Probing polydopamine adhesion to protein and polymer films: microscopic and spectroscopic evaluation

Polydopamine has been found to be a biocompatible polymer capable of supporting cell growth and attachment, and to have antibacterial and antifouling properties. Together with its ease of manufacture and application, it ought to make an ideal biomaterial and function well as a coating for implants. In this paper, atomic force microscopy was used to measure the adhesive forces between polymer-, protein- or polydopamine-coated surfaces and a silicon nitride or polydopamine-functionalised probes. Surfaces were further characterised by contact angle goniometry, and solutions by circular dichroism. Polydopamine was further characterised with infrared spectroscopy and Raman spectroscopy. It was found that polydopamine functionalisation of the atomic force microscope probe significantly reduced adhesion to all tested surfaces. For example, adhesion to mica fell from 0.27 ± 0.7 nN nm-1 to 0.05 ± 0.01 nN nm-1. The results suggest that polydopamine coatings are suitable to be used for a variety of biomedical applications

Non-thermal plasma jet-assisted development of phosphorus-containing functional coatings on 3D-printed PCL scaffolds intended for bone tissue engineering

The goal of this study was the exclusive deposition of phosphorus-containing coatings via the non-thermal plasma polymerization of triisopropyl phosphate (TIPP) on 3D-printed poly-e-caprolactone (PCL) scaffolds intended for bone tissue engineering. Given the difficulty of implementing a homogeneous surface treatment throughout porous scaffolds, a novel and appropriate atmospheric pressure plasma jet was used. In-situ analysis of the reactive species involved in the polymerization process using optical emission spectroscopy (OES) revealed the presence of P(II) and P(I) ions, CH, C2, O and CO species. X-ray photoelectron spectroscopy (XPS) was carried out at pre-determined locations on the top and throughout the cross-section of the scaffolds, which showed the uniform incorporation of O- and P-containing groups on the whole construct. This resulted in enhanced surface wettability and slightly enhanced surface roughness as perceived by water contact angle (WCA), field emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM) measurements. The in vivo ability of the scaffolds to promote apatite growth was evaluated via their biomimetic immersion in simulated body fluid (SBF). Interestingly, apatite deposits were successfully formed on the surface of the P-rich coating covering the scaffolds. Overall, one can conclude that this novel plasma-assisted deposition of homogeneous P-containing coatings on complex porous 3D structures enhances their osteo-bioactivity and thus, supporting bone tissue regeneration

Physicochemical surface analysis and germination at different irrigation conditions of DBD plasma‐treated wheat seeds

Plasma treatment is increasingly being explored as an effective presowing treatment improving seed germination. This study examines the synergetic effect of the irrigation condition and the physicochemical surface properties of wheat seeds subjected to atmospheric dielectric barrier discharge plasma activation on their water uptake and germination. Extensive surface analysis revealed a remarkably enhanced wettability of plasma‐treated seeds due to the insertion of oxygen‐containing functionalities on their surface. However, long plasma exposures damaged the outermost layers of the pericarp due to a pronounced oxidative etching effect. Although the seed germination capacity was not affected by the plasma treatments, short plasma exposures were shown to enhance water uptake and accelerate seed germination, especially under water‐scarcity conditions.The authors would like to thank the contribution of the scanning electron microscopy service of the Institute of Marine Sciences (ICM‐CSIC). The authors also thank EU‐FEDER funds and the MINECO (projects MAT2016–79866‐R, MINECO‐CSIC 201860E050) and Junta de Andalucía (project P12–2265 MO). Rouba Ghobeira would also like to thank the Research Foundation Flanders (FWO‐grant number 12ZC720N) for financing her post‐doctoral position.Peer reviewe

Dye wastewater degradation by the synergetic effect of an atmospheric pressure plasma treatment and the photocatalytic activity of plasma-functionalized Cu-TiO2 nanoparticles

In this paper, the photocatalytic activity of plasma-functionalized Cu-doped TiO2 nanoparticles (NPs) and the oxidization process of atmospheric pressure plasma jet were combined for the degradation of reactive red-198 (RR-198) in aqueous solution. The first part of the study was thus devoted to subject Cu-TiO2 NPs synthetized by the sol-gel method to various plasma treatments operating in air, argon, oxygen and nitrogen to improve their degradation efficiency. The physicochemical properties of the NPs were then assessed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) measurements. XRD results indicated the predominant presence of the anatase phase which is the most photoactive form of TiO2. The XPS analysis revealed that the different plasma treatments triggered the formation of oxygen vacancies, Ti3+ oxidation state and Cu2+ oxidation state on the surface of Cu-TiO2 NPs. These changes, known to prevent the recombination of electron-hole pair, have led to a reduction in the bandgap that was more pronounced for the N-2 plasma-treated NPs. The second part of the paper explored the actual degradation of RR-198 in aqueous solution by an Ar plasma treatment alone or combined with the plasma pre-treated Cu-TiO2 NPs. Optical emission spectroscopy (OES) and spectrophotometric analyses showed that the synergetic effect of Ar plasma and N-2 plasma-treated NPs produced the highest concentration of OH center dot radicals and H2O2 species which led to the highest RR-198 degradation efficiency. This was further confirmed by pH, electrical conductivity and total organic carbon (TOC) removal measurements. The degradation of RR-198 was determined using UV-Vis spectroscopy and high-performance liquid chromatography (HPLC). Overall, it can be concluded that plasma-assisted processes illustrated by a combination of a direct plasma treatment with plasma-functionalized Cu-TiO2 NPs can be used in various textile and pharmaceutical industries as a highly effective treatment of their effluents before discharging

Physicochemical surface analysis and germination at different irrigation conditions of DBD plasma‐treated wheat seeds

Plasma treatment is increasingly being explored as an effective presowing treatment improving seed germination. This study examines the synergetic effect of the irrigation condition and the physicochemical surface properties of wheat seeds subjected to atmospheric dielectric barrier discharge plasma activation on their water uptake and germination. Extensive surface analysis revealed a remarkably enhanced wettability of plasma‐treated seeds due to the insertion of oxygen‐containing functionalities on their surface. However, long plasma exposures damaged the outermost layers of the pericarp due to a pronounced oxidative etching effect. Although the seed germination capacity was not affected by the plasma treatments, short plasma exposures were shown to enhance water uptake and accelerate seed germination, especially under water‐scarcity conditions.The authors would like to thank the contribution of the scanning electron microscopy service of the Institute of Marine Sciences (ICM‐CSIC). The authors also thank EU‐FEDER funds and the MINECO (projects MAT2016–79866‐R, MINECO‐CSIC 201860E050) and Junta de Andalucía (project P12–2265 MO). Rouba Ghobeira would also like to thank the Research Foundation Flanders (FWO‐grant number 12ZC720N) for financing her post‐doctoral position.Peer reviewe