Nonthermal plasma treatment of polymers modulates biological fouling but can cause material embrittlement

Abstract

Plasma-based treatment is a prevalent strategy to alter biological response and enhance biomaterial coating quality at the surfaces of biomedical devices and implants, especially polymeric materials. Plasma, an ionized gas, is often thought to have negligible effects on the bulk properties of prosthetic substrates given that it alters the surface chemistry on only the outermost few nanometers of material. However, no studies to date have systematically explored the effects of plasma exposure on both the surface and bulk properties of a biomaterial. This work examines the time-dependent effects of a nonthermal plasma on the surface and bulk properties of polymeric implants, specifically polypropylene surgical meshes and sutures. Findings suggest that plasma exposure improved resistance to fibrinogen adsorption and Escherichia coli attachment, and promoted mammalian fibroblast attachment, although increased duration of exposure resulted in a state of diminishing returns. At the same time, it was observed that plasma exposure can be detrimental to the material properties of individual filaments (i.e. sutures), as well as the structural characteristics of knitted meshes, with longer exposures resulting in further embrittlement and larger changes in anisotropic qualities. Though there are few guidelines regarding appropriate mechanical properties of surgical textiles, the results from this investigation imply that there are ultimate exposure limits for plasma-based treatments of polymeric implant materials when structural properties must be preserved, and that the effects of a plasma on a given biomaterial should be examined carefully before translation to a clinical scenario.

Cyclodextrin polymer coatings resist protein fouling, mammalian cell adhesion, and bacterial attachment

“…The coating for the 0.08 pCD surface was found to have delaminated during a rinse step, so no data is shown for that sample. Plasma treatments were observed to reduce protein adsorption onto PP surfaces, in agreement with previous findings 83 , again possibly a result of increasing wettability.…”

“…Cell adhesion was equally low for untreated PP as for most pCD polymers (p > 0.293). Plasma treatment of PP increased cell adhesion (p = 0.01), consistent with prior findings 83 . Likewise, cell adhesion for TCPS (commercially plasma-treated PS) was higher than that for untreated PS (p < 0.003).…”

“…To maximize pCD coating adherence and stability, PP substrates were placed in a 4" diameter x 8" length quartz reaction chamber of a Branson/IPC Model #1005-248 Gas Plasma Cleaner and treated with nonthermal plasma (500 mTorr, 50 W, 13.56 MHz) using an inlet gas mixture of argon bubbled through water (Ar/H2O) 81,83 . PP substrates were treated for a fixed 10 min duration within 1 h of pCD coating application or direct biofoulant exposure (for plasmatreated bare PP controls).…”

Affinity Effects on the Release of Non-Conventional Antifibrotics from Polymer Depots

“…We herein used both in silico and in vitro measurements to predict and confirm the relative affinity of the selected drugs for β-CD or the base polymer without inclusion complex formation, dextran (Figures 1 and 2). Previous studies have demonstrated using cyclodextrin monomers polymerized into larger macrostructures such as coatings, disks, and particles in order to delay drug release by achieving a high concentration of affinity-binding sites [27,30,31,37,44,45]. The release results herein show differences in the loading efficiencies (Figure 3), release rates ( Figure 4), and cumulative amounts of drug release ( Figure 5) which may inform the future use and design of local drug delivery depots.…”

Using nonthermal plasma treatment to improve quality and durability of hydrophilic coatings on hydrophobic polymer surfaces

“…The lack of a need for hazardous chemical treatments is an advantageous aspect of substrate plasma activation, especially for coatings to be applied to polymeric biomedical implants, such as PP sutures and hernia meshes. Appropriate selection of plasma treatment parameters can ensure minimal impact on the bulk mechanical properties of such load-bearing substrates 6 . Apart from biomedical purposes, this research has important commercial applications as well.…”