η-Carbides (Co, Mo, or W) Nanoparticles from Octacyanometalates Precursors-Based Network.

This paper describes a simple, two-steps chemical pathway to obtain bimetallic carbide nanoparticles (NPs) of general formula MxM″yC, also called η-carbides. This process allows for a control of the chemical composition of metals present in the carbides (M = Co and M″ = Mo or W). The first step involves the synthesis of a precursor consisting of a network of octacyanometalates. The second step consists in a thermal degradation of the previously obtained octacyanometalates networks under neutral atmosphere (Ar or N2 ). It is shown that this process results in the formation of carbide NPs with diameter of ≈ 5nm, and the stoichiometries Co3 M'3 C, Co6 M'6 C, Co2 M'4 C for the CsCoM' systems.

A simple and efficient process for the synthesis of 2D carbon nitrides and related materials.

We describe here a new process for the synthesis of very high quality 2D Covalent Organic Frameworks (COFs), such a C2N and CN carbon nitrides. This process relies on the use of a metallic surface as both a reagent and a support for the coupling of small halogenated building blocks. The conditions of the assembly reaction are chosen so as to leave the inorganic salts by-products on the surface, to further confine the assembly reaction on the surface and increase the quality of the 2D layers. We found that under these conditions, the process directly returns few layers material. The structure/quality of these materials is demonstrated by extensive cross-characterizations at different scales, combining optical microscopy, Scanning Electron Microscopy (SEM)/Transmission Electron Microscopy (TEM) and Energy Dispersive Spectroscopy (EDS). The availability of such very large, high-quality layers of these materials opens interesting perspectives, for example in photochemistry and electronics (intrinsic transport properties, high gap substrate for graphene, etc...).

Deproto-metallation and computed CH acidity of 2-aryl-1,2,3-triazoles.

2-Aryl-1,2,3-triazoles were synthesized by cyclization of the corresponding glyoxal arylosazones, generated from commercial arylhydrazines. The deproto-metallation of 2-phenyl-1,2,3-triazole was attempted using different 2,2,6,6-tetramethylpiperidino-based mixed lithium-metal (Zn, Cd, Cu, Co, Fe) combinations, giving results in the case of Zn, Cd, and Cu. The lithium-zinc combination was next selected to apply the deprotonation-iodination sequence to all the 2-aryl-1,2,3-triazoles synthesized. The results were analyzed with the help of the CH acidities of the substrates, determined in THF solution using the DFT B3LYP method.

Bactericidal microparticles decorated by an antimicrobial peptide for the easy disinfection of sensitive aqueous solutions.

Silica and paramagnetic silica microparticles are surface-modified by an antibacterial macromolecular coating. For this, a hydrophilic copolymer brush based on oligo(ethylene glycol) methacrylates is grown on the particle surface by surface-initiated ATRP. Then, Magainin-I, a natural antimicrobial peptide, is grafted onto the hydroxyl groups of the brush through a heterolinker. The grafting of the peptide is evidenced by fluorescence microscopy and X-ray photoelectron spectroscopy. Moreover, culturability and viability assays performed in the presence of the magainin-grafted particles prove their bactericidal properties. The rapid recovery of the bactericidal particles based on paramagnetic silica and suspended in solution is shown under magnetization. Such particles offer the advantage to treat efficiently various sensitive aqueous solutions while avoiding any dissemination of bactericidal substances in the environment. As a consequence, they are of a great interest for various applications in medical, cosmetic, or biomedical fields.

Uptake and transcytosis of functionalized superparamagnetic iron oxide nanoparticles in an in vitro blood brain barrier model.

Two major hurdles in nanomedicine are the limited strategies for synthesizing stealth nanoparticles and the poor efficacy of the nanoparticles in translocating across the blood brain barrier (BBB). Here we examined the uptake and transcytosis of iron oxide nanoparticles (IONPs) grafted with biomimetic phosphorylcholine (PC) brushes in an in vitro BBB model system, and compared them with bare, PEG or PC-PEG mixture grafted IONPs. Hyperspectral imaging indicated IONP co-localization with cells. Quantitative analysis with total reflection X-ray fluorescence spectrometry showed that after 24 h, 78% of PC grafted, 68-69% of PEG or PC-PEG grafted, and 30% of bare IONPs were taken up by the BBB. Transcytosis of IONPs was time-dependent and after 24 h, 16-17% of PC or PC-PEG mixture grafted IONPs had passed the BBB model, significantly more than PEG grafted or bare IONPs. These findings point out that grafting of IONPs with PC is a viable strategy for improving the uptake and transcytosis of nanoparticles.

Human plasma proteome association and cytotoxicity of nano-graphene oxide grafted with stealth polyethylene glycol and poly(2-ethyl-2-oxazoline).

Polyethylene glycol (PEG) is a gold standard against protein fouling. However, recent studies have revealed surprising adverse effects of PEG, namely its immunogenicity and shortened bio-circulation upon repeated dosing. This highlights a crucial need to further examine 'stealth' polymers for controlling the protein 'corona', a new challenge in nanomedicine and bionanotechnology. Poly(2-ethyl-2-oxazoline) (PEtOx) is another primary form of stealth polymer that, despite its excellent hydrophilicity and biocompatibility, has found considerably less applications compared with PEG. Herein, we performed label-free proteomics to compare the associations of linear PEG- and PEtOx-grafted nano-graphene oxide (nGO) sheets with human plasma proteins, complemented by cytotoxicity and haemolysis assays to compare the cellular interactions of these polymers. Our data revealed that nGO-PEG enriched apolipoproteins, while nGO-PEtOx displayed a preferred binding with pro-angiogenic and structural proteins, despite high similarities in their respective top-10 enriched proteins. In addition, nGO-PEG and nGO-PEtOx exhibited similar levels of enrichment of complement proteins. Both PEG and PEtOx markedly reduced nGO toxicity to HEK 293 cells while mitigating nGO haemolysis. This study provides the first detailed profile of the human plasma protein corona associated with PEtOx-grafted nanomaterials and, in light of the distinctions of PEtOx in chemical adaptability, in vivo clearance and immunogenicity, validates the use of PEtOx as a viable stealth alternative to PEG for nanomedicines and bionanotechnologies.

Brushed polyethylene glycol and phosphorylcholine for grafting nanoparticles against protein binding.

To provide a molecular insight for guiding polymer coating in surface science and nanotechnology, here we examined the structures of brushed polyethylene glycol(bPEG)- and phosphorylcholine(bPC)-grafted iron oxide nanoparticles and analyzed their protein avoiding properties. We show bPC as an advantageous biomimetic alternative to PEG in rendering stealth nanostructures.