A Layer-by-Layer Biosensing Architecture Based on Polyamidoamine Dendrimer and Carboxymethylcellulose-Modified Graphene Oxide

A novel nanostructured architecture for the construction of electrochemical enzyme biosensors is here described. It implies the electrostatic layer-by-layer assembly of four-generation ethylenediamine core polyamidoamine G-4 dendrimers on glassy carbon electrodes coated with a graphene oxide-carboxymethylcellulose hybrid nanomaterial. This modified surface was further employed for the covalent immobilization of the model enzyme tyrosinase through a glutaraldehyde-mediated cross-linking. The prepared enzyme electrode allowed the amperometric detection of catechol in the 2-400 nM range. The biosensor showed excellent analytical performance with high sensitivity of 6.3 A/M and low detection limit of 0.9 nM. The enzyme electrode retained over 93% of the initial activity after 40 days at 4 degrees C.