Synthesis and characterization of copolyesters based on tartaric acid derivatives

Biodegradable Block Poly(ester amine)s with Pendant Hydroxyl Groups for Biomedical Applications

The article presents the results of the synthesis and characteristics of the amphiphilic block terpolymers, built of a hydrophilic polyesteramine block, and hydrophobic blocks made of lactidyl and glycolidyl units. These terpolymers were obtained during the copolymerization of L-lactide with glycolide carried out in the presence of previously produced macroinitiators with protected amine and hydroxyl groups. The terpolymers were prepared to produce a biodegradable and biocompatible material containing active hydroxyl and/or amino groups, with strong antibacterial properties and high surface wettability by water. The control of the reaction course, the process of deprotection of functional groups, and the properties of the obtained terpolymers were made based on 1H NMR, FTIR, GPC, and DSC tests. Terpolymers differed in the content of amino and hydroxyl groups. The values of average molecular mass oscillated from about 5000 g/mol to less than 15,000 g/mol. Depending on the length of the hydrophilic block and its composition, the value of the contact angle ranged from 50° to 20°. The terpolymers containing amino groups, capable of forming strong intra- and intermolecular bonds, show a high degree of crystallinity. The endotherm responsible for the melting of L-lactidyl semicrystalline regions appeared in the range from about 90 °C to close to 170 °C, with a heat of fusion from about 15 J/mol to over 60 J/mol.

Evaluation of the Antibacterial Activity and Cell Response for 3D-Printed Polycaprolactone/Nanohydroxyapatite Scaffold with Zinc Oxide Coating

Among 3D-printed composite scaffolds for bone tissue engineering, researchers have been attracted to the use of zinc ions to improve the scaffold's anti-bacterial activity and prevent surgical site infection. In this study, we assumed that the concentration of zinc ions released from the scaffold will be correlated with the thickness of the zinc oxide coating on 3D-printed scaffolds. We investigated the adequate thickness of zinc oxide coating by comparing different scaffolds' characteristics, antibacterial activity, and in vitro cell response. The scaffolds' compressive modulus decreased as the zinc oxide coating thickness increased (10, 100 and 200 nm). However, the compressive modulus of scaffolds in this study were superior to those of other reported scaffolds because our scaffolds had a kagome structure and were made of composite material. In regard to the antibacterial activity and in vitro cell response, the in vitro cell proliferation on scaffolds with a zinc oxide coating was higher than that of the control scaffold. Moreover, the antibacterial activity of scaffolds with 100 or 200 nm-thick zinc oxide coating on Escherichia coli was superior to that of other scaffolds. Therefore, we concluded that the scaffold with a 100 nm-thick zinc oxide coating was the most appropriate scaffold to use as a bone-regenerating scaffold, given its mechanical property, its antibacterial activity, and its in vitro cell proliferation.

One-pot oligoamides syntheses from l-lysine and l-tartaric acid

Oligoamides based on natural raw materials, l-lysine and l-tartaric acid, were synthesized using one-pot processes. A l-lysine diketopiperazine structure was obtained with good selectivity without protection/deprotection steps.