%0 Journal Article %1 citeulike:471073 %A Pemberton, R. M. %A Hart, J. P. %A Stoddard, P. %A Foulkes, J. A. %C Faculty of Applied Sciences, University of the West of England, Bristol, UK. %D 1999 %J Biosens Bioelectron %K amperometry competition immunoassay homogeneous immunosensor ag_detection electrochemistry immunoelectrode %N 5 %P 495--503 %R 10.1016/S0956-5663(99)00019-6 %T A comparison of 1-naphthyl phosphate and 4 aminophenyl phosphate as enzyme substrates for use with a screen-printed amperometric immunosensor for progesterone in cows' milk. %U http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=10451917 %V 14 %X 4-Aminophenyl phosphate (4-APP) and 1-naphthyl phosphate (1-NP) were compared as enzyme substrates for an amperometric milk progesterone biosensor utilising progesterone-conjugated alkaline phosphatase in a competitive immunoassay format. Cyclic voltammetry of the corresponding hydrolysis products, 4-aminophenol and 1-naphthol, at the surface of screen-printed carbon base transducers, uncoated or coated with anti-progesterone monoclonal antibody (mAb) showed well-defined anodic responses for both species, with the more sensitive being 4-aminophenol. Scan rate studies produced evidence that surface mAb could impede the diffusion of 4-aminophenol, but not 1-naphthol, toward the electrode surface. This was supported by computer simulation for the electrochemical rate constant (khet) using 4-aminophenol, which gave values at uncoated and mAb-coated electrodes of 6.5 x 10(-4) and 3.0 x 10(-4) cm s-1, respectively. The applied potential for oxidation of 4-aminophenol was 230 mV lower than for 1-naphthol. Nevertheless, by operating below +400 mV versus a saturated calomel reference electrode, it was possible to obtain a chronoamperometric signal for 1-naphthol in the absence of electrochemical interference from milk. Using mAb-coated SPCEs, calibration curves were obtained for progesterone in oestrus whole cow's milk spiked with standard concentrations over the range 0-50 ng/ml, using either 4-APP or 1NP as enzyme substrate. Precision values for triplicate sensors were 5.3-18.3% for 4-APP and 4.1-12.4% for 1-NP. An assay of real whole milk samples from different cows at various stages of the oestrus cycle produced correlations against a commercial EIA of r = 0.840 and 0.946 for 4-APP and 1-NP, respectively, 1-NP possesses the advantages over 4-APP of being inexpensive, easy to obtain and soluble (1-naphthol cf. 4-aminophenol) at high pH. From these observations, it is concluded that 1-NP is the preferred substrate for use with our proposed milk progesterone biosensor.

@article{citeulike:471073, abstract = {4-Aminophenyl phosphate (4-APP) and 1-naphthyl phosphate (1-NP) were compared as enzyme substrates for an amperometric milk progesterone biosensor utilising progesterone-conjugated alkaline phosphatase in a competitive immunoassay format. Cyclic voltammetry of the corresponding hydrolysis products, 4-aminophenol and 1-naphthol, at the surface of screen-printed carbon base transducers, uncoated or coated with anti-progesterone monoclonal antibody (mAb) showed well-defined anodic responses for both species, with the more sensitive being 4-aminophenol. Scan rate studies produced evidence that surface mAb could impede the diffusion of 4-aminophenol, but not 1-naphthol, toward the electrode surface. This was supported by computer simulation for the electrochemical rate constant (khet) using 4-aminophenol, which gave values at uncoated and mAb-coated electrodes of 6.5 x 10(-4) and 3.0 x 10(-4) cm s-1, respectively. The applied potential for oxidation of 4-aminophenol was 230 mV lower than for 1-naphthol. Nevertheless, by operating below +400 mV versus a saturated calomel reference electrode, it was possible to obtain a chronoamperometric signal for 1-naphthol in the absence of electrochemical interference from milk. Using mAb-coated SPCEs, calibration curves were obtained for progesterone in oestrus whole cow's milk spiked with standard concentrations over the range 0-50 ng/ml, using either 4-APP or 1NP as enzyme substrate. Precision values for triplicate sensors were 5.3-18.3% for 4-APP and 4.1-12.4% for 1-NP. An assay of real whole milk samples from different cows at various stages of the oestrus cycle produced correlations against a commercial EIA of r = 0.840 and 0.946 for 4-APP and 1-NP, respectively, 1-NP possesses the advantages over 4-APP of being inexpensive, easy to obtain and soluble (1-naphthol cf. 4-aminophenol) at high pH. From these observations, it is concluded that 1-NP is the preferred substrate for use with our proposed milk progesterone biosensor.}, added-at = {2006-07-07T01:10:50.000+0200}, address = {Faculty of Applied Sciences, University of the West of England, Bristol, UK.}, author = {Pemberton, R. M. and Hart, J. P. and Stoddard, P. and Foulkes, J. A.}, biburl = {https://www.bibsonomy.org/bibtex/28deec82fff87c8bcca45c218731d5566/biblio24}, citeulike-article-id = {471073}, comment = {john.hart@uwe.ac.uk}, doi = {10.1016/S0956-5663(99)00019-6}, interhash = {e12e1be17b4ec0033459778d26fea6ce}, intrahash = {8deec82fff87c8bcca45c218731d5566}, issn = {0956-5663}, journal = {Biosens Bioelectron}, keywords = {amperometry competition immunoassay homogeneous immunosensor ag_detection electrochemistry immunoelectrode}, month = May, number = 5, pages = {495--503}, priority = {2}, timestamp = {2006-07-07T01:10:50.000+0200}, title = {A comparison of 1-naphthyl phosphate and 4 aminophenyl phosphate as enzyme substrates for use with a screen-printed amperometric immunosensor for progesterone in cows' milk.}, url = {http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve\&db=pubmed\&dopt=Abstract\&list_uids=10451917}, volume = 14, year = 1999 }