While protein or enzyme immobilization methodologies are readily applicable in a majority of industrial processes, some lacunas still remain. For example, the multi-step, wet-chemical nature of current immobilization reactions limits straightforward bio-film fabrication in continuous production units. As such, a fast and preferably single step immobilization technique, minimizing solvent use and decoupling deposition substrate from used method is awaited. In this research, an atmospheric pressure plasma reaction environment is chosen for its flexibility in terms of reactivity and the ease of coating depositions on a wide variety of substrates. Organic coating precursors such as acetylene or pyrrole are injected simultaneously with an atomized enzyme solution directly in the discharge. By atomizing the enzyme solution, the enzyme molecules are surrounded by a watery shell. It is envisioned that such droplet act as ''shuttles'', delivering the enzymes to the discharge while protecting them from the harsh plasma conditions. In the discharge, polymerization of the added organic coating precursor takes place and consequently, the enzyme molecules become trapped in the growing polymer network. In addition, atomization of the protein solution favors the spatial distribution of the proteins in the coating. Several enzymes are evaluated and enhanced temperature and solvent stability is observed. Moreover, single molecule fluorescence, enzyme activity and bio-recognition experiments demonstrate protein integrity after plasma assisted immobilization.

Plasma coating technologies have been demonstrated as being promising for the fabrication of bioactive and biocompatible materials, among others. Reported efforts are exclusively focused on the two‐step approaches, in which the bioactive component is first immobilized on a substrate, followed by a (vacuum) plasma polymerization treatment or vice versa. However, we believe that upon minimizing the plasma energy, numerous bioactive substances such as enzymes and nucleic acids can be immobilized directly in plasmas via copolymerization with organic precursors, or by direct entrapment in the organic polymer. Therefore, a dielectric barrier discharge was employed at atmospheric pressure and ambient temperature to deposit organic coatings with reasonable growth rates at power input and frequency values as low as possible. Two promising precursors, acetylene and pyrrole, were selected out of 22 organic monomers for full physicochemical characterization. While the acetylene polymer film shows resemblance with its vacuum plasma analogue, polypyrrole coatings produced in vacuum and atmospheric plasmas differ significantly.

Cover: The aquamarine discharge exemplifies polymerization of acetylene in a DBD reactor. In total, over 20 precursors were classified for their “ease” of film deposition and growth at low energy input. Next to acetylene, pyrrole is the precursor of choice. In‐depth analysis of the polymer films offers insights in their physicochemical properties. The research was a combined effort of VITO and KULeuven. Further details can be found in the article by P. Heyse, R. Dams, S. Paulussen,* K. Houthoofd, K. Janssen, P. A. Jacobs, and B. F. Sels on page 145.