Activity, stability and inhibition of a bioactive paper prepared by large-scale coating of laccase microcapsules

Enzyme immobilization on paper by large-scale processes may play a valuable role in the development of economical and widely distributed biosensors. In this study, we report on the coating of laccase from Trametes versicolor on papers using a laboratory coater (Cylindrical Laboratory Coater) that simulates realistic conditions similar to those obtained with industrial coaters. In order to achieve an efficient retention of laccase in the coating, the enzymes were incorporated in poly(ethyleneimine) microcapsules. The microcapsules were suspended in a starch-based coating suspension, applied on paper by blade coating at a rate of 500 and 800 m/min thereupon dried by evaporation using an IR lamp at 36 kW. A technique based on the colorimetric reaction between the laccase and its substrate, p-phenylenediamine (PPD), was developed to evaluate the activity of the immobilized enzyme. Our results show that the use of microencapsulation allows for better activity retention in papers over time at room temperature (50% loss after 28 days) compared to papers modified with free laccase (50% loss after 4 days). Microcapsules also decrease the inhibition of laccase by azide.