Molecular adaptors

The invention relates to transmembrane protein pore for use in detecting a analyte in a sample. The pore comprises a molecular adaptor that facilitates an interaction between the pore and the analyte. The adaptor is covalently attached to the pore in an orientation that allows the analyte to be detected using the pore

Flexible serialized complementary coils for the detection of moving LF RFID tags

This paper focuses on bats detection, tagged at low frequency (134.2 kHz) with glasstags (typically : length 15 mm and radius 1 mm). The physical link is magnetic coupling. We propose the design of a reader antenna based on a multi-coil structure. The goal is to obtain the highest surface of detection, at a distance of 10-15 cm, i.e. defining a so called “volume of detection”. The cylindrical volume of the glasstags involves a high sensitivity to the magnetic field orientation. As the bats are flying, the tags equivalent surfaces are considered with a random orientation. Using complementary coils principle enables to detect fruitfully the glasstags in two perpendicular orientations named HM (horizontal mode) and VM (vertical mode). We propose the design of a flexible reader antenna structure by means of an adhesive copper tape fixed on a cloth. The prototype is designed after CST simulations and empirical formula evaluations. Measurements show a good agreement with the modelling and tests of detection are performed with the proposed reader antenna. By comparison with a commercial antenna, the prototype reaches the highest volume of detection in both HM and VM modes and fulfills the targeted distance of detection

Design of 1cm2 coils for HF RFID instruments tracking with detection range improvement

This paper concerns an application of magnetic coupling RFID technology at 13.56 MHz (HF band) for tracking devices such as instruments. The tag size is defined to be ergonomically small compared to the hand, and fixed inside a maximum surface of 1 cm 2. The case of multiple detections is considered, and consequently the reader surface of control is considered wide enough to include several instruments at the same time during a logistic control process. The use of such a small RFID tag is almost impossible using a large reader loop of 15×30 cm 2, as chosen for the tests. The key idea of the paper is then the addition of a resonator that enables to create the mandatory physical link by means of magnetic coupling between the tag coil and the resonator coil and between the resonator coil and the reader loop. Finally the detection range is highly improved by the presence of this resonator and results demonstrate that it is possible to detect these small RFID “1 by 1 cm 2 tags” at a distance of 1.5 cm to 3 cm, depending on their orientations

LF RFID chequered loop antenna for pebbles on the beach detection

This paper focus on low frequency (125 kHz) RFID by magnetic coupling, more precisely using glasstag type of tags in the context of pebble detection on the beach. The challenge is to detect over a wide area very small size tags which are highly sensitive to the orientation of the magnetic field. To improve the detection ability of the reader loop antenna, the paper proposes to exploit the principle of complementary loops. Theoretical simulations with MATLAB show the potential increase by means of mutual inductance value along a displacement of the tag. A prototype of a chequered loop structure is presented and tested with a classical low power RFID reader to demonstrate the improvement without increasing the current in LF reader loops. The detection performances reach 12,8% for a 900 cm 2 surface of a prototype reader loop, whatever the orientation of the glasstag

Coaxially distributed diameter sub-coil twisted loop antenna in HF RFID

This paper proposes an HF (High Frequency) transmitting coil less sensitive to the angular and position misalignments of the small receiving coil. The DDC (Distributed Diameter Coil) shape and TLA (Twisted Loop Antenna) allow respectively minimizing the disturbance of the magnetic link due to the lateral misalignment and the relative tilting direction of the transmitting coil to the receiving coil. The magnetic coupling link obtained from DDC TLA coils is illustrated by comparison with conventional TLA in the case of HF RFID

Kinetics of Wnt-Driven β-Catenin Stabilization Revealed by Quantitative and Temporal Imaging

The Wnt/β-catenin signal transduction pathway regulates a broad range of developmental processes. Aberrant activation of the Wnt pathway leads to cancer and degenerative diseases. β-catenin is a key signaling molecule that is frequently used as a direct monitor of Wnt pathway activation. This paper describes a multi-parametric method for quantitative analysis of cellular β-catenin protein levels in a rapid and high-throughput manner. The assay offers temporally resolved detection of Wnt-stimulated accumulation of β-catenin, simultaneously detecting cell number, and it sheds light onto the kinetics of posttranslational stabilization of β-catenin

