Determination of ICH-Q3D Elemental Impurity Leachables in Glass Vials by Inductively Coupled Plasma Mass Spectrometry.

Container closure systems that are used for packaging pharmaceutical products are required to satisfy numerous safety requirements. Maximum permitted limits on the concentrations of numerous toxic elemental impurities that potentially leach from the packaging are one such requirement. The implementation of ICH-Q3D Guideline for Elemental Impurities, in conjunction with the 2018 publication of USP <232> Elemental Impurities-Limits and USP <233> Elemental Impurities-Procedures, requires a critical risk assessment of all container closure systems to evaluate their contribution of certain elemental impurities to the enclosed drug product.

Revealing Conformational Variants of Solution-Phase Intrinsically Disordered Tau Protein at the Single-Molecule Level.

Intrinsically disordered proteins, such as tau protein, adopt a variety of conformations in solution, complicating solution-phase structural studies. We employed an anti-Brownian electrokinetic (ABEL) trap to prolong measurements of single tau proteins in solution. Once trapped, we recorded the fluorescence anisotropy to investigate the diversity of conformations sampled by the single molecules.

Tracking Lithium Ions via Widefield Fluorescence Microscopy for Battery Diagnostics.

Direct tracking of lithium ions with time and spatial resolution can provide an important diagnostic tool for understanding mechanisms in lithium ion batteries. A fluorescent indicator of lithium ions, 2-(2-hydroxyphenyl)naphthoxazole, was synthesized and used for real-time tracking of lithium ions via widefield fluorescence microscopy. The fluorophore can be excited with visible light and was shown to enable quantitative determination of the lithium ion diffusion constant in a microfluidic model system for a plasticized polymer electrolyte lithium battery.

Allosteric tertiary interactions preorganize the c-di-GMP riboswitch and accelerate ligand binding.

Cyclic diguanylate (c-di-GMP) is a bacterial second messenger important for physiologic adaptation and virulence. Class-I c-di-GMP riboswitches are phylogenetically widespread and thought to mediate pleiotropic genetic responses to the second messenger. Previous studies suggest that the RNA aptamer domain switches from an extended free state to a compact, c-di-GMP-bound conformation in which two helical stacks dock side-by-side.