In this study, trimethylsilane (TMS) plasma nanocoatings were deposited onto 316L

In this study, trimethylsilane (TMS) plasma nanocoatings were deposited onto 316L stainless steel coupons in direct current (DC) and radio frequency (RF) glow discharges and additional NH3/O2 plasma treatment to tailor the coating surface properties. surfaces were substantially increased after NH3/O2 plasma treatment. Contact angle measurements showed that DC TMS nanocoating MGCD0103 inhibitor with NH3/O2 treatment generated very hydrophilic surfaces. DC TMS nanocoatings with NH3/O2 treatment showed minimal surface chemistry change after 12 week immersion in SBF. However, nitrogen functionalities on RF-TMS coating with NH3/O2 post treatment were not as stable as in DC case. Cell culture studies revealed that the surfaces with DC coating and NH3/O2 post treatment demonstrated substantially improved proliferation of endothelial cells over the 12 week storage period at both dry and wet conditions, as compared to other coated surfaces. Therefore, DC nanocoatings with NH3/O2 post treatment may be chemically stable for long-term properties, including shelf-life storage and exposure to the bloodstream for coronary stent applications. and [25, 26]. Unfortunately, clinical evaluations have shown that DLC on vascular stents does not effectively mitigate restenosis [25]. Fluoropolymer-based coatings have also been investigated for restenosis mitigation. Fluoropolymer coatings appear to be highly promising as they were found to substantially reduce smooth muscle cell attachment while also promoting endothelialization [27, 28]. Plasma nanocoatings have attracted interest as a biocompatible material because they can be deposited onto many medical devices or implants, highly conformal and pinhole free [29C31], and have excellent adhesion to their substrates even MGCD0103 inhibitor after exposure to mineral-rich physiological medium [32]. With respect to stenting, plasma nanocoatings impart improved corrosion characteristics of the underlying substrate, potentially minimizing inflammation [33]. From an economic standpoint, plasma processes are inexpensive; and treatment/deposition gases are non-toxic [29, 34]. Furthermore, deposition times can be minimized, especially when the substrate serves as cathode [35]. Cathodic deposition can be easily obtained for electrically conductive substrates, including cardiovascular stents made of metals or alloys. The stability of functionality created on the surface of biomaterials by plasma coating technology is very critical to its successful application for coronary stents. It would need to provide a long-lasting bioactivity on the stent surface. The plasma coating also has to maintain its mechanical integrity since premature delamination or cracking will lessen its benefit. Stability of plasma coatings for biomedical applications has been widely studied through immersing specimens in water or phosphate buffered saline for a certain period of time [36C39]. In this paper, we report on the chemical stability of plasma nanocoatings after prolonged immersion in a simulated body fluid (SBF) at 37 C. The SBF chosen for this study was Dulbeccos phosphate buffered saline (DPBS). Radio frequency (RF) and direct current (DC) glow discharges were used to deposit 20C30 nm coatings on stainless steel coupons. Trimethylsilane (TMS) was utilized as the coating precursor. TMS nanocoatings were subsequently post-treated using NH3/O2 glow discharge plasma. NH3/O2 post treatments may produce chemical functionalities that could inhibit restenosis and platelet aggregation [40]. Surface roughness was determined through optical profilometry. Nanocoating surface chemical composition was assessed after SBF immersion using Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Finally, the biological response of aged coating surfaces was evaluated with 3-day MGCD0103 inhibitor endothelial cell culture test. This study should provide useful information on how the nanocoating composition is potentially affected by the physiological environment. 2. Materials and Methods 2.1. Plasma Nanocoatings Deposited with DC and RF Glow Discharges Anhydrous ammonia (purity 99.99%) was provided by Air Liquide (Plumsteadville, PA). Oxygen (purity 99.6%) was purchased from Airgas (Columbia, MO). TMS (purity 97%) was supplied by Gelest, Inc. (Morrisville, PA). Cleaned 316L stainless steel coupons (1 cm 1 cm 0.1 cm) were utilized for nanocoating deposition, of Foxd1 which surface chemistry and roughness analysis were conducted. DC glow discharges were created inside an 80 liter bell-jar reactor. Stainless steel coupons were attached to an aluminum holder positioned between two titanium electrodes in parallel. The MGCD0103 inhibitor square titanium electrodes had sides of length 18.2 cm. For all DC treatments, the coupon holder acted as the cathode whereas the two outer titanium electrodes served as the electrically grounded anodes. An oxygen plasma was used to remove organic contaminants on the sample surfaces and provide a controllable fresh surface for the subsequent coating deposition. The reactor was sealed and evacuated to a base pressure of 1 1 mTorr using a pump group consisting of mechanical and booster pumps connected in series. Oxygen was then introduced to the reactor at a flow rate of 1 1 sccm (standard cubic centimeters per minute) using an MKS mass flow controller (MKS Instruments, Andover, MA) and an MKS 247C readout to set the flow rate. The pressure inside the plasma reactor was allowed to stabilize at 50 mTorr using an MKS pressure controller. The.

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