Flow screen-printed amperometric detection of p-nitrophenol in alkaline phosphatase-based assays

Analytical and Bioanalytical Chemistry
Pablo Fanjul-BoladoAgustín Costa-García

Abstract

p-Nitrophenyl phosphate is one of the most widely used substrates for alkaline phosphatase in ELISAs because its yellow, water-soluble product, p-nitrophenol, absorbs strongly at 405 nm. p-Nitrophenol is also electroactive; an oxidative peak at 0.97 V (vs. an Ag pseudoreference electrode) is obtained when a bare screen-printed carbon electrode is used. When an amperometric detector was coupled to a flow-injection analysis system the detection limit achieved for p-nitrophenol was 2x10(-8) mol L(-1), almost two orders of magnitude lower than that obtained by measuring the absorbance of the compound. By use of this electrochemical detection method, measurement of 7x10(-14) mol L(-1) alkaline phosphatase was achieved after incubation for 20 min. The feasibility of coupling immunoassay to screen-printed carbon electrode amperometric detection has been demonstrated by performing an ELISA for detection of pneumolysin, a toxin produced by Streptococcus pneumoniae, which causes respiratory infections. The method is simple, reproducible, and much more sensitive than traditional spectrophotometry.

References

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Citations

Feb 27, 2014·Sensors·Ana Lorena Alvarado-GámezMaría Julia Arcos-Martínez
Jun 11, 2015·Scientific Reports·Wenhong ChenShijia Ding
Jun 15, 2011·Artificial Cells, Blood Substitutes, and Immobilization Biotechnology·Emine Yorganci, Erol Akyilmaz
Feb 1, 2013·Artificial Cells, Nanomedicine, and Biotechnology·Erol Akyilmaz, Erhan Dinçkaya

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