A glycoconjugate-based gold nanoparticle approach for the targeted treatment of Pseudomonas aeruginosa biofilms.

In this study, "core-shell" gold nanoparticles (AuNPs) have been functionalised using a simple one-pot approach to form fucose-based glycoconjugate AuNPs (Fuc-AuNPs) and galactose-based glycoconjugate AuNPs (Gal-AuNPs), respectively. Owing to the selective carbohydrate-based recognition of the key virulence factors of P. aeruginosa, LecB (fucose-specific lectin)/LecA (galactose-specific lectin), Fuc-AuNPs and Gal-AuNPs-based imaging and therapeutic strategies were evaluated towards P. aeruginosa. Both Fuc-AuNPs and Gal-AuNPs were non-covalently loaded with the fluorophore dicyanomethylene 4H-pyran (DCM) to afford two highly selective fluorescence imaging agents for the visualisation of P. aeruginosa. The loading of Fuc-AuNPs and Gal-AuNPs with the known antibiotic Ceftazidime (CAZ) exhibited an enhanced therapeutic effect, illustrating the significance of this targeted drug delivery strategy. Exploiting the phototherapeutic properties of AuNPs, photoirradiation (600 nm) of Fuc-AuNP@CAZ/Gal-AuNP@CAZ provided both photothermal and photodynamic therapeutic (PTT/PDT) effects, which facilitated the release of CAZ. Fuc-AuNP@CAZ and Gal-AuNP@CAZ were shown to be effective photo/chemotherapeutics resulting in almost complete eradication of P. aeruginosa biofilms formed on clinically relevant surfaces (glass slides and steel surface).

Selective fluorogenic imaging of hepatocellular H2S by a galactosyl azidonaphthalimide probe.

We have developed a galactosyl azidonaphthalimide probe for the selective fluorogenic imaging of hepatocellular H2S, an important gaseous transmitter produced in the liver.

Substitution pattern reverses the fluorescence response of coumarin glycoligands upon coordination with silver (I).

Development of sugar-based fluorescence (FL) chemo-probes is of much interest since sugars are biocompatible, water-soluble and structurally rigid natural starting materials. We report here that fluorescent glycoligands with two triazolyl coumarin moieties installed onto the different positions of an identical glucosyl nucleus exert completely reversed optical response to a metal ion. C3,4-, C2,3- and C4,6-di-substituted coumarin glucosides synthesized by a click reaction similarly showed a selective FL variation in the presence of silver (I) among a range of metal cations in an aqueous solution. However, the variation was determined to be converse: the FL of the C3,4-ligand was quenched whereas that of the C2,3/C4,6-ligand tangibly enhanced. FL and NMR titrations suggested that this divergence was due to the distinct complexation modes of the conformationally constrained ligands with the ion. The optimal motifs of the ligand-ion complexation were predicted by a computational simulation. Finally, the C2,3-ligand was determined to be of low cytotoxicity and applicable in the FL imaging of silver ions internalized by live cells.

Bis-triazolyl indoleamines as unique "off-approach-on" chemosensors for copper and fluorine.

Bis-triazolyl indoleamine-based chemosensors that respond to copper, and then fluorine as presumably facilitated by the high-affinity interaction between F(-) and the NH-proton of indole, are reported. Remarkable fluorimetric as well as colorimetric alternations upon the specific ligand-ion recognitions were observed.

Construction of triazolyl bidentate glycoligands (TBGs) by grafting of 3-azidocoumarin to epimeric pyranoglycosides via a fluorogenic dual click reaction.

Glycoligands, which feature a glycoside as the central template incorporating Lewis bases as metal chelation sites and various fluorophores as the chemical reporter, represent a range of interesting scaffolds for development of chemosensors. Here, new types of triazolyl bidentate glycoligands (TBGs) based on the grafting of 3-azidocoumarin to the C2,3- or C4,6-positions of three epimeric pyranoglycosides including a glucoside, a galactoside, and a mannoside were efficiently synthesized via a fluorogenic dual click reaction assisted by microwave irradiation. The desired TBGs were afforded in high conversion rates (>90%) and reasonable yields (∼70%). Moreover, a preliminary optical study of two hydroxyl-free glucoside-based TBGs indicates that these compounds are strongly fluorescent in pure water, implying their potential for ion detections in aqueous media.