Search results for "ARTICLES"
showing 10 items of 9626 documents
From Molecules to Systems: Sol-Gel Microencapsulation in Silica-Based Materials
2010
Chemical Reaction Monitoring Using Zero-Field Nuclear Magnetic Resonance Enables Study of Heterogeneous Samples in Metal Containers
2020
Abstract We demonstrate that heterogeneous/biphasic chemical reactions can be monitored with high spectroscopic resolution using zero‐field nuclear magnetic resonance spectroscopy. This is possible because magnetic susceptibility broadening is negligible at ultralow magnetic fields. We show the two‐step hydrogenation of dimethyl acetylenedicarboxylate with para‐enriched hydrogen gas in conventional glass NMR tubes, as well as in a titanium tube. The low frequency zero‐field NMR signals ensure that there is no significant signal attenuation arising from shielding by the electrically conductive sample container. This method paves the way for in situ monitoring of reactions in complex heteroge…
Mesoporous Silica Nanoparticles in Chemical Detection: From Small Species to Large Bio-Molecules
2021
A recompilation of applications of mesoporous silica nanoparticles in sensing from the last five years is presented. Its high potential, especially as hybrid materials combined with organic or bio-molecules, is shown. Adding to the multiplying effect of loading high amounts of the transducer into the pores, the selectivity attained by the interaction of the analyte with the layer decorating the material is described. Examples of the different methodologies are presented.
Biomolecule-corona formation confers resistance of bacteria to nanoparticle-induced killing: Implications for the design of improved nanoantibiotics
2018
Abstract Multidrug-resistant bacterial infections are a global health threat. Nanoparticles are thus investigated as novel antibacterial agents for clinical practice, including wound dressings and implants. We report that nanoparticles' bactericidal activity strongly depends on their physical binding to pathogens, including multidrug-resistant primary clinical isolates, such as Staphylococcus aureus , Klebsiella pneumoniae or Enterococcus faecalis . Using controllable nanoparticle models, we found that nanoparticle-pathogen complex formation was enhanced by small nanoparticle size rather than material or charge, and was prevented by 'stealth' modifications. Nanoparticles seem to preferentia…
Structural characterization of iron oxide/hydroxide nanoparticles in nine different parenteral drugs for the treatment of iron deficiency anaemia by …
2013
Drug products containing iron oxide and hydroxide nanoparticles (INPs) are important for the treatment of iron deficiency anaemia. Pharmaceuticals prepared by the complexation of different kinds of INPs and carbohydrates have different physicochemical and biopharmaceutic characteristics. The increasing number of parenteral non-biological complex drugs (NBCD) containing iron requires physicochemical methods for characterization and enabling of cross comparisons. In this context the structure and the level of crystallinity of the iron phases may be connected to the in vitro and in vivo dissolution rates, which etiologically determine the therapeutic and toxic effects. X-ray powder diffraction…
Impact of uncharged and charged stabilizers on in vitro drug performances of clarithromycin nanocrystals
2018
The purpose of this study was to evaluate the effect of charge on the in vitro drug performances of clarithromycin nanocrystals. To prepare different charges of nanocrystals, media milling was employed with the use of different stabilizing systems. The uncharged nanocrystals were prepared from poloxamer 407. The negatively and positively charged nanocrystals were stabilized using a combination of poloxamer 407 with sodium lauryl sulfate (SLS) and cetyltrimethylammonium bromide (CTAB), respectively. After production, the particle size of the negatively and positively charged nanocrystals was smaller than that of the uncharged one. The similar particle size of variously charged clarithromycin…
Tansy fruit mediated greener synthesis of silver and gold nanoparticles
2010
Abstract In this paper we have reported the green synthesis of silver (AgNPs) and gold (AuNPs) nanoparticles by reduction of silver nitrate and chloroauric acid solutions, respectively, using fruit extract of Tanacetum vulgare ; commonly found plant in Finland. The process for the synthesis of AgNPs and AuNPs is rapid, novel and ecofriendly. Formation of the AgNPs and AuNPs were confirmed by surface plasmon spectra using UV–Vis spectrophotometer and absorbance peaks at 452 and 546 nm. Different tansy fruit extract concentration (TFE), silver and gold ion concentration, temperature and contact times were experimented in the synthesis of AgNPs and AuNPs. The properties of prepared nanoparticl…
Comparison of quantum dot-binding protein tags: Affinity determination by ultracentrifugation and FRET
2013
Abstract Background Hybrid complexes of proteins and colloidal semiconductor nanocrystals (quantum dots, QDs) are of increasing interest in various fields of biochemistry and biomedicine, for instance for biolabeling or drug transport. The usefulness of protein–QD complexes for such applications is dependent on the binding specificity and strength of the components. Often the binding properties of these components are difficult and time consuming to assess. Methods In this work we characterized the interaction between recombinant light harvesting chlorophyll a / b complex (LHCII) and CdTe/CdSe/ZnS QDs by using ultracentrifugation and fluorescence resonance energy transfer (FRET) assay exper…
New Tools for Characterizing Metallic Nanoparticles: AgNPs, A Case Study.
2015
Currently, transmission electron microscopy (TEM) is the main technique for estimating the sizes of spherical nanoparticles (NPs) and through them, their concentrations. This paper demonstrates for the first time that C18 reversed-phase capillary liquid chromatography (Cap-LC) coupled to diode array detection (DAD) has the potential to estimate mean concentrations of silver nanoparticles (AgNPs) and thereby determine their average size. Direct injection of the sample without previous extraction or separation steps is carried out. Only a unique standard with a known AgNP size is needed for the calibration. In a first approach, the new method has been tested over silver nanoparticles, produce…
Precise Indication of Air Pollution Sources
2002
The present paper is a report of an application of Mossbauer spectroscopy, X-ray diffractometry, thermogravimetric analysis and PIXE in the characterization of the particulate matter in atmospheric aerosols in Vitoria Metropolitan Region (VMR), Brazil. The main sources of particulate matter, natural, industrial and antropogenic (from human activities), have been studied to identify its contribution in the atmospheric particles. Through the years 1995 to 1999 samples of total suspended particles (TSP, O ⩽; 100 μm) were collected from six points within VMR and in two points the inhalable particles (PM10, O ⩽ 10 μm). In addition, a receptor modeling was used helping in a precise indication of …