An Amperometric Nitrite Biosensor Based on the Bioelectrocatalysis of Hemoglobin Incorporated in Sol-gel Film

Abstract

A highly sensitive, fast and stable biosensor for determination of nitrite was developed using hemoglobin immobilized on a poly (N-isopropylacyamide-co-3-methacryloxypropyltrimethoxysilane) (PNM) modified glass carbon electrodes. The matrix provided a biocompatible microenvironment for retaining the native structure and activity of the entrapped hemoglobin. Nitrite could be reduced by the electrocatalysis of the entrapped hemoglobin without any mediator. The reagentless sensor exhibited a fast response (less than 8 s) and sensitivity as high as 0.73 μA mM cm -2 . The linear range for nitrite determination was from 0.11 to 1.88 mM with a detection limit of 2.0×10-5 mol L -1 .

Electrochemical Biosensor for Nitrite Based on Polyacrylic-Graphene Composite Film with Covalently Immobilized Hemoglobin

“…This was attributed to the deficiency of proton as the main reason for the failure to generate NO at pH 7 and above. Hence, the CV results confirmed the cathodic peak potential at −0.6 V was ascribed to the reduction of nitrite to NO catalyzed by the immobilized Hb in acidic medium, whilst the characteristic peak potential of Hb heme group remained intact at −0.3 V. Similar electrochemical findings were observed by Liu et al [ 7 ] at diffrerent pHs using a hydrogel supporting matrix for Hb immobilization on the glassy carbon electrode. Since oxygen is a major electroactive compound in natural oxygenated waters and can thus interfere with the developed biosensor in the measurement of nitrite in aqueous-based electrochemical system, and that oxygen can be removed by purging with an inert gas such as nitrogen or argon to avoid interference from oxygen reduction, reaction normally occurs at –0.1 V versus Ag/AgCl electrode.…”

“…The redox behavior of proteins is often strongly dependent on the pH of the surrounding solution [ 11 , 13 ]. As Figure 5 a indicates, the characteristic DPV peak potential of the Fe III /Fe II redox couple of Hb was noticed to shift to more negative potentials with the rise in pH from pH 5.0 to pH 7.0, which correspond to the electron transfer reaction accompanied by the exchange of proton [ 7 ]. A reduction peak was perceived at about −0.6 V when the reaction medium was adjusted to pH 5.5, indicating that the immobilized Hb catalyzed the direct reduction of 1 mg L −1 nitrite at the electrode surface.…”

“…Edible bird’s nests (EBNs) containing elevated levels of harmful nitrite have been reported where swiftlet nests were found to contain more than 1000 mg L −1 of nitrite [ 5 ]. The continued intake of nitrite can be harmful to human health [ 6 , 7 ], particularly for Chinese pregnant mothers who eat them regularly during their pregnancy stage. As a precaution, a nitrite analysis for all types of EBNs, including “cave” nests and “house” nests, is necessary before they are exported to international markets.…”

“…The common methods of Hb immobilization are by entrapment [ 7 ], electrostatic interaction [ 19 ], physical adsorption [ 8 ] and forming composite [ 20 ] with graphene. In this work we take a completely different approach, i.e., by covalently attaching Hb onto polyacrylic-graphene composite film for electrochemical quantitation of nitrite by differential pulse voltammetry (DPV) method.…”

A Biosensor for Genetic Modified Soybean DNA Determination via Adsorption of Anthraquinone‐2‐sulphonic Acid in Reduced Graphene Oxide

“…Palecek et al. suggested the addition of a redox active material would assist in the amplification of signal and sensitivity of the DNA biosensor, which could be seen in many previously reported studies applying various electroactive intercalators in the investigation of DNA hybridization reaction . It has been claimed that the use of anionic anthraquinone compound as a redox intercalator can effectively eliminate the background electrochemical signals and improve the overall DNA biosensor sensitivity performance , but the main drawback is that a prolonged incubation period is required for the intercalation activity to take place owing to the same charge of both double‐stranded DNA (dsDNA) and anthraquinone intercalative agent, which impedes the rapid DNA detection .…”