Nanostructure protein repellant amphiphilic copolymer coatings with optimized surface energy by Inductively Excited Low Pressure Plasma.

Statistically designed amphiphilic copolymer coatings were deposited onto Thermanox, Si wafer, and quartz crystal microbalance (QCM) substrates via Plasma Enhanced Chemical Vapor Deposition of 1H,1H,2H,2H-perfluorodecyl acrylate and diethylene glycol vinyl ether in an Inductively Excited Low Pressure Plasma reactor. Plasma deposited amphiphilic coatings were characterized by Field Emission Scanning Electron Microscopy, X-ray Photoelectron Spectroscopy, Atomic Force Microscopy, and Water Contact Angle techniques. The surface energy of the coatings can be adjusted between 12 and 70 mJ/m(2). The roughness of the coatings can be tailored depending on the plasma mode used. A very smooth coating was deposited with a CW (continuous wave) power, whereas a rougher surface with R(a) in the range of 2 to 12 nm was deposited with the PW (pulsed wave) mode. The nanometer scale roughness of amphiphilic PFDA-co-DEGVE coatings was found to be in the range of the size of the two proteins namely BSA and lysozyme used to examine for the antifouling properties of the surfaces. The results show that the statistically designed surfaces, presenting a surface energy around 25 mJ/m(2), present no adhesion with respect to both proteins measured by QCM.

Optimization of a low pressure plasma process for fabrication of a Drug Delivery System (DDS) for cancer treatment.

A low pressure ICP plasma setup was utilized to deposit thin organic barrier coatings on various substrates to fabricate DDS with encapsulated Carboplatin as a drug and Methylene Blue as a drug model. Choice of the substrates and optimal plasma parameters were discussed for the fabrication of DDS with required characteristics. Prepared thin films were analysed by FTIR, SEM, and the barrier properties were studied by measuring drug concentration released into the medium by UV-VIS and ICP-MS techniques.

Radio-frequency plasma polymerized biodegradable carrier for in vivo release of cis-platinum.

A low pressure plasma process based on plasma deposition has been used to develop a drug delivery strategy. In this study, a drug delivery system based on different layers of plasma co-polymerized Poly ε-caprolactone-Polyethylene glycol (PCL-PEG) co-polymers was deposited on biocompatible substrates. Cis-platinum (118 µgm/cm2) was used as an anti-cancer drug and incorporated for local delivery of the chemotherapeutic agent. The co-polymer layers and their interaction with cancer cells were analyzed by scanning electron microscopy. Our study showed that the plasma-PCL-PEG coated cellophane membranes, in which the drug, was included did not modify the flexibility and appearance of the membranes. This system was actively investigated as an alternative method of controlling localized delivery of drug in vivo. The loading of the anti-cancer drug was investigated by UV-VIS spectroscopy and its release from plasma deposited implants against BALB/c mice liver tissues were analyzed through histological examination and apoptosis by TUNEL assay. The histological examination of liver tissues revealed that when the plasma-modified membranes encapsulated the cis-platinum, the Glisson's capsule and liver parenchyma were damaged. In all cases, inflammatory tissues and fibrosis cells were observed in contact zones between the implant and the liver parenchyma. In conclusion, low pressure plasma deposited uniform nano-layers of the co-polymers can be used for controlled release of the drug in vivo.

Plasma functionalized carbon electrode for laccase-catalyzed oxygen reduction by direct electron transfer.

For the first time, a fast and versatile technique, an atmospheric pressure plasma jet (APPJ), has been used to functionalise graphite carbon electrodes for biofuel cell applications. The bioelectrode was functionalized by an atmospheric pressure plasma jet (APPJ) system using air, oxygen (O2) and nitrogen (N2) plasmas applied for only a few seconds. XPS analysis showed that carboxylic groups were created on the carbon substrates using both air and O2 plasmas, while mainly carbonyl and amine/amide functionalities were generated using N2 plasmas. A purified laccase from Trametes versicolor was both adsorbed and covalently bound (NHS/EDC method) to the plasma modified carbon. Higher laccase activity was obtained for the covalently grafted laccase compared to the physically adsorbed one: 13.2 (±2) 10(-3)U of laccase on air treated graphite and two-fold less (5.3 (±1.1) 10(-3)U) were obtained on N2 plasma treated surfaces (1mM ABTS as a substrate, 30°C, pH=3.0), one unit (U) being the quantity of ABTS (µmole) oxidized by laccase per minute. Dioxygen reduction was performed by direct electron transfer (DET). The highest current density, 108µA/cm(2) (at 0.2V (vs. SCE), pH 4.2, room temperature), was recorded for covalently immobilized laccase on N2 plasma treated surfaces (geometric surface=0.38cm(2)). This could be explained by the fact that the highly conductive graphite structure was retained in the case of this surface treatment and could also suggest a preferential orientation of the T1 Cu center of the laccase toward the surface of the N2 plasma treated electrode.

Development of silver nanoparticle loaded antibacterial polymer mesh using plasma polymerization process.

Plasma polymerized polyacrylic acid (PPAA) was deposited on a polymer substrate, namely polyethylene terephthalate (PET) mesh, for entrapment of silver nanoparticle (Ag-NP) in order to achieve antibacterial property to the material. Carboxylic groups of PPAA act as anchor as well as capping and stabilizing agents for Ag-NPs synthesized by chemical reduction method using NaBH(4) as a reducing agent. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy (XPS), and water contact angle analysis were used to characterize the PPAA coatings. The Ag-NPs loaded polymer samples were characterized by UV-visible spectroscopy, field emission scanning electron microscopy, energy dispersive X-ray, and XPS techniques. XPS analysis showed ~1.0 at.% loading of Ag-NPs on to the PPAA-PET-mesh, which was composed of 79% zero-valent (Ag°) and 21% oxidized nano-Ag (Ag(+) ). The plasma processed PET meshes samples were tested for antibacterial activity against two bacterial strains, namely Staphylococcus aureus (Gram positive) and Escherichia coli (Gram negative). Qualitative and quantitative tests showed that silver containing PPAA-PET meshes exhibit excellent antibacterial property against the tested bacteria with percent reduction of bacterial concentration >99%, compared to the untreated PET mesh.

Catalyst-Free Plasma-Assisted Copolymerization of Poly(ε-caprolactone)-poly(ethylene glycol) for Biomedical Applications.

Catalyst-free ring-opening polymerization (ROP) strategy was developed to overcome the disadvantage of incomplete and expensive removal of catalyst used during the multistep wet chemical processes. Nano-sized biocompatible and low molecular weight poly(ε-carolactone)-poly(ethylene glycol) (PCL-PEG) copolymer coatings were deposited via a single-step, low-pressure, pulsed-plasma polymerization process. Experiments were performed at different monomer feed ratio and effective plasma power. The coatings were analyzed by XPS, as well as MALDI ToF. Ellipsometric measurement showed deposition rates ranging from 1.3 to 3 nm/min, depending on the ratio of the PCL/PEG precursors introduced in the reactor. Our results have demonstrated that plasma copolymerized PCL-PEG coatings can be tailored in such a way to be cell adherent, convenient for biomedical implants such as artificial skin substrates, or cell repellent, which can be used as antibiofouling surfaces for urethral catheters, cardiac stents, and so on. The global objective of this study is to tailor the surface properties of PCL by copolymerizing it with PEG in the pulsed plasma environment to improve their applicability in tissue engineering and biomedical science.