Micro-computed tomography (μ-CT) as a potential tool to assess the effect of dynamic coating routes on the formation of biomimetic apatite layers on 3D-plotted biodegradable polymeric scaffolds

This work studies the influence of dynamic biomimetic coating procedures on the growth of bonelike apatite layers at the surface of starch/polycaprolactone (SPCL) scaffolds produced by a 3D-plotting technology. These systems are newly proposed for bone Tissue Engineering applications. After generating stable apatite layers through a sodium silicate-based biomimetic methodology the scaffolds were immersed in Simulated Body Fluid solutions (SBF) under static, agitation and circulating flow perfusion conditions, for different time periods. Besides the typical characterization techniques, Micro-Computed Tomography analysis (μ-CT) was used to assess scaffold porosity and as a new tool for mapping apatite content. 2D histomorphometric analysis was performed and 3D virtual models were created using specific softwares for CT reconstruction. By the proposed biomimetic routes apatite layers were produced covering the interior of the scaffolds, without compromising their overall morphology and interconnectivity. Dynamic conditions allowed for the production of thicker apatite layers as consequence of higher mineralizing rates, when comparing with static conditions. μ-CT analysis clearly demonstrated that flow perfusion was the most effective condition in order to obtain well-defined apatite layers in the inner parts of the scaffolds. Together with SEM, this technique was a useful complementary tool for assessing the apatite content in a non-destructive way

Facile preparation of copper impregnated aluminum pillared montmorillonite: nanoclays for wastewater treatment

Copper impregnated aluminum pillared montmorillonites (Cu-iAlpill-MMTs) were prepared by adding Cu2+ solution into dried aluminum polyohydroxy cation intercalated montmorillonite using various Cu2+ concentrations, i.e. 4, 7, 10 and 13 wt% and then calcining at 500°C. The Cu-iAlpill-MMTs possessed slit-liked mesopores with pore diameters of 3.3–3.8 nm and ~6–35 nm as observed from the nitrogen adsorption isotherms. The mesopore quantities of Cu-iAlpill-MMTs gradually decreased with the increase of impregnated Cu2+ concentrations. The impregnated CuO occupied not only the interior interlayers, but also the exterior surfaces of Cu-iAlpill-MMTs. The Cu-iAlpill-MMTs with 10 and 13 wt% of impregnated Cu2+ could inhibit the growth of Escherichia coli. The Cu-iAlpill-MMTs effectively acted as the heterogeneous catalyst for removal reactive orange 16 (RO16) in Fenton or photo-Fenton oxidation treatments. The higher impregnated Cu2+ and/or the longer treatment time brought about the higher percentage of RO16 removal

Facile synthesis of chitosan/CuO nanocomposites for potential use as biocontrol agents

Chitosan/CuO nanocomposites (Chi/CuO) were prepared by facile and eco-friendly technique. The 2%w/v chitosan solution was mixed with 0.5 %w/w sodium tripolyphosphate (STPP), resulting in the formation of ionically crosslinked chitosan. The crosslinked chitosan was soaked in an aqueous solution containing 0.001, 0.01 or 0.1 mol/L CuSO4·5H2O for 24 hrs, in which the Cu2+ ions were absorbed into the chitosan network, forming as the chitosan/Cu2+ precursors. The chitosan/Cu2+ precursors were hydrothermally reacted in two different basic media, i.e. NaOH and NH4OH, at 100°C for 24 hrs, resulting in the nano-sized CuO crystals hydrothermally grew and embedded in the crosslinked chitosan matrix. The CuO grown in the NaOH possessed larger crystallite size and higher crystallinity than that in the NH4OH. In addition, the CuO crystallite size in the nanocomposites increased with the increase of initial concentration of Cu2+ starting agent due to the increase of Cu2+ quantity in the chitosan/Cu2+ precursors. The chitosan/CuO nanocomposites prepared by using 0.01 and 0.1 mol/L Cu2+ could exhibit the antibacterial activities after intimate contact with Staphylococcus aureus and Escherichia coli under JIS L 1902:1998 (Qualitative) test method, indicating their potential use as biocontrol agents

Chemical and Dielectric Study of PMMA/Montmorionite Nano-Composite Films

International audienceTetrabutylphosphonium intercalated montmorillonite (P-MMT) was dispersed in toluene using sonication technique and a PMMA/toluene solution. The PMMA/P-MMT nano- suspension was then casted as a composite film on a glass plate, using spin coating technique with a rotation of 180 rpm. The composite films were characterized by various analytical techniques such as X-ray diffraction, X-ray fluorescence spectrometry thermo- gravimetric analysis, etc. The montmorillonite interlayer distance, estimated XRD results, was found to be equal to 1.6 nm. The PMMA/3 wt%P-MMT nano-composite film was found to completely decomposed at the temperature Td (PMMA/3 wt%P-MMT) = 370◦C which is slightly higher than that of the neat PMMA, i.e. 365◦C. It was also found that both plots of ε_r and ε__r versus frequency display equivalent behaviour. The optical absorption spectra show a rather large domain of transparency between 300 and 2700 nm, with a rather structured absorption band between 1700 and 2700 nm. Dielectric constant ranges near 1 to 3, depending on the frequency. This is very important for some electronic application, as underlined by former Authors