Hastings Hopkins (brandytile44)

We report a dual gate/common channel organic transistor architecture designed for quantifying the concentration of one of the strands of miRNA-21 in solution. The device allows one to measure the differential response between two gate electrodes, viz. one sensing and one reference, both immersed in the electrolyte above the transistor channel. Hybridization with oligonucleotide in the picomolar regime induces a sizable reduction of the current flowing through the transistor channel. The device signal is reported at various gate voltages, showing maximum sensitivity in the sublinear regime, with a limit of detection as low as 35 pM. We describe the dose curves with an analytical function derived from a thermodynamic model of the reaction equilibria relevant in our experiment and device configuration, and we show that the apparent Hill dependence on analyte concentration, whose exponent lies between 0.5 and 1, emerges from the interplay of the different equilibria. The binding free energy characteristic of the hybridization on the device surface is found to be approximately 20% lower with respect to the reaction in solution, hinting to partially inhibiting effect of the surface and presence of competing reactions. Impedance spectroscopy and surface plasmon resonance (SPR) performed on the same oligonucleotide pair were correlated to the electronic current transduced by the EGOFET, and confirmed the selectivity of the biorecognition probe covalently bound on the gold surface.As one of the most common and noticeable superbugs, methicillin-resistant Staphylococcus aureus (MRSA) has long been a major threat to public health. To meet the demand for effective diagnosis of MRSA-induced infection, it is urgent to establish rapid assay method for this type of pathogen. selleckchem In this study, an aqueous soluble cellular wall-binding domain (CWBD) protein from bacteriophage P108 was obtained with a recombinant expression technique. It can act as a wide-spectrum binding agent for all MRSA strains and exclude the interference from methicillin-susceptible strains of Staphylococcus aureus and other species of bacteria. To establish a lateral flow assay (LFA) method for MRSA, CWBD-coupled time-resolved fluorescent microspheres (FMs) were used as signal probes for tracing MRSA, and a nitrocellulose membrane immobilized with porcine IgG was used to capture MRSA. With the LFA based on sandwich format, MRSA can be assayed within 10 min with a broad linear range of 6.6 × 102-6.6 × 107 CFU/mL. Its application potential has been demonstrated by assaying different types of bacteria-contaminated real samples. The results suggest that the LFA strip using recombinant CWBD as the recognition agent provides a rapid, portable, cost-effective approach for point-of-care testing of MRSA.α-Glucosidase (α-Glu) and its inhibitors play critical roles in diabetes therapy. Herein, a simple and ultra-sensitive fluorescence sensing approach was fabricated for α-Glu activity monitoring and natural inhibitor screening by electrostatically confining negatively charged glutathione-capped copper nanoclusters (GSH-CuNCs) on exfoliation-free and positively charged 2D boehmite (Boe) nanosheets. Boe significantly improved the fluorescence emission/stability of GSH-CuNCs and simultaneously led to an obvious blue-shift of the excitation peak of CuNCs from 365 nm to 330 nm. As a result, the fluorescence emission of Boe@GSH-CuNCs was efficiently quenched by 4-nitrophenyl-α-D-glucopyranoside (PNPG) with a maximum absorbance peak (λmax) at 310 nm via inner filter effect, and sequentially recovered by α-Glu through the hydrolysis of PNPG to p-nitrophenol (λmax = 410 nm). Accordingly, an ultra-sensitive fluorescence assay for the determination of α-Glu activity was proposed by using Boe@GSH-CuNCs as fluorescence probes. The detection limit of 0.43 U/L was achieved, which was lower than most of other α-Glu activity assays. Furthermore, this method was capable of screening α-Glu