102 research outputs found

    Functionalization of the Implant Surface Made of NiTi Shape Memory Alloy

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    To functionalize and improve the biocompatibility of the surface of a medical implant made of NiTi shape memory alloy and used in practice, a clamp, multifunctional layers composed of amorphous TiO2 interlayer, and a hydroxyapatite coating were produced. Electrophoresis, as an efficient method of surface modification, resulted in the formation of a uniform coating under a voltage of 60 V and deposition time of 30 s over the entire volume of the implant. The applied heat treatment (800 ┬░C/2 h) let toa dense, crack-free, well-adhered HAp coating with a thickness of ca. 1.5 ╬╝m. and a high crack resistance to deformation associated with the induction of the shape memory effect in the in the deformation range similar to the real implant work after implantation. Moreover, the obtained coating featured a hydrophilic (CA = 59.4 ┬▒ 0.3┬░) and high biocompatibility

    Spatial consistency of cell growth direction during organ morphogenesis requires CELLULOSE SYNTHASE INTERACTIVE1

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    International audienceExtracellular matrices contain fibril-like polymers often organized in parallel arrays. Although their role in morphogenesis has been long recognized, it remains unclear how the subcellular control of fibril synthesis translates into organ shape. We address this question using the Arabidopsis sepal as a model organ. In plants, cell growth is restrained by the cell wall (extracellular matrix). Cellulose microfibrils are the main load-bearing wall component, thought to channel growth perpendicularly to their main orientation. Given the key function of CELLULOSE SYNTHASE INTERACTIVE1 (CSI1) in guidance of cellulose synthesis, we investigate the role of CSI1 in sepal morphogenesis. We observe that sepals from csi1 mutants are shorter, although their newest cellulose microfibrils are more aligned compared to wild-type. Surprisingly, cell growth anisotropy is similar in csi1 and wild-type plants. We resolve this apparent paradox by showing that CSI1 is required for spatial consistency of growth direction across the sepal

    Effects of TiO2, Ag-TiO2, and Cu-TiO2 nanoparticles on mechanical and anticariogenic properties of conventional pit and fissure sealants

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    The objective of this study was to determine the effects of TiO2, Ag-TiO2, and Cu-TiO2 nanoparticles (NPs) addition on the mechanical and antibacterial properties of resin-based sealants. TiO2, Ag-TiO2, and Cu-TiO2 NPs were characterized with FTIR, Raman, SEM-EDX, TEM, XPS, and XRD, and evaluated for cytotoxicity study. After characterization, the nanoparticles were mixed with commercial pit and fissure sealants (PAFS) in ratios of 1 and 2%. A total of 7 groups were made, control group (PAFS only) and experimental groups (1%-2% TiO2, 1%-2% Ag-TiO2, and 1%-2% Cu-TiO2). ISO standards were adopted to prepare samples for mechanical properties, i.e., compressive strength (CS), flexural strength (FS), and Vickers hardness evaluation. Samples were tested against Streptococcus mutans through an agar well diffusion test. The CS, FS, and Vickers hardness were increased for the Cu-TiO2 group with respect to Ag-TiO2 but values were less compared to TiO2 groups. The highest flow rate was measured in the control group which was 8.16┬▒0.06┬ámm and 9.17┬▒0.1┬ámm after 3 and 10 mins respectively. In the agar well diffusion test, the control group showed no zone of inhibition, and the lowest zone of bacterial inhibition was found in PAFS with 1% TiO2 NPs group (13.3┬á┬▒┬á1.5┬ámm) while the highest was found in PAFS with 2% Ag-TiO2 NPs (21.8┬á┬▒┬á1.7┬ámm). Cu-doped TiO2 NPs showed more biocompatibility as compared to Ag-doped TiO2. The outcomes were statistically significant for all the mechanical tests and agar well diffusion antibacterial test as the p-value ÔëĄ0.05 while for the cytotoxicity test, the p-value >0.05. The TiO2 addition generally improved both the mechanical and antibacterial properties of pit and fissure sealant

    Microwave Irradiation vs. Structural, Physicochemical, and Biological Features of Porous Environmentally Active SilverÔÇôSilica Nanocomposites

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    Heavy metals and other organic pollutants burden the environment, and their removal or neutralization is still inadequate. The great potential for development in this area includes porous, spherical silica nanostructures with a well-developed active surface and open porosity. In this context, we modified the surface of silica spheres using a microwave field (variable power and exposure time) to increase the metal uptake potential and build stable bioactive Ag2O/Ag2CO3 heterojunctions. The results showed that the power of the microwave field (P = 150 or 700 W) had a more negligible effect on carrier modification than time (t = 60 or 150 s). The surface-activated and silver-loaded silica carrier features like morphology, structure, and chemical composition correlate with microbial and antioxidant enzyme activity. We demonstrated that the increased sphericity of silver nanoparticles enormously increased toxicity against E. coli, B. cereus, and S. epidermidis. Furthermore, such structures negatively affected the antioxidant defense system of E. coli, B. cereus, and S. epidermidis through the induction of oxidative stress, leading to cell death. The most robust effects were found for nanocomposites in which the carrier was treated for an extended period in a microwave field

