Sialylated glycoproteins and sialyltransferases in digestive cancers: Mechanisms, diagnostic biomarkers, and therapeutic targets.

Sialic acid (SA), as the ultimate epitope of polysaccharides, can act as a cap at the end of polysaccharide chains to prevent their overextension. Sialylation is the enzymatic process of transferring SA residues onto polysaccharides and is catalyzed by a group of enzymes known as sialyltransferases (SiaTs). It is noteworthy that the sialylation level of glycoproteins is significantly altered when digestive cancer occurs. And this alteration exhibits a close correlation with the progression of these cancers. In this review, from the perspective of altered SiaTs expression levels and changed glycoprotein sialylation patterns, we summarize the pathogenesis of gastric cancer (GC), colorectal cancer (CRC), pancreatic ductal adenocarcinoma (PDAC), and hepatocellular carcinoma (HCC). Furthermore, we propose potential early diagnostic biomarkers and prognostic indicators for different digestive cancers. Finally, we summarize the therapeutic value of sialylation in digestive system cancers.

Ion-Specific Effects on Hydrogen Bond Network at a Submicropore Confined Liquid-Vacuum Interface: An in Situ Liquid ToF-SIMS Study.

The hydrogen bond (HB), one of the essential properties of water, tends to link water molecules to form dynamic water clusters. Extrinsic ions could change the size distribution of water clusters by influencing HBs. But the mechanism, especially the influence range of ions on HBs, is still in dispute due to limitation of analytical methods. Herein, we use in situ liquid ToF-SIMS analysis combined with density functional theory calculation to study the influence of different halide anions on HBs at a submicropore confined liquid-vacuum interface. Our experimental results demonstrated that anions show synchronous local and long-range effects on HBs. Specifically, the larger the anion is, the greater degree the long-range HB network and the local hydration number of anions are influenced. More importantly, we found that the long-range effect on the HB network is influenced by nuclear quantum effects, whereas the local effect on water molecules in the first hydration shell is not.

Diverse supramolecular structures self-assembled by a simple aryl chloride on Ag(111) and Cu(111).

Diverse self-assembled structures were obtained on Cu(111) and Ag(111) surfaces by using a simple and small 4,4''-dichloro-1,1':4',1''-terphenyl molecule. Surprisingly, a complicated supramolecular self-assembled vortex structure, composed of 15 molecules in a large unit, was realized through the collaboration of hydrogen bonding and halogen bonding.

On-surface synthesis of poly(p-phenylene ethynylene) molecular wires via in situ formation of carbon-carbon triple bond.

The carbon-carbon triple bond (-C≡C-) is an elementary constituent for the construction of conjugated molecular wires and carbon allotropes such as carbyne and graphyne. Here we describe a general approach to in situ synthesize -C≡C- bond on Cu(111) surface via homo-coupling of the trichloromethyl groups, enabling the fabrication of individual and arrays of poly(p-phenylene ethynylene) molecular wires. Scanning tunneling spectroscopy reveals a delocalized electronic state extending along these molecular wires, whose structure is unraveled by atomically resolved images of scanning tunneling microscopy and noncontact atomic force microscopy. Combined with density functional theory calculations, we identify the intermediates formed in the sequential dechlorination process, including surface-bound benzyl, carbene, and carbyne radicals. Our method overcomes the limitation of previous on-surface syntheses of -C≡C- incorporated systems, which require the precursors containing alkyne group; it therefore allows for a more flexible design and fabrication of molecular architectures with tailored properties.

A new colorimetric and fluorescent probe with a large stokes shift for rapid and specific detection of biothiols and its application in living cells.

In this work, a new reversible colorimetric and fluorescent probe for sequential recognition of copper ions and biothiols is synthesized easily. Based on the chelation-enhanced fluorescence quenching (CHEQ) effect, this probe shows high sensitivity and selectivity towards Cu2+, which can be detected by the naked eye. And this experimental phenomenon can also be realised upon addition of biothiols, restoring their initial fluorescence intensity. This probe also features a very high response speed (less than 5 seconds) and a large stokes shift (178 nm) toward Cu2+ and biothiols. Moreover, the detection limit for Cu2+ and biothiols is as low as 7.34 nM and 10.3 nM, respectively. Additionally, this ON-OFF-ON-type fluorescence recognition cycle can be repeated more than 5 times by addition of Cu2+ and biothiols in turn. Particularly, this 1-Cu2+ ensemble is further successfully applied for GSH detection in living cells.