA probe acutely in the rat brain and exposed the brain to a high potassium solution. During these multi-modal recordings, it was observed that high potassium elevated extracellular glutamate while suppressing the LFP irreversibly. This is one of the first studies in which a dual mode MEA probes is applied in vivo for neuronal death, and it is concluded that our MEA probes are capable of examining specific spatiotemporal relationships between electrical and chemical signaling in the brain.

Application of Planar Microelectrode Array Modified by Nano-structure Titanium Nitride on Dual Mode Neural Information Recording / 分析化学

The nano-structure TiN was modified on the laboratory self-made planar microelectrode array pMEA by magnetron sputtering method. The performance of modified pMEA was investigated. Research on neuroelectrical and neurochemical recording was studied in vitro. The impedance of the modified pMEA was decreased almost one order of magnitude, and the background noise level was reduced to ±6 μV. In the same testing environment, the signal-to-noise ratio (SNR) of modified electrodes was 1. 7 times of bare electrodes. The SNR of neuroelectrical recording on the brain slice of SD rats reached 10:1 , and the weak signal such as ±12 μV was separated easily. For neuroelectrical recordings, the detection limit of dopamine ( DA) solution reached 50 nmol/L with the 2:1 (S/N). During the concentration range of 0. 05-100 μmol/L, the linearly correlation coefficient of the DA oxidation currents was 0 . 998 . The modification of nano-structure TiN on pMEA reduced pMEA impedance and background noise level, meanwhile the SNR was increased. The weak signals of neuroelectrical and neurochemical recording were successfully recorded.

Detection of Human Chorionic Gonadotropin by Highly Sensitive Magnetic EnzymE-linked Chemiluminescent Immunoassay / 分析化学

A highly sensitive magnetic enzymE-linked chemiluminescent immunoassay method was developed for the detection of human chorionic gonadotropin(HCG). The monoclonal antibody was covalently coupled on the surface of carboxylated magnetic beads to generate magnetic-biotargeting; Alkaline phosphatase(ALP) was utilized as a labeled reagent of another monoclonal antibody, whereas 3-(2-spimadamantane) 4-methoxy-4-(3-phosphoryloxy)phenyl-1,2-dioxetane(AMPPD) was utilized as the chemiluminescent substrate. Based on this concept, a highly sensitive chemiluminescent immunoassay method was established to test HCG. Then, several modifications were made to optimize the method, and the detection sensitivity and procedure were improved accordingly. The detection of the assay could be fulfilled within 60 min and the test result of HCG concentration was linear over the range of 0.15 150 IU/L with good relativity(r=0.960). The relative standard deviation(RSD) were below 5% and the sensitivity of this method was 0.15 IU/L. The proposed method with wide linear range, simple operation and fast detection showed good prospect in practical application on-site.

Study of Key Electrochemical Problems in Transdermal Noninvasive Glucose Monitoring / 分析化学

Several key problems were analysed 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 glucose sensor,aiming at the unique "finite space" electrochemical problem in trans-dermal technique. In addition,electrode masks were utilized to solve the problem of electrode loss in longtime glucose monitoring. In animal in-vivo experiments,70.1 % of the noninvasive glucose data points were clinically accurate,while the remains were clinically acceptable. All solutions mentioned above were based on both theoretical analysis and experimental validation,promoting the realization and optimization of transdermal noninvasive glucose monitoring techniques.

Human Chorionicgonadotropin Measurement Method Based on Magnetic Nanoparticle Probes / 分析化学

The magnetic nanoparticle probe was prepared by specifically connecting the streptavidin-conjugated magnetic nanoparticles and the antibody of analyte via the strong streptavidin-biotin interaction. Based on the magnetic nanoparticle probes, the concentration of human chorionicgonadotropin (HCG) was detected and a new CL method for of hormone was further established. The performances of the magnetic nanoparticle probes were characterized by UV-Vis spectrometry, transmission electron microscopy and dynamic light scattering. The experimental conditions that affected the chemiluminescence were optimized. The optimal concentrations of luminal and H_2O_2 were 2×10~(-4) mol/L and 8×10~(-4) mol/L, respectively, and optimal pH was 13. Under the optimized experiment conditions, a linear response of chemiluminescence intensity to HCG concentration was obtained with a correlation coefficients of 0.9924. The linear range was from 0.5 to 250 μg/L and wider than the conventional ELISA method (5-200 μg/L). The relative standard deviation was 3.8%. Correlation analysis showed that there was significant correlation between the method of magnetic nanoparticle probes and ELISA in 34 clinical samples. The proposed method with characters of sensitive, effective, fast response and wide detection range provided good application prospect in analysis of other ultra-micro protein.