Considering the degradation effects of amino-functional plasma polymer coatings for biomedical application

Abstract

Materials for biomedical applications typically involve surface engineering. Scaffolds used for tissue engineering, for example, require a surface functionalization in order to support cell growth. The deposition of functional plasma polymer coatings seems to be an attractive approach to modify substrates for biomedical applications. Possible degradation of highly functional plasma polymers and the effect of its degradation products on cell growth, however, are not yet investigated in detail. Plasma polymer formation is governed by gas phase (mainly determining the chemical composition) and surface processes (inducing cross-linking) which both influence the incorporation of amino groups in a-C:H:N coatings deposited by NH 3 /C 2 H 4 discharges. Aging is studied in air and in aqueous conditions revealing the degradation of such plasma polymers (loss in thickness and loss of amino groups). Degradation products seem to influence viability and proliferation of mouse skeletal muscle cells on electrospun poly(ε-caprolactone) scaffolds. Thus, possible chemical changes as a function of time or exposure to different media must be taken into account in the design of functional plasma polymer coatings for biomedical applications in order to avoid possible adverse effects on cell growth.

Deposition of Plasma Polymer Films from Acetylene and Water Vapor

“…This is of particular importance for biomedical or biotechnical uses. The partial dissolution of N‐containing plasma polymers in aqueous media, for instance, has been reported by several authors . Preliminary investigations of this aspect for the H 2 O/C 2 H 2 plasmas polymer films are reported here.…”

Controlling the nanostructure and stability of a-C:H:N plasma polymers

“…The formed oxygen- containing groups are instable and react further to yield imines, amides and further oxygen/nitrogen-containing groups [33]. Indeed, we have found for our NH 3 /C 2 H 4 -derived plasma polymers that aging in ambient air for three weeks results in a decrease of primary amino groups down to 2-3% [NH 2 ]/[C] independent of the initial (higher) amino concentration [34]. Formation of imines and amides beside amine groups favors hydrolysis reactions when the a-C:H:N films are immersed in water (or stored in humid air).…”

“…These products were found to show adverse effects on cell growth [37][38][39], which has some important implications for biomedical applications, i.e. requiring washing or pre-incubations of plasma-coated samples used for tissue engineering [34,40].…”

Cyclopropylamine plasma polymers for increased cell adhesion and growth

“…The PP‐CPA layers exhibiting bad stability in water demonstrated lower cell proliferation compared to the uncoated reference surface. Although the surface chemistry of the amine‐rich layers should enhance the cell proliferation, the leaching of toxic oligomers from them negatively affected the viability of cells . Thus, more stable, i.e., more cross‐linked layers exhibited better results of the cell cultivation in spite of their lower NH x concentration.…”