纳米羟基磷灰石-胶原蛋白-壳聚糖复合生物材料

采用共沉淀法制备了纳米羟基磷灰石．胶原蛋白．壳聚糖复合生物材料，用IR、XRD、TEM及万能材料实验机等方法对材料性能进行了分析表征。结果表明：羟基磷灰石．胶原蛋白．壳聚糖复合生物材料在晶相组成、化学成分、羟基磷灰石尺寸上具有类骨结构，并具有良好的力学性能．其抗压强度达到128MPa，可满足骨组织修复与替代的要求。有望成为治疗骨缺损的承力替代物。     

Large scale synthesis of FeS coated Fe nanoparticles as reusable magnetic photocatalysts

The FeS coated Fe nanoparticles were prepared by using high temperature reactions between the commercial Fe nanoparticles and the S powders in a sealed quartz tube. The simple method developed in this work is effective for large scale synthesis of FeS/Fe nanoparticles with tunable shell/core structures, which can be obtained by controlling the atomic ratio of Fe to S. The structural, magnetic and photocatalytic properties of the nanoparticles were investigated systematically. The good photocatalytic performance originating from the FeS shell in degradation of methylene blue under visible light and the high saturation magnetization originating from the ferromagnetic Fe core make the FeS/Fe nanoparticles a good photocatalyst that can be collected and recycled easily with a magnet. An exchange bias up to 11 mT induced in Fe by FeS was observed in the Fe/FeS nanoparticles with ferro/antiferromagnetic interfaces. The enhanced coercivi-ty up to 32 mT was ascribed to the size effect of Fe core.     

New method for synthesis of Pt nanoparticles embedded in a carbon matrix

Platinum (Pt) nanoparticles embedded in a carbon matrix were synthesized for the first time in benzene by an electric plasma discharge generated in the cavitation field of benzene due to an ultrasonic horn. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) were used to study the particle size, structure and morphology of the synthesized nanoparticles. The Pt nanoparticles have FCC bulk Pt crystal structure. On the average Pt nanoparticle diameter ranged from 8 nm to 40 nm when synthesized at 4.1 kV and from 5 nm to 25 nm when synthesized at 3.4 kV. X-ray photoelectron Spectroscopy (XPS) and Energy dispersive X-ray Spectroscopy (EDX) were used to study the chemical composition of the synthesized nanoparticles. A cost effective new method for carbon supported Pt nanoparticles will be of potential interest in fuel cell and catalysis applications.     

Novel gold nanoparticles coated with somatostatin as a potential delivery system for targeting somatostatin receptors

Targeting of G-protein coupled receptors (GPCRs) like somatostatin-14 (SST-14) could have a potential interest in delivery of anti-cancer agents to tumor cells. Attachment of SST to different nano-carriers e.g. polymeric nanoparticles is limited due to the difficulty of interaction between SST itself and those nano-carriers. Furthermore, the instability problems associated with the final formulation. Attaching of SST to gold nanoparticles (AuNPs) using the positive and negative charge of SST and citrate-AuNPs could be considered a new technique to get stable non-aggregated AuNPs coated with SST. Different analyses techniques have been performed to proof the principle of coating between AuNPs and SST. Furthermore, cellular uptake studies on HCC-1806, HELA and U-87 cell lines has been investigated to show the ability of AuNPs coated SST to enter the cells via SST receptors. Dynamic light scattering (DLS) indicated a successful coating of SST on the MUA-AuNPs surface. Furthermore, all the performed analysis including DLS, SDS-PAGE and UV-VIS absorption spectra indicated a successful coating of AuNPs with SST. Cellular uptake studies on HCC-1806, HELA and U-87 cell lines showed that the number of AuNPs-SST per cell is signiflcantly higher compared to citrate-AuNPs when quantified using inductively coupled plasma spectroscopy. Moreover, the binding of AuNPs-SST to cells can be suppressed by addition of antagonist, indicating that the binding of AuNPs-SST to cells is due to receptor-specific binding. In conclusion, AuNPs could be attached to SST via adsorption to get stable AuNPs coated SST. This new formulation has a potential to target SST receptors localized in many normal and tumor cells.     

