Discrimination of redox-responsible biomolecules by a single molecular sensor

Optimised Synthesis of the Bacterial Magic Spot (p)ppGpp Chemosensor PyDPA

Guanosine penta- or tetraphosphate (pppGpp or ppGpp, respectively) is a nucleotide signalling molecule with a marked effect on bacterial physiology during stress. Its accumulation slows down cell metabolism and replication, supposedly leading to the formation of the antibiotic-tolerant persister phenotype. A specifically tailored fluorescent chemosensor, PyDPA, allows the detection of (p)ppGpp in solution with high selectivity, relative to that of other nucleotides. Herein, an optimised synthetic approach is presented that improves the overall yield from 9 to 67 % over 7 steps. The simplicity and robustness of this approach will allow groups investigating the many facets of (p)ppGpp easy access to this probe.

FRET-assisted selective detection of flavins via cationic conjugated polyelectrolyte under physiological conditions

Cationic conjugated polyelectrolyte PMI performs ppb level detection and discrimination of flavins (RF, FMN and FAD) in aqueous media as well as in biological medium like serum.

Design strategies for lab-on-a-molecule probes and orthogonal sensing

This review highlights the currently exploited working concepts of lab-on-a-molecule probes, with a particular focus on what is required for multianalyte detection and quantification in competitive assays. Both, chemosensor and chemodosimeter approaches are considered. The multifaceted design strategies and the orthogonal protocols are evaluated in order to identify and categorise the successful conceptions and to single out unknown territory and challenges for future work.

Novel reversible Zn2+-assisted biological phosphate "turn-on" probing through stable aryl-hydrazone salicylaldimine conjugation that attenuates ligand hydrolysis

A novel reversible zinc(II) chemosensing ensemble (2·Zn(2+)) allows for selective "turn-on" fluorescence sensing of ATP and PPi in aqueous media (detection limits: 2.4 and 1.0 μM, respectively) giving selective binding patterns: ATP ∼ PPi > ADP ≫ AMP > monophosphates ≈ remaining ions tested. The conjugated hydrazone [C═N-NH-R] resists hydrolysis considerably, compared to the imine [C═N-CH2-R, pyridin-2-ylmethanamine] functionality, and generalizes to other chemosensing efforts. Prerequisite Zn(2+)·[O(phenol)N(imine)N(pyr)] binding is selective, as determined by UV-vis and NMR spectroscopy; ATP or PPi extracts Zn(2+) to regenerate the ligand-fluorophore conjugate (PPi: turn-on, 512 nm; detection limit, 1.0 μM). Crystallography, 2-D NMR spectroscopy, and DFT determinations (B3LYP/631g*) support the nature of compound 2. 2-Hydrazinyl-pyridine-salicylaldehyde conjugation is unknown, as such; a paucity of chemosensing-Zn(2+) binding reports underscores the novelty of this modifiable dual cation/anion detection platform. A combined theoretical and experimental approach reported here allows us to determine both the potential uniqueness as well as drawbacks of this novel conjugation.