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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.
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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.
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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.
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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.
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BACKGROUND: Although nickel and chromium are essential elements of human body, over high concentration of them will produce many adverse effects to human body, therefore biological safety of nichrome material for dental restoration deserves attention.OBJECTIVE: To observe the changes of nickel and chromium content at 6 months and 1 year after porcelain-fused-to-nichrome crown restoration, and compare to healthy controls to investigate the long-term safety of nichorme in oral cavity.DESIGN, TIME AND SETTING: A case-control observation was performed between January 2006 and December 2007 at the First Affiliated Hospital of Hebei North University, Zhangjiakou, Hebei Province, China.PARTICIPANTS: Sixty patients who visited Department of Stomatology, the First Affiliated Hospital of Hebei North University, between January and December 2006 were included in test group, including 28 male, 32 female, the mean age was 40 years. Each of them had 3 anterior maxillary teeth restored by porcelain-fused-to-nichrome crowns, without other metal fillings or protheses. Sixty healthy cases visited the hospital at the same time were used as control, including 30 male, 30 female, the mean ages was 39 years.METHODS: Fasting venous blood of participants in two groups was harvested sterilely at 6 months and 1 year after test group restoration, serum nickel and chromium content were determined using graphite furnace atomic absorption spectrometry.MAIN OUTCOME MEASURES: ① Serum nickel content changes in test and control group. ②Serum chromium content changes in test and control groupRESULTS: All cases were involved in result analysis. ① Serum nickel content changes in test and control group: At 6 months postrestoration, there was no significant difference in serum nickel content between test group and control group (P>0.05). At 1 year after restoration, serum nickel content of test group was significantly higher than that of control group (P<0.05). ② Serum chromium content changes in test and control group: There was no significant difference in chromium content between test and control group at 6 months and 1 year after test group restoration (P>0.05).CONCLUSION: Nickel and chromium released from porcelain-fused-to-nichrome crowns after restoration under oral environment, serum nickel content had an increasing tendency with the prolongation of restoration time, but in small quantity and within biosafety range, to identify whether the increasing tendency will increased continuously with the prolongation of restoration time needs long-term follow-up.
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0.05). Conclusion:After Ni-Cr-Based porcelain-fused-to-metal crown application, the metal ion can be released and absorbed by human body. But the content is almost harmless to human body.