The Utility Of The Nitric Oxide Electrochemical Sensor In Biomedical Research

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Journal Club 1 :The Utility Of The Nitric Oxide Electrochemical Sensor In Biomedical Research

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The Utility Of The Nitric Oxide Electrochemical Sensor In Biomedical Research

  1. 1. <ul><ul><li>Review paper : Nitric Oxide Electrochemical Sensor in Biomedical Research </li></ul></ul>
  2. 2. OUT LINE <ul><li>Nitric Oxide </li></ul><ul><li>Electrochemical Sensor </li></ul><ul><li>Principles of Detection </li></ul><ul><li>Commercial </li></ul>
  3. 3. Nitric Oxide <ul><li>Nitric oxide or Nitrogen monoxide is a chemical compound with chemical formula NO. This gas is an important signaling molecule in the body of mammals </li></ul>
  4. 4. NITRIC OXIDE Molecular formula : NO Molar mass : 30.0061 Appearance : colourless gas Shape : Linear Melting point : −163.6°C Boiling point : −151.7°C The nitric oxide molecule is a free radical , high reactivity NO is a fundamental player in the fields of neuroscience, physiology, and immunology, and was proclaimed “Molecule of the Year” in 1992
  5. 5. NITRIC OXIDE <ul><li>NO is messenger molecule involved in many physiological processes </li></ul><ul><li>Levels of NO production are important in protecting an organ such as the liver from ischemic damage. </li></ul><ul><li>Levels of NO production result in direct tissue toxicity to the vascular collapse associated with septic shock. </li></ul><ul><li>Chronic expression of NO is associated with various carcinomas and inflammatory conditions including juvenile diabetes, multiple sclerosis, arthritis and ulcerative colitis. </li></ul>
  6. 6. Technical applications <ul><li>Although NO has relatively few direct uses, it is produced on a massive scale as an intermediate in the Ostwald process for the synthesis of nitric acid from ammonia. In 2005, the US alone produced 6M metric tons of nitric acid </li></ul>4NH 3 (g) + 5O 2 (g) -> 4NO(g) + 6H 2 O(g) 2NO(g) + O 2 (g) -> 2NO 2 (g) 3NO 2 (g) + H 2 O(l) -> 2HNO 3 (aq) + NO(g) 4NO 2 (g) + O 2 (g) + 2H 2 O(l) -> 4HNO 3 (aq)
  7. 7. Biological functions <ul><li>NO is signaling molecules in biological processes </li></ul><ul><li>Nitric oxide, known as the 'endothelium-derived relaxing factor', or 'EDRF' , is biosynthesised endogenously from arginine and oxygen by various nitric oxide synthase (NOS) enzymes </li></ul>
  8. 8. Biological functions <ul><li>NO is signaling molecules in biological processes </li></ul><ul><li>Nitric oxide, known as the 'endothelium-derived relaxing factor', or 'EDRF' , is biosynthesised endogenously from arginine and oxygen by various nitric oxide synthase (NOS) enzymes </li></ul>
  9. 9. Endothelium-derived relaxing factor(EDRF) <ul><li>Figure 1 . L-arginine - nitric oxide system. B 2 , bradykinin B 2 receptor; cGMP, cyclic guanosine 3',5'-monophosphate; eNOS, endothelial nitric oxide synthase; GC, guanylate cyclase; GTP, guanosine 5'-triphosphate; M, muscarinic receptor; NO, nitric oxide; .OH, hydroxyl radical; ONOO - , peroxynitrite. </li></ul>
