Sandra Cabanas-Polo

Electrophoretic deposition of nanostructured-TiO2/chitosan composite coatings on stainless steel

Novel chitosan composite coatings containing titania nanoparticles (n-TiO2) for biomedical applications were developed by electrophoretic deposition (EPD) from ethanol–water suspensions. The optimal ethanol–water ratio was studied in order to avoid bubble formation during the EPD process and to ensure homogeneous coatings. Different n-TiO2 contents (0.5–10 g L−1) were studied for a fixed chitosan concentration (0.5 g L−1) and the properties of the electrophoretic coatings obtained were characterized. Coating composition was analyzed by thermogravimetric analysis (TG), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analysis. Scanning electron microscopy (SEM) was employed to study both the surface and the cross section morphology of the coatings, and the thicknesses (2–6 μm) of the obtained coatings were correlated with the initial ceramic content. Contact angle measurements, as a preliminary study to predict hypothetic protein attachment on the coatings, were performed for different samples and the influence of a second chitosan layer on top of the coatings was also tested. Finally, the electrochemical behavior of the coatings, evaluated by polarization curves in DMEM at 37 °C, was studied in order to assess the corrosion resistance provided by the n-TiO2/chitosan coatings.

Electrophoretic co-deposition of polyvinyl alcohol (PVA) reinforced alginate–Bioglass® composite coating on stainless steel: Mechanical properties and in-vitro bioactivity assessment

PVA reinforced alginate-bioactive glass (BG) composite coatings were produced on stainless steel by a single step electrophoretic deposition (EPD) process. The present paper discusses the co-deposition mechanism of the three components and presents a summary of the relevant properties of the composite coatings deposited from suspensions with different PVA concentrations. Homogeneous composite coatings with compact microstructure and increased thickness, i.e. as high as 10 μm, were observed by scanning electron microscopy (SEM). The surface roughness of coatings with different PVA contents was slightly increased, while a significant increase of water contact angles due to PVA addition was detected and discussed. Improved adhesion strength of coatings containing different amounts of PVA was quantitatively and qualitatively confirmed by pull-off adhesion and cycled bending tests, respectively. In-vitro bioactivity tests were performed in simulated body fluid (SBF) for 0.5, 1, 2, 4, 7, and 14 days, respectively. The decomposition rate of the coatings was reduced with PVA content, and rapid hydroxyapatite forming ability of the composite coatings in SBF was confirmed by FTIR and XRD analyses. According to the results of this study, composite alginate-Bioglass® bioactive coatings combined with PVA are proposed as promising candidates for dental and orthopedic applications.

Electrophoretic Deposition of Chitosan/h-BN and Chitosan/h-BN/TiO2 Composite Coatings on Stainless Steel (316L) Substrates

This article presents the results of an experimental investigation designed to deposit chitosan/hexagonal boron nitride (h-BN) and chitosan/h-BN/titania (TiO2) composites on SS316L substrates using electrophoretic deposition (EPD) for potential antibacterial applications. The influence of EPD parameters (voltage and deposition time) and relative concentrations of chitosan, h-BN and TiO2 in suspension on deposition yield was studied. The composition and structure of deposited coatings were investigated by FTIR, XRD and SEM. It was observed that h-BN and TiO2 particles were dispersed in the chitosan matrix through simultaneous deposition. The adhesion between the electrophoretic coatings and the stainless steel substrates was tested by using tape test technique, and the results showed that the adhesion strength corresponded to 3B and 4B classes. Corrosion resistance was evaluated by electrochemical polarization curves, indicating enhanced corrosion resistance of the chitosan/h-BN/TiO2 and chitosan/h-BN coatings compared to the bare stainless steel substrate. In order to investigate the in-vitro inorganic bioactivity, coatings were immersed in simulated body fluid (SBF) for 28 days. FTIR and XRD results showed no formation of hydroxyapatite on the surface of chitosan/h-BN/TiO2 and chitosan/h-BN coatings, which are therefore non bioactive but potentially useful as antibacterial coatings.

Electrophoretic deposition of nanostructured TiO2/alginate and TiO2-bioactive glass/alginate composite coatings on stainless steel

Abstract Two alginate (Alg) based composite coatings on stainless steel AISI 316L substrates, one containing titania nanoparticles (n-TiO2) and another one a mixture (50/50 wt-%) of n-TiO2 and bioactive glass (BG), intended for biomedical applications, were developed by electrophoretic deposition (EPD) from ethanol/water suspensions. Different n-TiO2 (2–10 g L−1) and BG (1–5 g L−1) contents were studied for a fixed alginate concentration (2 g L−1), and the properties of the electrophoretically obtained coatings were characterised. Coatings with high ceramic content (up to 67 vol.-%) were obtained. The presence of BG particles improves the mechanical properties of the coatings by increasing the adhesion to the substrate and also accelerates the formation of hydroxyapatite after immersion of the coatings in simulated body fluid. The electrochemical behaviour of the coated substrates, evaluated by polarisation curves in Dulbecco’s modified eagle medium at 37°C, confirmed the corrosion protection function of the novel EPD coatings. The present polymer–ceramic composite coatings belong to an emerging family of bioactive, compliant coatings that are promising for a range of biomedical applications.

