Vertically aligned antimony nanowires as solid-state pH sensors.
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Antimony↗
Biomedical subjects
Jian-Shan Ye
Publications and source records attributed to Jian-Shan Ye.
Microelectrode array biochip: tool for in vitro drug screening based on the detection of a drug effect on dopamine release from PC12 cells.
Novel, yet simple detection techniques of drug effect, including the effect of a vesicular monoamine transporter inhibitor (reserpine), a dopamine precursor (L-dopa), and a dopamine transporter inhibitor (nomifensine), on dopamine release from dopaminergic PC12 cells were developed based on a microelectrode array (MEA) biochip. Upon multi-injections of KCl solution into the culture of PC12 cells attached on a MEA biochip, the K+-stimulated dopamine release was temporally and amperometrically recorded by biochip microelectrodes. Two parameters in the recorded amperometric spectra were defined in this study: the peak current of the first KCl injection (Max1), and the steady current after the fourth KCl injection (St4). Statistically significant effects of L-dopa and reserpine were demonstrated by comparing both Max1 and St4 of the second detections in drugs with those of the control without drug treatment. The values of both Max1 and St4 in the first detections were normalized as 1. In contrast, the statistically significant effect of nomifensine was detected by comparing the ratios of St4 to Max1 in the first detections in drug with those of the control. The reason for using different analytical methods for measurements between L-dopa/reserpine and nomifensine lies in the different mechanisms of action on PC12 cells among these drugs. The novel analytical methods developed use the same detection setup and parameters, and the data analysis for the effect of drugs becomes simple. The methods hence may provide a high-throughput in vitro drug screening approach for dopamine-related psychiatric disorders.
Animals↗
Differential mechanisms underlying the modulation of delayed-rectifier K+ channel in mouse neocortical neurons by nitric oxide.
The modulatory effects of nitric oxide (NO) on voltage-dependent K+ channels are intricate. In our present study, the augmentation and reduction of K+ currents by NO donor S-nitro-N-acetylpenicillamine (SNAP) and pure dissolved NO was observed in dissociated neurons from mice neocortex with both whole cell and cell-attached patch clamp. By using a specific electrochemical sensor, the critical concentrations of NO that increased or reduced the channel activities were accurately quantified. Low concentrations of SNAP (20 microM) or NO solution (0.1 microM) enhanced whole cell delayed rectifier K+ -current (IK) and left the fast inactivating A current (IA) unchanged. However, high concentrations of SNAP (100 microM) and NO (0.5 microM) reduced both IK and IA currents. In cell-attached experiments, a significant increase in channel open probability (NP0) was observed when using low concentrations of SNAP or NO. High concentrations of SNAP or NO dramatically decreased NP0. The increase in channel activities by low concentrations of SNAP was abolished in the presence of either inhibitors of soluble guaylate cyclase or inhibitors of cGMP-dependent protein kinase G, suggesting a link to the NO-cGMP signaling cascade. The reduction of channel activities by high concentrations of SNAP was reversed by the reducing agent dithiothreitol, implying a redox reaction mechanism. Thus both NO-cGMP signaling and a redox mechanism are involved in the modulation of IK channel activity for neuron excitability.
Animals↗
Preparation and characterization of aligned carbon nanotube-ruthenium oxide nanocomposites for supercapacitors.
A novel type of ruthenium oxide (RuO(2))-modified multi-walled carbon nanotube (MWNT) nanocomposite electrode (RuO(2)/MWNT) for supercapacitors has been prepared. The nanocomposites were formed by depositing Ru by magnetic-sputtering in an Ar/O(2) atmosphere onto MWNTs, which were synthesized on Ta plates by chemical vapor deposition. Cyclic voltammetry, chronopotentiometry, and electrochemical impedance measurements were applied to investigate the performance of the RuO(2)/MWNT nanocomposite electrodes. The capacitance of the MWNT electrodes in 1.0 M H(2)SO(4) is significantly increased from 0.35 to 16.94 mF cm(-2) by modification with RuO(2). The RuO(2) film on the surface of the nanotubes is composed of small crystal grains with tilted bundle-like microstructures, as observed by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The results demonstrate a promising route to prepare RuO(2)/MWNT-based double-layer supercapacitors.
Electrochemistry↗
Biosensing properties of diamond and carbon nanotubes.
The biochemical properties of boron-doped diamond (BDD), carbon nanofiber, fullerene, and multiwalled carbon nanotube (MWCNT) electrodes have been investigated comparatively. Physiochemical factors which affect the biosensing properties such as surface hydrophobicities, effective surface area, and intrinsic material properties are studied. Voltammetric responses of the as-grown thin film electrode and surface-modified electrode to biomolecules such as L-ascorbic acid (L-AA), dopamine (DA), and uric acid are examined. As-grown MWCNT electrodes exhibit selective voltammetric responses to the different biomolecules and faster electron-transfer kinetics compared to BDD. The selective response is due to the considerably lower anodic potential of L-AA on MWCNT (-48 mVvs Ag/AgCl compared to 575 mV on BDD). This electrocatalytic response can be replicated on a nonselective carbon nanofiber electrode by coating it with gold nanoparticles. BDD has no intrinsic selective response to L-AA, and surface modification by anodic polarization is necessary for resolving L-AA and DA.
