Polymeric luminol on pre-treated screen-printed electrodes for the design of performant reagentless (bio)sensors

A performant reagentless electrochemiluminescent (ECL) system for H2O2 detection based on electropolymerized luminol is first presented. In this work, polyluminol is formed under near-neutral conditions onto pre-treated screen-printed electrodes (SPEs). Pre-treatment conditions of the working electrode surface have been optimized so as to obtain the best ECL responses to H2O2 that were increased by a factor as high as 400. Galvanostatic polymerization has been tested as a new process to form polyluminol films. Good performances were obtained in terms of responses to H2O2, with quite the same linear range as the ones obtained under potentiostatic and potentiodynamic modes.The association of the polyluminol film with an H2O2-producing oxidase has also been investigated, using choline oxidase as a model enzyme. Silica glasses obtained by the sol–gel process have been employed for biomolecule immobilization. Polymeric luminol has been coupled with choline oxidase-immobilizing gel under bilayer or monolayer configurations. In the first case, enzyme has been immobilized in a silica gel formed on a polyluminol film. In the second case, the enzymatic gel formed on SPE was soaked in a solution containing monomeric luminol units, allowing them to diffuse and penetrate throughout the porous gel. Then, electrodeposition was performed to polymerize the luminophore within the silica matrix. In both cases, choline could be detected down to micromolar concentrations.