Exploiting Organometallic Chemistry to Functionalize Small Cuprous Oxide Colloidal Nanocrystals.

The ligand chemistry of colloidal semiconductor nanocrystals mediates their solubility, band gap, and surface facets. Here, selective organometallic chemistry is used to prepare small, colloidal cuprous oxide nanocrystals and to control their surface chemistry by decorating them with metal complexes. The strategy is demonstrated using small (3-6 nm) cuprous oxide (CuO) colloidal nanocrystals (NC), soluble in organic solvents.

Lithiated porous silicon nanowires stimulate periodontal regeneration.

Periodontal disease is a significant burden for oral health, causing progressive and irreversible damage to the support structure of the tooth. This complex structure, the periodontium, is composed of interconnected soft and mineralised tissues, posing a challenge for regenerative approaches. Materials combining silicon and lithium are widely studied in periodontal regeneration, as they stimulate bone repair via silicic acid release while providing regenerative stimuli through lithium activation of the Wnt/β-catenin pathway.

Liquid-phase sintering of lead halide perovskites and metal-organic framework glasses.

Lead halide perovskite (LHP) semiconductors show exceptional optoelectronic properties. Barriers for their applications, however, lie in their polymorphism, instability to polar solvents, phase segregation, and susceptibility to the leaching of lead ions. We report a family of scalable composites fabricated through liquid-phase sintering of LHPs and metal-organic framework glasses.

Palladium-doped hierarchical ZSM-5 for catalytic selective oxidation of allylic and benzylic alcohols.

Hierarchical zeolites have the potential to provide a breakthrough in transport limitation, which hinders pristine microporous zeolites and thus may broaden their range of applications. We have explored the use of Pd-doped hierarchical ZSM-5 zeolites for aerobic selective oxidation (selox) of cinnamyl alcohol and benzyl alcohol to their corresponding aldehydes. Hierarchical ZSM-5 with differing acidity (H-form and Na-form) were employed and compared with two microporous ZSM-5 equivalents.

Characterization of Amorphous Solid Dispersions and Identification of Low Levels of Crystallinity by Transmission Electron Microscopy.

Amorphous solid dispersions (ASDs) are used to increase the solubility of oral medicines by kinetically stabilizing the more soluble amorphous phase of an active pharmaceutical ingredient with a suitable amorphous polymer. Low levels of a crystalline material in an ASD can negatively impact the desired dissolution properties of the drug. Characterization techniques such as powder X-ray diffraction (pXRD), differential scanning calorimetry (DSC), and Fourier transform infrared spectroscopy (FTIR) are often used to detect and measure any crystallinity within ASDs.

Analysis of complex, beam-sensitive materials by transmission electron microscopy and associated techniques.

We review the use of transmission electron microscopy (TEM) and associated techniques for the analysis of beam-sensitive materials and complex, multiphase systems or close to their native state. We focus on materials prone to damage by radiolysis and explain that this process cannot be eliminated or switched off, requiring TEM analysis to be done within a dose budget to achieve an optimum dose-limited resolution. We highlight the importance of determining the damage sensitivity of a particular system in terms of characteristic changes that occur on irradiation under both an electron fluence and flux by presenting results from a series of molecular crystals.

Direct Visualization of Arsenic Binding on Green Rust Sulfate.

"Green rust" (GR), a redox-active Fe(II)-Fe(III) layered double hydroxide, is a potential environmentally relevant mineral substrate for arsenic (As) sequestration in reduced, subsurface environments. GR phases have high As uptake capacities at circum-neutral pH conditions, but the exact interaction mechanism between the GR phases and As species is still poorly understood. Here, we documented the bonding and interaction mechanisms between GR sulfate and As species [As(III) and As(V)] under anoxic and circum-neutral pH conditions through scanning transmission electron microscopy (STEM) coupled with energy-dispersive X-ray (EDX) spectroscopy and combined it with synchrotron-based X-ray total scattering, pair distribution function (PDF) analysis, and As K-edge X-ray absorption spectroscopy (XAS).

Low dose scanning transmission electron microscopy of organic crystals by scanning moiré fringes.

In the pharmaceutical industry, it is important to determine the effects of crystallisation and processes, such as milling, on the generation of crystalline defects in formulated products. Conventional transmission electron microscopy and scanning transmission electron microscopy (STEM) can be used to obtain information on length scales unobtainable by other techniques, however, organic crystals are extremely susceptible to electron beam damage. This work demonstrates a bright field (BF) STEM method that can increase the information content per unit specimen damage by the use of scanning moiré fringes (SMFs).

Toward Developing a Predictive Approach To Assess Electron Beam Instability during Transmission Electron Microscopy of Drug Molecules.

During drug development control of polymorphism, particle properties and impurities are critical for ensuring a good quality, reproducible, and safe medicine. A wide variety of analytical techniques are employed in demonstrating the regulators control over the drug substance and product manufacturing, storage, and supply. Transmission electron microscopy (TEM) offers the opportunity to analyze in detail pharmaceutical systems at a length scale and limit of detection not readily achieved by many traditional techniques.