Bio-Inspired Fluorescent Calcium Sulfate for the Conservation of Gypsum Plasterwork.

In this work, the potential of bio-inspired strategies for the synthesis of calcium sulfate (CaSO·nHO) materials for heritage conservation is explored. For this, a nonclassical multi-step crystallization mechanism to understand the effect of calcein- a fluorescent chelating agent with a high affinity for divalent cations- on the nucleation and growth of calcium sulfate phases is proposed. Moving from the nano- to the macro-scale, this strategy sets the basis for the design and production of fluorescent nano-bassanite (NB-C; CaSO·0.

Studying crystallisation processes using electron microscopy: The importance of sample preparation.

We present a comparison of common electron microscopy sample preparation methods for studying crystallisation processes from solution using both scanning and transmission electron microscopy (SEM and TEM). We focus on two widely studied inorganic systems: calcium sulphate, gypsum (CaSO·2HO) and calcium carbonate (CaCO). We find significant differences in crystallisation kinetics and polymorph selection between the different sample preparation methods, which indicate that drying and chemical quenching can induce severe artefacts that are capable of masking the true native state of the crystallising solution.

Structure of polymeric nanoparticles encapsulating a drug - pamoic acid ion pair by scanning transmission electron microscopy.

Drug-delivery systems based on polymeric nanoparticles are useful for improving drug bioavailability and/or delivery of the active ingredient for example directly to the cancerous tumour. The physical and chemical characterization of a functionalized nanoparticle system is required to measure drug loading and dispersion but also to understand and model the rate and extent of drug release to help predict performance. Many techniques can be used, however, difficulties related to structure determination and identifying the precise location of the drug fraction make mathematical prediction complex and in many published examples the final conclusions are based on assumptions regarding an expected structure.

Electron transparent nanotubes reveal crystallization pathways in confinement.

The cylindrical pores of track-etched membranes offer excellent environments for studying the effects of confinement on crystallization as the pore diameter is readily varied and the anisotropic morphologies can direct crystal orientation. However, the inability to image individual crystals within the pores in this system has prevented many of the underlying mechanisms from being characterized. Here, we study the crystallization of calcium sulfate within track-etched membranes and reveal that oriented gypsum forms in 200 nm diameter pores, bassanite in 25-100 nm pores and anhydrite in 10 nm pores.

Industrial-relevant TiO types do not promote cytotoxicity in the A549 or TK6 cell lines regardless of cell specific interaction.

Due to the expansive application of TiO and its variance in physico-chemical characteristics, the toxicological profile of TiO, in all its various forms, requires evaluation. This study aimed to assess the hazard of five TiO particle-types in relation to their cytotoxic profile correlated to their cellular interaction, specifically in human lymphoblast (TK6) and type-II alveolar epithelial (A549) cells. Treatment with the test materials was undertaken at a concentration range of 1-100 μg/cm over 24 and 72 h exposure.

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.

Nanoparticle corona artefacts derived from specimen preparation of particle suspensions.

Progress in the implementation of nanoparticles for therapeutic applications will accelerate with an improved understanding of the interface between nanoparticle surfaces and the media they are dispersed in. We examine this interface by analytical scanning transmission electron microscopy and show that incorrect specimen preparation or analysis can induce an artefactual, nanoscale, calcium phosphate-rich, amorphous coating on nanoparticles dispersed in cell culture media. We report that this ionic coating can be induced on five different types of nanoparticles (Au, BaTiO, ZnO, TiO and FeO) when specimen preparation causes a significant rise in pH above physiological levels.

Cryo-analytical STEM of frozen, aqueous dispersions of nanoparticles.

In situ characterisation of nanoparticle dispersion and surface coatings is required to further our understanding of the behaviour of nanoparticles in aqueous suspension. Using cryogenic transmission electron microscopy (cryo-TEM) it is possible to analyse a nanoparticle suspension in the frozen, hydrated state; however, this analysis is often limited to imaging alone. This work demonstrates the first use of analytical scanning TEM (STEM) in the examination of nanoparticles captured in a layer of vitreous ice.

Toxicological findings in driver and motorcyclist fatalities in Scotland 2012-2015.

Fatal motor vehicle crashes (MVCs) continue to be a common occurrence worldwide. This paper presents a retrospective analysis of the toxicological investigation of drivers and motorcyclists fatally injured in MVCs in Scotland from 2012 to 2015. One hundred and eighteen cases with full toxicological analysis, i.