Photofunctional Scope of Fluorescent Dithienylethene Conjugates with Aza-Heteroaromatic Cations.

A series of dithienylethene (DTE) photoswitches with aza-heteroaromatic cationic moieties is synthesized. The switches are characterized regarding their photochemical and photophysical properties in acetonitrile and in water. The efficiency of the switching and the photostationary state composition depend on the degree of π-conjugation of the heteroaromatic systems. Thus, DTEs with acridinium-derived moieties have very low quantum yields for the ring-closing process, which is in contrast to switches with pyridinium and quinolinium moieties. All switches emit fluorescence in their open forms. The involved electronic transitions are traced back to an integrative picture including the DTE core and the cationic arms. The emission can be fine-tuned by the π-conjugation of the heteroaromatic cations, reaching the red spectral region for DTEs with acridinium moieties. On ring-closing of the DTEs the fluorescence is not observable anymore. Theoretical calculations point to rather low-lying energy levels of the highly conjugated ring-closed DTEs, which would originate near-infrared emission (> 1200 nm). The latter is predicted to be very weak due to the concurrent non-radiative deactivation, according to the energy-gap law. In essence, an ON-OFF fluorescence switching as the result of the electrocyclic ring-closing reaction is observed.

Phototransduction in a supramolecular cascade: a mimic for essential features of the vision process.

The tailored design of a light-triggered supramolecular cascade results in an artificial machinery that assimilates the transduction of photons into chemical communication and the final release of a neurotransmitter. This is reminiscent of key steps in the natural vision process.

Deep coverage proteome analysis of hair shaft for forensic individual identification.

Hair shaft is one of the most common biological evidence found at crime scenes. However, due to the biogenic degradation of nuclear DNA in hair shaft, it is difficult to achieve individual identification through routine DNA analysis. In contrast, the proteins in hair shaft are stable and contain genetic polymorphisms in the form of single amino acid polymorphisms (SAPs), translated from non-synonymous single nucleotide polymorphisms (nsSNPs) in the genome. However, the number of SAPs detected still cannot meet the requirements of practical applications. This paper developed a deep coverage proteome analysis method by combining a three-step sequential ionic liquid-based protein extraction and 2D-RPLC-MS/MS with high and low pH to identify both variant and reference SAPs from 2-cm-long hair shafts. We identified 632 ± 243 protein groups from 10 individuals, with the average number of SAPs reaching 167 ± 21/person. These were further used to calculate random match probabilities (RMPs), a widely accepted forensic statistical term for human identification. The RMPs ranged from 6.53 × 10-4 to 3.10 × 10-14 (median = 2.62 × 10-8) when calculated with frequency of matching nsSNP genotype data from exomes, and ranged from 2.62 × 10-3 to 2.07 × 10-10 (median = 4.88 × 10-6) with SAP genotype frequency. All these results indicate that the deep coverage proteomics method is beneficial for improving SAP-based forensic individual identification in hair shaft, with great potential in crime investigation.