Modeling the Time Evolution of the Nanoparticle-Protein Corona in a Body Fluid

Background: Nanoparticles in contact with biological fluids interact with proteins and other biomolecules, thus forming a dynamic corona whose composition varies over time due to continuous protein association and dissociation events. Eventually equilibrium is reached, at which point the continued exchange will not affect the composition of the corona. Results: We developed a simple and effective dynamic model of the nanoparticle protein corona in a body fluid, namely human plasma. The model predicts the time evolution and equilibrium composition of the corona based on affinities, stoichiometries and rate constants. An application to the interaction of human serum albumin, high density lipoprotein (HDL) and fibrinogen with 70 nm N-iso-propylacrylamide/N-tert-butylacrylamide copolymer nanoparticles is presented, including novel experimental data for HDL. Conclusions: The simple model presented here can easily be modified to mimic the interaction of the nanoparticle protein corona with a novel biological fluid or compartment once new data will be available, thus opening novel applications in nanotoxicity and nanomedicine

Monitoring Voltage-Dependent Charge Displacement of Shaker B-IR K+ Ion Channels Using Radio Frequency Interrogation

Here we introduce a new technique that probes voltage-dependent charge displacements of excitable membrane-bound proteins using extracellularly applied radio frequency (RF, 500 kHz) electric fields. Xenopus oocytes were used as a model cell for these experiments, and were injected with cRNA encoding Shaker B-IR (ShB-IR) K+ ion channels to express large densities of this protein in the oocyte membranes. Two-electrode voltage clamp (TEVC) was applied to command whole-cell membrane potential and to measure channel-dependent membrane currents. Simultaneously, RF electric fields were applied to perturb the membrane potential about the TEVC level and to measure voltage-dependent RF displacement currents. ShB-IR expressing oocytes showed significantly larger changes in RF displacement currents upon membrane depolarization than control oocytes. Voltage-dependent changes in RF displacement currents further increased in ShB-IR expressing oocytes after ∼120 µM Cu2+ addition to the external bath. Cu2+ is known to bind to the ShB-IR ion channel and inhibit Shaker K+ conductance, indicating that changes in the RF displacement current reported here were associated with RF vibration of the Cu2+-linked mobile domain of the ShB-IR protein. Results demonstrate the use of extracellular RF electrodes to interrogate voltage-dependent movement of charged mobile protein domains — capabilities that might enable detection of small changes in charge distribution associated with integral membrane protein conformation and/or drug–protein interactions

Zeptomole Electrochemical Detection of Metallothioneins

Thiol-rich peptides and proteins possess a large number of biological activities and may serve as markers for numerous health problems including cancer. Metallothionein (MT), a small molecular mass protein rich in cysteine, may be considered as one of the promising tumour markers. The aim of this paper was to employ chronopotentiometric stripping analysis (CPSA) for highly sensitive detection of MT.In this study, we used adsorptive transfer stripping technique coupled with CPSA for detection of cysteine, glutathione oxidized and reduced, phytochelatin, bovine serum albumin, and metallothionein. Under the optimal conditions, we were able to estimate detection limits down to tens of fg per ml. Further, this method was applied to detect metallothioneins in blood serum obtained from patients with breast cancer and in neuroblastoma cells resistant and sensitive to cisplatin in order to show the possible role of metallothioneins in carcinogenesis. It was found that MT level in blood serum was almost twice higher as compared to the level determined in healthy individuals.This paper brings unique results on the application of ultra-sensitive electroanalytical method for metallothionein detection. The detection limit and other analytical parameters are the best among the parameters of other techniques. In spite of the fact that the paper is mainly focused on metallothionein, it is worth mentioning that successful detection of other biologically important molecules is possible by this method. Coupling of this method with simple isolation methods such as antibody-modified paramagnetic particles may be implemented to lab-on-chip instrument