Development of a new parallelized,optical biosensor platform for label-free detection of autoimmunity-related antibodies

Autoimmune diseases are characterized by the presence of autoantibodies in serum of affected patients. The heterogeneity of autoimmune relevant antigens creates a variety of different antibodies, which requires a simultaneous detection mode. For this reason, we developed a tool for parallelized, label-free, optical detection that accomplishes the characterization of multiple antigen–antibody interactions within a single measurement on a timescale of minutes. Using 11-aminoundecyltrimethoxysilane, we were able to immobilize proteinogenic antigens as well as an amino-functionalized cardiolipin on a glass surface. Assay conditions were optimized for serum measurements with a single spot antigen chip on a single spot 1-λ detection system. Minimized background signal allows a differentiation between patients and healthy controls with a good sensitivity and specificity. Applying polarized imaging reflectometric interference spectroscopy, we evaluated samples from three APS patients and three control subjects for this proof-of-principle and already obtained good results for β2-glycoprotein I and cardiolipin.     

Pharmaceutical approaches involving carvedilol characterization,compatibility with different excipients and kinetic studies

This study was performed to investigate the physical–chemical characteristics of carvedilol (CRV), complemented by compatibility studies with a great variety of pharmaceutical excipients. Thermogravimetry and differential scanning calorimetry, supported by diffuse reflectance infrared fourier transform spectroscopy (DRIFT), X-ray powder diffraction, and scanning electron microscopy (SEM) were selected as the solid-state techniques for the intended analyses. In addition, non-isothermal methods were employed to investigate kinetic data of CRV decomposition process under nitrogen and air atmospheres. CRV is characterized by an endothermic sharp event (T _peak = 389.81 K and ΔH _fusion of ?176.28 J g^?1) and a thermal decomposition behavior in two stages, totalizing 98 % of mass loss. The CRV pattern diffraction presents prominent peaks at 2θ: 5.92°, 14.90°, 18.62°, 24.47°, and 26.30°, and the DRIFT spectrum showed the main characteristics bands for CRV chemical functional groups. The SEM photomicrographs demonstrate that CRV is characterized by irregular blocky shaped crystals. Zero order kinetics was determined by Ozawa method in both nitrogen and air atmospheres. The compatibility results showed no evidence of any incompatibility among CRV and all the excipients analyzed.     

Monitoring stabilizing procedures of archaeological iron using electrochemical impedance spectroscopy

A methodology for monitoring washing procedures applied to stabilize archaeological iron is described. It is based on the combination of voltammetry of microparticles (VMP) with electrochemical impedance spectroscopy (EIS). A semi-empirical approach is used where the impedances at low and high frequencies were related with the fraction areas of passive and corrosion layers generated during the stabilizing treatment, the thickness, and the porosity of the corrosion layer. The variation of such parameters with the time of washing was determined from EIS data for four types of desalination procedures using concentrated NaOH and/or Na₂SO₃ aqueous solutions on archaeological iron artifacts. After 2 months of treatment, EIS data indicate that an essentially identical “stable” state was attained in all cases, as confirmed by the formation of a passive magnetite layer identified in VMP measurements while the rate of variation of corroded surface and porosity at short washing times varied significantly from one stabilization procedure to another.     

Supramolecular Luminescent Lanthanide Dimers for Fluoride Sequestering and Sensing

Lanthanide complexes (Ln=Eu, Tb, and Yb) that are based on a C₂‐symmetric cyclen scaffold were prepared and characterized. The addition of fluoride anions to aqueous solutions of the complexes resulted in the formation of dinuclear supramolecular compounds in which the anion is confined into the cavity that is formed by the two complexes. The supramolecular assembly process was monitored by UV/Vis absorption, luminescence, and NMR spectroscopy and high‐resolution mass spectrometry. The X‐ray crystal structure of the europium dimer revealed that the architecture of the scaffold is stabilized by synergistic effects of the Eu? F? Eu bridging motive, π stacking interactions, and a four‐component hydrogen‐bonding network, which control the assembly of the two [EuL] entities around the fluoride ion. The strong association in water allowed for the luminescence sensing of fluoride down to a detection limit of 24 nM .     

Voltammetry of immobilized particles for the future

Journal of Solid State Electrochemistry - The voltammetry of immobilized particles is an electroanalytical technique yielding compositional, thermochemical, and even structural information on...     

Unprecedented Kinetic Inertness for a Mn2+‐Bispidine Chelate: A Novel Structural Entry for Mn2+‐Based Imaging Agents

The search for more biocompatible alternatives to Gd³⁺‐based MRI agents, and the interest in ⁵²Mn for PET imaging call for ligands that form inert Mn²⁺ chelates. Given the labile nature of Mn²⁺, high inertness is challenging to achieve. The strongly preorganized structure of the 2,4‐pyridyl‐disubstituted bispidol ligand L₁ endows its Mn²⁺ complex with exceptional kinetic inertness. Indeed, MnL₁ did not show any dissociation for 140 days in the presence of 50 equiv. of Zn²⁺ (37 °C, pH 6), while recently reported potential MRI agents MnPyC3A and MnPC2A‐EA have dissociation half‐lives of 0.285 h and 54.4 h under similar conditions. In addition, the relaxivity of MnL₁ (4.28 mm ^?1 s^?1 at 25 °C, 20 MHz) is remarkable for a monohydrated, small Mn²⁺ chelate. In vivo MRI experiments in mice and determination of the tissue Mn content evidence rapid renal clearance of MnL₁. Additionally, L₁ could be radiolabeled with ⁵²Mn and the complex revealed good stability in biological media.     

Production of metakaolin from industrial cellulose waste

Research focused on the transformation and utilization of industrial wastes into products of commercial interest plays an increasingly important role. Residual pulp can become useful in the manufacture of different materials, providing high value to this waste and reducing its environmental impact when disposed of improperly in the environment. The main constituents of this waste are kaolin and calcium carbonate (CaCO₃). Starting from kaolin, metakaolin can be produced by calcination of the residue at 630?°C for 2?h in a rotary reactor with air flow, followed by solubilization with hydrochloric acid to remove the CaCO₃. The development of technological alternatives aimed at the reuse of certain wastes can result in applications of real economic interest to the chemical industry and ceramics and glass, which is the case in this study. The raw material and metakaolin obtained were analyzed by thermogravimetric analysis and derivative thermogravimetric analysis, X-ray diffraction, and X-ray fluorescence spectroscopy with promising results. This is because metakaolin was obtained free of contamination by other materials.     

Conformational analysis: a new approach by means of chemometrics

In conformational analysis, the systematic search method completely maps the space but suffers from the combinatorial explosion problem because the number of conformations increases exponentially with the number of free rotation angles. This study introduces a new methodology of conformational analysis that controls the combinatorial explosion. It is based on a dimensional reduction of the system through the use of principal component analysis. The results are exactly the same as those obtained for the complete search but, in this case, the number of conformations increases only quadratically with the number of free rotation angles. The method is applied to a series of three drugs: omeprazole, pantoprazole, lansoprazole-benzimidazoles that suppress gastric-acid secretion by means of H+, K+-ATPase enzyme inhibition.