The Experts below are selected from a list of 93 Experts worldwide ranked by ideXlab platform

Aidong Zhang - One of the best experts on this subject based on the ideXlab platform.

  • amperometric detection of triazophos pesticide using acetylcholinesterase biosensor based on multiwall carbon nanotube chitosan matrix
    Sensors and Actuators B-chemical, 2007
    Co-Authors: Dan Du, Xi Huang, Aidong Zhang
    Abstract:

    Abstract A simple method for immobilization of acetylcholinesterase (AChE) on multiwall carbon nanotubes (MWNTs)–chitosan (MC) composite was proposed and thus a sensitive, fast and stable amperometric sensor for quantitative determination of organophosphorous insecticide was developed. Atomic force microscopy showed that this matrix possessed homogeneously netlike structure, which prevented enzyme from leaving out of the electrode. MWNTs promoted electron transfer reactions at a lower potential and catalyzed the electro-oxidation of thiocholine, thus increasing detection sensitivity. Based on the inhibition of organophosphorous insecticide to the enzymatic activity of AChE, using triazophos as a model compound, the conditions for detection of the insecticide were explored. Under optimal conditions, the inhibition of triazophos was proportional to its concentration in two ranges, from 0.03 to 7.8 μM and 7.8 to 32 μM with a detection limit of 0.01 μM. A 95% reactivation of the inhibited AChE could be regenerated for using Pralidoxime Iodide within 8 min. The constructed biosensor processing prominent characteristics and performance such as good precision and reproducibility, acceptable stability and accuracy, fast response and low detection limit has potential application in the characterization of enzyme inhibitors and detection of toxic compounds against to enzyme.

  • Amperometric detection of triazophos pesticide using acetylcholinesterase biosensor based on multiwall carbon nanotube–chitosan matrix
    Sensors and Actuators B: Chemical, 2007
    Co-Authors: Xi Huang, Jie Cai, Aidong Zhang
    Abstract:

    Abstract A simple method for immobilization of acetylcholinesterase (AChE) on multiwall carbon nanotubes (MWNTs)–chitosan (MC) composite was proposed and thus a sensitive, fast and stable amperometric sensor for quantitative determination of organophosphorous insecticide was developed. Atomic force microscopy showed that this matrix possessed homogeneously netlike structure, which prevented enzyme from leaving out of the electrode. MWNTs promoted electron transfer reactions at a lower potential and catalyzed the electro-oxidation of thiocholine, thus increasing detection sensitivity. Based on the inhibition of organophosphorous insecticide to the enzymatic activity of AChE, using triazophos as a model compound, the conditions for detection of the insecticide were explored. Under optimal conditions, the inhibition of triazophos was proportional to its concentration in two ranges, from 0.03 to 7.8 μM and 7.8 to 32 μM with a detection limit of 0.01 μM. A 95% reactivation of the inhibited AChE could be regenerated for using Pralidoxime Iodide within 8 min. The constructed biosensor processing prominent characteristics and performance such as good precision and reproducibility, acceptable stability and accuracy, fast response and low detection limit has potential application in the characterization of enzyme inhibitors and detection of toxic compounds against to enzyme.

  • Comparison of pesticide sensitivity by electrochemical test based on acetylcholinesterase biosensor
    Biosensors & bioelectronics, 2007
    Co-Authors: Xi Huang, Jie Cai, Aidong Zhang
    Abstract:

    Abstract Based on the change in electrochemical behavior of enzymatic activity induced by pesticide, a novel electrochemical method has been devised for investigation of pesticide sensitivity using acetylcholinesterase (AChE) biosensor. Because of the excellent biocompatibility and good stability of chitosan matrix, it prevented leakage of the AChE from electrode. Multiwall carbon nanotube (MWNT) promoted electron transfer reaction at a lower potential and catalyzed the electro-oxidation of thiocholine, thus amplifying the sensitivity and amperometric response of the biosensor. Four pesticides of carbaryl, malathion, dimethoate and monocrotophos were selected to discuss their inhibition efficiencies to AChE. The inhibition curves were similar to Michealis–Menten and the Michealis–Menten constants ( K m ) were calculated to be 0.96 μM, 1.78 μM, 1.97 μM and 4.28 μM, respectively. Ninety-five percent reactivation of the inhibited AChE could be regenerated using Pralidoxime Iodide within 8 min. The proposed electrochemical pesticide sensitivity test exhibited high sensitivity, low cost and simplified procedures, which is a promising new tool for comparison of pesticide sensitivity and for selection of the most efficient enzyme inhibitors.

