Platform for Highly Sensitive Alkaline Phosphatase‐Based Immunosensors Using 1‐Naphthyl Phosphate and an Avidin‐Modified Indium Tin Oxide Electrode

Abstract

We report a versatile platform for highly sensitive alkaline phosphatase (ALP)-based electrochemical biosensors that uses an avidin-modified indium tin oxide (ITO) electrode as a sensing electrode and 1-naphthyl phosphate (NPP) as an ALP substrate. Almost no electrocatalytic activity of NPP and good electrocatalytic activity of 1-naphthol (ALP product) on the ITO electrodes allow a high signal-to-background ratio. The effective surface covering of avidin on the ITO electrodes allows very low levels of nonspecific binding of proteins to the sensing electrodes. The platform technology is used to detect mouse IgG with a detection limit of 1.0 pg/mL.

Sensitive and direct electrochemical detection of double-stranded DNA utilizing alkaline phosphatase-labelled zinc finger proteins

“…To overcome this problem, partial modification of the ITO electrode with highly electrocatalytic materials such as a gold nano-particle 32 and graphene 33 is required, or a different couple of an ALP substrate and product should be used. 25,34 AAP and AA were chosen for an ALP substrate and product couple, because the difference in formal potential is great and AA oxidation occurs sufficiently fast above 0.1 V at the bare ITO electrode. 25 Once the ALP label converts AAP into AA during a 10 min incubation, AA is accumulated near the ITO electrode.…”

Electrochemical Immunosensor for Human IgE Using Ferrocene Self-Assembled Monolayers Modified ITO Electrode

“…Various organic molecules containing anchor groups such as thiols, amines, or silanes are used for the formation of SAMs depending on the electrode materials [30,31]. The silanes and phosphate anchor groups are available for the SAMs formation on the ITO electrode [25,26,32].…”

Progress in Electrochemical Immunosensors with Alkaline Phosphatase as the Signal Label

“…Aiming to reduce the oxidation potential of enzyme products and avoid electrode fouling, a wide variety of alternative substrate/product pairs were developed for ALP-based electrochemical immunosensors, including p -aminophenyl phosphate (PAPP)/ p -aminophenol (PAP) [ 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 ], hydroquinone diphosphate(HQDP)/hydroquinone (HQ) [ 54 , 55 , 56 , 57 , 58 ], p -nitrophenylphosphate (PNPP)/ p -nitrophenol (PNP) [ 59 , 60 , 61 , 62 ], α-naphthyl phosphate (NPP)/α-naphthol [ 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 ], 3-indoxyl phosphate (3-IP)/indigo blue [ ...…”