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Due to the complexity of the synthetic process of cobalt phosphides (CoP), ongoing efforts concentrate on simplifying the preparation process of CoP. In this work, amino tris(methylene phosphonic acid) (ATMP, L1) and melamine (MA, L2) are assembled into two-dimensional (2D) organic nanostructures by hydrogen bonding and ionic interactions

Reasonable control of the redox states within the catalytic units together with the interconnection degrees of the substrate is of great significance in the modulation of a well-performing transducer. Herein, a novel carbon black (CB)-modified copper metal–organic framework nanomaterial (CB@Cu-MOF) prepared at room temperature was utilized as a precursor to synthesize mixed-valent copper–oxide composite catalysts (NC/CuxO-T). By tuning the carbonization process of the precursor at different temperatures (T = 100 °C, 200 °C, 300 °C and 400 °C), the different ratio configurations of the redox-alternated CuxO portions were successfully controlled with the simultaneous effective tailoring of the defect abundance in the N-doped carbon substrate. As a result, an optimized NC/CuxO-300 electrochemical H2O2 sensor was able to present a low detection limit (0.26 μM) and decent linear ranges (0.02–1.79 mM and 2.29–9.29 mM). Our strategy using easily available initial materials with mild preparation conditions is expected to promote the practical application of the star materials in laboratories.

Mercury ion (Hg(2+)) is an extremely toxic ion, which will accumulate in human bodies and cause severe nervous system damage. Therefore, the sensitive and efficient monitoring of Hg(2+) in human bodies is of great importance. Upconversion nanoparticle (UCNPs) based nano probes exhibit no autofluorescence, deep penetration depth and chemical stability in biological samples, as well as a large anti-stokes shift. In this study, we have developed thiazole-derivative-functionalized UCNPs, and employed an upconversion emission intensity ratio of 540 nm to 803 nm (I540/I803) as a ratiometric signal to detect Hg(2+) in living cells showing excellent photo stability and high selectivity. Our nano probe was characterized using transmission electron microscopy (TEM) and powder X-ray diffraction (PXRD). The low cytotoxicity of our probe was confirmed by an MTT assay and the UCL test in HeLa cells was carried out by confocal microscopy. Our results demonstrated that organic-dye-functionalized UCNPs should be a good strategy for detecting toxic metal ions when studying cellular biosystems.

Horseradish peroxidase (HRP) was immobilized on redox buckypapers followed by electropolymerization of pyrrole-modified concanavalin A enabling the subsequent additional immobilization of the glycoprotein glucose oxidase (GOx). Biocatalytic buckypapers were formed using pyrene-modified 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) or bis-Pyr-ABTS, a redox mediator, as a cross-linker. ABTS-functionalized buckypaper enhances the electron transfer of the bioelectrocatalytic reduction of H2O2 by HRP. Since H2O2 is produced during glucose oxidation by GOx in the presence of oxygen, the bienzymatic GOx–HRP biocathode achieves the complete reduction of oxygen into water. A clearly improved performance of the biocathode was obtained by using an improved biocompatible immobilization strategy, enabling the prevention of enzyme loss while ensuring both diffusion of glucose and O2 and the local production of H2O2. These freestanding flexible oxygen-reducing biocathodes can operate under physiological conditions and show a high onset potential at 0.60 (±0.01) V. In the presence of glucose (5 mM), such biocathodes exhibit a stable current density output of 1.1 (±0.1) mA cm−2 at 0.1 V under continuous one-hour discharge. Furthermore, a marked increase in lifetime was observed, the biocathode displaying 64% of its initial electrocatalytic activity after 15 days. Accepted version

Two methods for phenol determination based on the suppression of chemiluminescence (CL) produced upon HRP-catalysed oxidation of luminol were developed. One method used an enhanced CL reaction with 3-(10′-phenothiazinyl)-propane-1-sulfonate and 4-morpholinopyridine as primary and secondary enhancers, respectively, and another one is free of the enhancers. A comparison of the phenol assay with enhancers showed much higher sensitivity and lower LDL value than the assay without enhancers. In addition, the amount of HRP used in the assay with enhancers is 40 times less than in the assay without them. The study of the specificity of the developed assays demonstrated that in the assay without enhancers several phenol compounds, for instance, unsubstituted phenol, suppressed the CL intensity, whereas other phenols, such as 4-chlorophenol and 2,4-dichlorophenol, increased the light output. In contrast to that assay, in the assay with enhancers all tested phenols suppressed the CL intensity. Upon the analysis of phenols in the water plant effluents using the assay without the enhancers, a high matrix effect was observed. On the other hand, the analysis of the same effluents using the assay with enhancers did not show any matrix effect, and the recovery values from the spiked samples were found to be 92–96%.

A sensitive electrochemical DNA biosensor based on the amplification of Au nanoparticles (AuNPs) has been developed. The AuNPs were modified with two types of signaling reporter DNAs, i.e. a methylene blue probe (MB-probe 2-SH) and T10 with a methylene blue signaling molecule (MB-T10-SH), forming DNA-AuNP conjugates. The MB-probe 2-SH is complementary to the target DNA, while MB-T10-SH is not. The presence of MB-T10-SH reduces the cross-reaction between target DNA and MB-probe 2-SH on the AuNPs, resulting in increased sensitivity of the biosensor. In our assay, the DNA sensor is fabricated by immobilizing a capture probe on the surface of the Au electrode, which then hybridizes with the corresponding target DNA, and further hybridizes with a DNA-Au conjugate. The signal of MB is measured by differential pulse voltammetry, while the DNA-Au conjugate enables the detection of target DNA in the linear range of 10(-13) to 10(-8) M with the detection limit as low as 50 fM.

Over the last decade Metal-Enhanced Fluorescence (MEF) has emerged as the next generation of fluorescence spectroscopy, i.e. near-field fluorescence. However, in contrast to our collective knowledge and understanding of classical far-field fluorescence, we know relatively little. MEF is a consequence of the near-field interactions of fluorophores (dipoles) with the surface plasmons generated in plasmon supporting materials, where the optical properties of the metal afford for a wavelength dependence of MEF. In this paper we show that we are not limited to the properties of the individual metals for MEF, but in fact, surface deposits of mixed metals can create new dephased plasmon resonance bands, not present in the individual metals themselves. Subsequently, mixed metal substrates (MMS) offer significant opportunities for the multifarious and forever growing applications of MEF.

Novel benzylether type aldehyde and acetal terminated dendrons were synthesized and attached to a silica gel support; a linear spacer was also introduced as a control material. The supported dendritic compounds were mainly characterized by solid state 13C CPMAS NMR, elemental analysis and X-ray photoelectron spectroscopy (XPS) and the presence of free aldehydes was determined by the purpald test. Bovine serum albumin (BSA) protein was coupled to the dendronized support by imine bond formation, followed by irreversible reduction of the carbon–nitrogen double bond. A significant positive dendritic effect was observed on the antibody binding capacity of immobilised BSA as measured by fluorescence immunoassay (FIA).