Bifunctional Temperature and Oxygen Dual Probe Based on Anthracene and Europium Complex Luminescence.

In this work, we synthesized a polydimethylsiloxane membrane containing two emitter groups chemically attached to the membrane structure. For this, we attached the anthracene group and the [Eu(bzac)3] complex as blue and red emitters, respectively, in the matrix via hydrosilylation reactions. The synthesized membrane can be used as a bifunctional temperature and oxygen ratiometric optical probe by analyzing the effects that temperature changes and oxygen levels produce on the ratio of anthracene and europium(III) emission components. As a temperature probe, the system is operational in the 203-323 K range, with an observed maximum relative sensitivity of 2.06% K-1 at 290 K and temperature uncertainties below 0.1 K over all the operational range. As an oxygen probe, we evaluated the ratiometric response at 25, 30, 35, and 40 °C. These results show an interesting approach to obtaining bifunctional ratiometric optical probes and also suggest the presence of an anthracene → europium(III) energy transfer, even though there is no chemical bonding between species.

Comparison of Aß (1-40, 1-28, 11-22, and 29-40) aggregation processes and inhibition of toxic species generated in early stages of aggregation by a water-soluble ruthenium complex.

Neurotoxicity of amyloid beta (Aß) species generated in early stages of aggregation has been associated with development of Alzheimer's disease (AD). Consequently, the field of action of compounds that can identify and inhibit the formation of these species has enlarged considerably. This study investigates the effect and influence of the luminescent, water soluble metal complex cis-[Ru(phen)2(3,4Apy)2]2+ (RuApy, 3,4Apy = 3,4-diaminopyridine, phen = 1,10-phenanthroline) on the aggregation process and toxicity of Aß1-40 and its Aß1-28, Aß11-22 and Aß29-40 fragments since their early stages. The absence of correlation between the conformations generated by Aß fragments and the full length 1-40 peptide during aggregation and the absence of toxicity of Aß fragments to PC12 cells in all stages of aggregation indicated that the aggregation pathway and toxicity found to the full-length Aß1-40 depends on specific interactions between the three fragments. The toxicity of Aß1-40 was dependent on the aggregation step investigated: species generated at the beginning (15 min) of aggregation were toxic, whereas mature (120 min) fibrils were not. The RuApy complex is not toxic to PC12 cells up to 60 µM, and does not interfere with the aggregation pathway of the Aß fragments, but interferes with the aggregation of Aß1-40 and protects the PC12 cells, maintaining 100% of cell viability against the toxicity of Aß1-40 species generated in early stages of aggregation.