Construction and Analytical Characterization of Prussian Blue-Based Carbon Paste Electrodes and Their Assembly as Oxidase Enzyme Sensors

Abstract

This paper reports on the development and characterization of Prussian Blue-modified carbon paste electrodes. New methods of matrix modification with Prussian Blue are reported. Two different carbon pastes have been prepared, using mineral oil or solid paraffin, thus obtaining different types of sensors whose behavior toward the electrochemical reduction of hydrogen peroxide has been fully characterized. Results obtained with Prussian Bluemodified electrodes showed a long operational lifetime, an excellent stability in a wide range of pH (3-9), a high sensitivity, and a fast response time. In addition, the coupling of solid carbon paste modified with Prussian Blue and the enzymes glucose oxidase and choline oxidase led to the assembling of biosensors that showed an optimum working range at alkaline pH. Potassium iron(III)hexacyanoferrate(II) or Prussian Blue (PB)is an inorganic polycrystal with well-known electrochromic and electrocatalytical properties. Since it was deposited on solid electrodes by Neff, 1 it has been the subject of many studies: because of its changes in color (colorless when reduced to Prussian White, yellow when oxidized to Prussian Yellow), this compound has been employed in the development of electrochromic devices; 2,3 it can be used as a power source in rechargeable batteries, 4 and its electrocatalytical properties have been investigated by Itaya and co-workers, who first described an electrochemical method for growing PB films and their electrochemical behavior. 5,6 They showed that the reduced form of PB, the Prussian White, does have a catalytic activity for the reduction of O 2 and H 2 O 2 and also the oxidized form of PB shows a catalytic activity for the oxidation of H 2 O 2 . 6 Others PB analogues, as Cu, Co, Cr, and Ni hexacyanometalates, have been used as electrocatalysts for developing electrochemical sensors for the detection of H 2 O 2 7-9 and other compounds such as perborate, 10 persulfate, 11 hydrazine, 12,13 and cytocrome c. 14 In fact, these transition metal hexacyanometalates are able to reduce the overpotential necessary for nonmodified electrodes to reduce or to oxidize of the previous mentioned species. 13 The ability of PB in reducing H 2 O 2 has attracted the attention of the biosensor community, and recently, in some papers, 15-17 PB has been defined as an "artificial peroxidase" because of its analogy with the biological family of peroxidase enzymes, responsible in nature for reduction hydrogen peroxide. 18 This reduction, in fact, occurs at electrodes modified by PB in different ways at a potential range between -200 and 0 mV (vs Ag/AgCl), defined as the "range offering the most sensitive and interference-free detection" 18 for amperometric biosensors. In fact, this range is low enough to reduce the signal of the electrochemical interfering species often present in real matrixes. In addition, PB does not lack in long-term stability and relatively high costs which are often related to the use of biological components.Recently, a considerable number of pap...

Prussian Blue based screen printed biosensors with improved characteristics of long-term lifetime and pH stability

“…The hydroxyl ions are known to be able to break the Fe Ã/CN Ã/Fe bond, hence solubilizing the PB (Karyakin, 2001). In our opinion, the good results here achieved, similar to those observed in a previous paper (Moscone et al, 2001), are due to the proposed method of deposition, which involves the chemical synthesis of PB in the presence of graphite, allowing its capillary adsorption. Moreover, the SPEs anodization pretreatment carried out at 1.7 V could produce carboxylic groups similar to those produced with aqua regia on graphite powder in our mentioned previous work, and the presence of these groups seems to contribute to the formation of PB films (Jaffari and Turner, 1997).…”

“…In our previous work (Moscone et al, 2001), we successfully applied the latter procedure by chemical synthesis of PB onto graphite powder particles, obtaining a very effective modified matrix. The carbon ink used for the SPEs printing process is obtained by mixing graphite and other different compounds, such as polymeric binders and solvents in order to improve its viscosity.…”

“…Recently, we reported a new method of graphite powder modification with 'in situ' chemically synthesised PB, which resulted in a very active and very stable matrix suitable for the construction of PB modified carbon paste and solid carbon paste electrodes (where solid paraffin replaces mineral oil in the paste; Moscone et al, 2001).…”

Prussian Blue Modified Carbon Nanotube Paste Electrodes: A Comparative Study and a Biochemical Application

“…10 m 2 /g. [25] CNTs were modified with Prussian Blue using the same procedure already optimized in previous articles [20][21][22] dealing with graphite and glassy carbon, which has brought to high electrochemical activity and good stability of the Prussian Blue layer. In Fig.…”

“…Performances of carbon nanotube paste were evaluated studying the parameters of cyclic voltammetry towards several electroactive molecules. Due to their high surface area, [13,14] single walled carbon nanotubes required a higher amount of mineral oil (40%) in respect of what observed with graphite (34%) [22] and glassy carbon (20%) [20] in the assembling of paste electrodes. Moreover, electrodes showed an enhanced electroactivity towards hydrogen peroxide, dopamine, NADH oxidation in respect of classic graphite based paste electrodes.…”