Design and application of anti-biofouling coatings on stainless steel by plasma enhanced chemical vapor deposition




Ellis-Terrell, Carol A.

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<p>Presently, stents are the primary practice to treat coronary artery blockage. However, in-stent restenosis remains a problem that affects approximately 10-30% of patients with bare metal stents (BMS).<sup>1,2</sup> To mitigate this problem, BMS are coated with either drug-eluting (active) or a biologically inert (passive) coatings to provide anti-biofouling properties. Plasma based surface modification is a method used to impart specific surface properties on medical devices. Coatings produced by plasma-enhanced chemical vapor deposition (PECVD) techniques are known to be effective at reducing cell adhesion, similar to conventional solution-based coating methods. Despite radio frequency (RF) power supplies being the most commonly used power generator for PECVD, there are a couple of drawbacks to this power source: 1. difficult adaptability to large scale industrial processes; 2. limited control of deposition process. Instead, pulsed-direct current (DC) PECVD is more translatable to industrial processes and has been shown to allow for more selective fragmentation of chemical precursors due to the use of short duty cycles. In this work, plasma-polymerized hexamethyldisiloxane (HMDSO) coatings were deposited on flat stent-like material with pulsed-DC PECVD and evaluated as anti-biofouling coatings to inhibit or promote accumulation of specific cells to the surface. The anti-biofouling coatings were prepared at three different flow rates of HMDSO (2, 2-3, and 3 g/hr) and two different voltages (1000 V and 1500 V). The interaction of human umbilical vein endothelial cells (HUVECs) and human coronary artery smooth muscle cells (HCASMCs) was investigated on the coated surfaces after 2 and 7 days of incubation. Two fluorescent stains, 4,6-diamidino-2-phenylindole dihydrochloride (DAPI) and CytoPainter Phalloidin iFluor 594 were used for imaging the nucleus and cytoskeleton of the cells adhered to the surface.</p> <p>Our results show that the coating chemistry, thickness and wetting properties are adaptable with respect to the applied voltage and monomer flow rate. An organosilicon polymer-like (1000 V) and silicon oxycarbide (1500 V) coating were deposited on 321 and 316 L stainless steel foil. An average water contact angle at 3 g/hr at 1000 V and 1500 V was 97 ° and 75 °, respectively on 316 L stainless steel foil, indicating a statistical difference. The cellular response of HUVECs and HCASMCs to the two different coated stent-like materials on deposited at 3 g/hr flow rate at 1000 V and 1500 V 316 L SS revealed a reduction in HCASMC cells adhering and proliferating across the organosilicon polymer-like coating (3 cells/mm<sup>2</sup> after 2 days and 7 cells/mm2 after 7 days in comparison to uncoated 316 L SS foil (10 cells/mm<sup>2</sup> after 2 days and 18 cells/mm<sup>2</sup> after 7 days).</p>



Anti-biofouling, Pulsed-DC, Plasma enhanced chemical vapor deposition


Ellis-Terrell, C. A. (2020). <i>Design and application of anti-biofouling coatings on stainless steel by plasma enhanced chemical vapor deposition</i> (Unpublished dissertation). Texas State University, San Marcos, Texas.


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