Fabrication mechanism of nanostructured HA/TNTs biomedical coatings: an improvement in nanomechanical and in vitro biological responses.

In this paper, a mechanism for fabrication of nanostructured hydroxyapatite coating on TiO2 nanotubes is presented. Also, the physical, biological, and nanomechanical properties of the anodized Ti6Al4V alloy consisting TiO2 nanotubes, electrodeposited hydroxyapatite, and the hydroxyapatite/TiO2 nanotubes double layer coating on Ti6Al4V alloy implants are compared. Mean cell viability of the samples being 84.63 % for uncoated plate, 91.53 % for electrodeposited hydroxyapatite, and 94.98 % for hydroxyapatite/TiO2 nanotubes coated sample were in the acceptable range. Merely anodized prototype had the highest biocompatibility of 110 % with respect to the control sample. Bonding strength of hydroxyapatite deposit to the substrate increased from 12 ± 2 MPa to 25.4 ± 2 MPa using intermediate TiO2 nanotubes layer. Hardness and elastic modulus of the anodized surface were 956 MPa and 64.7 GPa, respectively. The corresponding values for hydroxyapatite deposit were approximately measured 44.3 MPa and 0.66 GPa, respectively, while the average obtained values for hardness (159.3 MPa) and elastic modulus (2.25 GPa) of the hydroxyapatite/TiO2 nanotubes double coating improved more than 30 % of the pure hydroxyapatite deposit. Friction coefficient (ξ) of the anodized surface was 0.32 ± 0.02. The calculated friction coefficient enhanced from 0.65 ± 0.04 for sole hydroxyapatite layer to the 0.46 ± 0.02 for hydroxyapatite/TiO2 nanotubes due to presence of nanotubular TiO2 intermediate layer.

Conductive nerve conduit with piezoelectric properties for enhanced PC12 differentiation.

Restoration of nerve tissue remains highly challenging, mainly due to the limited regeneration capacity of the nervous system and the development of fibrosis. This limitation necessitates designing new nerve guidance channel to promote nerve repairing. In this study, we developed a novel core/shell conduit to induce PC12 differentiation. Co-electrospinning method was utilized to produce a fibrous shell containing polycaprolactone/polyvinylidene fluoride PCL/PVDF, gelatin and polyaniline/graphene (PAG) nanocomposite. The core section of the conduit was filled with chitosan-gelatin hydrogel containing PAG and ZnO nanoparticles. Such conduit shows antibacterial activity, electrical conductivity and piezoelectric property. The effect of such engineered conduit on PC12 differentiation was investigated by analyzing differentiation markers Nestin and microtubule-associated protein 2 (MAP2) through immunocytochemistry and PCR-RT techniques. The result revealed that such conduit could significantly induce Nestin and MAP2 gene expression in the PC12 cells and, thus, it is a viable option for effective cell differentiation and nerve regeneration.

Fabrication of biocompatible titanium scaffolds using space holder technique.

Open-pore titanium scaffolds were fabricated by sintering of compressed mixtures of TiH(1.924) and urea. Spherical and irregular shaped space holders were used to investigate the effect of pore shape on cellular behavior. After removal of the space holder, the shape of the spacers was replicated to the pores. Average diameter of the pores was in the range of 300-600 µm. SEM images showed that titanium hydride resulted in higher surface roughness and larger micro porosities than pure titanium. In vitro evaluations were carried out by using MTT assay, measuring alkaline phosphatase activity and alizarin red staining in flow perfusion bioreactor for cell culture. Observations revealed excellent attachment and proliferation of G-292 cells to the highly porous scaffolds fabricated with titanium hydride and urea of this research.

Simple SPR-based colorimetric sensor to differentiate Mg2+ and Ca2+ in aqueous solutions.

L-tryptophan functionalized AgNPs were successfully fabricated using a one-pot synthesis method and assessed as a colorimetric probe for rapid and accurate determination of Mg2+ ions. The developed sensor showed a selective response towards Mg2+ with no interference from Ca2+ in the wide concentration range of 1-200 µM. The sensor's response was optimized in the pH range of 9-10, which can be attributed to the protonation of amine groups and their interaction with Mg2+ ions. The stability and selectivity of the sensor were examined in different salt (NaCl) and other metal ions, respectively. The L-tryptophan-AgNPs sensor detected Mg2+ with the limit of detection of 3 µM, which is way lower than the concentration range of magnesium in human serum (0.75-1.05 mM). The recovery values of the developed sensor were in the range of 96-102% for the determination of Mg2+ in urine samples. The obtained performances proved the potential application of the developed sensor for clinical diagnostic of Mg2+ ions where an accurate and rapid response is needed.

