Local detection of pH-induced disaggregation of biocompatible micelles by fluorescence switch ON.

Fluorogenic nanoparticles (NPs) able to sense different physiological environments and respond with disaggregation and fluorescence switching OFF/ON are powerful tools in nanomedicine as they can combine diagnostics with therapeutic action. pH-responsive NPs are particularly interesting as they can differentiate cancer tissues from healthy ones, they can drive selective intracellular drug release and they can act as pH biosensors. Controlled polymerization techniques are the basis of such materials as they provide solid routes towards the synthesis of pH-responsive block copolymers that are able to assemble/disassemble following protonation/deprotonation.

Lighting up the Electrochemiluminescence of Carbon Dots through Pre- and Post-Synthetic Design.

Carbon dots (CDs), defined by their size of less than 10 nm, are a class of photoluminescent (PL) and electrochemiluminescent (ECL) nanomaterials that include a variety of carbon-based nanoparticles. However, the control of their properties, especially ECL, remains elusive and afflicted by a series of problems. Here, the authors report CDs that display ECL in water via coreactant ECL, which is the dominant mechanism in biosensing applications.

Exploring the Role of the Central Carbide of the Nitrogenase Active-Site FeMo-cofactor through Targeted C Labeling and ENDOR Spectroscopy.

Mo-dependent nitrogenase is a major contributor to global biological N reduction, which sustains life on Earth. Its multi-metallic active-site FeMo-cofactor (FeMoSC-homocitrate) contains a carbide (C) centered within a trigonal prismatic CFe core resembling the structural motif of the iron carbide, cementite. The role of the carbide in FeMo-cofactor binding and activation of substrates and inhibitors is unknown.

Superstructured Biomaterials Formed by Exchange Dynamics and Host-Guest Interactions in Supramolecular Polymers.

Dynamic and reversible assembly of molecules is ubiquitous in the hierarchical superstructures of living systems and plays a key role in cellular functions. Recent work from the laboratory reported on the reversible formation of such superstructures in systems of peptide amphiphiles conjugated to oligonucleotides and electrostatically complimentary peptide sequences. Here, a supramolecular system is reported upon where exchange dynamics and host-guest interactions between -cyclodextrin and adamantane on peptide amphiphiles lead to superstructure formation.

Peptide-siRNA Supramolecular Particles for Neural Cell Transfection.

Small interfering ribonucleic acid (siRNA)-based gene knockdown is an effective tool for gene screening and therapeutics. However, the use of nonviral methods has remained an enormous challenge in neural cells. A strategy is reported to design artificial noncationic modular peptides with amplified affinity for siRNA via supramolecular assembly that shows efficient protein knockdown in neural cells.

Instantaneous hydrolysis of nerve-agent simulants with a six-connected zirconium-based metal-organic framework.

A nerve-agent simulant based on a phosphate ester is hydrolyzed using a MOF-based catalyst. Suspensions of MOF-808 (6-connected), a material featuring 6-connected zirconium nodes, display the highest hydrolysis rates among all MOFs that have been reported to date. A plug-flow reactor was also prepared with MOF-808 (6-connected) as the active layer.

Robust passive and active efflux of cellular cholesterol to a designer functional mimic of high density lipoprotein.

The ability of HDL to support macrophage cholesterol efflux is an integral part of its atheroprotective action. Augmenting this ability, especially when HDL cholesterol efflux capacity from macrophages is poor, represents a promising therapeutic strategy. One approach to enhancing macrophage cholesterol efflux is infusing blood with HDL mimics.

Biocompatible infinite-coordination-polymer nanoparticle-nucleic-acid conjugates for antisense gene regulation.

Herein, we report the synthesis of DNA-functionalized infinite-coordination-polymer (ICP) nanoparticles as biocompatible gene-regulation agents. ICP nanoparticles were synthesized from ferric nitrate and a ditopic 3-hydroxy-4-pyridinone (HOPO) ligand bearing a pendant azide. Addition of Fe(III) to a solution of the ligand produced nanoparticles, which were colloidally unstable in the presence of salts.

EPR, ENDOR, and electronic structure studies of the Jahn-Teller distortion in an Fe(V) nitride.

The recently synthesized and isolated low-coordinate Fe(V) nitride complex has numerous implications as a model for high-oxidation states in biological and industrial systems. The trigonal [PhB((t)BuIm)3Fe(V)≡N](+) (where (PhB((t)BuIm)3(-) = phenyltris(3-tert-butylimidazol-2-ylidene)), (1) low-spin d(3) (S = 1/2) coordination compound is subject to a Jahn-Teller (JT) distortion of its doubly degenerate (2)E ground state. The electronic structure of this complex is analyzed by a combination of extended versions of the formal two-orbital pseudo Jahn-Teller (PJT) treatment and of quantum chemical computations of the PJT effect.

Directed Assembly of Periodic Materials from Protein and Oligonucleotide-Modified Nanoparticle Building Blocks.

DNA hybridization enables the three-dimensional assembly of Au nanoparticles and streptavidin. The high-density DNA-modified Au nanoparticles were stable to nonspecific binding of streptavidin. Structural and melting investigations on the assemblies showed their formation was reversible.

Oxide Addition to a Reactive Polysulfide Flux: Synthesis of K Ba[Ti OS ] Containing Isolated [Ti OS (S ) ] Clusters.

The zero-dimensional cluster compound K Ba[Ti OS (S ) ] has been synthesized from a reactive flux similar to that of K S and Ti used in the synthesis of the one-dimensional compound K Ti S , but augmented by the deliberate introduction of TiO . The picture shows the structure of the [Ti OS (S ) ] ion.