Peptide and Protein Stereocomplexes

Stereocomplexation in peptides and proteins is a fascinating phenomenon arising from their inherent stereoisomerism. Peptides and proteins, with their three-dimensional helical structures, exhibit stereoselectivity and form intertwined complexes when complementary left- and right-handed structures are mixed together. Stereocomplexation provides an unprecedented opportunity to impart some valuable biological, chemical, and physical properties in peptide and protein polymeric platforms that can be employed in various applications such as catalysis and drug delivery and to improve the stability of these therapeutics. However, exploration of stereocomplexation in peptides and proteins remains limited. We report on a comprehensive understanding of stereocomplexation in peptides and proteins, compiling existing reports, discussing its implications, and highlighting its role in different applications, aiming to inspire further research and advancements in this direction.

Theoretical Design of Blue-Color Phosphorescent Complexes for Organic Light-Emitting Diodes: Emission Intensities and Nonradiative Transition Rate Constants in Ir(ppy)2(acac) Derivatives

Theoretical calculations of phosphorescent spectra and nonradiative transition (NRT) rate constants for S₁ ⇝ T₁, T₁ ⇝ S₀, and S₁ ⇝ S₀ were carried out to determine the best candidate for a blue-color phosphorescent complex among several derivatives of bis(2-phenylpyridine)(acetylacetonate)iridium(III). The geometries of the ground state (S₀), the lowest triplet state (T₁), and the lowest excited singlet state (S₁) were optimized at the levels of density functional theory, in which B3LYP functionals and SBKJC+p basis sets were used. The NRT rate constants were derived by using a generating function method within the displaced harmonic oscillator model. The results of the calculation for phosphorescence showed that the introduction of F and/or CN substituents at the 4'/6'-th and 5'-th sites in 2-phenylpyridinate (ppy) ligands, respectively, causes a blue shift of the emission spectra. They also suggest that Ir(5-CN,6-F-ppy)₂(acac), denoted 3(56) in the text, is a good candidate for a blue-color phosphorescent complex because a blue shift of emission spectra and a moderate intensity are obtained for phosphorescence and, furthermore, this complex is calculated to have a large rate constant for S₁ ⇝ T₁ and relatively smaller rate constants for T₁ ⇝ S₀ and S₁ ⇝ S₀ based on the calculations of spin-orbit coupling and nonadiabatic coupling constants.

Synthesis and Characterization of Dendrimer-Based Polysarcosine Star Polymers: Well-Defined, Versatile Platforms Designed for Drug-Delivery Applications

This paper describes the synthesis of star polymers designed for future drug-delivery applications. A generation-5 lysine dendrimer was used as a macroinitiator for the ring-opening polymerization of the sarcosine N-carboxyanhydride monomer to produce 32-arm star polymers with narrow molar mass distributions and desirable hydrodynamic size control. Fluorescent dye-labeled polymers were dosed in mice to measure plasma pharmacokinetics. Long circulation times were observed, representing ideal properties for biophysical targeting of tumors. In vivo efficacy of one of these star polymers conjugated to the therapeutic molecule SN-38 was evaluated in mice bearing SW620 xenografted tumors to demonstrate high antitumor activity and low body weight loss compared to the SN-38 prodrug irinotecan and this shows the potential of these delivery systems. As a further build, we demonstrated that these star polymers can be easily chain-end-functionalized with useful chemical moieties, giving opportunities for future receptor-targeting strategies. Finally, we describe the synthetic advantages of these star polymers that make them attractive from a pharmaceutical manufacturing perspective and report characterization of the polymers with a variety of techniques.

The accelerated blood clearance phenomenon of PEGylated nanoemulsion upon cross administration with nanoemulsions modified with polyglycerin

For investigating the accelerated blood clearance (ABC) phenomenon of polyglycerin modified nanoemulsions upon cross administration with polyethylene glycol (PEG) covered nanoemulsion, we used the 1,2-distea-royl-sn-glycero-3-phosphoethanolamine-n-polyglycerine-610 and the 1,2-distearoyl-n-glycero-3-phosphoethanolamine-n-[me-thoxy(polyethylene glycol)-2000] as modify materials, the dialkylcarbocyanines as fluorescence indicator. Exhausted macrophages rat model was established and new material containing polycarboxyl structure was synthesized. The microplate reader and the in vivo optical imaging system were applied to measure the concentration of nanoemulsions in tissues. The results show that the first dose of polyglycerin modified nanoemulsion can induce the ABC phenomenon of the second dose of PEGylated nanoemulsion. With the increase in the amount of the surface polyglycerin, the extent of the ABC phenomenon decreases. Liver accumulation has positive relationship with the ABC phenomenon. Furthermore, kupffer cells in liver can get more immune information from polyhydroxy structure than polycarboxyl group in the modify compound. The results of our work imply that the polycarboxyl structure has advantages to eliminate the ABC phenomenon.