Study of horseradish peroxidase activity in alternate-layer Langmuir–Blodgett films

A previously proposed method of alternate-layer deposition, which enables the inclusion into the film of adsorbed proteins, was applied to the deposition of LB films with the structure (monolayer 1/adsorbed layer of horseradish peroxidase (HRP)/monolayer 2). Various combinations of the monolayers 1 and 2 were tested with regard to the following goals: to obtain a high efficiency of protein adsorption with retained enzymatic activity; to avoid detachment of protein molecules from the substrate in aqueous solutions; to increase duration of the activity preservation of HRP during sample storage; and to provide easy removal of protective monolayer 2 when the film is used for measurements. Creation of films with such characteristics is important for their successful bioanalytical applications. Spectrophotometric measurements of the HRP activity as well as quartz crystal microbalance studies reveal an interconnection between the properties of the deposited biologically active media, experimental conditions of their preparation, and film composition. To increase structural stability of films, electron beam sensitive polymer monolayers were used for the fabrication of some variants of the alternate-layer Langmuir–Blodgett (LB) films and enzymatic activity of irradiated samples was studied as well.