    A multi-analytical approach for the analysis of cation distribution in a aluminoceladonite structure

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    In this paper cation arrangement in two samples of aluminoceladonite, emerald green and dark-green were studied by M├Âssbauer, Raman and X-ray photoelectron spectroscopies. The X-ray photoelectron spectroscopy (XPS) spectra obtained in the region of the Si2p, Al2p, Fe2p, K2p, and O1s core levels provided information, for the first time highlighting a route to identify the position of Si, Al, K, and Fe cations in a structure of layered silicates. The XPS analysis showed the presence of Al in tetrahedral and octahedral coordination while the K2p line indicated the possibility of K+ substitution by other cations in interlayer sites. M├Âssbauer spectroscopy provided information about crystal chemistry with respect to the local electronic and geometric environment around the Fe atom and to distortions of the polyhedra. It turned out that iron was located mostly in the cis-octahedra position wherein about 75% of iron appeared in the form of Fe3+. The most preferred cation combinations around Fe corresponded to 3Fe3+ ions and MgFe2+Fe3+/2MgFe3+. Raman spectroscopy illustrated aluminium substitution in silicon and iron positions wherein the concentration of the aluminium determined the degree of structural distortion within the layered system. These isomorphic substitutions implied a typical band arrangement in the hydroxyl region, which has not been observed in celadonites so far

    Effect of the Indentation Load on the Raman Spectra of the InP Crystal

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    Nanoindentations and the Raman spectroscopy measurements were carried out on the (001) surface of undoped and S-doped InP crystal. The samples were indented with the maximum load ranging from 15 mN to 100 mN. The phase transition B3!B1 was not confirmed by spectroscopic experiments, indicating a plastic deformation mechanism governed by dislocations activity. Increasing the maximum indentation load shifts and the longitudinal and transverse optical Raman bands to lower frequencies reveals a reduction in the elastic energy stored in the plastic zone right below the indentation imprint. Mechanical experiments have shown that a shift in Raman bands occurs alongside the indentation size effect. Indeed, the hardness of undoped and S-doped InP crystal decreases as a function of the maximum indentation load

    Synthesis and applications of [60]fullerene nanoconjugate with 5- aminolevulinic acid and its glycoconjugate as drug delivery vehicles

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    The 5-aminolevulinic acid (5-ALA) prodrug is widely used in clinical applications, primarily for skin cancer treatments and to visualize brain tumors in neurosurgery. Unfortunately, its applications are limited by unfavorable pharmacological properties, especially low lipophilicity; therefore, efficient nanovehicles are needed. For this purpose, we synthesized and characterized two novel water-soluble fullerene nanomaterials containing 5-ALA and D-glucuronic acid components. Their physicochemical properties were investigated using NMR, XPS, ESI mass spectrometry, as well as TEM and SEM techniques. In addition, HPLC and fluorescence measurements were performed to evaluate the biological activity of the fullerene nanomaterials in 5-ALA delivery and photodynamic therapy (PDT); additional detection of selected mRNA targets was carried out using the qRT-PCR methodology. The cellular response to the [60]fullerene conjugates resulted in increased levels of ABCG2 and PEPT-1 genes, as determined by qRT-PCR analysis. Therefore, we designed a combination PDT approach based on two fullerene materials, C60-ALA and C60-ALA-GA, along with the ABCG2 inhibitor Ko143

    Glass Transition Dynamics of Poly(phenylmethylsiloxane) Confined within Alumina Nanopores with Different Atomic Layer Deposition (ALD) Coatings

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    Dielectric spectroscopy (DS) and differential scanning calorimetry (DSC) were employed to study the effect of changes in the surface conditions on the segmental dynamics of poly(phenylmethylsiloxane) confined in alumina nanopores (AAO). The inner surface of the pores was modified by using the atomic layer deposition technique. Coated membranes include 5 nm thick layers of hafnium oxide, titanium oxide, and silicon oxide, exhibiting different wetting properties. Modification of the surface conditions dramatically affects the interfacial interactions between the polymer and confining surface. The interfacial energy calculations indicate a decrease of ╬│SL value from 18.7 mN/m in SiO2-coated to 0.5 mN/m in HfO2-coated nanopores. The results of the dielectric relaxation study demonstrate that the segmental relaxation time of confined PMPS 2.5k depends on the thermal treatment protocol and the hydrophilic/hydrophobic character of the pore walls. From calorimetric measurements, we found that the two glass transitions events are still observed, even in the absence of strong interfacial interactions. Values of both Tgs do not depend strongly on the chemical nature of the surface. In this way, changes in the glass-transition behavior of the tested polymer confined in ALD-coated nanopores cannot be rationalized in terms of the polymer/substrate interfacial energy. Eliminating strongly adhered surfaces does not eliminate the puzzling two-Tgs effect seen in cylindrical nanopores
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