Takehiko Takatori - One of the best experts on this subject based on the ideXlab platform.

  • Hydrolysis of an acetylthiocholine by Pralidoxime Iodide (2-PAM)
    Toxicology letters, 2006
    Co-Authors: Koichi Sakurada, Hiroshi Ikegaya, Hikoto Ohta, Tomoko Akutsu, Takehiko Takatori
    Abstract:

    Pralidoxime Iodide (2-PAM), an antidote approved for the reactivation of inhibited acetylcholinesterase (AChE) in organophosphate poisoning, dose-dependently hydrolyzed an acetylthiocholine Iodide (ASCh). The AChE (0.3 U) activity inhibited by VX analog (ENMP, 0.1 microM) increased to approximately 200% of normal levels after a dosage of 5 mM 2-PAM (control 0.132+/-0.012 U/ml, 5 mM 0.253+/-0.026 U/ml). This result indicates that 2-PAM produced a thiocholine from the ASCh by hydrolysis. High-performance liquid chromatography (HPLC) analysis was then performed to further clarify the hydrolysis of ASCh with 2-PAM. It was clear that 2-PAM was converted to acetylated 2-PAM with acetic acid produced from ASCh by hydrolysis. Next, we tried to compare this esterase-like activity of 2-PAM with that of obidoxime, which is known as a strong reactivator of inhibited AChE, and with diacetylmonoxime, known as a weak reactivator. All of these oximes showed esterase-like activity, and their strengths were consistent with those of known reactivators of inhibited AChE. These results indicate that a great deal of the data obtained previously with ASCh relating to the effects of oximes must be rechecked. It is clear that oximes easily hydrolyze ASCh. We therefore strongly caution that the method of determining AChE activity with ASCh is not suitable for examining the effects of oximes.

  • Pralidoxime Iodide (2-PAM) Penetrates Across the Blood-Brain Barrier
    Neurochemical Research, 2003
    Co-Authors: Koichi Sakurada, Kazuo Matsubara, Keiko Shimizu, Hiroshi Shiono, Yasuo Seto, Koichiro Tsuge, Mineo Yoshino, Ikuko Sakai, Harutaka Mukoyama, Takehiko Takatori
    Abstract:

    The in vivo rat brain microdialysis technique with HPLC/UV was used to determine the blood-brain barrier (BBB) penetration of Pralidoxime Iodide (2-PAM), which is a component of the current nerve agent antidote therapy. After intravenous dosage of 2-PAM (10, 50, 100 mg/kg), 2-PAM appeared dose-dependently in the dialysate; the striatal extracellular/blood concentration ratio at 1 h after 50 mg/kg dosage was 0.093 ± 0.053 (mean ± SEM). This finding offered conclusive evidence of the BBB penetration of 2-PAM. We also examined whether the BBB penetration of 2-PAM was mediated by a certain specific transporter, such as a neutral or basic amino acid transport system. Although it was unclear, the neural uptake of 2-PAM was Na^+ dependent. The mean BBB penetration by 2-PAM was approximately 10%, indicating the intravenous administration of 2-PAM might be to a degree effective to reactivation of the blocked cholinesterase in the brain.

Xi Huang - One of the best experts on this subject based on the ideXlab platform.

