The dual activity of an antibiotic-loaded micellar arsenal, harnessed in tandem, snowballs into enhanced killing of MRSA and biofilm inhibition on surgical suture.
A diformyl-quinoline based receptor (L1) exhibits selective colorimetric and fluorometric sensing of Zn(2+) in aqueous medium at pH 7.4 based on the intraligand charge transfer (ICT) process. The in situ formed phenoxo-bridged complex, L1·2Zn can selectively and specifically sense PPi among all the other biologically important anions including ATP through reversible binding. The detection limit for Zn(2+) and PPi were found to be approximately 56 and 2 ppb, respectively. The unique selectivity of the PPi by the L1-Zn ensemble could be used as an analytical tool to probe PPi generation in a prototype polymerase chain reaction (PCR) setup and track DNA amplification with higher sensitivity as compared to conventional agarose gel electrophoresis. Interestingly, the principle of PPi estimation in PCR rendered rapid estimation of bacterial cell numbers with a limit of detection of 10 CFU of Escherichia coli MTCC 433 in as early as 10 PCR cycles. The proposed method of PPi sensing offers interesting application potential in PCR-based rapid diagnostics for pathogenic agents and microbiological quality control.
We report the synthesis of a metal-free chemosensor for highly selective sensing of pyrophosphate (PPi) anion in physiological medium. The novel phenylbenzimidazole functionalized imine containing chemosensor (L; [2,6-bis(((4-(1H-benzo[d]imidazol-2-yl)phenyl)imino) methyl)-4 methyl phenol]) could sense PPi anion through "turn-on" colorimetric and fluorimetric responses in a very competitive environment. The overall sensing mechanism is based on the aggregation-induced emission (AIE) phenomenon. Moreover, a real time in-field device application was demonstrated by sensing PPi in paper strips coated with L. Interestingly, detection of intracellular PPi ions in model human cells could also be possible by fluorescence microscopic studies without any toxicity to these cells.
The dysregulation of metal homeostasis is reported to enhance the aggregation of tau, a key neuronal microtubuleassociated protein. Herein, we found that ferric (Fe 3+ ) ions enhanced tau aggregation. Fe 3+ and Al 3+ induced tau aggregation while several trivalent metal ions such as Cr 3+ , La 3+ , and V 3+ had no discernable effect on tau aggregation. Fe 3+ reduced the critical concentration of tau required for the liquid−liquid phase separation (LLPS); however, Cr 3+ , La 3+ , and V 3+ did not affect tau droplet formation. Dynamic light scattering, atomic force microscopic, and transmission electron microscopic analysis suggested that Fe 3+ significantly increased the formation of tau oligomers and fibrils. In contrast, Fe 2+ neither enhanced tau droplet formation nor increased the heparin-induced aggregation of tau. Using a tryptophan mutant (Y310W-tau) of tau, Fe 3+ was found to bind to tau with four times higher affinity than Fe 2+ . Acrylamide quenching of the tryptophan fluorescence of Y310W-tau, 1-anilino-8-naphthalene sulfonate (ANS) fluorescence experiment, and far-UV circular dichroism analysis indicated that Fe 3+ decreased the solvent exposure of the tryptophan residue, perturbed the hydrophobic surface arrangement, and disrupted the secondary structure of tau, respectively. The increase in the β-sheet content and a subsequent decrease in the disordered content of tau due to the binding of Fe 3+ may favor tau aggregation. Fe 3+ may enhance and stabilize the non-covalent interactions between disordered domains of tau molecules leading to tau aggregation. The data highlighted the relationship between the dysregulation of ferric ions and neurodegenerative disorders.
A quinoline functionalized fluorophore exhibited high selectivity towards Fe3+ ions and the ligand–metal complex showed excellent selectivity towards F− ions.
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