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Summary:Translating the potential of transition metal catalysis to biological and living environments promises to have a profound impact in chemical biology and biomedicine. A major challenge in the field is the creation of metal-based catalysts that remain active over time. Here, we demonstrate that embedding a reactive metallic core within a microporous metal-organic framework-based cloak preserves the catalytic site from passivation and deactivation, while allowing a suitable diffusion of the reactants. Specifically, we report the fabrication of nanoreactors composed of a palladium nanocube core and a nanometric imidazolate framework, which behave as robust, long-lasting nanoreactors capable of removing propargylic groups from phenol-derived pro-fluorophores in biological milieu and inside living cells. These heterogeneous catalysts can be reused within the same cells, promoting the chemical transformation of recurrent batches of reactants. We also report the assembly of tissue-like 3D spheroids containing the nanoreactors and demonstrate that they can perform the reactions in a repeated manner.
Abstract:A Pd catalyst made from a Pd(0) source and a bulky biaryl phosphine ligand promotes highly efficient intramolecular (3 + 2) heterocycloadditions between alkylidenecyclopropanes (ACPs) and carbonyls. The annulations provide a straightfor-ward access to fused polycyclic systems featuring β-methylene tetrahydrofuran moieties. DFT data support a pallada-ene process and shed light on the critical role of hemilabile interactions between the Pd center and the bulky biaryl phosphine. Significantly, these Pd(0) catalysts are also effective for promoting intermolecular formal cycloadditions between ACPs and trifluoromethyl ketones, thus providing for a direct entry to chiral THFs bearing trifluoromethyl–substituted carbons
External link: https://pubs.acs.org/doi/10.1021/acscatal.0c01827
Abstract:We describe the nickel(II)‐mediated self‐assembly of a multimeric DNA binder composed by two metal‐chelating peptides derived from a bZIP transcription factor ( brHis 2 ) and one short AT‐hook domain equipped with two bipyridine ligands ( HkBpy 2 ). These peptides reversibly assemble in the presence of Ni(II) ions at selected DNA sequences of 13 base pairs.
Abstract: The generation of catalytically active metalloproteins inside living mammalian cells is a major research challenge at the interface between catalysis and cell biology. Herein we demonstrate that basic domains of bZIP transcription factors, mutated to include two histidine residues at i, i+4 positions, react with palladium (II) sources to generate catalytically active, stapled pallado‐miniproteins. The resulting constrained peptides are efficiently internalized into living mammalian cells, where they can perform palladium‐promoted depropargylation reactions, without cellular fixation. Control experiments confirm the requirement of the peptide scaffolding and the palladium staple for attaining the intracellular reactivity.
External link: https://onlinelibrary.wiley.com/doi/10.1002/anie.202002032
Abstract:When nanoparticles (NPs) are exposed to biological media, proteins are adsorbed, forming a so-called protein corona (PC). This cloud of protein aggregates hampers the targeting and transport capabilities of the NPs, thereby compromising their biomedical applications. Therefore, there is a high interest in the development of technologies that allow control over PC formation, as this would provide a handle to manipulate NPs in biological fluids. We present a strategy that enables the reversible disruption of the PC using external stimuli, thereby allowing a precise regulation of NP cellular uptake. The approach, demonstrated for gold nanoparticles (AuNPs), is based on a biorthogonal, supramolecular host–guest interactions between an anionic dye bound to the AuNP surface and a positively charged macromolecular cage. This supramolecular complex effectively behaves as a zwitterionic NP ligand, which is able not only to prevent PC formation but also to disrupt a previously formed hard corona. With this supramolecular stimulus, the cellular internalization of AuNPs can be enhanced by up to 30-fold in some cases, and even NP cellular uptake in phagocytic cells can be regulated. Additionally, we demonstrate that the conditional cell uptake of purposely designed gold nanorods can be used to selectively enhance photothermal cell death.
External link: https://twitter.com/MetBioCat/status/1235837116090691585
Abstract:MitoBlue is a fluorescent bisamidine that can be used to easily monitor the changes in mitochondrial degradation processes in different cells and cellular conditions. MitoBlue staining pattern is exceptional among mitochondrial dyes and recombinant fluorescent probes, allowing the dynamic study of mitochondrial recycling in a variety of situations in living cells. MitoBlue is a unique tool for the study of these processes that will allow the detailed characterization of communication between mitochondria and lysosomes.
External link: https://twitter.com/MetBioCat/status/1233074377048064007
Starting this brand new 2020 year... we are glad to announce our most recent publication at ACS Catalysis journal, entitled "Palladium-catalyzed formal (4+2) cycloaddition between alkyl amides and dienes initiated by the activation of C(sp3)−H bonds" and authored by B. Cendón, M. Font, J. L. Mascareñas and M. Gulías, is already available as just accepted manuscript.
Abstract:We report a formal (4+2) cycloaddition between alkyl-nosylamides and dienes enabled by a palladium-catalyzed activation of C(sp3)−H bonds beta to the amide group. This atom economical reaction which proceeds under operationally simple conditions, is compatible with a wide variety of dienes, and provides a straightforward method to assemble different types of saturated lactams. The annulation is favored over alternative pathways in part because of the key role of the extra double bond of the diene partner. The use of suitable nitrogen-based additives as palladium ligands, which enable the C(sp3)−H activation without interfering in subsequent steps of the catalytic cycle, is also critical for the success of the reaction.
External link: https://twitter.com/MetBioCat/status/1230768577738764290
External link: https://erc.europa.eu/news/PoC-recipients-2019-third-round