Ascorbic Acid↗
Induction of transient ion channel-like pores in a cancer cell by antibiotic peptide.
The anticancer activity of anti-bacterial cecropins makes them potentially useful as peptide anti-cancer drugs. We used the cell-attached patch to study the effect of cecropin B (CB; having one hydrophobic and one amphipathic alpha-helix) and its derivative, cecropin B3 (CB3; having two hydrophobic alpha-helices) on the membrane of Ags cancer cells. Application of 10-60 microM CB onto the membrane of the cancer cell produces short outward currents. Comparative study with CB3, which induces no outward currents, shows that the amphipathic group of CB is necessary for the pore formation. The results provide a rationale to study the cell-killing activity of antimicrobial peptides at the single cancer cell level.
Anti-Bacterial Agents↗
Nanostructured platinum-lipid bilayer composite as biosensor.
The present work describes the preparation of supported bilayer lipid membrane (s-BLM) doped with metal nanoparticles for the design of biosensors. Platinum (Pt) nanoparticles were deposited through s-BLM to build a hybrid device of nanoscale electrode array by potential cycling in 1 mM K(2)PtCl(6) solution containing 0.1 M KCl. The properties of Pt nanoparticle-doped s-BLM composite were then characterized by cyclic voltammetry, electrochemical impedance spectroscopy (EIS) and atomic force microscopy (AFM). Our results showed that Pt nanoparticles grew in voids of the s-BLMs, through which the underlying glassy carbon (GC) electrode was connected, with maximum length extended out of the lipid membrane around 40 nm. Doping of Pt nanoparticles through s-BLM increased the membrane capacitance and decreased the membrane resistance of s-BLM. Pt nanoparticles array in s-BLM electrocatalyzed the reduction of oxygen (O(2)) in phosphate buffer solution (PBS). Practical application of Pt nanoparticle-doped s-BLM for the construction of glucose biosensor was also demonstrated in terms of its dose-response curve, stability and reproducibility. Thus, lipid membrane doped with Pt nanoparticles is a novel electrode system at nanoscale that can penetrate through the insulating membrane to probe molecular recognition and catalytic events at the lipid membrane-solution interface.
Biosensing Techniques↗
Augmentation of hypoxia-induced nitric oxide generation in the rat carotid body adapted to chronic hypoxia: an involvement of constitutive and inducible nitric oxide synthases.
Acute hypoxia increases the endogenous release of nitric oxide (NO) in rat carotid body and the expression of nitric oxide synthases is modulated by chronic hypoxia. The aim of the study was to examine hypoxia-induced NO generation in rat carotid body adapted to chronic hypoxia with inspired oxygen at 10% for 4 weeks. The concentration of NO was measured electrochemically with a Pt/Nafion/Pd-IrOx/POAP modified electrode inserted into the isolated carotid body superfused with bicarbonate-buffer saline at 35 degrees C. Acute hypoxia increased the concentration of NO by 471.3+/-71.4 nM in the carotid body of chronically hypoxic (CH) rats. The amount of NO release induced by hypoxia was significantly augmented when compared with that of the normoxic control (87.6+/-15.9 nM). The hypoxia-induced NO generation was markedly attenuated by pretreatment with L- NG-nitroarginine methylester (L-NAME; 500 microM), a non-selective nitric oxide synthase (NOS) inhibitor and also by removal of extracellular calcium with the calcium chelator EGTA (5 mM). Additionally, NO generation during hypoxia was reduced by 30% in the CH carotid body treated with S-methylisothiourea (SMT; 50 microM), a specific blocker of inducible NOS (iNOS). Immunohistochemical study revealed that positive iNOS protein immunoreactivity was detected in clusters of glomus cells in the carotid bodies of CH rats, but not in the normoxic group. Thus, chronic hypoxia enhances hypoxia-induced NO generation mediated by calcium-dependent NOSs and iNOS in the carotid body. Extracellular recording of sinus nerve activity of CH carotid bodies showed that L-NAME treatment enhanced the afferent discharge in response to hypoxia, confirming that the generation of NO suppresses the activities of carotid chemoreceptors. Taken together, our results suggest that hypoxia-induced NO production increases in the rat carotid body adapted to chronic hypoxia and that constitutive and inducible NOSs are involved in the NO generation. The enhancement of NO generation may play a physiological role in blunting the hypoxic chemosensitivity during chronic hypoxia.
Animals↗