Gas-liquid detonation synthesis of graphite coated copper nanoparticles and tribological performance as lubricant additives

Graphite coated copper (Cu@G) nanoparticles were successfully prepared by a gas-liquid detonation method, using copper acetate, ethanol, hydrogen and oxygen as the detonation precursors. The composition, morphology and microstructure of detonation products were analyzed by X-ray diffraction (XRD) and transmission electron microscopy-energy dispersive X-ray spectrometry (TEM-EDX). And a four-ball wear test was carried out to clarify the tribological properties of the mixed lubricating oils, which mainly consisted of the SN150 base oils containing five different concentrations of Cu@G nanoparticles. The results indicated that Cu@G nanoparticles are made up of face-centered cubic (FCC) copper nanocrystal and graphitic shells. The size distribution of core-shell structural products is mainly in range of 10–40 nm and the graphitic shells is about 4–8 nm. From the four-ball tests, the friction coefficient and wear scar diameter (WSD) decrease firstly and then increase with the increase of the contents of Cu@G nanoparticles. When the content of Cu@G nanoparticles is 0.6%, there is a minimum friction coefficient and WSD.     

Iron pyrophosphate matrix as a form for immobilization of cesium radionuclides

Several modifications of CsFeP₂O₇ were prepared by fine dispersion procedure: glass, glass ceramic, and finely crystalline composite. The cesium leach rates from these CsFe pyrophosphate forms at 90°C were determined. The pyrophosphate glass shows promise as a form for isolation of fission products in a deep underground repository.     

Photochemical synthesis of biopolymer coated Aucore-Agshell type bimetallic nanoparticles

Spherical Au nanoparticles have been prepared in the presence of a biopolymer, sodium alginate using UV-photoactivation technique. The particles are sodium alginate coated and are extremely stable. These Au nanoparticles have been used as seed for the synthesis of Aucore-Agshell type bimetallic nanoparticles. Sodium alginate is a carbohydrate-based biopolymer. In this synthesis it acts both as a reducing agent and a stabilizer for the evolved particles. Therefore, no extra capping agent is required from outside to make the generated particle stable. By varying the seed to silver ion ratios and using photoactivation technique Aucore-Agshell type bimetallic nanoparticles with various sizes and compositions have been synthesized. The method is very simple and reproducible and does not need any manipulative skill. Characterizations of these bimetallic nanoparticles have been done from their UV-visible spectroscopy, TEM/EDX, and AFM results. UV-visible extinction spectra reveal that the seed particles have an absorption maxima approximately 527 nm, attributed to the surface plasmon of the pure gold nanoparticles. From the TEM images the particle size of the gold seed particles was calculated to be 8.6 nm. The growth of bimetallic nanoparticles with time has been monitored. The finally evolved bimetallic Aucore-Agshell nanoparticles have a size in the range between approximately 10-14 nm. The particles are very stable and may have the potential for biological and catalytic applications.     

Preparation and characterization of nanobiocomposites containing iron nanoparticles prepared from blood and coated with chitosan and gelatin

In this study, we report the preparation of magnetic iron nanoparticles (INPs) from goat blood using incineration method. FT-IR and XRD studies have confirmed that the prepared nanoparticles were INPs. These INPs were coated with a mixture of chitosan and gelatin to prepare INP-CG nanobiocomposite and the TEM picture of these composite particles has shown an average particle size of 80-300 nm. MRI scan exhibited magnetic property and VSM studies revealed a magnetic saturation of 18.97 emu/g. This may be used as a MRI contrast agent to enhance cellular imaging and as magnetic nanocarrier for targeted delivery of drugs in the diagnosis and treatment of cancer.     

In situ biomimetic synthesis,characterization and in vitro investigation of bone-like nanohydroxyapatite in starch matrix

In this work, we report the synthesis of bone-like hydroxyapatite (HAp) nanorods in wheat starch matrix via a biomimetic process. Characterization of the samples was performed by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). Scanning and transmission electron microscopy (SEM and TEM) were used to determine the size, shape and morphology of nano-HAp. The results indicate that, the shape and morphology of nHAp is influenced by the presence of starch as a template agent and rod-like nHAp similar to the inorganic component in the human body is obtained at room temperature. In vitro bioactivity of the synthesized HAp nanocomposites was finally verified by comparison of the HAp's structures and morphology before and after immersion in simulated body fluid (SBF) solution for 3, 7, and 14 days.     

