Rapid fingerprinting of bacterial species using nanocavities created on screen-printed electrodes modified by β-cyclodextrin.

Rapid and precise identification of infectious microorganisms is important across a range of applications where microbial contamination can cause serious issues ranging from microbial resistance to corrosion. In this paper a screen-printed, polymeric β-cyclodextrin (β-CD) modified electrode, affording nanocavities for inclusion of the analytes, is shown as a disposable sensor capable of identifying bacteria by their metabolites. Three bacterial species were tested: two from the genus, () and (), and (), a member of the family, .

An Electrochemistry and Computational Study at an Electrified Liquid-Liquid Interface for Studying Beta-Amyloid Aggregation.

Amphiphilic peptides, such as Aß amyloids, can adsorb at an interface between two immiscible electrolyte solutions (ITIES). Based on previous work (vide infra), a hydrophilic/hydrophobic interface is used as a simple biomimetic system for studying drug interactions. The ITIES provides a 2D interface to study ion-transfer processes associated with aggregation, as a function of Galvani potential difference.

New Blatter-type radicals from a bench-stable carbene.

Stable benzotriazinyl radicals (Blatter's radicals) recently attracted considerable interest as building blocks for functional materials. The existing strategies to derivatize Blatter's radicals are limited, however, and synthetic routes are complex. Here, we report that an inexpensive, commercially available, analytical reagent Nitron undergoes a previously unrecognized transformation in wet acetonitrile in the presence of air to yield a new Blatter-type radical with an amide group replacing a phenyl at the C(3)-position.

Emulsification at the Liquid/Liquid Interface: Effects of Potential, Electrolytes and Surfactants.

Emulsification of oils at liquid/liquid interfaces is of fundamental importance across a range of applications, including detergency. Adsorption and partitioning of the anionic surface active ions at the interface between two immiscible solutions is known to cause predictable chaos at the transfer potential region of the surfactant. In this work, the phenomenon that leads to the chaotic behaviour shown by sodium dodecylbenzene sulfonate (SDBS) at the water/1,2-dichloroethane interface is applied to commercial surfactants and aqueous/glyceryl trioleate interface.

Graphene oxide nanocapsules within silanized hydrogels suitable for electrochemical pseudocapacitors.

Soft biocompatible gels comprised of rolled up graphene oxide nanocapsules within the pores of silanized hydrogels may be used as electrochemical pseudocapacitors with physiological glucose or KOH as a reducing agent, affording a material suitable for devices requiring pulses with characteristic time less than a second.

Platinum(II) complexes of N^C^N-coordinating 1,3-bis(2-pyridyl)benzene ligands: thiolate coligands lead to strong red luminescence from charge-transfer states.

A new family of platinum(II) complexes of the form PtL(n)SR have been prepared, where L(n) represents a cyclometalating, N^C^N-bound tridentate ligand and SR is a monodentate thiolate ligand. The complexes fall into two groups, those of PtL(1)SR where HL(1) = 1,3-bis(2-pyridyl)benzene, and those of PtL(2)SR, where HL(2) = methyl 3,5-bis(2-pyridyl)benzoate. Each group consists of five complexes, where R = CH3, C6H5, p-C6H4-CH3, p-C6H4-OMe, p-C6H4-NO2.

Modification of electrode surfaces by self-assembled monolayers of thiol-terminated oligo(phenyleneethynylene)s.

The wire-like properties of four S-(4-{2-[4-(2-phenylethynyl)phenyl]ethynyl}phenyl) thioacetate derivatives, PhC≡CC(6)H(4)C≡CC(6)H(4)SAc (1), H(2)NC(6)H(4)C≡CC(6)H(4)C≡CC(6)H(4)SAc (2), PhC≡CC(6)H(2)(OMe)(2)C≡CC(6)H(4)SAc (3) and AcSC(6)H(4)C≡CC(6)H(4)C≡CC(6)H(4)SAc (4) (Figure 1), all of which possess a high degree of conjugation along the oligo(phenyleneethynylene) (OPE) backbone, were investigated as self-assembled monolayers (SAMs) on gold and platinum electrodes by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The redox probe [Fe(CN)(6)](4)(-) was used in both the CV and impedance experiments. The results indicate that the thiolates derived from thioacetate-protected precursor molecules 1 and 2 form well-ordered monolayers on a gold electrode, whereas SAMs derived from 3 and 4 exhibit randomly distributed pinholes.

