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An efficient and mild multicomponent reaction (MCR) for the preparation of vinyl sulfone is reported, which is achieved by the hydrogenation/difunctional sulfonylation of an alkynyl ester with the corresponding N-allyl bromodifluoroacetamide, DABSO and H2O under visible light conditions without the need for any metal catalysts or additives. This transformation is the first example of a conversion using H2O as the hydrogen source to interact with DABCO to form [DABCO-H]+, which ultimately reacts with the vinyl group, with the advantage of high chemoselectivity and step economy. Notably, the method produces different sulfonylation products with the same substrate regulated by the presence or absence of H2O, which greatly reduces the cost of the chemical reaction and exhibits good functional group tolerance and substrate range. In addition, gram-scale experiments proceeded smoothly, proving the practicality of the methodology. [ABSTRACT FROM AUTHOR]

We have developed a dearomatization–rearomatization strategy for the modification of peptides/proteins through a thiol-Michael addition to the electrophilic cyclohexadienone intermediate that is generated in situ via the oxidation of tyrosine. This strategy enriches the conjugation toolbox and has great potential for applications in medicinal chemistry and chemical biology. [ABSTRACT FROM AUTHOR]

A convenient and efficient strategy was developed for accessing chlorotoxin-derived bicyclic peptide-biomolecule conjugates by cyclizing fully-unprotected linear peptides with a designed tetrafunctional chemical linker. Among these peptides, bicycle-P3 bearing the N-terminal sequence of chlorotoxin shows high tumor selectivity and penetration ability, which is promising for treatment of gliomas. [ABSTRACT FROM AUTHOR]

A highly specific recognition-before-labeling strategy has been developed for sensitive detection of non-small cell lung cancer A549 cells, by using fluorescent QDs as signal units and DNA aptamers as recognition elements. A QD–aptamer system used for cell imaging and bioanalysis mostly relies on the recognition-after-labeling strategy in which aptamers were firstly labeled with QDs and then the QD–aptamer conjugates as a whole were utilized for specific recognition. Here in our strategy, aptamers were used firstly to recognize target cells, and then fluorescent QDs were sequentially added to bind the aptamers and light the target cells. The proposed recognition-before-labeling strategy didn't require the complex process of QD functionalization, and avoided the possible impact on the aptamer configuration from steric hindrance. Meanwhile, QDs, with strong fluorescence and good photostability, also give this method a high signal-to-background ratio (S/B). The recognition-before-labeling strategy is simple and sensitive, suggesting a new method for in vitro diagnostic assays of cancer cells. [ABSTRACT FROM AUTHOR]

We developed a facile one-step method to produce ready-to-use quantum dots based on a peptide sequence containing a hexahistidine(his6-tag), poly(ethylene glycol) (PEG), and a functional group, which lead to stable and customized peptide–QDs conjugates that could serve as fluorescent nanoprobes for biological imaging and detection. [ABSTRACT FROM AUTHOR]

Here we report a facile switchable fluorescent QD probe for F(-) ions, which is based on the hydrogen bonding-driven aggregation and the analyte-triggered disaggregation.