Laccase thin films produced by MAPLE and ESI techniques: Effect of some solvents

Matrix Assisted Pulsed Laser Evaporation (MAPLE) and ElectroSpray Ionization (ESI) can represent useful techniques for producing enzyme thin films [1-2] exploitable in biosensors. Previous studies were carried out to deposit Laccase thin films by MAPLE using water or benzene as solvents [3-4]. Laccase was chosen since it is a redox enzyme widely used as a biological recognition component in biosensors for the detection of polyphenols. In this work, Laccase films deposited by MAPLE using water or benzene were compared and Laccase films deposited by ESI using acetonitrile or ethanol, both at 10% concentration, were also investigated. The efficiency of the deposition processes as well as the preservation of the biomolecular structure and functionality strongly depend on the solvent. The Laccase film funzionality in terms of enzymatic activity, was determined by spectrophotometric analysis by using syringaldazine as the enzyme substrate. These analysis highlighted that MAPLE using benzene allows obtaining more active films in a shorter time with respect to those obtained with water. Also ESI using ethanol allows obtaining more active Laccase films than those obtained by ESI using acenonitrile. Therefore a successful deposition of Laccase by MAPLE or ESI requires a careful choice of the solvent.