Lipid-matrix effects on tyrosinase immobilization in Langmuir and Langmuir-Blodgett films

Abstract

The immobilization of the enzyme tyrosinase (Tyr) in lipid matrices can be explored to produce biosensors for detecting polyphenols, which is relevant for the food industry. Herein, we shall demonstrate the importance of the lipid composition to immobilize the enzyme tyrosinase in Langmuir-Blodgett (LB) fi lms. Tyr could be incorporated into Langmuir monolayers of arachidic acid (AA), 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and 1,2-dipalmitoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (sodium salt) (DPPG), having as the main effect an expansion in the monolayers. Results from polarization-modulated infrared refl ection-absorption spectroscopy (PM-IRRAS) pointed to electrostatic interactions between the charged residues of Try and the lipid headgroups, in addition to changes in the order of lipid chains. The interaction between Tyr and DPPC in Langmuir monolayers can be correlated with the superior performance of DPPC/Tyr LB fi lms used as biosensors to detect catechol by cyclic voltammetry. The molecular-level interactions assessed via PM-IRRAS are therefore believed to drive an immobilization process for Tyr in the lipid LB matrix and may serve as a general criterion to identify matrices that preserve enzyme activity.

The Past and the Future of Langmuir and Langmuir–Blodgett Films

“…389 The enzyme tyrosinase (Tyr) was incorporated into LB films of different lipids to detect polyphenols relevant to the food industry. 390 In the latter example, PM-IRRAS was used not only to investigate enzyme adsorption in Langmuir monolayers but also to determine the molecular-level interactions responsible for the detection. Enhanced sensitivity in lipidbased LB biosensors was achieved by introducing carbon nanotubes (CNT) in stearic acid films that contained asparaginase (ASNase).…”

“…For instance, the enzyme polyphenol oxidase (PPO) was immobilized in LB films with a positively charged lipid, octadecylamine (ODA+), to detect pyrocatechol . The enzyme tyrosinase (Tyr) was incorporated into LB films of different lipids to detect polyphenols relevant to the food industry . In the latter example, PM-IRRAS was used not only to investigate enzyme adsorption in Langmuir monolayers but also to determine the molecular-level interactions responsible for the detection.…”