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We report on a supramolecular sensor array using fluorogenic peptide probes and graphene oxide that can target glycoproteins on a viral caspid, facilitating the differentiation of ebola virus from marburg virus and receptor-extensive vesicular stomatitis virus using principal component analysis.

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).

Correction for ‘Fluorescent glycoconjugates and their applications’ by Baptiste Thomas et al., Chem. Soc. Rev., 2020, 49, 593–641, DOI: 10.1039/C8CS00118A.

The development of small-molecule fluorescent probes for the detection of ions and biomacromolecules and for cellular and in vivo imaging has been a very active research area. Nevertheless, many problems exist for traditional probes including their poor water solubility, toxicity and the inability to target specific tissues. Because of the enhanced water solubility, biocompatibility and targeting ability for specific cells, there has been an emerging movement to use carbohydrates as either the backbone or as a warhead to decorate conventional fluorescent probes, producing "glycoprobes" with enhanced properties. This feature article provides an overview of recently developed glycoprobes for ion and protein detection as well as targeted (receptor targeting) cellular imaging and theranostics. Here, we summarise the tactics for preparing small molecular glycoprobes and their supramolecular 2D material composites.

Here we demonstrate that low-dimensional materials (LDMs) enhance the conjugation between fluorogenic boronic acids (BAs) and saccharides. Among the LDMs investigated, 1D carbon nanotubes significantly lower the limit of detection and enhance the binding of the BA with D-fructose.

We have developed a theranostic nanocomposite of metallic nanoparticles that uses two distinct fluorescence mechanisms: Forster Resonance Energy Transfer (FRET) and Metal-Enhanced Fluorescence (MEF) controlled by ligand-receptor interaction. Supramolecular assembly of the fluorophore-labeled glycoligands to cyclodextrin-capped gold nanoparticles produces a nanocomposite with a quenched fluorescence due to FRET from the fluorophore to the proximal particle. Subsequently, interaction with a selective protein receptor leads to an aggregation of the composite, reactivating the fluorescence by MEF from the distal metallic particles to fluorophores encapsulated in the aggregates. The aggregation also causes a red-shift in absorbance of the composite, thereby enhancing the production of reactive oxygen species (ROS) on red-light irradiation. Our nanocomposite has proven suitable for targeted cancer cell imaging as well as multimode therapy using both the photodynamic and drug delivery properties of the composite.

Small-molecular probes capable of monitoring and interfering with the activity of biomacromolecules – such as polysaccharides, nucleotides and proteins – are of paramount importance to the advancement of life science. However, such probes that can detect and simultaneously modulate the construction of biomacromolecules are elusive. Here we report a fluorogenic, foldable glycoprobe that can recognize and assemble a protein receptor in a synchronous fashion. The glycoprobe synthesized by introducing a glycoligand (for protein recognition) to a bola-type bis-fluorophore conjugate shows a “self-shielded” fluorescence in the folded state. Association with a receptor protein rapidly unfolds the probe, releasing a fluorophore capable of crosslinking the proteins – as determined using small-angle X-ray scattering – thereby producing a unique fluorescent supramolecular construct. We have demonstrated the use of the foldable glycoprobe in order to track the endocytic cycle of a transmembrane receptor.

Industrial treatment (such as washing and rescaling) of copper-based equipment with acids requires the use of corrosion inhibitors to mitigate environmental pollution. However, the currently used organic inhibitors for copper, such as benzotriazole (BTA), are protonated in acidic solutions, thereby weakening the adsorption to a positively charged copper surface. Here we show that the use of an effective copper-ion chelator can overcome the repulsion between protonated inhibitors and a cationic copper surface in acidic solutions. With a variety of surface techniques including time of flight secondary ion mass spectrometry, X-ray photoelectron spectroscopy and X-ray diffraction, we determine that bis-triazolyl indoleamines (BTIs) can strongly coat onto a cationic copper surface in acidic solutions through chelation with Cu(I) species. The electrochemical techniques used suggest that the BTIs are much better corrosion inhibitors than BTA, showing consistently an outstanding inhibitive efficiency in spite of the reduction of the inhibitor concentration by 100-fold and the increase of solution temperature and acidic strength. A preliminary cell viability assay suggests that our BTI is much less toxic than BTA towards two healthy cell lines.

We report an interlocked supramolecular ensemble formed between a conjugated polymer (CP) and a fluorescent glycoprobe for receptor-targeting cancer cell theranostics.

We demonstrate the use of an effective Diels–Alder reaction to produce a library of heterocyclic, polyaromatic benzo[c]carbazole derivatives with good corrosion inhibitive potency for copper against HCl.

Here we demonstrate the simple construction and characterization of a pyrenyl glycoside-coated 2D MoS2 material composite capable of selectively capturing proteins and live cells on an electrode, as determined by differential pulse voltammetry.

