Understanding the Structural Parameters of Biocompatible Nanoparticles Dictating Protein Fouling

The development of nanocarriers for biomedical applications requires that these nanocarriers have special properties, including resistance to nonspecific protein adsorption. In this study, the fouling properties of PLA- and PCL-based block copolymer nanoparticles (NPs) have been evaluated by placing them in contact with model proteins. Block copolymer NPs were produced through the self-assembly of PEO_<i>m</i>-<i>b</i>-PLA_<i>n</i> and PEO_<i>m</i>-<i>b</i>-PCL_<i>n</i>. This procedure yielded nanosized objects with distinct structural features dependent on the length of the hydrophobic and hydrophilic blocks and the volume ratio. The protein adsorption events were examined in relation to size, chain length, surface curvature, and hydrophilic chain density. Fouling by BSA and lysozyme was considerably reduced as the length of the hydrophilic PEO-stabilizing shell increases. In contrast to the case of hydrophilic polymer-grafted planar surfaces, the current investigations suggest that the hydrophilic chain density did not markedly influence protein fouling. The protein adsorption took place at the outer surface of the NPs since neither BSA nor lysozyme was able to diffuse within the hydrophilic layer due to geometric restrictions. Protein binding is an exothermic process, and it is modulated mainly by polymer features. The secondary structures of BSA and lysozyme were not affected by the adhesion phenomena

Pt^II Phosphors with Click-Derived 1,2,3-Triazole-Containing Tridentate Chelates

A series of Pt^II complexes featuring 1,2,3-triazole-derived N^∧N^∧N-, N^∧C^∧N- and C^∧N^∧C-coordinating ligands were studied both experimentally and computationally aiming at the design of new Pt^II phosphors. By virtue of click chemistry, the new complexes were readily functionalized, e.g., with bulky groups in order to suppress aggregation of the complexes. For a N^∧C^∧N-type cyclometalated Pt^II complex, the high energy of the π* orbitals of the 1,2,3-triazole units gave rise to deep-blue phosphorescence; the poor luminescence quantum yield was attributed to an inadequate energy separation between the emissive state and the d–d states. However, when the 1,2,3-triazole donor moiety acted as a spectator/ancillary ligand only, an intense green emission could be achieved (Φ_PL = 0.57, τ = 4.6 μs)

Iron-Catalyzed Synthesis of Conformationally Restricted Bicyclic N‑Heterocycles via [2+2]-Cycloaddition: Exploring Ring ExpansionMechanistic Insights and Challenges

We present an efficient iron-catalyzed method for synthesizing conformationally restricted cyclobutane-fused N-heterocycles from unactivated precursors. This method is orthogonal to the established photocatalytic methods, extends the range of substrates, and provides a single-step route to previously unattainable cyclobutane-fused piperidines and azepanes. Ring stereochemistry depends on size, with five- and six-membered rings adopting a cis configuration and seven-membered rings preferring a trans configuration. A key aspect of this method is the use of a catalyst design based on an electron-deficient, redox-active, pyrimidinediimine scaffold. Mechanistic investigations suggest that the π-acidic core significantly enhances catalyst stability against deleterious intramolecular C–H activation pathways, while the electron-rich flanking groups accelerate the reaction rate. Mechanistic insights were obtained by extracting kinetic profiles and establishing catalyst–activity relationships. Computational studies established that the oxidative cyclization step proceeds with the highest energy barrier, which is further confirmed by experimental Hammett analysis

PD-L1 overexpression correlates with JAK2-V617F mutational burden and is associated with 9p uniparental disomy in myeloproliferative neoplasms

-L1 overexpression correlates with JAK2-V617F mutational burden and is associated with 9p uniparental disomy in myeloproliferative neoplasm

Nanoparticle–Cell Interactions: Surface Chemistry Effects on the Cellular Uptake of Biocompatible Block Copolymer Assemblies

The development of nanovehicles for intracellular drug delivery is strongly bound to the understating and control of nanoparticles cellular uptake process, which in turn is governed by surface chemistry. In this study, we explored the synthesis, characterization, and cellular uptake of block copolymer assemblies consisting of a pH-responsive poly­[2-(diisopropyl­amino)­ethyl methacrylate] (PDPA) core stabilized by three different biocompatible hydrophilic shells (a zwitterionic type poly­(2-methacryl­oyloxyethyl phosphorylcholine) (PMPC) layer, a highly hydrated poly­(ethylene oxide) (PEO) layer with stealth effect, and an also proven nontoxic and nonimmunogenic poly­(<i>N</i>-(2-hydroxypropyl)­methacrylamide) (PHPMA) layer). All particles had a spherical core–shell structure. The largest particles with the thickest hydrophilic stabilizing shell obtained from PMPC₄₀-<i>b</i>-PDPA₇₀ were internalized to a higher level than those smaller in size and stabilized by PEO or PHPMA and produced from PEO₁₂₂-<i>b</i>-PDPA₄₃ or PHPMA₆₄-<i>b</i>-PDPA₇₂, respectively. Such a behavior was confirmed among different cell lines, with assemblies being internalized to a higher degree in cancer (HeLa) as compared to healthy (Telo-RF) cells. This fact was mainly attributed to the stronger binding of PMPC to cell membranes. Therefore, cellular uptake of nanoparticles at the sub-100 nm size range may be chiefly governed by the chemical nature of the stabilizing layer rather than particles size and/or shell thickness

Rapid Synthesis of Radioactive Transition-Metal Carbonyl Complexes at Ambient Conditions

Carbonyl complexes of radioactive transition metals can be easily synthesized with high yields by stopping nuclear fission or fusion products in a gas volume containing CO. Here, we focus on Mo, W, and Os complexes. The reaction takes place at pressures of around 1 bar at room temperature, i.e., at conditions that are easy to accommodate. The formed complexes are highly volatile. They can thus be transported within a gas stream without major losses to setups for their further investigation or direct use. The rapid synthesis holds promise for radiochemical purposes and will be useful for studying, e.g., chemical properties of superheavy elements