Chinese Journal of Polymer Science最新文献

Abstract

L-glutamic acid (LA) is a bio-based, non-toxic, environmentally friendly material derived from biomass. The present study reports the application of Passerini three-component polymerization (P-3CP) for the straightforward preparation of LA-based light-responsive polyesters (PLTDs) under mild conditions. PLTDs with molar masses up to 8500 g/mol and high yields exceeding 90% are obtained. The chemical structures and light-responsive self-immolative behavior of PLTDs are comprehensively characterized by employing ultraviolet-visible (UV-Vis) spectroscopy, size exclusion chromatography (SEC), nuclear magnetic resonance (NMR) spectroscopy, and liquid chromatography mass spectrometry (LC-MS). Meanwhile, monodisperse PLTD-based doxorubicin-loaded nanoparticles (PLTD-DOX-NP) (size=193 nm, PDI=0.018) are formulated by nanoprecipitation method. Upon light-induced depolymerization, the PLTD-DOX-NP undergoes rapid decomposition, resulting in a burst release of 80% cargo within 13 s. Furthermore, according to biological toxicity tests, the PLTD-NP possesses adequate biosafety, both before and after irradiation. Overall, the incorporation of P-3CP with biorenewable LA-based monomer adheres to the principles of green chemistry, significantly simplifying the synthetic pathway of light-responsive polymers.

Abstract

Bacterial biofilms present a significant challenge in treating drug-resistant infections, necessitating the development of innovative nanomedicines. In this study, we introduce triclosan-conjugated, lipase-responsive polymeric micelles designed to exploit biofilm properties and serve as a responsive drug delivery platform. The micelles were created using an amphiphilic block polymer synthesized via ring-opening polymerization of ε-caprolactone (CL) and triclosan-containing cyclic trimethylene carbonate (MTC-Tri). Poly(ethylene glycol) (PEG-OH) acted as the macro-initiator, resulting in micelles with a PEG shell that facilitated their penetration into bacterial biofilms. An important advantage of our micelles lies in their interaction with local bacterial lipases within biofilms. These lipases triggered rapid micelle degradation, releasing triclosan in a controlled manner. This liberated triclosan effectively eliminated bacteria embedded in the biofilms. Notably, the triclosan-conjugated micelles displayed minimal toxicity to murine fibroblasts, indicating their biocompatibility and safety. This finding emphasizes the potential application of these micelles in combatting drug resistance observed in bacterial biofilms. Our triclosan-conjugated, lipase-responsive polymeric micelles exhibit promising characteristics for addressing drug resistance in bacterial biofilms. By harnessing biofilm properties and implementing a responsive drug delivery system, we seek to provide an effective solution in the fight against drug-resistant bacteria.

Abstract

Polyelectrolyte brushes (PEBs) are commonly used to modify surface that have attracted great research interest. The dielectric permittivity of the grafted surface is typically significantly different from that of solution, which results in surface polarization (SP) effect with a jump of electric field. It is thus important to study how SP alters the PEB’s structure and properties. In this work, the SP effects on PEB structure was studied using a statistical thermodynamic theory. The free energy functional to describe SP effect was constructed by using the image-charge method. Meanwhile, the electrostatic potential was solved from a modified Poisson-Boltzmann equation taking the ion solvation effect into consideration. In the absence of SP, the thickness of PEB exhibited a continuous collapse transition when decreasing the solvent quality. In the presence of SP, the collapse became a jump-like transition. Free energy analysis showed that the long-range Coulombic interaction dominated the transition because of the enhanced counterion condensation in the presence of SP. The theory provides an effective tool to study SP effect on PEBs, and the results explain the underlying physics in PEB collapse transition.

