Label-Free Identification of Persistent Particles in Association with Primary Immune Cells by Imaging Flow Cytometry.

The frequency of human exposure to persistent particles via consumer products, air pollution, and work environments is a modern-day hazard and an active area of research. Particle density and crystallinity, which often dictate their persistence in biological systems, are associated with strong light absorption and reflectance. These attributes allow several persistent particle types to be identified without the use of additional labels using laser light-based techniques such as microscopy, flow cytometry, and imaging flow cytometry.

Imaging flow cytometry methods for quantitative analysis of label-free crystalline silica particle interactions with immune cells.

Exposure to respirable fractions of crystalline silica quartz dust particles is associated with silicosis, cancer and the development of autoimmune conditions. Early cellular interactions are not well understood, partly due to a lack of suitable technological methods. Improved techniques are needed to better quantify and study high-level respirable crystalline silica exposure in human populations.

Silicon Forms a Rich Diversity of Aliphatic Polyol Complexes in Aqueous Solution.

A detailed examination of aqueous Si complexation by alditols and aldonic acids was conducted using high-sensitivity Si NMR spectroscopy of isotopically enriched solutions combined with theoretical modeling. Contrary to previous thinking, we have established that aliphatic polyols do not require a pair of hydroxy groups to form hypercoordinated Si complexes, although formation constants may be orders of magnitude higher if they are present. Thirteen distinctly different molecular assemblages containing 4-, 5-, or 6-coordinate Si centers have been identified, with significant concentrations of 5-coordinate Si -ligand complex being detected even under biologically relevant solution conditions.

Ultrasmall silica nanoparticles directly ligate the T cell receptor complex.

The impact of ultrasmall nanoparticles (<10-nm diameter) on the immune system is poorly understood. Recently, ultrasmall silica nanoparticles (USSN), which have gained increasing attention for therapeutic applications, were shown to stimulate T lymphocytes directly and at relatively low-exposure doses. Delineating underlying mechanisms and associated cell signaling will hasten therapeutic translation and is reported herein.

Non-Functionalized Ultrasmall Silica Nanoparticles Directly and Size-Selectively Activate T Cells.

Sub-micron-sized silica nanoparticles, even as small as 10-20 nm in diameter, are well-known for their activation of mononuclear phagocytes. In contrast, the cellular impact of those <10 nm [ i.e.

Imaging flow cytometry assays for quantifying pigment grade titanium dioxide particle internalization and interactions with immune cells in whole blood.

Pigment grade titanium dioxide is composed of sub-micron sized particles, including a nanofraction, and is widely utilized in food, cosmetic, pharmaceutical, and biomedical industries. Oral exposure to pigment grade titanium dioxide results in at least some material entering the circulation in humans, although subsequent interactions with blood immune cells are unknown. Pigment grade titanium dioxide is employed for its strong light scattering properties, and this work exploited that attribute to determine whether single cell-particle associations could be determined in immune cells of human whole blood at "real life" concentrations.