Electrophoretic deposition of ZnO/alginate and ZnO-bioactive glass/alginate composite coatings for antimicrobial applications

Two organic/inorganic composite coatings based on alginate, as organic matrix, and zinc oxide nanoparticles (n-ZnO) with and without bioactive glass (BG), as inorganic components, intended for biomedical applications, were developed by electrophoretic deposition (EPD). Different n-ZnO (1-10 g/L) and BG (1-1.5 g/L) contents were studied for a fixed alginate concentration (2 g/L). The presence of n-ZnO was confirmed to impart antibacterial properties to the coatings against gram-negative bacteria Escherichia coli, while the BG induced the formation of hydroxyapatite on coating surfaces thereby imparting bioactivity, making the coating suitable for bone replacement applications. Coating composition was analyzed by thermogravimetric analysis (TG), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDS) analyses. Scanning electron microscopy (SEM) was employed to study both the surface and the cross section morphology of the coatings. Polarization curves of the coated substrates made in cell culture media at 37 °C confirmed the corrosion protection function of the novel organic/inorganic composite coatings.

Electrophoretic deposition of antibiotic loaded PHBV microsphere-alginate composite coating with controlled delivery potential

Electrophoretic deposition (EPD) technique has been developed for the fabrication of antibiotic-loaded PHBV microsphere (MS)-alginate antibacterial coatings. The composite coatings deposited from suspensions with different MS concentrations were produced in order to demonstrate the versatility of the proposed method for achieving functional coatings with tailored drug loading and release profiles. Linearly increased deposit mass with increasing MS concentrations was obtained, and MS were found to be homogeneously stabilized in the alginate matrix. Chemical composition, surface roughness and wettability of the deposited coatings were measured by Fourier transform infrared (FTIR) spectroscopy, laser profilometer and water contact angle instruments, respectively. The co-deposition mechanism was described by two separate processes according to the results of relevant measurements: (i) the deposition of alginate-adsorbed MS and (ii) the non-adsorbed alginate. Qualitative antibacterial tests indicated that MS containing coatings exhibit excellent inhibition effects against E. coli (gram-negative bacteria) after 1h of incubation. The proposed coating system combined with the simplicity of the EPD technique can be considered a promising surface modification approach for the controlled in situ delivery of drug or other biomolecules.

Development and Characterization of PEEK/B2O3-Doped 45S5 Bioactive Glass Composite Coatings Obtained by Electrophoretic Deposition

Three different glasses were synthesized by doping 45S5 bioactive glass with B2O3. The bioactivity of the glasses was evaluated by immersion in simulated body fluid (SBF) up to 3 days; all glasses showed the precipitation of hydroxyapatite (HAp) after one day of soaking in SBF. Electrophoretic deposition (EPD) was used to prepare PEEK/B2O3-doped 45S5 glass composite coatings on stainless steel substrates. The coatings were characterized by means of tape test (ASTM D3359-B), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), contact angle measurements, thermogravimetric analysis and in vitro bioactivity test. All composite coatings exhibited a porous and homogenous structure with a hydrophobic surface, according to the wettability test. The in vitro test in SBF demonstrated that the coatings were highly bioactive.

Electrophoretic Deposition of Nanostructured Titania-Bioactive Glass/Alginate Coatings on Stainless Steel

An alginate (Alg) based coating containing nanoparticles of titania (nTiO2) and bioactive glass 45S5 (nBG) was deposited on stainless steel substrates by electrophoretic deposition (EPD). The composite nTiO2-nBG/Alg coating developed for potential biomedical applications, was produced from a stable ethanol/water suspension (ζ–potential of-53±13mV) using 7V of deposition potential and 1min of deposition time as optimal conditions. Morphology and composition of the coatings were studied by FTIR, EDX, SEM and XRD, showing that all components were successfully deposited on the final coating. According to TG analysis the coatings presents a 62.4wt% of ceramic phase and 37.6wt% polymer. The coating shows corrosion protection properties compared with the bare uncoated material when analyzed via polarization curves in Dulbecco ́s MEM.

Understanding the Colloidal Behaviour or 45S5 Bioactive Glass Particles to Obtain Bioactive-Glass Based Composite Coatings by EPD

The interaction between bioactive glass particles and polymers with different functional groups has been established in this work to better understand and control the colloidal processing of the bioactive glass phase. Cationic polyvinylpyrrolidone (PVP), anionic polyacrylic acid (PAA) and neutral polyvinyl alcohol (PVA) were selected and the surface reactions in alcoholic media and between bioactive glass particles and polymers were considered. All three polymers were successfully employed to obtain soft composite coatings incorporating bioactive glass particles.

Bioactive Glass-Biopolymer Multilayer Coatings Fabricated by Electrophoretic Deposition Combined with Layer-by-Layer Assembly

45S5 bioactive glass (BG) based multilayer coatings on stainless steel were produced by a combination of electrophoretic deposition (EPD) and layer-by-layer (LbL) deposition. The properties of the multilayer coating were tested with different characterization methods including SEM, FTIR, XRD, laser profilometer and water contact angle measurements. Degradation and in-vitro bioactivity behaviors were tested in simulated body fluid (SBF) over different time periods. The decomposition of the coating was inhibited and the hydroxyapatite (HA) formation after short immersion period (0.5d) was confirmed. At the same time, levofloxacin, used as a model antibiotic, was incorporated into the multilayer structure for antibacterial purpose.