Treatment with silica-gold nanostructures decreases inflammation-related gene expression in collagen-induced arthritis.

Gold salts have been used to treat rheumatoid arthritis (RA) since the 1940s, and, with advances in nanotechnology, the use of nanogold provides multiple options for anti-inflammatory therapies. This paper presents the synthesis and characterization of silica-gold nanostructures (SGNs) and their therapeutic effect in collagen-induced arthritis (CIA) in DBA/1 mice. At the end of the treatment, the synovial membranes, kidneys, livers, and spleens were dissected and analyzed by inductively coupled plasma mass spectroscopy (ICP) showing less than 0.0001 and 0.1% of the administered doses of Au and Si, respectively. Remains of the SGNs were visually identified in the synovial membrane by scanning electron microscopy (SEM), and the bone density of the hind paws was observed by computerized tomography (CT) indicating a reduction of porosity in the CIA-experimental group. The DNA microarray analysis carried out with RNA obtained from the hind paws showed 2628 differentially expressed genes (DEGs) by SGNs. The bioinformatic analysis showed that DEGs were significantly associated with several inflammatory signalling pathways including chemokines, cytokine-cytokine receptor interaction, PI3K-Akt, TNF, IL-17, NFκß, MAPK, and RA. SGNs downregulated relevant inflammatory genes in the arthritic joints, including Tnf, Ifng, Il6, and Cxcl5; immunohistochemistry (IHC) confirmed the reduction of TNFα, IL-6, NFκß, and VEGF in the joints due to the effect of SGNs. TNFα and IL-6 were also reduced in the serum of DBA/1 mice treated with SGNs.

Antimicrobial Resistance and Inorganic Nanoparticles.

Antibiotics are being less effective, which leads to high mortality in patients with infections and a high cost for the recovery of health, and the projections that are had for the future are not very encouraging which has led to consider antimicrobial resistance as a global health problem and to be the object of study by researchers. Although resistance to antibiotics occurs naturally, its appearance and spread have been increasing rapidly due to the inappropriate use of antibiotics in recent decades. A bacterium becomes resistant due to the transfer of genes encoding antibiotic resistance. Bacteria constantly mutate; therefore, their defense mechanisms mutate, as well. Nanotechnology plays a key role in antimicrobial resistance due to materials modified at the nanometer scale, allowing large numbers of molecules to assemble to have a dynamic interface. These nanomaterials act as carriers, and their design is mainly focused on introducing the temporal and spatial release of the payload of antibiotics. In addition, they generate new antimicrobial modalities for the bacteria, which are not capable of protecting themselves. So, nanoparticles are an adjunct mechanism to improve drug potency by reducing overall antibiotic exposure. These nanostructures can overcome cell barriers and deliver antibiotics to the cytoplasm to inhibit bacteria. This work aims to give a general vision between the antibiotics, the nanoparticles used as carriers, bacteria resistance, and the possible mechanisms that occur between them.

Nano-structured hydroxyapatite and titanium dioxide enriching PENTA /UDMA adhesive as aesthetic coating for tooth enamel.

OBJECTIVES: The aim of this study was to investigate the effect of the nanostructured hydroxyapatite (NHAp) and titanium dioxide nanoparticles (NTiO2) on dispersion in an adhesive containing monomers of Dipenta erythritol penta-acrylate monophosphate (PENTA) and Urethane dimethacrylate (UDMA), as well as evaluating the structural, optical and mechanical behavior of the composite material for dental aesthetic application. METHODS: The NHAp powders were synthesized through the wet chemical methods of hydrothermal and ultrasound-assisted precipitation. The microstructure, morphology and composition analysis of the powder of NHAp and NTiO2 were performed by scanning and transmission electron microscopy. The optical microscopic identification of the different colors was obtained due to varying the amounts of NHAp and NTiO2 in the adhesive. On the other hand, the diffuse reflectance spectra of the coatings were evaluated every 2nm with the wavelength from 400 to 800nm for combined specular and diffuse reflectance. The nanomechanical properties of the aesthetic coating such as (H), elastic modulus (E) and nanoscratching were evaluated by nanoindentation. The roughness of the composite coatings were evaluated by AFM. RESULTS: From different powders combinations, NHAP 75%Wt-NTiO2 %25Wt, at (10Wt %) into a dental adhesive, the resulting mixture manifested the optimum aesthetic white appearance. The scanning and transmission electron microscopy images confirmed that the HAp nanorods and TiO2 nanoparticles sized were 55nm and 20nm respectively prepared by the high-energy ball mixed process. The values of nanomechanical properties of the optimum aesthetic coating were hardness, H=3.2±0.3GPa, elastic modulus, E=78±3GPa, Yield point, Y=107MPa±2 and scratching, maximum wear track deformation 3.7±0.12 µm2. The percentage of reflectance to optimum aesthetic white appearance was of 46.83% at 423nm of wavelength. CONCLUSIONS: The nanocomposite PENTA/UDMA with mixtures of Nanohydroxyapatite and titanium dioxide may be considerate as a mechanical toughened, also an option to modify shade qualities for dental aesthetic applications.

Reduction of Au(III) by a ß-cyclodextrin polymer in acid medium. A stated unattainable reaction.

Gold nanoparticles (AuNPs) can be prepared from the reduction of Au(III) with cyclodextrins acting as both, reducing and capping agent. It has been stated that a basic medium (pH=9-12) is a mandatory condition to achieve such reduction. We demonstrated, for the first time, the reduction of Au(III) by a crosslinked ß-cyclodextrin-epichlorohydrin polymer (ßCDP) in acid medium (pH ∼3). The coordination of Au(III) to the ßCD in ßCDP polymer required a ßCD:[AuCl4]- ratio of 4:1. The same ratio was necessary to achieve a 50% of the reduction of Au(III) to Au0 within the first 24h of reaction. During this initial time, the reaction showed a concentration-dependent reduction rate while for longer times the reduction rate was diffusion-dependent. An overall mechanism to explain this dependency has been proposed. The 13C NMR spectrum identified the oxidation of the COH groups to carboxylic ones by recording a signal at 175.6ppm. Gold nanoparticles cores (AuNPs) with a diameter of 34.2±7.7nm, determined by Transmission Electron Microscopy (TEM), was prepared by refluxing HAuCl4 in an aqueous solution of ßCDP. The AuNPs core was capped by dimers of the ßCDP polymer as determined by Dynamic Light Scattering measurements.