Improved performance of carbon paste amperometric biosensors through the incorporation of fumed silica

Abstract

The sensitivin and stability of carbon paste enzyme electrodes are greatly enhanced through the incorporation of fumed silica within the paste matrix. The improved performance is attributed to the adsorptive and electrocatalytic properties of the silica nanoparticles. The electrocatal\-tic action results in a substantial lowering of the overvoltage for both the oxidation and reduction of the enqmatically liberated peroxide species. Highly selective, low-potential, biosensing of glucose is thus accomplished in the presence of coexisting acetaminophen. ascorbic acid, or uric acid. The enhanced performance accrued from the presence of silica is also illustrated for mediator (dimethyl ferrocene)-containing pastes. High enzymatic activin is maintained over prolonged periods. The silica modification strategy provides an effective, fast, and inexpensive route for immobilizing enz).mes within carbon paste matrices.

Analytical Applications of Silica-Modified Electrodes -A Comprehensive Review

“…Moreover, the silica support was found to stabilize Meldola's Blue species (acting as a mediator in the oxidation of NADH), preventing somewhat their leaching from the electrode matrix. Similar improvements were then observed for the biosensing of glucose [250]. The presence of fumed silica into the carbon paste-glucose oxidase-electrode resulted in a substantial lowering of the overvoltage for both the oxidation and reduction of the enzymatically liberated peroxide species, with a concomitant increase in the sensor sensitivity.…”

“…Wang and co-workers [62,250] improved the performance of carbon paste biosensors through the incorporation of fumed silica. The sensitivity and stability of the carbon paste containing either alcohol or lactate dehydrogenase was greatly enhanced by the incorporation of fumed silica [62].…”

In vitro simulation studies of silica deposition induced by lignin from rice

“…Many scientists believe that silica deposition in higher plants is associated with lignification (Parry and Kelso, 1975;Montgomery and Parry, 1979;Wang and Naser, 1994;Chérif et al, 1994). In order to provide direct evidence to support this hypothesis, the first step was to isolate pure lignin from rice straw.…”

Tendências em modificação de eletrodos amperométricos para aplicações eletroanalíticas

“…Particularmente no caso de biossensores baseados em sílica, nos quais esta é utilizada como suporte para imobilização de enzimas, é possível incorporar outros materiais para aumentar a estabilidade e a sensibilidade destes dispositivos. Podemos destacar alguns biossensores eletroquímicos empregando eletrodos modificados à base de sílica, utilizados na determinação de analitos de interesse biológico, tais como etanol e lactato 107 , frutose 108 , glicose [109][110] 130 . Estas enzimas são dependentes de um cofator, nicotinamida adenina dinucleotídeo, o qual pode existir na forma oxidada (NAD(P) + ) ou reduzida (NAD(P)H).…”