Recent Advances in Polyallenes: Preparation, Self-Assembly, and Stimuli-Responsiveness

Enhanced Antibacterial Activity of Vancomycin Loaded on Functionalized Polyketones

Today, polymeric drug delivery systems (DDS) appear as an interesting solution against bacterial resistance, having great advantages such as low toxicity, biocompatibility, and biodegradability. In this work, two polyketones (PK) have been post-functionalized with sodium taurinate (PKT) or potassium sulfanilate (PKSK) and employed as carriers for Vancomycin against bacterial infections. Modified PKs were easily prepared by the Paal-Knorr reaction and loaded with Vancomycin at a variable pH. All polymers were characterized by FT-IR, DSC, TGA, SEM, and elemental analysis. Antimicrobial activity was tested against Gram-positive Staphylococcus aureus ATCC 25923 and correlated to the different pHs used for its loading (between 2.3 and 8.8). In particular, the minimum inhibitory concentrations achieved with PKT and PKSK loaded with Vancomycin were similar, at 0.23 μg/mL and 0.24 μg/mL, respectively, i.e., six times lower than that with Vancomycin alone. The use of post-functionalized aliphatic polyketones has thus been demonstrated to be a promising way to obtain very efficient polymeric DDS.

Helical Crystals in Aliphatic Copolyesters: From Chiral Amplification to Mechanical Property Enhancement

We demonstrate herein a bottom-up strategy for achieving helical crystals via chiral amplification in copolyesters by incorporating a small amount of (d)-isosorbide into semicrystalline polyester, poly(ethylene brassylate) (PEB). During bulk crystallization of poly(ethylene-co-isosorbide brassylate)s, the molecular chirality of isosorbide in the amorphous region is transferred to PEB crystal chirality and amplified by the formation of right-handed helical crystals. Increasing isosorbide content or reducing crystallization temperature leads to thinner PEB lamellae crystals, strengthening chiral amplification by forming superhelices with a smaller helical pitch. Moreover, the superhelices with smaller helical pitch (larger chiral amplification) endow aliphatic copolyesters with enhanced modulus, strength, and toughness without sacrificing elongation-at-break. The principle outlined here could apply to the design of strong and tough materials.

Recent advances in the metal-catalyzed asymmetric synthesis of chiral allenes

Recent advances in the metal-catalyzed asymmetric synthesis of chiral allenes are summarized. This review is categorized based on the starting material, including alkynes, racemic allenes, and conjugated dienes.

Thermotropic chirality enhancement of nanoparticles constructed from foldamer/bis(amino acid) complexes

Herein, chiral nanoparticles are constructed by mixing an artificial foldamer bearing aza-18-crown-6 pendants with l-homocystine perchlorate salt, showing a thermotropic chirality enhancement due to the binding mode changes in the heating process.