Amyloid peptide hydrogels via formation of coordination polymers with Ag+ by its core peptide equipped with a C-cysteine.

We report that the core sequence of amyloid ß (Aß) peptide, KLVFF, when equipped with a C-terminal cysteine residue, exhibited an extremely low minimum hydrogelation concentration of 0.05 wt% in the presence of Ag+ in pH 5 buffer, with this concentration 2 orders of magnitude lower than that of the pentapeptide itself. The CD signal of the Ag+-L-KLVFFC hydrogel was observed to be sensitive to the early-stage aggregation of amyloid ß peptide.

Helical nanofibers of N-(perfluorooctanoyl)cysteine ethyl ester in coordination polymers of Ag.

We propose using the formation of coordination polymers of Ag+ to probe differences between the perfluorinated alkyl chain and the alkyl chain by deriving a thiol ligand, N-(perfluoroalkanoyl)cysteine. Rapid formation in EtOH of P-/M-helical nanofibrils of high thermostability was found for N-(perfluorooctanoyl)-l-/d-cysteine ethyl esters at the µM level upon mixing with Ag+, but not for the octanoyl counterpart. This difference was also observed in terms of circular dichroism-enantiomeric excess dependence.

Ag+ coordination polymers of a chiral thiol ligand bearing an AIE fluorophore.

We report that in the Ag+ coordination polymers of a chiral thiol ligand containing an AIE fluorophore, tetraphenylethene (TPE), the TPE chromophores experience H-type aggregation, and yet a substantial enhancement of the fluorescence is observed, though to a lesser extent than that in the aggregates of the thiol ligand itself, which undergoes J-type aggregation. We show that this is not due to the difference in the freedom of the rotation of the fluorophore in the two types of aggregate, but is due to a small increase in the radiation rate constant in the coordination polymers while the much higher radiationless rate constant remains more or less unchanged.

Supramolecular aggregates as sensory ensembles.

As a new emerging area in chemical sensing, sensing using supramolecular aggregates exhibits unique advantages over that using conventional small-molecule chemical sensors, in terms of high sensitivity and selectivity, and the simplicity of the sensory building blocks. This Feature Article outlines the recent research progress made in sensing based on induced supramolecular aggregation-disaggregation. The reviewed sensory building blocks, in general, in the form of a small molecular sensor, yet with a much simpler structure, which form aggregates, are those of perylene derivatives, pyrene derivatives, tetraphenylethylene derivatives, metallophilic species and metal-organic frameworks.

Chirality sensing using Ag⁺-thiol coordination polymers.

We report here chirality sensing using achiral Ag(+)-thiol coordination polymers as the framework which becomes CD active upon interaction with chiral species, taking p-mercaptophenylboronic acid as a thiol ligand that bears a binding group for monosaccharides.

[The correlation study of PTEN gene expression and Akt phosphorylation in myelodysplastic syndrome].

OBJECTIVE: To investigate the relationship between PTEN gene expression and Akt phosphorylation (p-Akt) in myelodysplastic syndrome (MDS) and to explore the progression of MDS and the mechanism of high risk transformation to acute myeloid leukemia. METHODS: RT-PCR was used to detect the PTEN mRNA expression in leukemia cell lines K562 (as negative control) and Jurkat (as positive control) and 65 MDS and MDS/AML patients. Flow cytometry was used to detect p-Akt in HL-60 and Jurkat cells and 30 MDS patients. RESULTS: (1) K562 cells present PTEN gene expression while Jurkat cells did not. Of 65 MDS and MDS/AML patients, 27 (41.5%) expressed PTEN mRNA, being significantly lower than that in normal group (85.7%) (P < 0.01). (2) Jurkat cell showed high expression (86.9%) of p-Akt, while HL-60 cell as negative control did not express. P-Akt levels of 30 MDS patients were increased (1.35% - 58.23%), being much higher as compared with that of the normal contrast group (0.54% - 2.34%) (P < 0.01). Moreover, with the rate of blast cells increasing, the p-Akt level was rising up. There is a positive correlation (r = 0.93, P < 0.01) between the low expression rate of PTEN and the positive rate of p-Akt. CONCLUSION: The loss of PTEN gene expression is one of the important factors of p-Akt high expression in MDS patients, moreover, it may speed up the progress of the MDS or transformation to acute myeloid leukemia.