  • amperometric detection of triazophos pesticide using acetylcholinesterase biosensor based on multiwall carbon nanotube chitosan matrix
    Sensors and Actuators B-chemical, 2007
    Co-Authors: Dan Du, Xi Huang, Aidong Zhang
    Abstract:

    Abstract A simple method for immobilization of acetylcholinesterase (AChE) on multiwall carbon nanotubes (MWNTs)–chitosan (MC) composite was proposed and thus a sensitive, fast and stable amperometric sensor for quantitative determination of organophosphorous insecticide was developed. Atomic force microscopy showed that this matrix possessed homogeneously netlike structure, which prevented enzyme from leaving out of the electrode. MWNTs promoted electron transfer reactions at a lower potential and catalyzed the electro-oxidation of thiocholine, thus increasing detection sensitivity. Based on the inhibition of organophosphorous insecticide to the enzymatic activity of AChE, using triazophos as a model compound, the conditions for detection of the insecticide were explored. Under optimal conditions, the inhibition of triazophos was proportional to its concentration in two ranges, from 0.03 to 7.8 μM and 7.8 to 32 μM with a detection limit of 0.01 μM. A 95% reactivation of the inhibited AChE could be regenerated for using Pralidoxime Iodide within 8 min. The constructed biosensor processing prominent characteristics and performance such as good precision and reproducibility, acceptable stability and accuracy, fast response and low detection limit has potential application in the characterization of enzyme inhibitors and detection of toxic compounds against to enzyme.

  • Amperometric detection of triazophos pesticide using acetylcholinesterase biosensor based on multiwall carbon nanotube–chitosan matrix
    Sensors and Actuators B: Chemical, 2007
    Co-Authors: Xi Huang, Jie Cai, Aidong Zhang
    Abstract:

    Abstract A simple method for immobilization of acetylcholinesterase (AChE) on multiwall carbon nanotubes (MWNTs)–chitosan (MC) composite was proposed and thus a sensitive, fast and stable amperometric sensor for quantitative determination of organophosphorous insecticide was developed. Atomic force microscopy showed that this matrix possessed homogeneously netlike structure, which prevented enzyme from leaving out of the electrode. MWNTs promoted electron transfer reactions at a lower potential and catalyzed the electro-oxidation of thiocholine, thus increasing detection sensitivity. Based on the inhibition of organophosphorous insecticide to the enzymatic activity of AChE, using triazophos as a model compound, the conditions for detection of the insecticide were explored. Under optimal conditions, the inhibition of triazophos was proportional to its concentration in two ranges, from 0.03 to 7.8 μM and 7.8 to 32 μM with a detection limit of 0.01 μM. A 95% reactivation of the inhibited AChE could be regenerated for using Pralidoxime Iodide within 8 min. The constructed biosensor processing prominent characteristics and performance such as good precision and reproducibility, acceptable stability and accuracy, fast response and low detection limit has potential application in the characterization of enzyme inhibitors and detection of toxic compounds against to enzyme.

  • Comparison of pesticide sensitivity by electrochemical test based on acetylcholinesterase biosensor
    Biosensors & bioelectronics, 2007
    Co-Authors: Xi Huang, Jie Cai, Aidong Zhang
    Abstract:

    Abstract Based on the change in electrochemical behavior of enzymatic activity induced by pesticide, a novel electrochemical method has been devised for investigation of pesticide sensitivity using acetylcholinesterase (AChE) biosensor. Because of the excellent biocompatibility and good stability of chitosan matrix, it prevented leakage of the AChE from electrode. Multiwall carbon nanotube (MWNT) promoted electron transfer reaction at a lower potential and catalyzed the electro-oxidation of thiocholine, thus amplifying the sensitivity and amperometric response of the biosensor. Four pesticides of carbaryl, malathion, dimethoate and monocrotophos were selected to discuss their inhibition efficiencies to AChE. The inhibition curves were similar to Michealis–Menten and the Michealis–Menten constants ( K m ) were calculated to be 0.96 μM, 1.78 μM, 1.97 μM and 4.28 μM, respectively. Ninety-five percent reactivation of the inhibited AChE could be regenerated using Pralidoxime Iodide within 8 min. The proposed electrochemical pesticide sensitivity test exhibited high sensitivity, low cost and simplified procedures, which is a promising new tool for comparison of pesticide sensitivity and for selection of the most efficient enzyme inhibitors.

