Synthesis of antibacterial composite coating containing nanocapsules in an atmospheric pressure plasma.

Antibacterial coating is an important strategy preventing bacterial colonization and biofilm formation. One-step synthesis of nanocapsule-containing antibacterial coatings with controlled release of Ag+ ions was achieved in the current work by aerosol-assisted atmospheric pressure plasma deposition. The experimental parameters of deposition including the discharge power, silver nitrate concentration, aerosol flow rate, continuous and pulsed mode of operation were studied in order to analyze their effects on surface morphology and chemical composition of the coating. Formation of nanocapsules embedded in the polymeric coating was observed. A core-shell structure was found for nanocapsule with silver in the core and polymer in the shell. Antibacterial coatings on polyethylene terephthalate film were studied in terms of Ag+ ion release, antibacterial properties against Escherichia coli and Staphylococcus aureus, and cytotoxicity with murine fibroblasts. Two-phase release kinetics of Ag+ ions was observed as initially a short-term burst release followed by a long-term slow release. It was revealed that high antibacterial efficiency of the coatings deposited on polyethylene terephthalate films can be coupled with low cytotoxicity. These biocompatible antibacterial coatings are very promising in different fields including biological applications.

Effect of Dispersion Solvent on the Deposition of PVP-Silver Nanoparticles onto DBD PlasmaTreated Polyamide 6,6 Fabric and Its Antimicrobial Efficiency.

Polyvinylpyrrolidone-coated silver nanoparticles (PVP-AgNPs) dispersed in ethanol, water and water/alginate were used to functionalize untreated and dielectric barrier discharge (DBD) plasma-treated polyamide 6,6 fabric (PA66). The PVP-AgNPs dispersions were deposited onto PA66 by spray and exhaustion methods. The exhaustion method showed a higher amount of deposited AgNPs. Water and water-alginate dispersions presented similar results. Ethanol amphiphilic character showed more affinity to AgNPs and PA66 fabric, allowing better uniform surface distribution of nanoparticles. Antimicrobial effect in E. coli showed good results in all the samples obtained by exhaustion method but using spray method only the DBD plasma treated samples displayed antimicrobial activity (log reduction of 5). Despite the better distribution achieved using ethanol as a solvent, water dispersion samples with DBD plasma treatment displayed better antimicrobial activity against S. aureus bacteria in both exhaustion (log reduction of 1.9) and spray (methods log reduction of 1.6) due to the different oxidation states of PA66 surface interacting with PVP-AgNPs, as demonstrated by X-Ray Photoelectron Spectroscopy (XPS) analysis. Spray method using the water-suspended PVP-AgNPs onto DBD plasma-treated samples is much faster, less agglomerating and uses 10 times less PVP-AgNPs dispersion than the exhaustion method to obtain an antimicrobial effect in both S. aureus and E. coli.

Atmospheric Pressure Plasma Deposition of Organosilicon Thin Films by Direct Current and Radio-frequency Plasma Jets.

Thin film deposition with atmospheric pressure plasmas is highly interesting for industrial demands and scientific interests in the field of biomaterials. However, the engineering of high-quality films by high-pressure plasmas with precise control over morphology and surface chemistry still poses a challenge. The two types of atmospheric-pressure plasma depositions of organosilicon films by the direct and indirect injection of hexamethyldisiloxane (HMDSO) precursor into a plasma region were chosen and compared in terms of the films chemical composition and morphology to address this. Although different methods of plasma excitation were used, the deposition of inorganic films with above 98% of SiO2 content was achieved for both cases. The chemical structure of the films was insignificantly dependent on the substrate type. The deposition in the afterglow of the DC discharge resulted in a soft film with high roughness, whereas RF plasma deposition led to a smoother film. In the case of the RF plasma deposition on polymeric materials resulted in films with delamination and cracks formation. Lastly, despite some material limitations, both deposition methods demonstrated significant potential for SiOx thin-films preparation for a variety of bio-related substrates, including glass, ceramics, metals, and polymers.

Chemical profiling of the major components in natural waxes to elucidate their role in liquid oil structuring.

Elucidating the composition of waxes is of utmost importance to explain their behavior in liquid oil structuring. The chemical components (hydrocarbons - HCs, free fatty acids - FFAs, free fatty alcohols - FALs and wax esters - WEs) of natural waxes were analyzed using HPLC-ELSD and GC-MS followed by evaluation of their oil structuring properties. The gel strength, including the average storage modulus and oscillation yield stress, displayed a negative correlation with FALs and a positive correlation with HCs, FFAs and WEs. The components dictating the gel strength are HCs, FFAs and WEs in a descending order of importance. The consistency of the oleogels increased with the increasing amount of FFAs and HCs and the decreasing amount of WEs and FALs. The presence of more WEs results in a strong but brittle gel with a high initial flow yield stress. We believe these results might be useful in selecting the right waxes to combine in certain fat-based food products.

