Fluorescence lifetime microscopy reveals the biologically-related photophysical heterogeneity of oxyblepharismin in light-adapted (blue) Blepharisma japonicum cells.

The step-up photophobic response of the heterotrich ciliate Blepharisma japonicum is mediated by a hypericinic pigment, blepharismin, which is not present in any of the known six families of photoreceptors, namely rhodopsins, phytochromes, xanthopsins, cryptochromes, phototropins, and BLUF proteins. Upon irradiation, native cells become light-adapted (blue) by converting blepharismin into the photochemically stable oxyblepharismin (OxyBP). So far, OxyBP has been investigated mainly from a photophysical point of view in vitro, either alone or complexed with proteins. In this work, we exploit the vivid fluorescence of OxyBP to characterize its lifetime emission in blue B. Japonicum cells, on account of the recognized role of the fluorescence lifetime to provide physicochemical insights into the fluorophore environment at the nanoscale. In a biological context, OxyBP modifies its emission lifetime as compared to isotropic media. The phasor approach to fluorescence lifetime microscopy in confocal mode highlights that fluorescence originates from two excited states, whose relative balance changes throughout the cell body. Additionally, Cilia and kinetids, i.e., the organelles involved in photomovement, display lifetime asymmetry between the anterior and posterior part of the cell. From these data, some hypotheses on the phototransduction mechanism are proposed.

Live cell cytoplasm staining and selective labeling of intracellular proteins by non-toxic cell-permeant thiophene fluorophores.

A structurally correlated series of cell-permeant thiophene fluorophores, characterized by intense green or red fluorescence inside live mouse embryonic fibroblasts, was developed. The fluorophores displayed rapid internalization, excellent retention inside the cells, and high optical stability in the cytosolic environment and did not alter cell viability and reproducibility. Depending on the molecular structure, they experienced distinct fate inside the cells: from bright and lasting staining of the cytoplasm to selective tagging of a small set of globular proteins.

Hue-based quantification of mechanochromism towards a cost-effective detection of mechanical strain in polymer systems.

HSV is a digital colour space easily accessible by the transformation of RGB images. In this work, the hue parameter H was used to assess mechanically induced colour changes of the aggregation-sensitive fluorescent dye 4,4'-bis-(2-benzoxazolyl)stilbene (BBS), thus implementing a cheap and reliable method for the detection of mechanical deformation in a polymer matrix.

Ageing and oxidative stress: a role for dolichol in the antioxidant machinery of cell membranes?

Dolichol is a polyprenol compound broadly distributed in membranes, biosynthetized by the general isoprenoid pathway from acetate via mevalonate and farnesyl pyrophosphate. Dolichol lays inside the membrane between the two leaflets of the lipid bilayer very close to the tail of phospholipid fatty acids. No definite catabolic pathways for this molecule have yet been identified. Evidence is produced that dolichol levels increase dramatically with increasing age; that anti-ageing caloric restriction retards this age-associated change; that dolichol may act as a radical scavenger of peroxidized lipids belonging to the cell membranes. In view of the polyunsaturated fatty acids (PUFA), dolichol and Vitamin E location and stechiometry, it is proposed that molecules might interact each-other to form a highly matched free-radical-transfer chain, whose malfunctioning might be involved in statin toxicity and neurodegenerative diseases.

Nanoparticle systems for the targeted release of active principles of proteic nature.

The preparation and characterization of nanoparticles based on biodegradable/bioerodible polymers is reported. They have been designed for the controlled-targeted release of proteic drugs such as alpha-interferon and for the release of active principles in tissue engineering. The amenability of some of the prepared polymeric matrices to be used in the fabrication of micro and nano patterned scaffolds is also described.