Porous carbon composite/enzyme glucose microsensor

Abstract

An enzyme glucose microsensor using a glucose oxidase-immobilized porous carbon/Teflon composite microelectrode was developed. The microsensor was fabricated by etching a platinum microelectrode (platinum, radius of 25 and 50 micrometers) in hot aqua regia to create a cavity at the tip and then packing a porous carbon/Teflon composite, which was made from acetylene black and Teflon emulsion, into the cavity. Nafion was impregnated into the inner surface of porous carbon/Teflon composite electrode following immobilization of Os(bpy)3+2/+3 as electron transfer mediators. The loading amount of Os(bpy)3+2/+3 in the Nafion/porous carbon/Teflon composite electrode was found to be 7.0x10(-8) mole cm(-2), which is much higher than that in polymer modified electrodes reported in literatures. The microsensor was further dipped overnight in buffer solution containing glucose oxidase for enzyme modification. With both glucose oxidase and mediators in the porous carbon/Teflon composite surface, the sensor performance was evaluated in buffer solutions containing different glucose concentrations and serum samples for glucose determination. The microsensor showed directly electrochemical glucose oxidation on the Os(bpy)3+2/+3 impregnated enzyme/porous carbon/Teflon composite surface with linear response over concentration range of 0-15 mM and Machaelis behavior. Reliability and reproducibility were conducted in serum samples and glucose buffer solution, and the results demonstrated there was no significant decrease of amperometric response in air-saturated solution for one month. The sensor demonstrated potential in clinical diagnostic applications.

Size dependence of nanostructures: Impact of bond order deficiency

“…The high efficiency of electronic behavior is general irrespective particular catalytic material [409]. Recently, the powder ultramicroelectrode has been used to biosensor to enhance the enzymatic catalysis process [410].…”

“…For instance, calculations suggested that [145] atomic relaxations on the stepped Ag (410) and Cu(320) surfaces extend several layers into the bulk with a non-uniform character in damping magnitudes of interlayer relaxations. LEED analysis for Ag (410) initially suggested [146] that there was no measurable [128], Co [129], and Re [130] Fe-W, Fe-Fe [139] Fe(310) [140], Ni(210) [141] Al(001) [142] Ni, Cu, Ag, Au, Pt and Pd dimer [112] Ti, Zr [109] V [109] [148]. On the other hand, LEED measurements of Cu(320) revealed a 24% contraction for d 12 and 16% contraction for d 23 , followed by 10% expansion for d 34 .…”

Directly Grown K0.33WO3 Nanosheet Film Electrode for Fast Direct Electron Transfer of Protein

“…Biosensors have continued to fuel great interest in recent years for their important applications in clinical diagnosis, environmental monitoring and food quality control. [44][45][46][47] Direct-electrochemistry-based enzymatic biosensors [3][4][5][6][7][8] can offer high sensitivity due to their fast electron transfer rates and superior selectivity, as the low redox potential reduce or eliminate interference reactions. [9] As a model example, we demonstrate herein an as-grown K 0.33 WO 3 nanosheet film electrode that simultaneously possesses good conductivity, high hydrophilicity and low interfacial resistance for fast direct electrochemistry of glucose oxidase (GOD), thus leading to a novel direct-electrochemistry-based glucose biosensor with very high sensitivity and low detection limit in the presence of interfering agents, among the best ones to date in both cost and sensing performance.…”

“…Direct electrochemistry, the direct electron transfer between electrode and protein or microbe has been extensively studied due to not only its fundamental importance in biological organisms and bioelectrochemistry, but also due its remarkable potential applications in biofuel cells, [1,2] biosensors [3][4][5][6][7][8] and bioelectronics. [1] Nevertheless, it often encounters a major obstacle resulting from the deeply embedded redox centers in a surrounding "insulation layer" of a protein or microbe.…”

Glucose Oxidase-Coated ZnO Nanowires for Glucose Sensor Applications

“…Most popular glucose sensing is based on the electrochemical biosensors using enzyme electrodes [1][2][3] and there are only a few fluorescence-based methods for glucose sensing which are mainly using optical fibers 4,5) or fluorescent quantum dots. 6) Direct fluorimetric glucose detection using the enzyme such as glucose oxidase (GOx) 7,8) is very rare, and moreover, fluorescence-based glucose biosensors using GOx-coated nanowires have not been reported yet.…”