Perspective on Plasma Polymers for Applied Biomaterials Nanoengineering and the Recent Rise of Oxazolines

Abstract

Plasma polymers are unconventional organic thin films which only partially share the properties traditionally attributed to polymeric materials. For instance, they do not consist of repeating monomer units but rather present a highly crosslinked structure resembling the chemistry of the precursor used for deposition. Due to the complex nature of the deposition process, plasma polymers have historically been produced with little control over the chemistry of the plasma phase which is still poorly understood. Yet, plasma polymer research is thriving, in par with the commercialisation of innumerable products using this technology, in fields ranging from biomedical to green energy industries. Here, we briefly summarise the principles at the basis of plasma deposition and highlight recent progress made in understanding the unique chemistry and reactivity of these films. We then demonstrate how carefully designed plasma polymer films can serve the purpose of fundamental research and biomedical applications. We finish the review with a focus on a relatively new class of plasma polymers which are derived from oxazoline-based precursors. This type of coating has attracted significant attention recently due to its unique properties.

Nanoengineered Antibacterial Coatings and Materials: A Perspective

“…Oxazoline derived plasma polymer coatings were also demonstrated to efficiently modulate the immune responses exhibited by the reduction in secretion of pro-inflammatory cytokines and the composition of protein corona forming on the biomaterial surface [15,56,59]. In the context of this article, the most interesting property of oxazoline based plasma deposited coatings is the inhibition of biofilm formation [14,15,53,60]. An example is shown in Figure 2, which depicts four cell culture wells after incubation in a culture of S. epidermidis for 24 h. A surface coated with an amine plasma polymer was used as a positive control.…”

“…A recently developed class of plasma polymers are those deposited from oxazoline precursors, such as 2-methyl-2-oxazoline and 2-ethyl-2-oxazoline [15,36,[51][52][53][54]. Regardless of the precursor used, when appropriate conditions for deposition are used, the process results in coatings with properties that are very useful for biomedical applications.…”

Deposition of 2‐oxazoline‐based plasma polymer coatings using atmospheric pressure helium plasma jet

“…In contrast, it was found that the plasma coatings retained oxazoline ring moieties, which could be further utilised to couple biomolecules having carboxylic acid functionality. A recent review paper by Macgregor and Vasilev summarises the principles of various plasma polymerisation processes, including those of oxazolines. It also highlights how a plasma polymerisation process can be carefully designed to deliver thin film coatings with unique chemistries for specific applications.…”

Cold atmospheric pressure plasma: simple and efficient strategy for preparation of poly(2-oxazoline)-based coatings designed for biomedical applications

“…To name a few examples, poly(2-methyl-2-oxazoline)-grafted surfaces 53 , hydrophilic POx bottle-brush brushes 54 and hydrogels 36 were shown to diminish the cell adhesion. On the other hand, it should be mentioned that the plasma polymerized POx usually promote good cell adhesion 44,55 , however, their chemical structure differs significantly from POx prepared by living polymerization methods. Surprisingly, the ongoing discussion on these different adhesion properties is often limited to comparison of chemistry of the surface layer, i.e., hydrophilic vs. hydrophobic POx, presence of certain functional groups, the molar mass of the polymer chain.…”

“…As mentioned above, various chemical and physical properties of the surfaces affect the cell adhesion. The introduction of the polar functional groups, such as carboxyl, hydroxyl and amine on inert surface increase the hydrophilicity and promote the cell adhesion 55,58 . XPS measurements revealed the appearance of oxygen containing functional groups on POx surfaces.…”