Koichi Sakurada - One of the best experts on this subject based on the ideXlab platform.

  • Hydrolysis of an acetylthiocholine by Pralidoxime Iodide (2-PAM)
    Toxicology letters, 2006
    Co-Authors: Koichi Sakurada, Hiroshi Ikegaya, Hikoto Ohta, Tomoko Akutsu, Takehiko Takatori
    Abstract:

    Pralidoxime Iodide (2-PAM), an antidote approved for the reactivation of inhibited acetylcholinesterase (AChE) in organophosphate poisoning, dose-dependently hydrolyzed an acetylthiocholine Iodide (ASCh). The AChE (0.3 U) activity inhibited by VX analog (ENMP, 0.1 microM) increased to approximately 200% of normal levels after a dosage of 5 mM 2-PAM (control 0.132+/-0.012 U/ml, 5 mM 0.253+/-0.026 U/ml). This result indicates that 2-PAM produced a thiocholine from the ASCh by hydrolysis. High-performance liquid chromatography (HPLC) analysis was then performed to further clarify the hydrolysis of ASCh with 2-PAM. It was clear that 2-PAM was converted to acetylated 2-PAM with acetic acid produced from ASCh by hydrolysis. Next, we tried to compare this esterase-like activity of 2-PAM with that of obidoxime, which is known as a strong reactivator of inhibited AChE, and with diacetylmonoxime, known as a weak reactivator. All of these oximes showed esterase-like activity, and their strengths were consistent with those of known reactivators of inhibited AChE. These results indicate that a great deal of the data obtained previously with ASCh relating to the effects of oximes must be rechecked. It is clear that oximes easily hydrolyze ASCh. We therefore strongly caution that the method of determining AChE activity with ASCh is not suitable for examining the effects of oximes.

  • Pralidoxime Iodide (2-PAM) Penetrates Across the Blood-Brain Barrier
    Neurochemical Research, 2003
    Co-Authors: Koichi Sakurada, Kazuo Matsubara, Keiko Shimizu, Hiroshi Shiono, Yasuo Seto, Koichiro Tsuge, Mineo Yoshino, Ikuko Sakai, Harutaka Mukoyama, Takehiko Takatori
    Abstract:

    The in vivo rat brain microdialysis technique with HPLC/UV was used to determine the blood-brain barrier (BBB) penetration of Pralidoxime Iodide (2-PAM), which is a component of the current nerve agent antidote therapy. After intravenous dosage of 2-PAM (10, 50, 100 mg/kg), 2-PAM appeared dose-dependently in the dialysate; the striatal extracellular/blood concentration ratio at 1 h after 50 mg/kg dosage was 0.093 ± 0.053 (mean ± SEM). This finding offered conclusive evidence of the BBB penetration of 2-PAM. We also examined whether the BBB penetration of 2-PAM was mediated by a certain specific transporter, such as a neutral or basic amino acid transport system. Although it was unclear, the neural uptake of 2-PAM was Na^+ dependent. The mean BBB penetration by 2-PAM was approximately 10%, indicating the intravenous administration of 2-PAM might be to a degree effective to reactivation of the blocked cholinesterase in the brain.

Jie Cai - One of the best experts on this subject based on the ideXlab platform.

