Biosensing invertase-based Langmuir–Schaefer films: Preparation and characteristic

The formation of hybrid films of the industrially important enzyme invertase and fatty lipids under enzyme-friendly conditions is described. The approach involves a simple physical adsorption protocol wherein invertase adsorbs into the preformed cationic phospholipid–octadecylamine Langmuir–Schaefer (LS) film. Immobilization of invertase onto the film is highly pH-dependent, underlining the role of attractive electrostatic interactions between the enzyme and the lipid layer. The stability of the enzyme in the lipid matrix was confirmed by biocatalytic activity measurements. Withal, the sensor sensitization was achieved by an amphiphilic conducting structure – N-hexadecyl-2,8-bis(thianthrene)phenothiazine admixed into the film. The interlaced compound was expected to facilitate the electron transfer as well as to enhance the sensor sensitivity. The control of molecular architecture and choice of a suitable phospholipid–octadecylamine matrix allows invertase-containing Langmuir–Schaefer films to be used in sucrose sensing devices.