Electrospray deposition as a smart technique for laccase immobilisation on carbon black-nanomodified screen-printed electrodes

Enzymes immobilisation represents a critical issue in the design of biosensors to achieve standardization as well as suitable analytical performances in terms of sensitivity, selectivity, and stability. In this work electrospray deposition (ESD) has been exploited as a novel technique for the immobilisation of laccase enzyme on carbon black modified screen-printed electrodes. The aim is to fabricate an amperometric biosensor for phenolic compound detection. The electrodes produced by ESD have been analysed by scanning electron microscopy and characterised electrochemically to prove that this immobilisation technique is suited to manufacture high performance biosensors. The results show that the laccase enzyme maintains its activity after undergoing the electrospray ionisation process and deposition and the fabricated biosensor has improved performances in terms of storage (up to 3 months at room temperature) and working (up to 25 measurements on the same electrode) stability. The laccase-based biosensor has been tested for phenolic compound detection, with catechol as target analyte, in the linear range 2.5-50 mu M, with 2.0 mu M limit of detection, without interference from lead, cadmium, atrazine, and paraoxon, and without matrix effect in drinking, surface, and wastewater.