Rapid Point-of-Care Electrochemical Sensor for the Detection of Cancer Tn Antigen Carbohydrate in Whole Unprocessed Blood.

Improving outcomes for cancer patients during treatment and monitoring for cancer recurrence requires personalized care which can only be achieved through regular surveillance for biomarkers. Unfortunately, routine detection for blood-based biomarkers is cost-prohibitive using currently specialized laboratories. Using a rapid self-assembly sensing interface amenable to methods of mass production, we demonstrate the ability to detect and quantify a small carbohydrate-based cancer biomarker, Tn antigen (αGalNAc-Ser/Thr) in a small volume of blood, using a test format strip reminiscent of a blood glucose test. The detection of Tn antigen at picomolar levels is achieved through a new transduction mechanism based on the impact of Tn antigen interactions on the molecular dynamic motion of a lectin cross-linked lubricin antifouling brush. In tests performed on retrospective blood plasma samples from patients presenting three different tumor types, differentiation between healthy and diseased patients was achieved, highlighting the clinical potential for cancer monitoring.

Frequency Dependent Silica Dissolution Rate Enhancement under Oscillating Pressure via an Electrochemical Pressure Solution-like, Surface Resonance Mechanism.

From atomic force microscopy (AFM) experiments, we report a new phenomenon in which the dissolution rate of fused silica is enhanced by more than 5 orders of magnitude by simply pressing a second, dissimilar surface against it and oscillating the contact pressure at low kHz frequencies in deionized water. The silica dissolution rate enhancement was found to exhibit a strong dependence on the pressure oscillation frequency consistent with a resonance effect. This harmonic enhancement of the silica dissolution rate was only observed at asymmetric material interfaces (e.g., diamond on silica) with no evidence of dissolution rate enhancement observed at symmetric material interfaces (i.e., silica on silica) within the experimental time scales. The apparent requirement for interface dissimilarity, the results of analogous experiments performed in anhydrous dodecane, and the observation that the silica "dissolution pits" continue to grow in size under contact stresses well below the silica yield stress refute a mechanical deformation or chemo-mechanical origin to the observed phenomenon. Instead, the silica dissolution rate enhancement exhibits characteristics consistent with a previously described 'electrochemical pressure solution' mechanism, albeit, with greatly amplified kinetics. Using a framework of electrochemical pressure solution, an electrochemical model of mineral dissolution, and a recently proposed "surface resonance" theory, we present an electro-chemo-mechanical mechanism that explains how oscillating the contact pressure between dissimilar surfaces in water can amplify surface dissolution rates by many orders of magnitude. This reaction rate enhancement mechanism has implications not only for dissolution but also for potentially other reactions occurring at the solid-liquid interface, e.g. catalysis.

Percolation in networks of 1-dimensional objects: comparison between Monte Carlo simulations and experimental observations.

Planar networks composed of 1-dimensional nanometer scale objects such as nanotubes or nanowires have been attracting growing interest in recent years. In this work we directly compare the percolation threshold of silver nanowire networks to predictions from Monte Carlo simulations, focusing particularly on understanding the impact of real world imperfections on the percolation onset in these systems. This work initially determines the percolation threshold as calculated from an ideal system using Monte Carlo methods. On this foundation we address the effects of perturbations in length, angular anisotropy and radius of curvature of the 1-dimensional objects, in line with those observed experimentally in purposely fabricated samples. This work explores why two-dimensional stick models in the literature currently underestimate the percolation onset in real systems and identifies which of the network's features play the most significant role in that deviation.

Transparent Electrodes Based on Silver Nanowire Networks: From Physical Considerations towards Device Integration.

The past few years have seen a considerable amount of research devoted to nanostructured transparent conducting materials (TCM), which play a pivotal role in many modern devices such as solar cells, flexible light-emitting devices, touch screens, electromagnetic devices, and flexible transparent thin film heaters. Currently, the most commonly used TCM for such applications (ITO: Indium Tin oxide) suffers from two major drawbacks: brittleness and indium scarcity. Among emerging transparent electrodes, silver nanowire (AgNW) networks appear to be a promising substitute to ITO since such electrically percolating networks exhibit excellent properties with sheet resistance lower than 10 Ω/sq and optical transparency of 90%, fulfilling the requirements of most applications. In addition, AgNW networks also exhibit very good mechanical flexibility. The fabrication of these electrodes involves low-temperature processing steps and scalable methods, thus making them appropriate for future use as low-cost transparent electrodes in flexible electronic devices. This contribution aims to briefly present the main properties of AgNW based transparent electrodes as well as some considerations relating to their efficient integration in devices. The influence of network density, nanowire sizes, and post treatments on the properties of AgNW networks will also be evaluated. In addition to a general overview of AgNW networks, we focus on two important aspects: (i) network instabilities as well as an efficient Atomic Layer Deposition (ALD) coating which clearly enhances AgNW network stability and (ii) modelling to better understand the physical properties of these networks.