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The fluorescence quenching strategy has been developed as an exceedingly selective and sensitive method for the determination of Cu2+ ions in the presence of CO32− ions in an aqueous medium.

We report a novel P2-type Na0.5Ni0.26Cu0.07Mn0.67O2 (NCM) mixed oxide obtained by conventional solid-state method as a prospective cathode for sodium-ion battery (SIB) applications. X-ray diffraction analysis shows that NCM exhibits a hexagonal structure with a P63/mmc (No. 194) space group, in which Na-ions are located in a prismatic environment. The introduction of Cu into the lattice enhances its structural stability, showing a capacity retention of 83% after 100 cycles, which is much better than its native compound. MgO encapsulation was performed to further improve the interfacial kinetics and suppress P2–O2 phase transition. MgO coating significantly improves the electrochemical activity at high cut-off voltages, for instance, highest capacity of 131 mA h g−1 was noted with superior rate performance of 83 and 51 mA h g−1 at 5 and 20C, respectively. As expected, dual modification by Cu-ion doping and MgO coating provides a novel strategy for designing high-rate SIB cathodes.

Rapid pathogen testing is expected to play a critical role in infection control and in limiting epidemics. Smartphones equipped with state-of-the-art computing and imaging technologies have emerged as new point-of-use (POU) sensing platforms. We herein report a new assay format for fast, sensitive and portable detection of avian influenza-associated antibodies.

Lanthanide-doped upconverting nanoparticles (UCNPs) have recently attracted enormous attention in the field of biological imaging owing to their unique optical properties: (1) efficient upconversion photoluminescence, which is intense enough to be detected at the single-particle level with a (nonscanning) wide-field microscope setup equipped with a continuous wave (CW) near-infrared (NIR) laser (980 nm), and (2) resistance to photoblinking and photobleaching. Moreover, the use of NIR excitation minimizes adverse photoinduced effects such as cellular photodamage and the autofluorescence background. Finally, the cytotoxicity of UCNPs is much lower than that of other nanoparticle systems. All these advantages can be exploited simultaneously without any conflicts, which enables the establishment of a novel UCNP-based platform for wide-field two-photon microscopy. UCNPs are also useful for multimodal in vivo imaging because simple variations in the composition of the lattice atoms and dopant ions integrated into the particles can be easily implemented, yielding various distinct biomedical activities relevant to magnetic resonance imaging (MRI), computed tomography (CT), and positron emission tomography (PET). These multiple functions embedded in a single type of UCNPs play a crucial role in precise disease diagnosis. The application of UCNPs is extended to therapeutic fields such as photodynamic and photothermal cancer therapies through advanced surface conjugation schemes.

We describe a simple method for synthesizing mesoporous silica-coated luminescent europium-doped gadolinium vanadate (GdVO4:Eu3+@mSiO2) nanoparticles. Their biomedical applications as a potential imaging nanoprobe for both fluorescence imaging and magnetic resonance imaging (MRI) and as a simultaneous anti-cancer drug delivery vehicle are also discussed. Eu3+ doped GdVO4 nanoparticles exhibit strong red photoluminescence and the Gd3+ in GdVO4 can be used as a T1 contrast agent for MRI. T1-weighted MR contrast enhancement as well as sustained intracellular drug delivery can be achieved by the mesoporous silica layer coating onto a single nanoparticle. Enhanced T1 MR contrast was proven by relaxometric studies on water access to the paramagnetic core. GdVO4:Eu3+@mSiO2 nanoparticles as a new type of theragnostic (imaging and treatment) agent can provide new opportunities in a cancer treatment.

Correction for ‘Cu-doped P2-Na0.5Ni0.33Mn0.67O2 encapsulated with MgO as a novel high voltage cathode with enhanced Na-storage properties’ by Hari Vignesh Ramasamy et al., J. Mater. Chem. A, 2017, DOI: 10.1039/c6ta10334k.

Magnetic biosensors, based on nanomaterials and miniature electronics, have emerged as a powerful diagnostic platform. Benefiting from the inherently negligible magnetic background of biological objects, magnetic detection is highly selective even in complex biological media. The sensing thus requires minimal sample purification and yet achieves a high signal-to-background contrast. Moreover, magnetic sensors are also well-suited for miniaturization to match the size of biological targets, which enables sensitive detection of rare cells and small amounts of molecular markers. We herein summarize recent advances in magnetic sensing technologies, with an emphasis on clinical applications in point-of-care settings. Key components of sensors, including magnetic nanomaterials, labeling strategies and magnetometry, are reviewed.

We report a transformation of hydrophobic iron oxide nanoparticles to hydrophilic and biocompatible maghemite nanocrystals by controlled thermal treatment followed by dextran coating. Sodium sulfate salt was used as matrix for preventing aggregation during the thermal treatment at high temperature. Through the thermal treatment and subsequent isolation process, highly crystalline bare maghemite nanocrystals with high magnetization were produced. Subsequent coating with dextran derivatives produced hydrophilic and biocompatible iron oxide nanocrystals. Among various kinds of dextran derivatives, polyanionic carboxymethyl dextran (CM-dextran) was most efficient for stabilizing the nanocrystals in aqueous media. CM-dextran coated nanocrystals exhibited high relaxivity originating from the high magnetization and assembled structure.

We report the simple synthesis of poly(ethylene glycol) (PEG)-derivatized phosphine oxide ligands for water-dispersible metal oxide nanocrystals.