Chiral acid selectivity displayed by PEDOT electropolymerised in the presence of chiral molecules.

Chiral conducting polymers prepared by electropolymerising PEDOT in the presence of chiral anions such as hyaluronic acid and anionic collagen or in a chiral nematic phase (hydroxypropyl cellulose, HPC) show excellent chiral acid recognition. This paper demonstrates the enantioselective recognition and transfer of protonated mandelic acid and protons using chiral PEDOTs. Discrimination between (R)-(-)- and (S)-(+)-mandelic acid was observed using cyclic voltammetry and square-wave voltammetry.

Electron transport in supported and tethered lipid bilayers modified with bioelectroactive molecules.

Tethered bilayer lipid membranes (tBLMs) are commonly used as model membranes. However, in biophysical studies, free-standing membranes (“black” lipid membranes) are more realistic models of cellular processes. In this article, we discuss the rates of electron transfer in both types of bilayer lipid membranes.

Chiral interactions of the drug propranolol and α1-acid-glycoprotein at a micro liquid-liquid interface.

The investigation of chiral interactions of drugs with plasma proteins is of fundamental importance for drug efficacy and toxicity studies. In this paper, we demonstrate a simple liquid-liquid interface procedure for investigating chiral interactions. Chiral discrimination of the enantiomers of a basic drug, propranolol, was achieved at a micro liquid-liquid interface, using α(1)-acid-glycoprotein (AGP) as a chiral acute phase plasma protein.

A thermally actuated microgripper as an electrochemical sensor with the ability to manipulate single cells.

The design and fabrication of a thermally actuated polymeric microgripper incorporating a bare gold working electrode is described. Initial electrochemical tests confirm that the microgripper sensor works as an effective microelectrode, opening up exciting possibilities in single cell measurements.

Comparative electrochemical and impedance studies of self-assembled rigid-rod molecular wires and alkanethiols on gold substrates.

A study of the charge transfer and self-assembly characteristics of two new rigid-rod molecular wires 1 and 2 assembled on polycrystalline gold electrodes was carried out using electrochemical impedance spectroscopy and cyclic voltammetry. This class of wires have precisely controlled (ca. 1.

Modification of the chiral selectivity of D-glucose oxidase and L-lactate oxidase in a collagen matrix.

A chiral, biocompatible, conducting material comprising collagen I, silica gel and ferrocene was found to modify and invert, the chiral selectivity of D-glucose oxidase and L-lactate oxidase. This result may have implications as collagen matrices are widely used in drug delivery, biosensing and tissue engineering. Investigations were carried out using electrochemical methods, FTIR spectroscopy and circular dichroism.

Chiral detection at a liquid-liquid interface.

Chiral ion transfer and detection at a liquid-liquid interface using chiral stationary phases such as cyclodextrins; could lead to alternative methods of chiral detection and separation.

A biosensor for monitoring formaldehyde using a new lipophilic tetrathiafulvalene-tetracyanoquinodimethane salt and a polyurethane membrane.

A format for a disposable screen-printed biosensor was investigated for monitoring formaldehyde. The screen-printed sensor format comprised a working electrode (WE) modified with platinised carbon, a new lipophilic tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ) salt as mediator, a plasticised polyurethane membrane (TECOFLEX SG80, PU) with anionic sites and the enzyme (formaldehyde dehydrogenase FOH) and co-factor (beta-NAD(+)). The new lipophilic TTF-TCNQ salt gave a smooth, robust electrode surface rather than microcrystalline deposits of the salt observed with TTF-TCNQ salts.

A study of the effect of proteins and endogenous cations on a lipophilic beta-cyclodextrin-based potentiometric lidocaine sensor using discrete solution and flow-injection analysis.

2,6 Didodecyl beta cyclodextrin (2,6ddbetaCD) modified ion-selective electrodes (ISEs) were used in discrete solutions and in a flow injection analysis manifold for monitoring the local anaesthetic lidocaine hydrochloride (lignocaine) in the presence of endogenous cations and proteins. Membrane matrices comprised of either high molecular weight poly (vinyl chloride) (PVC) or polyurethane (Tecoflex SG 80) were compared. The behaviour of these electrodes in the presence of bovine serum albumin (BSA), alpha(1) acid glycoprotein (AAG) and human serum (HS) indicate that the Tecoflex-based membrane matrices are preferable to PVC as the drift induced by proteins on baseline lines and peak height reproducibility was considerably reduced in the former.

