Improving the detection of hydrogen peroxide of screen-printed carbon paste electrodes by modifying with nonionic surfactants.

Nonionic surfactants, such as Triton X-100 and Tween-20, were shown in this study to improve the electrocatalytic activity of screen-printed carbon paste electrodes (SPCE). The electrochemical response of SPCE to hydrogen peroxide increased 8-10-fold with the modification of nonionic surfactants. In addition, the glucose biosensors fabricated from nonionic surfactant-modified SPCE exhibited 6.4-8.6-fold higher response to glucose than that fabricated from unmodified SPCE. A concentration effect is proposed for nonionic surfactant to bring neutral reactants to the surface of electrode. Moreover, nonionic surfactant-modified SPCE exhibits a capability of repetitive usage and good reproducibility (R.S.D.<5%) in the measurement of H(2)O(2). Interestingly, the nonionic surfactant-modified SPCE exhibited an opposite effect to ascorbic acid, a common electroactive agent, which causes interference during clinical diagnosis. The differential responses of nonionic surfactant-modified SPCE to H(2)O(2) and ascorbic acid suggest its potential in the development of biosensors for clinical diagnosis.

Application of SiO2-poly(dimethylsiloxane) hybrid material in the fabrication of amperometric biosensor.

Silica xerogel was widely used in the development of biosensors by coupling the desired biological components to various transducers. Unfortunately, the application of xerogels is limited due to their poor mechanical properties and poor structural maintenance of entrapped biomaterials. In this study, the availability of poly(dimethylsiloxane) (PDMS)-modified silica sol-gel (TEOS/PDMS Ormosil) glass in the immobilization of enzymes and its application in the fabrication of amperometric biosensor was investigated. We demonstrated that most of activity of encapsulated horseradish peroxidase can be preserved in PDMS-modified SiO2 glass compared with conventional silica xerogel. The synthesized monoliths exhibited high transparency and crack-free. The enzyme electrode based on glucose oxidase encapsulated TEOS/PDMS Ormosil glass on Pd electrode was fabricated and characterized electrochemically. The characteristics of the biosensor were studied by cyclic voltammetry and chronoamperometry. The biosensor exhibited a series of good properties: high sensitivity (1.63 microA mM(-1) analyte), short response time and high reproducibility. The results indicate that TEOS/PDMS Ormosil glass has great potential to the immobilization of biomaterials as well as the fabrication of biosensors.