  • Amperometric detection of triazophos pesticide using acetylcholinesterase biosensor based on multiwall carbon nanotube–chitosan matrix
    Sensors and Actuators B: Chemical, 2007
    Co-Authors: Xi Huang, Jie Cai, Aidong Zhang
    Abstract:

    Abstract A simple method for immobilization of acetylcholinesterase (AChE) on multiwall carbon nanotubes (MWNTs)–chitosan (MC) composite was proposed and thus a sensitive, fast and stable amperometric sensor for quantitative determination of organophosphorous insecticide was developed. Atomic force microscopy showed that this matrix possessed homogeneously netlike structure, which prevented enzyme from leaving out of the electrode. MWNTs promoted electron transfer reactions at a lower potential and catalyzed the electro-oxidation of thiocholine, thus increasing detection sensitivity. Based on the inhibition of organophosphorous insecticide to the enzymatic activity of AChE, using triazophos as a model compound, the conditions for detection of the insecticide were explored. Under optimal conditions, the inhibition of triazophos was proportional to its concentration in two ranges, from 0.03 to 7.8 μM and 7.8 to 32 μM with a detection limit of 0.01 μM. A 95% reactivation of the inhibited AChE could be regenerated for using Pralidoxime Iodide within 8 min. The constructed biosensor processing prominent characteristics and performance such as good precision and reproducibility, acceptable stability and accuracy, fast response and low detection limit has potential application in the characterization of enzyme inhibitors and detection of toxic compounds against to enzyme.

  • Comparison of drug sensitivity using acetylcholinesterase biosensor based on nanoparticles–chitosan sol–gel composite
    Journal of Electroanalytical Chemistry, 2007
    Co-Authors: Shizhen Chen, Jie Cai, Dandan Song
    Abstract:

    Abstract Based on the change in electrochemical behavior of enzymatic activity induced by medicines related to Alzheimer’s disease (AD), a simple electrochemical method has been developed for investigation of medicine sensitivity using acetylcholinesterase (AChE) biosensor. The sol–gel-derived silicate network incorporating gold nanoparticles (AuNPs-SiSG) provided a biocompatible microenvironment around the enzyme molecule to stabilize its biological activity and prevent them from leaking out of the interface. AuNPs provided a conductive pathway for electron transfer and improved electrochemical reactions at a lower potential. Typical medicines for treatment of AD such as galantamine and neostigmine were selected for medicine sensitivity test. Due to the inhibitions of medicines, the electrochemical responses of substrate on AChE-sensor decreased greatly. The inhibition curves were similar to Michaelis–Menten and the Michaelis–Menten constants ( K m ) were calculated to be 0.14 μM and 0.19 μM, respectively. The inhibition curves showed good correspondence with the results by UV spectrophotometry assay. Ninety-six percent reactivation of the inhibited AChE could be regenerated for using Pralidoxime Iodide within 8 min. The proposed electrochemical drug sensitivity test exhibited high sensitivity, low cost and simplified procedures, which provided a new promising tool for investigation of drug sensitivity.

  • Comparison of pesticide sensitivity by electrochemical test based on acetylcholinesterase biosensor
    Biosensors & bioelectronics, 2007
    Co-Authors: Xi Huang, Jie Cai, Aidong Zhang
    Abstract:

    Abstract Based on the change in electrochemical behavior of enzymatic activity induced by pesticide, a novel electrochemical method has been devised for investigation of pesticide sensitivity using acetylcholinesterase (AChE) biosensor. Because of the excellent biocompatibility and good stability of chitosan matrix, it prevented leakage of the AChE from electrode. Multiwall carbon nanotube (MWNT) promoted electron transfer reaction at a lower potential and catalyzed the electro-oxidation of thiocholine, thus amplifying the sensitivity and amperometric response of the biosensor. Four pesticides of carbaryl, malathion, dimethoate and monocrotophos were selected to discuss their inhibition efficiencies to AChE. The inhibition curves were similar to Michealis–Menten and the Michealis–Menten constants ( K m ) were calculated to be 0.96 μM, 1.78 μM, 1.97 μM and 4.28 μM, respectively. Ninety-five percent reactivation of the inhibited AChE could be regenerated using Pralidoxime Iodide within 8 min. The proposed electrochemical pesticide sensitivity test exhibited high sensitivity, low cost and simplified procedures, which is a promising new tool for comparison of pesticide sensitivity and for selection of the most efficient enzyme inhibitors.