ABSTRACT
We describe a novel glucose biosensor based on a nanoband array electrode design, manufactured using standard semiconductor processing techniques, and bio-modified with glucose oxidase immobilized at the nanoband electrode surface. The nanoband array architecture allows for efficient diffusion of glucose and oxygen to the electrode, resulting in a thousand-fold improvement in sensitivity and wide linear range compared to a conventional electrode. The electrode constitutes a robust and manufacturable sensing platform.
Subject(s)
Biosensing Techniques/methods , Glucose Oxidase/metabolism , Glucose/analysis , Nanotechnology/methods , Biosensing Techniques/instrumentation , Electrochemistry , Electrodes , Enzymes, Immobilized/chemistry , Enzymes, Immobilized/metabolism , Glucose/chemistry , Glucose Oxidase/chemistry , Limit of Detection , Nanotechnology/instrumentation , Platinum/chemistry , Surface PropertiesABSTRACT
In this study, we investigated whether probiotic lysates can modify the tight-junction function of human primary keratinocytes. The keratinocytes were grown on cell culture inserts and treated with lysates from Bifidobacterium longum, Lactobacillus plantarum, Lactobacillus reuteri, Lactobacillus fermentum, or Lactobacillus rhamnosus GG. With the exception of L. fermentum (which decreased cell viability), all strains markedly enhanced tight-junction barrier function within 24 h, as assessed by measurements of transepithelial electrical resistance (TEER). However, B. longum and L. rhamnosus GG were the most efficacious, producing dose-dependent increases in resistance that were maintained for 4 days. These increases in TEER correlated with elevated expression of tight-junction protein components. Neutralization of Toll-like receptor 2 abolished both the increase in TEER and expression of tight-junction proteins induced by B. longum, but not L. rhamnosus GG. These data suggest that some bacterial strains increase tight-junction function via modulation of protein components but the different pathways involved may vary depending on the bacterial strain.
Subject(s)
Bifidobacterium/chemistry , Keratinocytes/microbiology , Lactobacillus/chemistry , Probiotics/administration & dosage , Tight Junctions/microbiology , Bifidobacterium/classification , Bifidobacterium/genetics , Humans , Keratinocytes/metabolism , Lactobacillus/classification , Lactobacillus/genetics , Probiotics/chemistry , Tight Junctions/metabolism , Toll-Like Receptor 2/metabolismABSTRACT
The performance of two electrode architectures with broadly similar overall active electrode areas are examined. The first is an electrode comprising a single contiguous area (a disc) and the second is an electrode in which the cumulative electrode area is dispersed over a wide area as a 50 nm thickness platinum nanoband. A direct comparison of the electrochemical performance of these two electrodes has been made. The relatively simple nanoband electrode architecture is shown to have benefits, including two orders of magnitude greater mass transport limited currents, the ability to measure faster electrode kinetics (by a similar factor), a three orders of magnitude lowering of the Limit of Detection and a significantly reduced susceptibility to hydrodynamic perturbations. The consequences and implications of these performance characteristics on the uses of such a nanoband electrode have been considered.