Efficient intracellular delivery of protein drugs is critical for protein therapy. The combination of protein drugs with chemotherapeutics represents a promising strategy in enhancing anti-cancer effect. However, co-delivery systems for efficient delivery of these two kinds of drugs are still lacking because of their different properties. Herein, we show a well-designed delivery system based on dynamic covalent bond for efficient intracellular co-delivery of ribonuclease A (RNase A) and doxorubicin (DOX). Two polymers, PEG-b-P(Asp-co-AspDA) and PAE-b-P(Asp-co-AspPBA), and two 2-acetylphenylboronic acid (2-APBA)-functionalized drugs, 2-APBA-RNase A and 2-APBA-DOX, self-assemble into mixed-shell nanoparticles (RNase A/DOX@MNPs) via dynamic phenylboronic acid (PBA)-catechol bond between PBA and dopamine (DA) moieties. The PBA-catechol bond endows the nanoparticles with high stability and excellent stimulus-responsive drug release behavior. Under the slight acidic environment at tumor tissue, RNase A/DOX@MNPs are positively charged, promoting their endocytosis. Upon cellular uptake into endosome, further protonation of PAE chains leads to the rupture of endosomes because of the proton sponge effect and the cleavage of PBA-catechol bond promotes the release of two drugs. In cytoplasm, the high level of GSH removed the modification of 2-APBA on drugs. The restored RNase A and DOX show a synergistic and enhanced antic-cancer effect. This system may be a promising platform for intracellular co-delivery of protein drugs and chemotherapeutics.

Poly(lactide acid) (PLA) foams have shown considerable promise as eco-friendly alternatives to nondegradable plastic foams, such as polystyrene (PS) foams. Nevertheless, PLA foam typically suffers from low heat-resistance and poor cellular structure stemming from its inherent slow crystallization rate and low melt strength. In this study, a high-performance PLA foam with well-defined cell morphology, exceptional strength and enhanced heat-resistance was successfully fabricated via a core-back microcellular injection molding (MIM) process. Differential scanning calorimetry (DSC) results revealed that the added hydrazine-based nucleating agent (HNA) significantly increased the crystallization temperature and accelerated the crystallization process of PLA. Remarkably, the addition of a 1.5 wt% of HNA led to a significant reduction in PLA’s cell size, from 43.5 µm to 2.87 µm, and a remarkable increase in cell density, from 1.08×10⁷ cells/cm³ to 2.15×10¹⁰ cells/cm³. This enhancement resulted in a final crystallinity of approximately 55.7% for the PLA blend foam, a marked improvement compared to the pure PLA foam. Furthermore, at 1.5 wt% HNA concentration, the tensile strength and tensile toughness of PLA blend foams demonstrated remarkable improvements of 136% and 463%, respectively. Additionally, the Vicat softening temperature of PLA blend foam increased significantly to 134.8 °C, whereas the pure PLA foam exhibited only about 59.7 °C. These findings underscore the potential for the preparation of lightweight injection-molded PLA foam with enhanced toughness and heat-resistance, which offers a viable approach for the production of high-performance PLA foams suitable for large-scale applications.

Rubbers or elastomers play an important role in hi-tech technology and civilian daily life because of their unique and strategical properties. Generally, the rubber additives are essential components for rubbers’ practical application. Nowadays, developing novel multifunctional additives has attracted increasing research attention. In this work, low-cost crude carbon dots (CCDs) were used as multifunctional additives for natural rubber/silica system (without any additional modification) through industrial compatible melt-mixing method. The results revealed that the CCDs could disperse well in the NR/silica system, and they could not only endow the rubber compound with excellent anti-aging capability due to CCDs’ radical scavenging activity because of their plenty of nitrogen-containing species, but also improve the curing rate and mechanical performance of the rubber composite. Also, the CCDs could reduce the rolling resistance of the rubber composites (tanδ value at 7% strain of the rubber composite could be decreased by 34%), which is promising for the application of energy-saving tire industry. Lastly, the addition of CCDs could effectively reduce the ZnO dosage by at least 40% in the rubber composite without deteriorating its performance. Overall, this work provides valuable guidance to develop novel cheap yet effective additives for the elastomer.

The rich phase behavior of block copolymers (BCPs) has drawn great attention in recent years. However, the double diamond (DD) phase is rarely obtained because of the competition between the minimization of interfacial energy and packing frustration. Here, a rod-coil BCP containing mesogen-jacketed liquid crystalline polymer is designed to acquire ordered bicontinuous network nanostructures. The reduction of internal energy originating from the orientational interaction among the rod blocks can compensate for the free energy penalty of packing frustration to stabilize the DD structure. The resulting BCP can also experience lamellae-to-DD and double gyroid-to-lamellae transitions by changing the annealing temperature. These results make the rod-coil BCP an excellent candidate for the self-assembly of ordered network structures, demonstrating great potential in nanopatterning and metamaterials.