SPR-based assay kit for rapid determination of Pb2.

A recyclable optical nanosensor was developed by immobilizing l-tyrosine functionalized silver nanoparticles (AgNPs) on the polyethylene terephthalate (PET) substrate for rapid determination of Pb2+ ions. At first, the l-tyrosine functionalized AgNPs were assessed in the solution phase; the response time was lower than 15 s, and a limit of detection lower than 9 nM was obtained in the dynamic range of 1-1000 nM. For fabrication of the optical assay kit, the design of experiment (DOE) was used to optimize the immobilization efficiency of the nanoparticles on PET films by studying AgNO3 concentration and pH as two crucial parameters. The assay kit in optimal conditions showed a sharp localized surface plasmon resonance band suitable for sensitive determination of Pb2+. The fabricated sensor showed promising results for rapid determination of lead ions with the limit of detection value as low as 1 nM (S/N = 3). The sensor reproduced the obtained results even after three consecutive runs, which proved the recyclability of the optical assay kit. The recoveries of the spiked concentration in real samples were in the range of 95%-103%, which confirmed the applicability of the sensor in practical applications.

Photocatalytic decoloration of Acid Red 27 in presence of SnO2 nanoparticles.

In this paper, the photocatalytic decoloration of Acid Red 27 (AR27) has been investigated using ultraviolet (UV) irradiation in presence of SnO2 nanoparticles. SnO2 nanoparticles were synthesized via hydrothermal process. The SnO2 nanoparticles' average crystallite sizes derived from X-ray analyses which were synthesized for 2, 12 and 24 hrs were about 3.73, 5.31 and 7.6 nm, respectively. Brunauer-Emmett-Teller (BET) analyses showed high surface area of about 183, 120 and 90(m2/g), respectively for aforementioned synthesized samples. Our investigations indicated that reaction rate constant and photocatalytic efficiency of AR27 decoloration have a direct relation with SnO2 nanoparticles' specific surface areas and band gap energies. Decoloration kinetics was investigated by using Langmuir-Hinshelwood model. The values of the adsorption equilibrium constant, K[AR27], and the kinetic rate constant of surface reaction, kc, were found to be 0.0924 (l/mg) and 0.2535 (mg/l min), respectively.

Porous shape memory dental implant by reactive sintering of TiH2-Ni-Urea mixture.

We produced bifurcated bone-like shape memory implant (BL-SMI) with desirable tooth-root fixation capability by compact-sintering of TiH2-Ni-urea mixture. The primary constituents of the porous product were Ni and Ti. We could adjust the pores' shape, size, and interconnectivity for favorite bone ingrowth by using urea as a space holder. Without urea, we obtained an average porosity of 0.30, and a mean void size of 100 µm. With 70 vol % urea, we got 62% interconnected pores of 400 µm average size. Aging allowed us to tune the austenite-martensite transformation temperatures towards the needed body tissue arouse. Differential scanning calorimetry measured the transformation temperatures. Their austenite start, austenite peak, and austenite finish values were As = 4, Ap = 22, and Af = 34 °C, respectively. They retained functional shape recovery and superelastic effect at the body temperature. Mechanical properties, including Young's modulus of the specimens, matched well to maxilla and mandible bone tissue. The measured Young's modulus of the NiTi specimens was as low as 3.5 GPa, which decreased to ∼2.1 GPa with further porosity increase at higher space holder percentages. Superelasticity regime and low Young's modulus of the implant could potentially prevent stress-shielding from the surrounding bone tissues and give rise to secure fixation of the implant into the bone socket. Bending tests showed 0.9 mm recoverable deflection for specimens which assisted immediate self-fixation of the implant into the jaw bone cavity.

Ultrasonic induced photoluminescence decay in sonochemically obtained cauliflower-like ZnO nanostructures with surface 1D nanoarrays.

