RESUMEN
Micellar-nanocarrier-based drug delivery systems possessing characteristics such as an excellent circulation stability, inhibited premature release and on-demand site-specific release are urgently needed for enhanced therapeutic efficacy. Therefore, a novel kind of shell-sheddable core-crosslinked polymeric micelles with pH and oxidation dual-triggered on-demand drug release behavior was facilely constructed. The multifunctional micelles were self-assembled from a carefully designed amphiphilic triblock PEGylated polyurethane (PEG-acetal-PUBr-acetal-PEG) employing an acid-labile acetal linker at the hydrophilic-hydrophobic interface and pendant reactive bromo-containing polyurethane (PU) as the hydrophobic block, followed by a post-crosslinking via oxidation-cleavable diselenide linkages. These well-defined micelles exhibited an enhanced structural stability against dilution, achieved through the incorporation of diselenide crosslinkers. As expected, they were found to possess dual pH- and oxidation-responsive dissociation behaviors when exposure to acid pH (~5.0) and 50 mM H2O2 conditions, as evidenced using dynamic light-scattering (DLS) and atomic force microscopy (AFM) analyses. An in vitro drug release investigation showed that the drug indomethacin (IND) could be efficiently encapsulated in the micelles, which demonstrated an inhibited premature release compared to the non-crosslinked ones. It is noteworthy that the resulting micelles could efficiently release entrapped drugs at a fast rate in response to either pH or oxidation stimuli. Moreover, the release could be significantly accelerated in the presence of both acid pH and oxidation conditions, relative to a single stimulus, owing to the synergetic degradation of micelles through pH-induced dePEGylation and oxidation-triggered decrosslinking processes. The proposed shell-sheddable core-crosslinked micelles with a pH and oxidation dual-response could be potential candidates as drug carriers for on-demand drug delivery.
RESUMEN
As an efficient and green synthesis method, the electrocatalysis hydrogen evolution coupling reaction has been widely used by chemists to realize the combining of two nucleophiles. In this work, an alternative method to synthesize 6-phosphorylated phenanthridines has been developed by synergistically utilizing electrocatalysis and Mn catalysis, with moderate to relatively good yields achieved. Mild and oxidant-free conditions make this synthetic method applicable in various settings.
RESUMEN
An efficient copper-catalyzed cascade alkynylation/cyclization/isomerization reaction of aurone-derived azadienes with terminal alkynes has been developed, giving a series of 1,2-dihydrobenzofuro[3,2-b]pyridines with excellent yields. The obtained 1,2-dihydrobenzofuro[3,2-b]pyridines can be conveniently transformed into the corresponding benzofuro[3,2-b]pyridines under basic conditions. Additionally, benzofuro[3,2-b]pyridines can also be prepared from azadienes and terminal alkynes in a one-pot reaction. The synthetic utility was demonstrated by the synthesis of three bioactive molecules with potent topoisomerase inhibition in high yields. This strategy provides a facile approach to 1,2-dihydrobenzofuro[3,2-b]pyridines and benzofuro[3,2-b]pyridines.
RESUMEN
Axially chiral biimidazole ligands have been rarely synthesized and studied, in contrast to the significant achievements in the synthesis and application of central chiral imidazole ligands. Herein, a series of novel axially chiral 2,2'-biimidazole ligands were synthesized from the reaction of 2,2'-bis(bromomethyl)-1,1'-binaphthalene and 2,2'-biimidazole in one step through the strategy of remote chirality delivery. These ligands have been proven to be efficient for Cu- or Fe-catalyzed asymmetric insertion of α-aryl-α-diazoacetates into the N-H bond of carbazoles with up to 96% ee.
RESUMEN
The first highly enantioselective hydrogenation of carbocyclic aromatic amines has been successfully realized using in situ-generated chiral ruthenium complex as catalyst, affording facile access to chiral exocyclic amines with up to 98% ee.