Cobalt nanoparticles coated with graphitic shells as localized radio frequency absorbers for cancer therapy

Graphitic carbon-coated ferromagnetic cobalt nanoparticles (C-Co-NPs) with diameters of around 7?nm and cubic crystalline structures were synthesized by catalytic chemical vapor deposition. X-ray diffraction and x-ray photoelectron spectroscopy analysis indicated that the cobalt nanoparticles inside the carbon shells were preserved in the metallic state. Fluorescence microscopy images and Raman spectroscopy revealed effective penetrations of the C-Co-NPs through the cellular plasma membrane of the cultured HeLa cells, both inside the cytoplasm and in the nucleus. Low radio frequency (RF) radiation of 350 kHz induced localized heat into the metallic nanoparticles, which triggered the killing of the cells, a process that was found to be dependent on the RF application time and nanoparticle concentration. When compared to carbon nanostructures such as single-wall carbon nanotubes, these coated magnetic cobalt nanoparticles demonstrated higher specificity for RF absorption and heating. DNA gel electrophoresis assays of the HeLa cells after the RF treatment showed a strong broadening of the DNA fragmentation spectrum, which further proved the intense localized thermally induced damages such as DNA and nucleus membrane disintegration, under RF exposure in the presence of C-Co-NPs. The data presented in this report indicate a great potential of this new process for in vivo tumor thermal ablation, bacteria killing, and various other biomedical applications.     

Tamibarotene-loaded citric acid-crosslinked alkali-treated collagen matrix as a coating material for a drug-eluting stent

Abstract

Tamibarotene-loaded biodegradable matrices with antithrombogenic and drug-releasing properties were prepared in a crosslinking reaction between amino groups of alkali-treated collagen (AlCol) and active ester groups of trisuccinimidyl citrate. The resulting matrices were characterized by their residual amino group concentrations, swelling ratios and thermal, antithrombogenic and drug-releasing properties. It was clarified that the addition of tamibarotene does not inhibit matrix formation. After immersion in water, the swelling ratio of a matrix became lower than that prior to immersion. Thermal analysis indicated that AlCol interacted with tamibarotene. The addition of tamibarotene to the matrix did not influence the antithrombogenic property of the resulting matrix. A matrix with a high crosslinking density had a prolonged tamibarotene elution time. These results demonstrate that tamibarotene-loaded matrices have great potential as a coating material for drug-eluting stents.     

Regeneration of critical bone defects with anionic collagen matrix as scaffolds

The aim of this study was to make a histomorphometric evaluation of the osteogenic potential of anionic collagen matrix as scaffolds; either crosslinked in glutaraldehyde or not cross-linked and, implanted in critical bone defects in rat calvaria. Seventy-two rats were randomly distributed in three groups: anionic collagen scaffolds treated for 24 h of selective hydrolysis (ACSH); anionic collagen scaffolds treated for 24 h of selective hydrolysis and 5 min of crosslinking in glutaraldehyde 0.05 % (ACSHGA); empty bone defect (Control), evaluated at the biological points of 15, 45, 90 and 120 days. The results showed that the biomaterials implanted were biocompatible and showed a high osteogenic potential. These biomaterials presented a speed of biodegradation compatible with bone neoformation, which was shown to be associated with angiogenesis inside the scaffolds at all biological points. The percentage of mineralization of ACSH (87 %) differed statistically from that found in ACSHGA (66 %). It was concluded that the regeneration of critical bone defect was more evident in anionic collagen without crosslinking (ACSH).     

Spherical polyelectrolyte brushes as a nanoreactor for synthesis of ultrafine magnetic nanoparticles

Ultrafine magnetic nanoparticles (MNP, 1.4-5.8?nm) were generated within a nanoreactor of spherical polyelectrolyte brushes (SPB). SPB consist of a solid polystyrene (PS) core and densely grafted poly(acrylic acid) (PAA) chains. Due to strong chemical coordination between carboxyl groups in PAA and MNP surfaces, the obtained magnetic spherical polyelectrolyte brushes (MSPB) kept excellent stability and maintained pH sensitivity. The magnetic properties of MSPB were confirmed by a vibrating sample magnetometer (VSM). The size and the size dispersion of MNP can be modulated by varying adding sequences (conventional coprecipitation or reverse coprecipitation), or nanoreactor structure (with or without crosslinking). MNP content in MSPB could be adjusted by multicycle reactions. This new strategy makes it possible to synthesize ultrafine inorganic nanoparticles with tunable size in SPB.     

Chitosan as template for the synthesis of ceria nanoparticles

Cerium oxide (CeO₂), nanoparticles were prepared using chitosan as template, cerium nitrate as a starting material and sodium hydroxide as a precipitating agent. The resultant ceria–chitosan spheres were calcined at 350 °C. The synthesized powders were characterized by, XRD, HRTEM, UV–vis, FTIR, and TG-DTA. The average size of the nanoparticles obtained was ∼4 nm and BET specific surface area ∼105 m² g⁻¹. Blueshifts in the ultraviolet absorption spectra have been observed in cerium oxide nanocrystallites. The band-gap was found to be 4.5 eV. The blueshifts are well explained for diameters down to less than a few nanometers by the change in the electronic band structure.     