  10. 10. The Nobel Prize in Physiology or Medicine 1998 <ul><li>Robert F Furchgott Louis J Ignarro Ferid Murad </li></ul><ul><li>Discoveries concerning &quot;the nitric oxide as a signalling molecule in the cardiovascular system&quot;. </li></ul><ul><li>Effects include blood vessel dilatation, neurotransmission modulation of the hair cycle , and penile erections . Nitroglycerin and amyl nitrite serve as vasodilators because they are converted to nitric oxide in the body </li></ul><ul><li>Popularly known by the trade name Viagra </li></ul>
  11. 11. Immune response <ul><li>Nitric oxide is also generated by macrophages and neutrophils as part of the human immune response. </li></ul><ul><li>Nitric oxide is toxic to bacteria and other human pathogens . </li></ul>
  12. 12. Reactions <ul><li>When exposed to oxygen, NO is converted into nitrogen dioxide . 2NO + O 2 -> 2NO 2 </li></ul><ul><li>NO react with oxygen and water to form HNO2 or nitrous acid . 4 NO + O 2 + 2 H 2 O -> 4 HNO 2 </li></ul>
  13. 13. Preparation <ul><li>nitric oxide is produced industrially by the direct reaction of O 2 and N2 at high temperatures. </li></ul><ul><li>In the laboratory, it is conveniently generated by reduction of nitric acid : 8HNO 3 + 3Cu -> 3Cu(NO 3 )2 + 4H2O + 2NO </li></ul><ul><li>or by the reduction of nitrous acid : 2 NaNO 2 + 2 NaI + 2 H 2 SO 4 -> I 2 + 4 NaHSO 4 + 2 NO 2 NaNO 2 + 2 FeSO 4 + 3 H2SO 4 -> Fe2(SO4) 3 + 2 NaHSO 4 + 2 H 2 O + 2 NO 3 KNO 2 (l) + KNO 3 (l) + Cr 2 O 3 (s) -> 2 K 2 CrO 4 (s) + 4 NO (g) </li></ul>
  14. 14. Some of the methods commonly used for the determination of NO include <ul><li>Chemiluminescence </li></ul><ul><li>Electron paramagnetic </li></ul><ul><li>Resonance (EPR) spectrometry </li></ul><ul><li>The Griess method </li></ul><ul><li>Spectrophotometric assays </li></ul><ul><ul><li>They can not be used for continuous monitoring </li></ul></ul><ul><ul><li>or local measurement of NO concentrations in </li></ul></ul><ul><ul><li>real time. </li></ul></ul>
  15. 15. Electrochemical techniques i = nFCAke -(E-E0)(- α nF/RT)
  16. 16. NO-electrochemical microsensors <ul><li>Structure </li></ul><ul><ul><li>Printed Screen </li></ul></ul><ul><ul><li>Nedle </li></ul></ul><ul><li>Electrode </li></ul><ul><ul><li>Carbon fiber </li></ul></ul><ul><ul><li>Pt </li></ul></ul><ul><ul><li>Glassy Carbon </li></ul></ul><ul><ul><li>Gold </li></ul></ul>
  17. 17. NO-electrochemical microsensors <ul><li>Modifier(s) Layer </li></ul><ul><ul><li>Nafion </li></ul></ul><ul><ul><li>Cellulose </li></ul></ul><ul><ul><li>O-PD </li></ul></ul><ul><ul><li>NiTHMP </li></ul></ul><ul><ul><li>NiTMPyP </li></ul></ul><ul><ul><li>Neoprene </li></ul></ul><ul><ul><li>CytC-PITO </li></ul></ul><ul><ul><li>PolyCoTAPc </li></ul></ul><ul><ul><li>etc.. </li></ul></ul>
  18. 20. Problematic interfering <ul><li>Nitrite </li></ul><ul><li>ascorbate </li></ul><ul><li>dopamine </li></ul>
  19. 21. Nafion®
  20. 22. NO-electrochemical microsensors <ul><li>Detection limit 0.5 nM </li></ul><ul><li>Carbon (fiber; o=30-40μm;length=200-250 μm) </li></ul><ul><li>NiTHMP1/Nafion3/AAO4/polylysine4 </li></ul><ul><li>0.65V /Ag;AgCl </li></ul><ul><li>(aerated PBS, pH=7.4) </li></ul>
  21. 23. Activator for WPI nitric oxide sensors <ul><li>NSA SPECIFICATIONS </li></ul><ul><li>Battery 1.5 V AAA </li></ul><ul><li>Applied Potential 860 mV </li></ul><ul><li>Battery Useful Life One year </li></ul><ul><li>1 mM </li></ul>

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