Fluorescence biosensing micropatterned surfaces based on immobilized human acetylcholinesterase

Human acetylcholinesterase (AChE) is a widely studied target enzyme in drug discovery for Alzheimer’s disease (AD). In this paper we report evaluation of the optimum structure and chemistry of the supporting material for a new AChE-based fluorescence sensing surface. To achieve this objective, multilayered silicon wafers with spatially controlled geometry and chemical diversity were fabricated. Specifically, silicon wafers with silicon oxide patterns (SiO₂/Si wafers), platinum-coated silicon wafers with SiO₂ patterns (SiO₂/Pt/Ti/Si wafers), and Pt-coated wafers coated with different thicknesses of TiO₂ and SiO₂ (SiO₂/TiO₂/Pt/Ti/Si wafers) were labelled with the fluorescent conjugation agent HiLyte Fluor 555. Selection of a suitable material and the optimum pattern thickness required to maximize the fluorescence signal and maintain chemical stability was performed by confocal laser-scanning microscopy (CLSM). Results showed that the highest signal-to-background ratio was always obtained on wafers with 100 nm thick SiO₂ features. Hence, these wafers were selected for covalent binding of human AChE. Batch-wise kinetic studies revealed that enzyme activity was retained after immobilization. Combined use of atomic-force microscopy and CLSM revealed that AChE was homogeneously and selectively distributed on the SiO₂ microstructures at a suitable distance from the reflective surface. In the optimum design, efficient fluorescence emission was obtained from the AChE-based biosensing surface after labelling with propidium, a selective fluorescent probe of the peripheral binding site of AChE.

Enantioselective Extraction of Dinitrophenyl Amino Acids Mediated by Lipophilic Deoxyguanosine Derivatives: Chiral Discrimination by Self-Assembly

The transfer of potassium salts of dinitrophenyl amino acids from water to chloroform by the lipophilic guanosine derivative 1 takes place enantioselectively. Depending on the K⁺: 1 ratio, G-quartets of 1 self-assemble into octamers ( O ) or polymers.     

Time series forecasting with neural network ensembles: an application for exchange rate prediction

This paper investigates the use of neural network combining methods to improve time series forecasting performance of the traditional single keep-the-best (KTB) model. The ensemble methods are applied to the difficult problem of exchange rate forecasting. Two general approaches to combining neural networks are proposed and examined in predicting the exchange rate between the British pound and US dollar. Specifically, we propose to use systematic and serial partitioning methods to build neural network ensembles for time series forecasting. It is found that the basic ensemble approach created with non-varying network architectures trained using different initial random weights is not effective in improving the accuracy of prediction while ensemble models consisting of different neural network structures can consistently outperform predictions of the single ‘best’ network. Results also show that neural ensembles based on different partitions of the data are more effective than those developed with the full training data in out-of-sample forecasting. Moreover, reducing correlation among forecasts made by the ensemble members by utilizing data partitioning techniques is the key to success for the neural ensemble models. Although our ensemble methods show considerable advantages over the traditional KTB approach, they do not have significant improvement compared to the widely used random walk model in exchange rate forecasting.     

Graphene-based electrically reconfigurable deep-subwavelength metamaterials for active control of THz light propagation

This work studies the terahertz light propagation through graphene-based reconfigurable metasurfaces where the unit cell dimensions are much smaller than the terahertz wavelength. The proposed devices, which poses deep-subwavelength unit cell and active region dimensions can operate as amplitude and/or phase modulators in certain specific frequency bands determined by the device geometry. Reconfigurability is attained via electrostatically tuning the optical conductivity of patterned graphene layers, which are strategically located in each unit cell. The ultra-small unit cell dimensions can be advantageous for beam shaping applications.     

Oxidation of amines catalyzed by cyclohexanone monooxygenase

Cyclohexanone monooxygenase catalyzed the oxidation of tertiary, secondary and hydroxylamines to N-oxides, hydroxylamines and nitrones respectively.     

Role of the solvent in the dynamical transitions of proteins: the case of the lysozyme-water system

We study the dynamics of hydration water in the protein lysozyme in the temperature range 180 K相似文献