A Disposable Alkaline Phosphatase-Based Biosensor for Vanadium Chronoamperometric Determination

Abstract

A chronoamperometric method for vanadium ion determination, based on the inhibition of the enzyme alkaline phosphatase, is reported. Screen-printed carbon electrodes modified with gold nanoparticles were used as transducers for the immobilization of the enzyme. The enzymatic activity over 4-nitrophenyl phosphate sodium salt is affected by vanadium ions, which results in a decrease in the chronoamperometric current registered. The developed method has a detection limit of 0.39 ± 0.06 μM, a repeatability of 7.7% (n = 4) and a reproducibility of 8% (n = 3). A study of the possible interferences shows that the presence of Mo(VI), Cr(III), Ca(II) and W(VI), may affect vanadium determination at concentration higher than 1.0 mM. The method was successfully applied to the determination of vanadium in spiked tap water.

A Chronoamperometric Screen Printed Carbon Biosensor Based on Alkaline Phosphatase Inhibition for W(VI) Determination in Water, Using 2-Phospho-l-Ascorbic Acid Trisodium Salt as a Substrate

“…To develop the alkaline phosphatase biosensor, initially two substrates were used, p-nitrophenylphosphate, and 2-phospho- l -ascorbic acid trisodium salt, because in previous papers we reported its use to determine V(V) and As(V) [ 15 , 24 ]. Based on different experiments results, we decided to work with 2-phospho- l -ascorbic acid trisodium salt, which had been tested only with acid phosphatase, but not with the alkaline enzyme.…”

“…The biologically sensitive layer of the biosensor was formed by cross-linking the enzyme alkaline phosphatase on the surface of the AuNPs-modified SPCEs, by dropping 10 μL of a 2:1:2 mixture of 0.6% of enzyme solution, 1.75% (w/v) of BSA solution and 2.5% (w/v) of GA solution onto the surface of a screen-printed working electrode. Volume and concentration of ALP, GA and BSA were optimized to obtain the maximum analytical response for the inhibition of the enzyme with W(VI) [ 15 , 22 ]. Finally, the mixture was left to react at 4 °C during one hour and the ALP-AuNPs-SPCEs were stored at 4 °C.…”

“…For instance, in 1974, Van Etten [ 14 ] demonstrated the influence of vanadate, molybdate and tungstate on phosphohydrolases such as acid phosphatases which are relatively nonspecific enzymes that catalyze the hydrolysis of several alkyl and aryl phosphate esters at pH values between 4 and 6. Our research group recently reported promising results using two different biosensors with this enzyme for vanadium detection at trace levels in water [ 15 , 16 ], studying modification of electrode surfaces with gold nanoparticles in order to provide a micro-environment similar to native systems of redox proteins and allowing these molecules more freedom in orientation, thereby reducing the insulating effect of the protein shell towards direct electron transfer through gold nanocrystal conducting tunnels [ 17 – 19 ].…”

Fluorescent Biosensor for Phosphate Determination Based on Immobilized Polyfluorene–Liposomal Nanoparticles Coupled with Alkaline Phosphatase

“…This low biocatalytic selectivity enables the use of the enzyme for a wide range of substrates in enzyme activity assays, one of which is p -nitrophenyl phosphate (PNPP). In recent years, the catalytic activity of ALP has been exploited in the design of immunosensors and biosensors, either for direct monitoring of analytes (enzymes or substrates) or for indirect monitoring of organic (i.e., pesticides) or inorganic salts (i.e., phosphate, heavy metals) which act as inhibitors. − Studies of ALP activity and screening of its inhibitors are required in clinical diagnosis to develop potential drug therapies for different diseases, as well as in environmental monitoring of pollutants . The choice of the substrates for these analytical applications depends on the transduction methods, i.e., fluorescence, chemiluminescence, or amperometry, and on the purpose of the analytical measurements .…”