Search

A study is conducted on a series of stable, crystalline bis-catecholate(super 8a) and bis-dithiocatecholate derivatives. Synthesis, spectroscopic properties and aspects of bonding are obtained using photoelectron spectroscopic measurements and extended Huckel molecular orbital calculations. The tetraaalkoxy diborane compounds B2(OCH2CMe2CH2O)2 and B2(OCMe2CMe2O)2 are also described.

A study is conduced on the X-ray crystal structures of bis-catecholate, bis-dithiocatecholate and tetraalkoxy diborane compounds. These include B2(1,2-O2C6H4)2, B2(1,2-O2-4-Bu(super t)C6H3)2, B2(1,2-O2-3,5-Bu(super t)2C6H2)2, B2(1,2-S2C6H4)2, B2(1,2-S2-4-MeC6H3)2 and B2(OCH2CMe2CH2O2)2. The compound (B2Cl4(NHMe2)2) that was isolated as a side product from some reactions is also analyzed.

The synthesis, structure, spectroscopic characteristics and chemical reactions related to metal-boryl compounds were reviewed. The transition metal-boryl compound possesses a covalent two-center, two-electron bond occurring between the metal center and a three-coordinate, sp2-hybridized boron atom. The synthesis of the compound involved the reaction of anionic transition metal complexes with haloboranes and in the absence of these complexes, reactions required a combination of oxidative addition and reduction of hydrogen.

A new type of 1,4-bis(diphenylphosphino)-1,3-butadiene-bridged diphosphine was synthesized using zirconium-mediation.

Protein-based 18 F-PET tracers offer new possibilities in early disease detection and personalized medicine. Their development relies heavily on the availability and effectiveness of 18 F-prosthetic groups. We prepared and evaluated a novel arginine-selective prosthetic group, 4-[ 18 F]fluorophenylglyoxal ([ 18 F]FPG). [ 18 F]FPG was radiosynthesized by a one-pot, two-step procedure with a non-decay-corrected (n.d.c.) isolated radiochemical yield (RCY) of 41 ± 8% ( n = 10). [ 18 F]FPG constitutes a generic tool for 18 F-labeling of various proteins, including human serum albumin (HSA), ubiquitin, interleukin-2, and interleukin-4 in ∼30-60% n.d.c. isolated RCYs. [ 18 F]FPG conjugation with arginine residues is highly selective, even in the presence of a large excess of lysine, cysteine, and histidine. [ 18 F]FPG protein conjugates are able to preserve the binding affinity of the native proteins while also demonstrating excellent in vivo stability. The [ 18 F]FPG-HSA conjugate has prolonged blood retention, which can be applied as a potential blood pool PET imaging agent. Thus, [ 18 F]FPG is an arginine-selective bioconjugation reagent that can be effectively used for the development of 18 F-labeled protein radiopharmaceuticals.

We describe a cysteine-rich, membrane-penetrating, joint-targeting, and remarkably stable peptide, EgK5, that modulates voltage-gated K V 1.3 potassium channels in T lymphocytes by a distinctive mechanism. EgK5 enters plasma membranes and binds to K V 1.3, causing current run-down by a phosphatidylinositol 4,5-bisphosphate-dependent mechanism. EgK5 exhibits selectivity for K V 1.3 over other channels, receptors, transporters, and enzymes. EgK5 suppresses antigen-triggered proliferation of effector memory T cells, a subset enriched among pathogenic autoreactive T cells in autoimmune disease. PET-CT imaging with 18 F-labeled EgK5 shows accumulation of the peptide in large and small joints of rodents. In keeping with its arthrotropism, EgK5 treats disease in a rat model of rheumatoid arthritis. It was also effective in treating disease in a rat model of atopic dermatitis. No signs of toxicity are observed at 10-100 times the in vivo dose. EgK5 shows promise for clinical development as a therapeutic for autoimmune diseases., Competing Interests: The authors declare no competing financial interest., (Copyright © 2020 American Chemical Society.)

Reversible addition-fragmentation chain transfer (RAFT) polymerization has been employed to synthesize branched block copolymer nanoparticles possessing 1,4,7,10-tetraazacyclododecane-N,N,'N,″N,‴-tetraacetic acid (DO3A) macrocycles within their cores and octreotide (somatostatin mimic) cyclic peptides at their periphery. These polymeric nanoparticles have been chelated with Gd 3+ and applied as magnetic resonance imaging (MRI) nanocontrast agents. This nanoparticle system has an r 1 relaxivity of 8.3 mM -1 s -1 , which is 3 times the r 1 of commercial gadolinium-based contrast agents (GBCAs). The in vitro targeted binding efficiency of these nanoparticles shows 5 times greater affinity to somatostatin receptor type 2 (SSTR2) with K i = 77 pM (compared to somatostatin with K i = 0.385 nM). We have also evaluated the tumor targeting molecular imaging ability of these branched copolymer nanoparticle in vivo using nude/NCr mice bearing AR42J rat pancreatic tumor (SSTR2 positive) and A549 human lung carcinoma tumor (SSTR2 negative) xenografts.