In vitro prediction of human intestinal absorption and blood-brain barrier partitioning: development of a lipid analog for micellar liquid chromatography.

Over the past decades, several in vitro methods have been tested for their ability to predict either human intestinal absorption (HIA) or penetration across the blood-brain barrier (BBB) of drugs. Micellar liquid chromatography (MLC) has been a successful approach for retention time measurements of drugs to establish models together with other molecular descriptors. Thus far, MLC approaches have only made use of commercial surfactants such as sodium dodecyl sulfate (SDS) and polyoxyethylene (23) lauryl ether (Brij35), which are not representative for the phospholipids present in human membranes. Miltefosine, a phosphocholine-based lipid, is presented here as an alternative surfactant for MLC measurements. By using the obtained retention factors and several computed descriptors for a set of 48 compounds, two models were constructed: one for the prediction of HIA and another for the prediction of penetration across the BBB expressed as log BB. All data were correlated to experimental HIA and log BB values, and the performance of the models was evaluated. Log BB prediction performed better than HIA prediction, although HIA prediction was also improved a lot (from 0.5530 to 0.7175) compared to in silico predicted HIA values.

Model-based determination of the influence of textile fabric on bioassay analysis and the effectiveness of a textile slow-release system of DEET in mosquito control.

BACKGROUND: Determining the effectiveness of a product in repelling mosquitoes or other flying insects is a difficult task. One approach is to use a bioassay with textile fabric. We investigated the role of the textile substrate in a bioassay with a numerical model, and compared the outcome with known results for DEET. The model was then used to determine the effectiveness of textile slow-release formulations based on coatings, and results were compared with those of a field study in the Cameroon. Slow-release formulations are difficult to evaluate with standard tests, as the compound needs a build-up time not present in these tests. RESULTS: We found excellent correspondence between the model and the known DEET results without matching parameters. Slow-release approaches are deemed possible but have several drawbacks. Modelling can help in identifying optimal use conditions. The field test with a slow-release system performed better than anticipated by the model, with initially more than 90% repellency. DEET-coated textile was considered not to be marketable, however. CONCLUSION: We advise that bioassays characterise in more detail the type of textile fabric used so as to allow conclusions to be drawn by textile modelling. As regards coated-textile slow-release systems, more research is needed. We nevertheless advise usage mainly at entry points, e.g. as scrims.

Evaluation of sphingomyelin, cholester, and phosphatidylcholine-based immobilized artificial membrane liquid chromatography to predict drug penetration across the blood-brain barrier.

Over the past decades, several in vitro methods have been tested for their ability to predict drug penetration across the blood-brain barrier. So far, in high-performance liquid chromatography, most attention has been paid to micellar liquid chromatography and immobilized artificial membrane (IAM) LC. IAMLC has been described as a viable approach, since the stationary phase emulates the lipid environment of a cell membrane. However, research in IAMLC has almost exclusively been limited to phosphatidylcholine (PC)-based stationary phases, even though PC is only one of the lipids present in cell membranes. In this article, sphingomyelin and cholester stationary phases have been tested for the first time towards their ability to predict drug penetration across the blood-brain barrier. Upon comparison with the PC stationary phase, the sphingomyelin- and cholester-based columns depict similar predictive performance. Combining data from the different stationary phases did not lead to improvements of the models.

Predicting drug penetration across the blood-brain barrier: comparison of micellar liquid chromatography and immobilized artificial membrane liquid chromatography.

Several in vitro methods have been tested for their ability to predict drug penetration across the blood-brain barrier (BBB) into the central nervous system (CNS). In this article, the performance of a variety of micellar liquid chromatographic (MLC) methods and immobilized artificial membrane (IAM) liquid chromatographic approaches were compared for a set of 45 solutes. MLC measurements were performed on a C18 column with sodium dodecyl sulfate (SDS), polyoxyethylene (23) lauryl ether (Brij35), or sodium deoxycholate (SDC) as surfactant in the micellar mobile phase. IAM liquid chromatography measurements were performed with Dulbecco's phosphate-buffered saline (DPBS) and methanol as organic modifier in the mobile phase. The corresponding retention and computed descriptor data for each solute were used for construction of models to predict transport across the blood-brain barrier (log BB). All data were correlated with experimental log BB values and the relative performance of the models was studied. SDS-based models proved most suitable for prediction of log BB values, followed closely by a simplified IAM method, in which it could be observed that extrapolation of retention data to 0% modifier in the mobile phase was unnecessary.

Development of the first sphingomyelin biomimetic stationary phase for immobilized artificial membrane (IAM) chromatography.

A prototype sphingomyelin stationary phase for Immobilized Artificial Membrane (IAM) chromatography was synthesized by an ultra-short, solid-phase inspired methodology, in which an oxidative release monitoring strategy played a vital role. Evaluated in a proof-of-concept model for blood-brain barrier passage, partial least squares regression demonstrated its potential as an in vitro prediction tool.