MATRIX ASSISTED PULSED LASER EVAPORATION FOR LACCASE BASED BIOSENSORS

Matrix Assisted Pulsed Laser Evaporation (MAPLE) is a laser‐based deposition technique used to deposit films of soft material [1]. In MAPLE, a pulsed laser beam is focused inside a vacuum chamber and impinges on the surface of a rotating target. The target consists of a frozen solution of the material of interest that is diluted in an appropriate solvent. Thus, when the laser beam impacts the target, the laser pulsed energy is mainly absorbed by the solvent and converted to thermal energy, allowing the solvent to vaporize while the material of interest is deposited as a thin film [1]. Therefore, MAPLE is exploitable as an alternative strategy for the immobilization of enzymes [2]. In this study we focused our attention on Laccase, since it is an enzyme widely used as biological recognition component in biosensors for detecting polyphenols that are important compounds in foodstuffs [3] because of their recognized nutritional value. Laccase has been deposited by MAPLE onto suitable substrates from water and benzene solutions, and the effectiveness of the process has been evaluated in terms of characteristic of chemical bonds (Fourier Transform InfraRed), morphology (Atomic Force Microscopy), enzyme loading (quartz crystal microbalance), and enzyme activity (colorimetric assay). The deposition process has been also performed onto screen printed carbon electrodes, and the obtained biosensor has been characterized in terms of linearity, LOD, LOQ, repeatability and stability of response. Moreover, the potential of the Laccase biosensor has been also tested by the determination of total polyphenols content in vegetable ethanolic extracts and the results have been compared with those obtained by the Folin‐Ciocalteau method.