Cauliflower-like ZnO nanostructures with average crystallite size of about 55 nm which have surface one dimensional (1D) nanoarrays with 10 nm diameter were successfully fabricated through a simple sonochemical route. X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and room temperature photoluminescence (PL) characterizations were performed to investigate the morphological and structural properties of the obtained nanostructures. It has been shown that the synthesized cauliflower-like ZnO nanostructures irradiated UV luminescence and a green peak in visible band. Ultrasonic post-treatment of the particles for about 2 h increased the density of surface defects resulted in an increase in the green emission intensity.

Synthesis of wide band gap nanocrystalline NiO powder via a sonochemical method.

A sonochemistry-based synthesis method was used to produce nanocrystalline nickel oxide powder with ≈ 20 nm average crystallite diameter from Ni(OH)(2) precursor. Ultrasound waves were applied to the primary solution to intensify the Ni(OH)(2) precipitation. Dried precipitates were calcined at 320°C to form nanocrystalline NiO particles. The morphology of the produced powder was characterized by transmission electron microscopy. Using sonochemical waves resulted in lowering of the size of the nickel oxide crystallites. FT-IR spectroscopy and X-ray diffraction revealed high purity well-crystallized structure of the synthesized powder. Photoluminescence spectroscopy confirmed production of a wide band-gap structure.

Large pore volume mesoporous copper particles and scaffold microporous carbon material obtained from an inorganic-organic nanohybrid material, copper-succinate-layered hydroxide.

Copper-succinate-layered hydroxide (CSLH), a new nanohybrid material, was synthesized as an inorganic-organic nanohybrid, in which organic moiety was intercalated between the layers of a single cation layered material, copper hydroxide nitrate. Microporous scaffold carbon material was obtained by thermal decomposition of the nanohybrid at 500 °C under argon atmosphere followed by acid washing process. Furthermore, the heat-treated product of the nanohybrid at 600 °C was ultrafine mesoporous metallic copper particles. The results of this study confirmed the great potential of CSLH to produce the carbon material with large surface area (580 m(2)/g) and high pore volume copper powder (2.04 cm(3)/g).

Bone-like apatite layer formation on the new resin-modified glass-ionomer cement.

In this study, the apatite-forming ability of the new resin-modified glass-ionomer cement was evaluated by soaking the cement in the simulated body fluid. The Fourier Transform Infrared (FTIR) spectrometer and X-Ray Diffraction (XRD) patterns of the soaked cement pointed to the creation of poorly crystalline carbonated apatite. It was found that the releasing of calcium ions from the soaked cement will dominate the undesirable effect of polyacrylic acid on apatite formation. Consequently, the ionic activity products (IAPs) of the apatite in the surrounding medium increased which accelerated apatite nucleation induced by the presence of the Si-OH and COOH groups. Accordingly, the apatite nuclei started to form via primary heterogeneous nucleation and continued by secondary nucleation. Therefore, nucleation and growth occurs as in the layer-by-layer mode so that finite numbers of monolayers are produced. Subsequent formation of film occurs by formation of discrete nuclei (layer-plus-island or SK growth).

Synthesis of nano-hydroxyapatite under a sonochemical/hydrothermal condition.

In this study, hydroxyapatite (denoted as HAp) nanostructure with uniform morphologies, controllable size, nano-dispersion and narrow size distribution in diameter has been synthesized successfully by low-temperature hydrothermal process, and the as-synthesized powders were characterized by XRD, scanning electron microscopy, high-resolution transmission microscopy, FT-IR, Zetasizer and inductively coupled plasma. In the present work, a novel sonochemical technique using CaHPO(4)2H(2)O/NaOH/distilled water with cetyltrimethylammonium bromide ((CH(3)(CH(2))(15)N(+)(CH(3))(3)Br(-)) designated as CTAB) under a hydrothermal condition to synthesize HAp nanostructure was described. Furthermore, the usage of a high basic condition and a water environment are the two crucial keys in ensuring the formation of HAp in the hydrothermal/sonochemical processes. However, the crystallite size and crystallinity degree of the HAp increased with increasing annealing temperature. Indeed, the present work will introduce a new method in synthesizing HAs for scientific and medical engineering.