Towards multifunctional microelectrode arrays.

A single microelectrode array platform, divided into groups of microelectrodes with flexible multiplexing can enable a 'defective' cluster of microelectrodes to be readily identified, by comparing normalised currents with the numbers of microelectrodes in the groups of arrays. This generic design principle may be extended for integrating multiple analyte sensing in a single microarray platform. The calibration of the microelectrode arrays, using white light interferometry and electrochemistry is described.

Enantioselectivity of potentiometric sensors with application of different mechanisms of chiral discrimination.

In the recent years, numerous successful applications of various chiral selectors in high performance separation methods have generated an increasing interest in the application of some of these compounds as electroactive species in potentiometric sensors. The objective of this work was to examine the enantioselectivy of several different sensors employing substituted cyclodextrins, example antibiotic teicoplanin and electrodeposited conductive polymers for various chiral analytes. Varying degrees of enantioselectivity were found for the ion-selective electrodes examined, depending on the chiral selector used and the target analyte.

Mutations in the FAD binding domain cause stress-induced misoxidation of the endoplasmic reticulum oxidoreductase Ero1beta.

Disulfide bond catalysis is an essential component of protein biogenesis in the secretory pathway, from yeast through to man. In the endoplasmic reticulum (ER), protein-disulfide isomerase (PDI) catalyzes the oxidation and isomerization of disulfide bonds and is re-oxidized by an endoplasmic reticulum oxidoreductase (ERO). The elucidation of ERO function was greatly aided by the genetic analysis of two ero mutants, whose impairment results from point mutations in the FAD binding domain of the Ero protein.

An introduction to thiol redox proteins in the endoplasmic reticulum and a review of current electrochemical methods of detection of thiols.

This aim of this paper is to expound the complexity of thiol redox systems in the endoplasmic reticulum of eukaryotic cells to the electroanalytical community. A summary of the state of the art in electrochemical methods for detection of thiols gives an insight into the challenges that need to be addressed to bridge the disparity between current analytical techniques and applications in a 'real' biological scenario.

Recommendation for measuring and reporting chloride by ISEs in undiluted serum, plasma or blood.

The proposed recommendation for measuring and reporting chloride in undiluted plasma or blood by ion-selective electrodes (ISEs) will provide results that are identical to chloride concentrations measured by coulometry for standardized normal plasma or blood samples. It is applicable to all current ISEs dedicated to chloride measurement in undiluted samples that meet the requirements. However, in samples with reduced water concentration, results by coulometry are lower than by ion-selective electrode due to volume displacement.

Modular assembly of a preorganised, ditopic receptor for dicarboxylates.

Two types of calix[4]arene derived hosts for anions with, respectively, 1,3-alternate and cone conformations have been prepared; the 1,3-alternate system binds dicarboxylate anions in a ditopic manner while the cone compounds are deprotonated by carboxylates.

Individually addressable recessed gold microelectrode arrays with monolayers of thio-cyclodextrin nanocavities.

Four, individually addressable 30 microm diameter, e-beam deposited, gold microelectrodes recessed by 6 microm were suitably spaced on a single substrate to avoid diffusional overlap between each microelectrode. The single substrate device was functionalised with thiolated alpha-, beta-, and gamma-cyclodextrin nanocavities without spacer groups to ensure close proximity of the cavities to the electrode surface. The microelectrodes were assessed in two stages.

Tissue-specific expression and dimerization of the endoplasmic reticulum oxidoreductase Ero1beta.

Endoplasmic reticulum oxidoreductases (Eros) are essential for the formation of disulfide bonds. Understanding disulfide bond catalysis in mammals is important because of the involvement of protein misfolding in conditions such as diabetes, arthritis, cancer, and aging. Mammals express two related Ero proteins, Ero1alpha and Ero1beta.

Potential of enzyme mimics in biomimetic sensors: a modified-cyclodextrin as a dehydrogenase enzyme mimic.

This paper reports the application of a dehydrogenase enzyme mimic as a biomimetic sensor. The model compound investigated was a beta-cyclodextrin (beta-CD) derivative with a nicotinamide group attached to the secondary face of a beta-CD (Fig. 1g).