Branched Poly(ε-caprolactone)-Based Copolyesters of Different Architectures and Their Use in the Preparation of Anticancer Drug-Loaded Nanoparticles

A Comparative analysis of PESC and PPSC copolyesters: Insights into viscosity, thermal behavior, crystallinity, and biodegradability

The study examined various properties of synthesized copolyesters PESC and PPSC. Inherent viscosities of the copolyesters, measured in 1,4-dioxane at 32 °C, were 0.65 dL/g for PESC and 0.73 dL/g for PPSC. Fourier-Transform Infrared Spectroscopy (FT-IR) revealed distinct absorption bands associated with ester carbonyl stretching, C-H bending vibration, C-H group symmetry stretching, and C-O stretching vibrations. 1H and 13C Nuclear magnetic Resonance (NMR) spectroscopy were used to identify specific protons and carbon groups in the polymer chain, revealing the molecular structure of the copolyesters. Differential Scanning Calorimetry (DSC) identified the glass transition, melting, and decomposition temperatures for both copolyesters, indicating variations in the crystalline nature of the copolymers. XRD Spectral studies further elaborated on the crystalline nature, indicating that PPSC is less amorphous than PESC. Biodegradation analysis showed that PESC degrades more quickly than PPSC, with degradation decreasing as the number of methylene groups increase. Scanning Electron Microscopy (SEM) images depicted the surface morphology of the copolyesters before and after degradation, revealing a more roughened surface with pits post-degradation. These findings provide comprehensive insights into the structural and degradable properties of PESC and PPSC copolyesters.

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Blends with Poly(caprolactone) and Poly(lactic acid): A Comparative Study

Poly(hydroxybutyrate-co-hidroxyvalerate) (PHBV) is a biodegradable polymer, which is a potential substitute for plastics made from fossil resources. Due to its practical interest in the field of tissue engineering, packaging, sensors, and electronic devices, the demand for PHBV with specific thermal, electrical, as well as mechanical requirements is growing. In order to improve these properties, we have developed PHBV blends with two thermoplastic biodegradable polyesters, including poly(caprolactone) (PCL) and poly(lactic acid) (PLA). We analysed the effect of these biopolymers on the morphological, wetting, structural, thermal, mechanical, and electrical characteristics of the materials. Further, the biodegradation of the samples in simulated body fluid conditions was evaluated, as well as the antibacterial activity. The results demonstrate that the blending with PCL and PLA leads to films with a dense morphology, increases the hydrophilic character, and induces a reinforcement of the mechanical characteristics with respect to pristine PHBV. In addition, a decrease in dielectric constant and a.c. electrical conductivity was noticed for PHBV/PLA and PHBV/PCL blends compared to neat PHBV polymer. All neat polymers and blends showed antibacterial properties against S. aureus, with more than 40% bacterial reduction, which increased to 72% in the presence of PCL polymer for a blend ratio of 50/50. Thus, it is demonstrated a suitable way to further tailor a variety of functionalities of PHBV for specific applications, by the development of polymer blends with PLA or PCL.

Rationally designed block copolymer-based nanoarchitectures: An emerging paradigm for effective drug delivery

Various polymeric materials have been investigated to produce unique modes of delivery for drug modules to achieve either temporal or spatial control of bioactives delivery. However, after intravenous administration, phagocytic cells quickly remove these nanostructures from the systemic circulation via the reticuloendothelial system (RES). To overcome these concerns, ecofriendly block copolymers are increasingly being investigated as innovative carriers for the delivery of bioactives. In this review, we discuss the design, fabrication techniques, and recent advances in the development of block copolymers and their applications as drug carrier systems to improve the physicochemical and pharmacological attributes of bioactives.

Branched Amphiphilic Polylactides as a Polymer Matrix Component for Biodegradable Implants

The combination of biocompatibility, biodegradability, and high mechanical strength has provided a steady growth in interest in the synthesis and application of lactic acid-based polyesters for the creation of implants. On the other hand, the hydrophobicity of polylactide limits the possibilities of its use in biomedical fields. The ring-opening polymerization of L-lactide, catalyzed by tin (II) 2-ethylhexanoate in the presence of 2,2-bis(hydroxymethyl)propionic acid, and an ester of polyethylene glycol monomethyl ester and 2,2-bis(hydroxymethyl)propionic acid accompanied by the introduction of a pool of hydrophilic groups, that reduce the contact angle, were considered. The structures of the synthesized amphiphilic branched pegylated copolylactides were characterized by ¹H NMR spectroscopy and gel permeation chromatography. The resulting amphiphilic copolylactides, with a narrow MWD (1.14-1.22) and molecular weight of 5000-13,000, were used to prepare interpolymer mixtures with PLLA. Already, with the introduction of 10 wt% branched pegylated copolylactides, PLLA-based films had reduced brittleness, hydrophilicity, with a water contact angle of 71.9-88.5°, and increased water absorption. An additional decrease in the water contact angle, of 66.1°, was achieved by filling the mixed polylactide films with 20 wt% hydroxyapatite, which also led to a moderate decrease in strength and ultimate tensile elongation. At the same time, the PLLA modification did not have a significant effect on the melting point and the glass transition temperature; however, the filling with hydroxyapatite increased the thermal stability.