Facile immobilization of enzyme by entrapment using a plasma-deposited organosilicon thin film

Over the years, immobilization of biologically active species such as enzymes onto solid support gave rise to a wide range of analytical and industrial applications. The development of fast, simple and efficient immobilization strategies is becoming of great importance in specific Biological MicroElectromechanical Systems (BioMEMS) manufacturing. Thus, the current work focuses on an original methodology and mild procedure for beta-galactosidase immobilization. Using as support either silicon or a thin film obtained from polymerization of 1,1,3,3-tetramethyldisiloxane (ppTMDSO) deposited by Plasma Enhanced Chemical Vapor Deposition in afterglow mode, the strategy developed here consisted in adsorption of p-galactosidase followed by its overcoating by the same siloxane plasma polymer. After sample washing, the enzymes were characterized to be efficiently entrapped within the porous polymer matrix while allowing the penetration and hydrolysis of the synthetic substrate ortho-nitrophenyl-beta-D-galactopyranoside (o-NPG) with stability over at least 8 assays. The entrapment procedure allowed obtaining bio-functionnal coatings where beta-galactosidase was expected to be included in the plasmapolymerized films while preserving its native structure and its activity. This latter was modulated by mass transfer limitations of the substrate according to the thickness of the ppTMDSO coatings. The dryprocess-based-preparation of such a thin bio-functional film (from similar to 200 nm to similar to 650 nm) is fast and compatible with biochip or microreactor fabrication processes while avoiding the use of lot of chemicals and multi-step treatments commonly encountered in enzyme immobilization procedures. (C) 2014 Elsevier B.V. All rights reserved.