title: Alkaline phosphatase based amperometric biosensor immobilized by cysteamine-glutaraldehyde modified self-assembled monolayer.
abstract: Alkaline phosphatase (ALP) was immobilized with cross-linking agents glutaraldehyde and cysteamine by forming a self-assembled monolayer on a screen printed gold electrode. ALP converts p-nitrophenyl phosphate to p-nitrophenol and phosphate. p-Nitrophenol loses H(+) ion and turns into the negatively charged compound p-nitrophenolate at medium pH. As a result, the unstable product formed is measured chronoamperometrically at an application potential of + 0.95 V. The biosensor response depends linearly on p-nitrophenyl phosphate concentration between 0.05 - 0.6 mM with a response time of 40 seconds. Detection limit of the biosensor is 0.033 mM.
authors.affiliation: Department of Biochemistry, Ege University, Bornova-Izmir, Turkey.
authors.forename: Emine
authors.initials: E
authors.lastname: Yorganci
authors.forename: Erol
authors.initials: E
authors.lastname: Akyilmaz
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism*; D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods*; D002623:Chemistry Techniques, Analytical; D003432:Cross-Linking Reagents / Q000737:chemistry; D003543:Cysteamine / Q000737:chemistry; D004563:Electrochemistry; D004566:Electrodes; D004800:Enzymes, Immobilized / Q000378:metabolism*; D005976:Glutaral / Q000737:chemistry; D006046:Gold / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D057230:Limit of Detection; D009596:Nitrophenols / Q000032:analysis / Q000378:metabolism*; D010710:Phosphates / Q000378:metabolism; D011199:Potentiometry; D015203:Reproducibility of Results; D013696:Temperature
chemical_list: D003432:Cross-Linking Reagents; D004800:Enzymes, Immobilized; D009596:Nitrophenols; D010710:Phosphates; C024719:4-nitrophenyl; D003543:Cysteamine; D006046:Gold; D000469:Alkaline Phosphatase; D005976:Glutaral