Here we demonstrate that 2D MoS2 can enhance the receptor-targeting and imaging ability of a fluorophore-labelled ligand. The 2D MoS2 has an enhanced working concentration range when compared with graphene oxide, resulting in the improved imaging of both cell and tissue samples.

This review summarizes the recent progress in quantum dot (QD) based sensors used for the photoluminescent detection of a variety of species in vitro and in vivo. New trends in using these nanomaterials for sensing applications are highlighted.

With this research we demonstrate that glycosylation of a naphthalimide zinc ion probe, using click chemistry, leads to an improvement of the aqueous sensitivity, working pH range and targeting ability for specific cells, together with significantly reduced cytotoxicity.

Construction of composite materials based on the self-assembly of fluorescently labeled biomolecules with a variety of micro- or nano-quenching materials (by the Förster Resonance Energy Transfer mechanism) for the fluorogenic recognition of disease-related proteins has become a dynamic research topic in the field of fluorescence recognition. Here we summarize the recent progress on the composition of fluorescence dye-labeled biomolecules including sugars, peptides and nucleotides with organic (graphene and carbon nanotubes) and inorganic (gold nanoparticles) materials. Their application in the fluorescence detection of proteins and enzymes on both the molecular and cellular levels is discussed. Perspectives are proposed with respect to the future directions of employing these composite materials in the recognition of pathological proteins.

Recently, there has been increasing interest in the construction of graphene oxide (GO) based fluorogenic composite materials (FCMs) for the detection of ligand-protein recognitions, which modulate numerous physiological and pathological processes in nature. In the sensing systems developed, GO has been used as a platform to assemble, and thus quench the fluorescence of dye-labelled ligands for the fluorogenic (fluorescence off-on) detection of proteins through the competitive formation of ligand-protein complexes, disassembling the GO composite. Here we show that the size, structure and loading concentration of GO may largely impact the sensing performance of GO-based FCMs. We synthesized four glycodyes that incorporate diverse natural glycoligands (as recognition groups) coupled with fluorescent dyes (as both the graphene binding and signal reporting group) with different emission wavelengths for comparison with GOs with different sizes. We determined that with the increase of size, the quenching ability of GO for the glycodyes increased, whereas the GO with a moderate size showed the best sensing performance for lectins (proteins that recognize glycoligands). The plausible mechanism of action was proposed. This research suggests that judicious quality control of GO is crucial for the construction of GO-based FCMs as biosensors.

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

Correction for ‘Glycosylation enhances the aqueous sensitivity and lowers the cytotoxicity of a naphthalimide zinc ion fluorescence probe’ by Lei Dong et al., Chem. Commun., 2015, DOI: 10.1039/c5cc04357c.

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.

There has been increasing interest in the development of protein tyrosine phosphatase 1B (PTP1B) inhibitors for the treatment of type 2 diabetes, obesity and breast cancer. We report here the identification of a series of mono- and bis-phenylalaninyl and tyrosinyl glucoside derivatives as novel PTP1B inhibitors. The designed compounds bearing one or two phenylalanine or tyrosine derivatives on the 6-, 2,3-, 2,6-, 3,4- and 4,6-positions of the glucosyl scaffolds were efficiently constructed via the microwave-assisted Cu(I)-catalyzed azide–alkyne cycloaddition in moderate-to-excellent yields. Successive biological assays identified these compounds as novel PTP1B inhibitors, with the 4,6-disubstituted tyrosinyl glucoside being the most potent. A kinetic study established that both mono- and bis-triazole-linked glycosyl acids act as typical competitive inhibitors whereas the bis-triazolyl ester that also exhibited inhibitory activity on PTP1B displayed a mixed-type inhibition pattern. Furthermore, docking simulation plausibly proposed the diverse binding modes of these compounds with the enzymatic target.

A protocol is described for the reductive cleavage of the C–O bond of aromatic and aliphatic acetals to ethers catalyzed by Cu(OTf)2 or Bi(OTf)3 at room temperature in excellent yields, without affecting aromatic rings, nitro, nitrile, ester and hydroxyl groups. This protocol represents an improvement in terms of atom economy compared to the previous methods, by distinctly decreasing the amount of the reducing reagent, 1,1,3,3-tetramethyldisiloxane (TMDS), and using a small amount of catalyst.

1-O-alkyl glycerol and diglycerol ethers are obtained in high yields and high selectivity by catalytic reductive alkylation of glycerol and diglycerol with linear aldehydes in the presence of 0.5 mol% of Pd/C under 10 bars of hydrogen using a Bronsted acid as co-catalyst. All byproducts were identified. A mechanism for the reductive alkylation is proposed.