Low Potential Stable Glucose Detection at Dendrimers Modified Polyaniline Nanotubes

The utilization of nanostructured materials for development of biosensors is a growing field in medical diagnostics. In this work a glucose biosensor based on bioactive polyglycerol (PGLD) and chitosan dendrimers (CHD) was developed. PGLD and CHD were bioconjugated with the enzyme glucose oxidase (GOx) to obtain dendrimers with glucose sensing properties. Polyaniline nanotubes (PANINT's) were used as electron mediator due to their high ability to promote electron-transfer reactions involving GOx. The PGLD-GOx and CHD-GOx were entrapped in PANINT's during template electrochemical polymerization of aniline. The prepared PGLD-GOx/PANINT's and CHD-GOx/PANINT's biosensors exhibit a strong and stable amperometric response to glucose even at a low potential of +100 mV. The based PGLD-GOx/PANINT's and CHD-GOx/PANINT's biosensors showed a good performance in glucose concentrations range in human blood. A comparison of the sensitivities to glucose showed that both biosensors have a linearity range between 0.02 and 10 mM, though PGLD-GOx/PANINT's is more sensitive (10.41 vs. 7.04 nA.mM(-1)). The difference in the biosensor behavior and the high sensitivity of the PGLD-GOx/PANINT's may be due to the specific organization of GOx layer at surface of the modifier macromolecule PGLD and their distribution in PANINT's. The enzyme affinity for the substrate, K-M(aPP) remains quite good after GOx immobilization on PGLD and CHD dendrimers and entrapment of the bioconjugates in PANINT's.