Reversible Thermoresponsive Plasmonic Core-Satellite Nanostructures That Exhibit Both Expansion and Contraction (UCST and LCST)

The assembly of sophisticated gold nanoparticle constructs where thermoresponsive core-satellite nanostructures are created and the satellites are close enough to the core for strong surface plasmon resonance coupling to occur, has begun to be developed. The linker between the core and the satellites being a thermoresponsive polymer means that a dispersion of these nanostructures will show temperature-dependent optical properties as the distance between the core and the satellites changes. Unlike previous related thermoresponsive core-satellite systems that undergo a single thermoresponsive transition, herein a polymer system with dual thermoresponsive transitions (block copolymer with both lower critical solution temperature and upper critical solution temperature) is employed as a linker that modulates the gap distance between the “core” and “satellites” in response to the temperature. In this way, optical properties of dispersions can be dynamically tuned. The system permits wide and reversible control of the optical properties, which may render them excellent candidates for reversible nanosensors

Post-functionalization of ATRP polymers using both thiol/ene and thiol/disulfide exchange chemistry

In this communication, we report on a new route to the functionalization of ATRP polymers exploiting their halide end-groups, which were converted successfully into reactive disulfide end-groups, using sodium methanethiosulfonate. The resultant disulfide-terminated polymers could then be reacted with different functional thiols to yield functional polymers exploiting either thiol/disulfide exchange chemistry or thiol/ene ‘‘click’’ reactions

The analytical performance of a porous silicon Bloch surface wave biosensors as protease biosensor

We investigate the analytical performance of label free porous silicon Bloch surface wave (BSW) devices as protease sensors. Protease detection is based on the digestion of gelatin, which was covalently immobilized onto the surface modified PSi structure. Exposure to the protease enzyme, subtilisin initiates catalytic degradation of the gelatin gel network. The degradation of this network which is present in the top layer of the sensor, causes a blue shift in the spectral position of the Bloch surface mode. The magnitude of the resonance shift is directly proportional to the concentration of subtilisin and the digestion time. The lowest concentration of subtilisin detected was 370 pM. Secondary spectral features, such as band-edge modes, are relatively insensitive to refractive index changes in the superficial layers and thus can be utilised as an internal reference to exclude any nonspecific adsorption and bonding that may occur through the bulk of the film. The advantages of the system here include fast diffusion of digested product and self-referencing capability

A versatile method for the preparation of carbon-rhodium hybrid catalysts on graphene and carbon black

Strategies for combining the selectivity and efficiency of homogeneous organometallic catalysts with the versatility of heterogeneous catalysts are urgently needed. Herein a direct and modular methodology is presented that provides rapid access to well-defined carbon-rhodium hybrid catalysts. A pre-synthesized Rh(i) complex containing a carbene-triazole ligand was found to be stable for direct immobilization onto unactivated graphene, carbon black and glassy carbon electrodes. Characterization of the heterogeneous systems using X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), inductively coupled plasma-optical emission spectroscopy/mass spectrometry (ICP-OES/MS), Raman spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) confirmed the well-defined nature of the hybrid catalysts. The hybrid catalysts show excellent activity, comparable to that of the homogeneous system for the hydrosilylation of diphenylacetylene, with turnover numbers ranging from 5000 to 48 000. These catalysts are the best reported to date for the hydrosilylation of diphenylacetylene. In common with conventional heterogeneous catalysts, high reusability, due to a lack of Rh metal leaching, was also observed for all carbon-rhodium complexes under investigation

Micropatterning of porous silicon Bragg reflectors with poly(ethylene glycol) to fabricate cell microarrays: Towards single cell sensing

The work presented here describes the development of an optical label-free biosensor based on a porous silicon (PSi) Bragg reflector to study heterogeneity in single cells. Photolithographic patterning of a poly(ethylene glycol) (PEG) hydrogel with a photoinitiator was employed on RGD peptide-modified PSi to create micropatterns with cell adhesive and cell repellent areas. Macrophage J774 cells were incubated to form cell microarrays and single cell arrays. Moreover, cells on the microarrays were lysed osmotically with Milli-Q™ water and the infiltration of cell lysate into the porous matrix was monitored by measuring the red shift in the reflectivity. On average, the magnitude of red shift increased with the increase in the number of cells on the micropatterns. The red shift from the spots with single cells varied from spot to spot emphasizing the heterogeneous nature of the individual cells

Micropatterning of porous silicon Bragg reflectors with poly(ethylene glycol) to fabricate cell microarrays: Towards single cell sensing.

