Self-assembled monolayer-based piezoelectric flow immunosensor for the determination of canine immunoglobulin

Metal induced self-assembly of designed V-shape protein into 2D wavy supramolecular nanostructure

In order to understand and imitate the more complex bio-processes and fascinating functions in nature, protein self-assembly has been studied and has attracted more and more interest in recent years. Artificial self-assemblies of proteins have been constructed through many strategies. However, the design of complicated protein self-assemblies utilizing the special profile of building blocks remains a challenge. We herein report linear and 2D nanostructures constructed from a V shape SMAC protein and induced by metal coordination. Zigzag nanowires and wavy 2D nanostructures have been demonstrated by AFM and TEM. The zigzag nanowires can translate to a 2D nanostructure with an excess of metal ions, which reveals the step by step assembly process. Fluorescence and UV/Vis spectra have also been obtained to further study the mechanism and process of self-assembly. Upon the protein nanostructure, fluorescence resonance energy transfer (FRET) could also be detected using fluorescein modified proteins as building blocks. This article provides an approach for designing and controlling self-assembled protein nanostructures with a distinctive topological morphology.

Direct determination of a small-molecule drug, valproic Acid, by an electrically-detected microcantilever biosensor for personalized diagnostics

Direct, small-molecule determination of the antiepileptic drug, valproic acid, was investigated by a label-free, nanomechanical biosensor. Valproic acid has long been used as an antiepileptic medication, which is administered through therapeutic drug monitoring and has a narrow therapeutic dosage range of 50-100 μg·mL-1 in blood or serum. Unlike labeled and clinically-used measurement techniques, the label-free, electrical detection microcantilever biosensor can be miniaturized and simplified for use in portable or hand-held point-of-care platforms or personal diagnostic tools. A micromachined microcantilever sensor was packaged into the micro-channel of a fluidic system. The measurement of the antiepileptic drug, valproic acid, in phosphate-buffered saline and serum used a single free-standing, piezoresistive microcantilever biosensor in a thermally-controlled system. The measured surface stresses showed a profile over a concentration range of 50-500 μg·mL-1, which covered the clinically therapeutic range of 50-100 μg·mL-1. The estimated limit of detection (LOD) was calculated to be 45 μg·mL-1, and the binding affinity between the drug and the antibody was measured at around 90 ± 21 μg·mL-1. Lastly, the results of the proposed device showed a similar profile in valproic acid drug detection with those of the clinically-used fluorescence polarization immunoassay.

Engineering the 3D architecture and hydrophobicity of methyltrichlorosilane nanostructures

Three-dimensional nano-architectures with varying shape, morphology and size were fabricated by the phase separation of methyltrichlorosilane (CH(3)SiCl(3)) on commercially available glass and SiO(2) substrates. By changing the synthesis conditions, CH(3)SiCl(3) nanostructures evolved from discrete to quasi-network or from fibrous to spherical forms. Individual nanofibers and nanospheres have diameters of 18-90 and 240-300 nm, respectively, while the film thicknesses could reach 320 nm. The possible mechanisms for the three-dimensional growth of nanofibers and nanospheres are proposed. The resultant morphologies exhibited two main energy states: Wenzel and Cassie-Baxter states. Moreover, superhydrophobic surfaces with both high contact angle and high hysteresis resulted from the growth of the nanostructures. The new approaches presented herein are important additions to the current range of surface modification methods and could harness novel physical and chemical properties conducive to optimal performance in biosensing, antistiction, droplet manipulation, drag reduction, protein adsorption, and cell adhesion studies.