A novel fluorescent probe for NAD-consuming enzymes

A novel, fluorescent NAD derivative is processed as substrate by three different NAD-consuming enzymes. The new probe has been used to monitor enzymatic activity in a continuous format by changes in fluorescence and, in one case, to directly visualize alternative reaction pathways

Increasing frailty is associated with higher prevalence and reduced recognition of delirium in older hospitalised inpatients: results of a multi-centre study

Purpose: Delirium is a neuropsychiatric disorder delineated by an acute change in cognition, attention, and consciousness. It is common, particularly in older adults, but poorly recognised. Frailty is the accumulation of deficits conferring an increased risk of adverse outcomes. We set out to determine how severity of frailty, as measured using the CFS, affected delirium rates, and recognition in hospitalised older people in the United Kingdom. Methods: Adults over 65 years were included in an observational multi-centre audit across UK hospitals, two prospective rounds, and one retrospective note review. Clinical Frailty Scale (CFS), delirium status, and 30-day outcomes were recorded. Results: The overall prevalence of delirium was 16.3% (483). Patients with delirium were more frail than patients without delirium (median CFS 6 vs 4). The risk of delirium was greater with increasing frailty [OR 2.9 (1.8–4.6) in CFS 4 vs 1–3; OR 12.4 (6.2–24.5) in CFS 8 vs 1–3]. Higher CFS was associated with reduced recognition of delirium (OR of 0.7 (0.3–1.9) in CFS 4 compared to 0.2 (0.1–0.7) in CFS 8). These risks were both independent of age and dementia. Conclusion: We have demonstrated an incremental increase in risk of delirium with increasing frailty. This has important clinical implications, suggesting that frailty may provide a more nuanced measure of vulnerability to delirium and poor outcomes. However, the most frail patients are least likely to have their delirium diagnosed and there is a significant lack of research into the underlying pathophysiology of both of these common geriatric syndromes

Reaction chemistry/nanocrystal property relations in the hot injection synthesis, the role of the solute solubility

Various literature studies show that increasing the concentration of free acid in the hot Injection synthesis of colloidal nanocrystals raises the diameter of the resulting nanocrystals. We analyze this reaction chemistry/nanocrystal property relation by combining reaction simulations with an experimental study on a particular CdSe nanocrystal synthesis. We find that increasing the free acid concentration has the same effect on a real synthesis as raising the solute solubility in the simulations. Both lead to larger sizes and a deterioration of the size dispersion at constant reaction rate. Since free acids are used to coordinate the cation precursors in these syntheses, this leads to a meaningful link between a parameter in reaction simulations and the composition of an experimental reaction mixture. We thus explain the increase of the nanocrystal size with the acid concentration as resulting from an enhanced consumption of the solute by nanocrystal growth, which reduces the number of nanocrystals formed. This link between a simulation parameter and the composition of the reaction mixture provides a rational basis to further explore and understand reaction chemistry/nanocrystal property relations in the hot injection synthesis

Length matters: how the ligand chain length affects the nanocrystal size in the hot injection synthesis

Colloidal semiconductor nanocrystals or quantum dots (QDs) are a very interesting class of nanomaterials since their properties can be tuned by their size due to quantum confinement. QDs are typically produced via a hot injection synthesis (HIS), which involves the injection of precursors in a hot mixture of a non-coordinating solvent and coordinating ligands such as carboxylic acids, thiols or phosphonic acids. For QDs to be implemented in a broad range of applications, a precise control over their size is essential. As a result, recent developments in the hot injection synthesis focus on producing QDs with predefined sizes, sharp size distributions and high reaction yields. In this study, we show that efficient size tuning at high reaction yield is possible by changing the chain length of the carboxylic acid. By combining an extended experimental reaction screening with reaction simulations, we demonstrate that the acid chain length affects the nanocrystal size by changing the diffusion coefficient and the solubility of the reactive monomers. In addition, we show that the relation between chain length and nanocrystal size can be used to assess the interaction of different coordinating species – including amines and phosphine oxides – with the reactive monomers. In this way, this work contributes to an enhanced, rational understanding of the widely used hot injection methods for the synthesis of colloidal nanocrystals

Controlling the size of hot injection made Nanocrystals by manipulating the diffusion coefficient of the solute

We investigate the relation between the chain length of ligands used and the size of the nanocrystals formed in the hot injection synthesis. With two different CdSe nanocrystal syntheses, we consistently find that longer chain carboxylic acids result in smaller nanocrystals with improved size dispersions. By combining a more in-depth experimental investigation with kinetic reaction simulations, we come to the conclusion that this size tuning is due to a change in the diffusion coefficient and the solubility of the solute. The relation between size tuning by the ligand chain length and the coordination of the solute by the ligands is further explored by expanding the study to amines and phosphine oxides. In line with the weak coordination of CdSe nanocrystals by amines, no influence of the chain length on the nanocrystals is found, whereas the size tuning brought about by phosphine oxides can be attributed to a solubility change. We conclude that the ligand chain length provides a practical handle to optimize the outcome of a hot injection synthesis in terms of size and size dispersion and can be used to probe the interaction between ligands and the actual solute

Comprehensive Route to the Formation of Alloy Interface in Core/Shell Colloidal Quantum Dots

The electronic properties of colloidal quantum dots (CQDs) have shown intriguing potential in recent years for implementation in various optoelectronic applications. However, their chemical and photochemical stabilities, mainly derived from surface properties, have remained a major concern. This paper reports a new strategic route for the synthesis of surface-treated CQDs, the CdSe/CdS core/shell heterostructures, based on low-temperature coating of a shell constituent, followed by a programmed annealing process. A comprehensive follow-up of the stability and the optical properties through the various synthesis stages is reported, suggesting that the low-temperature coating is responsible for the formation of a sharp interface between the core and the shell, whereas a postcoating annealing process leads to the generation of a thin alloy interfacial layer. At the end of the process, the CdSe/CdS CQDs show a significant improvement of the photoluminescence quantum yield, as well as an exceptional photostability. Consequently, the work reported here provides a convenient generic route to the formation of core/shell CQDs to be employed as a procedure for achieving various other heterostructures