The work presented here describes the development of an optical label-free biosensor based on a porous silicon (PSi) Bragg reflector to study heterogeneity in single cells. Photolithographic patterning of a poly(ethylene glycol) (PEG) hydrogel with a photoinitiator was employed on RGD peptide-modified PSi to create micropatterns with cell adhesive and cell repellent areas. Macrophage J774 cells were incubated to form cell microarrays and single cell arrays. Moreover, cells on the microarrays were lysed osmotically with Milli-Q™ water and the infiltration of cell lysate into the porous matrix was monitored by measuring the red shift in the reflectivity. On average, the magnitude of red shift increased with the increase in the number of cells on the micropatterns. The red shift from the spots with single cells varied from spot to spot emphasizing the heterogeneous nature of the individual cells

Dual bioresponsive mesoporous silica nanocarrier as an "AND" logic gate for targeted drug delivery cancer cells

Despite the rapid development of drug delivery vehicles that react to a specific biological environment, the complexity of triggering drug release in a particular target area remains an enduring challenge. Here, the engineering of bioresponsive polymer-mesoporous silica nanoparticles (MSNs) with function akin to an AND logic gate is described. Polycaprolactone (esterase degradable) is immobilized into the core of MSNs while polyacrylic acid (PAA), which is pH responsive, covered the outside of the MSNs to create a PAA-PCL-MSNs construct. Fluorescence spectroscopy indicates that the construct releases the payload (doxorubicin, cancer drugs) in the presence of, and only in the presence of, both low pH AND esterase. Confocal microscopy and fluorescence lifetime microscopy (FLIM) demonstrate uptake of the intact construct and subsequent intracellular doxorubicin (DOX) delivery into the nucleus. Further in vitro IC50 studies demonstrate the AND logic gate delivery system results in more than an eightfold efficacy against neuroblastoma (SKN-BE(2)) cells in comparison with normal fibroblasts (MRC-5). These results demonstrate the utility of MSN-polymer construct to create an AND gate capable of selectively delivering a drug payload

Heat-treated stainless steel felt as scalable anode material for bioelectrochemical systems

Copyright © 2015 Elsevier Ltd. All rights reserved. This work reports a simple and scalable method to convert stainless steel (SS) felt into an effective anode for bioelectrochemical systems (BESs) by means of heat treatment. X-ray photoelectron spectroscopy and cyclic voltammetry elucidated that the heat treatment generated an iron oxide rich layer on the SS felt surface. The iron oxide layer dramatically enhanced the electroactive biofilm formation on SS felt surface in BESs. Consequently, the sustained current densities achieved on the treated electrodes (1 cm(2)) were around 1.5±0.13 mA/cm(2), which was seven times higher than the untreated electrodes (0.22±0.04 mA/cm(2)). To test the scalability of this material, the heat-treated SS felt was scaled up to 150 cm(2) and similar current density (1.5 mA/cm(2)) was achieved on the larger electrode. The low cost, straightforwardness of the treatment, high conductivity and high bioelectrocatalytic performance make heat-treated SS felt a scalable anodic material for BESs

Surfactant treatment of carbon felt enhances anodic microbial electrocatalysis in bioelectrochemical systems

This study reports a simple and effective method to make carbon felt surface hydrophilic and positively-charged by means of cetyltrimethylammonium bromide (CTAB) soaking. X-ray photoelectron spectroscopy and cyclic voltammetry indicated that CTAB could form a surfactant layer on carbon felt surface with the polar heads exposing outwardly. In an acetate-fed bioanode, the start-up time of current production and the time to reach stable current output at the CTAB-treated felt anodes were 36.1% and 49.4% shorter than the untreated anodes, respectively. Moreover, the maximum current output with these treated electrodes was 23.8% higher than the untreated counterparts. These results indicate that the CTAB treatment of carbon felt accelerates the anodic biofilm formation and enhances current output of BESs. © 2013 Elsevier B.V