Magnetic nanoparticles coated with anacardic acid derived from cashew nut shell liquid

Magnetic nanoparticles functionalized with biomolecules have received special attention due to their various biomedical applications, such as drug delivery and magnetic hyperthermia treatment for cancer. In this study, we present the synthesis and characterization of new nanoparticles coated with anacardic acid derived from cashew nut shell liquid. The results showed that Fe₃O₄ nanoparticles coated with anacardic acid (AA-MAG) have superparamagnetic behavior and the magnetization is almost equal when compared with the pure Fe₃O₄. This coating provides stability by preventing the aggregation nanoparticles without losing its magnetization potential. The AA-MAG demonstrates excellent and fast magneto-temperature response which can be used as high-performance hyperthermia agents.     

Synthesis and characterization of magnetic nanoparticles coated with a uniform silica shell

Magnetic nanoparticles with a proper surface coating are of outstanding interest for several applications, especially in the biomedical field. In this paper we present the synthesis of CoFe₂O₄ magnetic nanoparticles covered by a uniform silica shell. These particles were characterized by means of Transmission Electron Microscopy (TEM) and Small Angle Scattering of Polarized Neutrons (SANSPOL). This newly developed technique, taking advantage from the variation of magnetic contrast, allowed us to verify that the thickness of the silica shell can be accurately tailored through a very simple synthetic approach.     

An investigation on synthesis and magnetic properties of ferromagnetic nanoparticles of nickel ferrite coated with TiO2

TiO₂-coated nickel ferrite (NiFe₂O₄) nanoparticles were obtained by the hydrolysis of titanium tetrabutyloxide in the presence of NiFe₂O₄ nanoparticles in water/oil (w/o) microemulsion. The effects of TiO₂ coating on the magnetic properties of NiFe₂O₄ nanoparticles were investigated. The structural, morphological and magnetic properties of as-prepared samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectra, transmission electron microscopy (TEM) and magnetic measurements. The morphology analysis confirmed that the obtained composite nanoparticles consisted of NiFe₂O₄ coated by TiO₂. It was shown that the saturation magnetization and coercivity of NiFe₂O₄ decreased after TiO₂ coating, which can be interpreted by the interparticle dipole–dipole interactions related to the magnetic particle volume fraction in the composite nanoparticles.     

Silver nanoparticles dispersed in polyaniline matrixes coated on titanium substrate as a novel electrode for electro-oxidation of hydrazine

Silver nanoparticles dispersed in polyaniline matrixes coated on titanium substrate, as a novel electrode, was easily synthesized by electro-polymerization of aniline on titanium and then electrodeposited silver nanoparticles on PAni electrode. The electrochemical behavior and electro-catalytic activity of silver nanoparticles/PAni/Ti electrodes were characterized by cyclic voltammetry. The morphology of silver nanoparticles on PAni/Ti electrodes were characterized by scanning electron microscopy and energy-dispersive X-ray techniques, respectively. Results indicated that silver nanoparticles with a diameter of about 40–70 nm were homogeneously dispersed on the surface of polyaniline film. The silver nanoparticles/PAni/Ti electrodes were examined for electro-catalytic activity toward oxidation of hydrazine. The results show that these modified electrodes are highly active for electro-catalytic oxidation of hydrazine.     

Laser-induced modification of polymeric beads coated with gold nanoparticles

A direct laser writing method for modifying colloidal crystals and single colloids is presented. This method takes advantage of the highly efficient conversion of photons into heat exhibited by gold nanoparticles. The easy control of experimental parameters allowed control of the spatial resolution of the patterns. This may open the way to practical applications for the technology.     

One-step preparation of FeCo nanoparticles in a SBA-16 matrix as catalysts for carbon nanotubes growth

Nanocomposites containing FeCo alloy nanoparticles dispersed in a highly ordered 3D cubic Im3m mesoporous silica (SBA-16) matrix were prepared by a novel, single-step templated-assisted sol-gel technique. Two different approaches were used in the synthesis of nanocomposites; a pure SBA-16 sample was also prepared for comparison. Low-angle X-ray diffraction, transmission electron microscopy and N2 physisorption at 77 K show that after metal loading, calcination at 500 degrees C and reduction in H2 flux at 800 degrees C the nanocomposites retain the cubic mesoporous structure with pore size not very different from the pure matrix. X-ray absorption fine structure (EXAFS) analysis at Fe and Co K-edges demonstrates that the FeCo nanoparticles have the typical bcc structure. The final nanocomposites were tested as catalysts for the production of carbon nanotubes by catalytic chemical vapour deposition and high-resolution TEM shows that good quality multi-walled carbon nanotubes are obtained.