The antibacterial activity of a photoactivatable diarylacetylene against Gram-positive bacteria.

The emergence of antibiotic resistance is a growing threat to human health, and therefore, alternatives to existing compounds are urgently needed. In this context, a novel fluorescent photoactivatable diarylacetylene has been identified and characterised for its antibacterial activity, which preferentially eliminates Gram-positive over Gram-negative bacteria. Experiments confirmed that the Gram-negative lipopolysaccharide-rich outer surface is responsible for tolerance, as strains with reduced outer membrane integrity showed increased susceptibility.

Bullseye Analysis: A Fluorescence Microscopy Technique to Detect Local Changes in Intracellular Reactive Oxygen Species (ROS) Production.

Reactive oxygen species (ROS) are naturally produced compounds that play important roles in cell signaling, gene regulation, and biological defense, including involvement in the oxidative burst that is central to the anti-microbial actions of macrophages. However, these highly reactive, short-lived radical species also stimulate cells to undergo programmed cell death at high concentrations, as well as causing detrimental effects such as oxidation of macromolecules at more moderate levels. Imaging ROS is highly challenging, with many researchers working on the challenge over the past 10-15 years without producing a definitive method.

Cellular localisation of structurally diverse diphenylacetylene fluorophores.

Fluorescent probes are increasingly used as reporter molecules in a wide variety of biophysical experiments, but when designing new compounds it can often be difficult to anticipate the effect that changing chemical structure can have on cellular localisation and fluorescence behaviour. To provide further chemical rationale for probe design, a series of donor-acceptor diphenylacetylene fluorophores with varying lipophilicities and structures were synthesised and analysed in human epidermal cells using a range of cellular imaging techniques. These experiments showed that, within this family, the greatest determinants of cellular localisation were overall lipophilicity and the presence of ionisable groups.