Gold Nanoclusters with Two Sets of Embedded Enzyme Nanoparticles for Applications as Electrochemical Sensors for Glucose

Enzyme-based electrochemical biosensors have been widelyused becauseof their sensitivity, rapidity, and highly target-specific reactions.However, the immobilized enzymes can hinder electron transfer on thesurface of the electrode and can decrease the sensitivity of electrochemicalbiosensors. To overcome this problem, we synthesized conductive goldnanoclusters with two sets of embedded enzyme nanoparticles, whichare called gold nanocluster-embedded dual-enzyme nanoparticles (AuNC-DENPs)composed of a glucose oxidase-stabilized gold nanocluster (GO(X)-AuNC) and a horseradish peroxide-stabilized gold nanocluster(HRP-AuNC). Moreover, the application of these nanoparticles as anenzyme-based highly sensitive electrochemical sensor was investigated.Owing to the effect of AuNCs, these nanoparticles have good conductivitycompared to bare protein nanoparticles. In addition, the synthesizedAuNC-DENPs enabled the combination of a two-enzyme cascade reaction,in which the GO(X)-AuNC component of the nanoparticle oxidizedglucose to generate hydrogen peroxide, which then reacted with theadjacent HRP-AuNC component on the nanoparticle. Given the proximityof the two enzyme components in a single nanoparticle, the AuNC-DENPsmarkedly reduced the diffusion and decomposition of H2O2 during the cascade reaction and showed an enhanced catalyticreaction compared to a mixture of enzymes. As a result, the biosensorexhibited high sensitivity (18,944 & mu;A/mM cm(2)) andcould detect very low concentrations of glucose ranging from 5 to320 nM and a LOD of 2.58 nM. In addition, by analyzing nontarget materialsand serum together with glucose, it was confirmed that the sensorhas good selectivity for glucose.

Automated summary

Enzyme-based electrochemical biosensors are widely used due to their sensitivity and specificity. This study synthesized conductive gold nanoclusters with embedded dual-enzyme nanoparticles, which showed enhanced catalytic reaction and high sensitivity for glucose detection.