Search Results (306)

The nano-technological approach and supramolecular chemistry principles relation to the encapsulation of enzymes pave the way for creating next-generation nano-system-functionalized nano-compartments. The most promising approach for prophylaxis and the treatment of organophosphate (OP) poisoning is the use of stable, bioavailable nano-compartments containing OP-scavenging enzymes. Such enzymes, like butyrylcholinesterase (BChE), wild type and mutants, could also be used for the detoxification of other poisonous esters. There are two types of IRD-labeled human BChE-containing nano-scavengers: PEGylated liposomes and polyethyleneglycol–polypropylenesulfide polymersomes, which were developed with diameter close to 100 nm. BChE-polymersomes have higher encapsulation efficiency (95%) and slower release rate of enzymes (more than 7 days) compared to BChE-liposomes. The catalytic properties of encapsulated enzymes were analyzed for nano-compartment formulations, lipophilicity, the structure of block copolymers, and for different ester substrate polarity: positively charged butyrylthiocholine iodide, neutral phenyl acetate, and negatively charged aspirin. The highest k_cat (more than three times) compared to non-encapsulated BChE was for polymersomes based on diblock PEG-PPS polymersomes towards the neutral phenyl acetate substrate. Full article

Polylactide (PLA) was melt blended with block copolymers of ethylene glycol and propylene glycol: a triblock copolymer (PPG-b-PEG-b-PPG) with a molar mass of 2700 g/mol and 40 wt% PEG content, and a diblock copolymer (PPG-b-PEG) with a molar mass of 4000 g/mol and 50 wt% PEG content. The structure as well as the thermal and mechanical properties of both amorphous and crystallized blends were investigated. Due to the copolymers’ chemical composition and the resulting phase structure, the 10 wt% amorphous blends with PPG-b-PEG-b-PPG and PPG-b-PEG, with T_g values of 38 °C and 46 °C, respectively, exhibited relatively high yield stress, close to 45 MPa, along with remarkable elongation at break. Notably, the blend with the triblock copolymer showed a 70-fold increase in elongation at break compared to neat amorphous PLA. Furthermore, the tensile impact strength of the blend with the diblock copolymer surpassed that of neat PLA. Upon crystallization, the 10 wt% blends showed reduced yield stress and elongation at break; however, the elongation at break exceeded 7–25 times that of neat crystalline PLA. Furthermore, their tensile impact strength increased to more than three times the value of crystalline PLA. Full article

Τhe self-assembly behavior of a series of amphiphilic diblock copolymers, each consisting of a hydrophilic poly(N-vinyl pyrrolidone) (PNVP) block and a hydrophobic block derived from n-alkyl vinyl esters, namely poly(vinyl butyrate) (PVBu), poly(vinyl decanoate) (PVDc), and poly(vinyl stearate) (PVSt), in aqueous solutions was investigated. Dynamic and static light scattering (DLS and SLS) techniques were employed to monitor the micellization behavior. In addition, the self-assembled structures were observed with Transmission Electron Microscopy (TEM). The effect of the nature of the hydrophobic block, the copolymer composition and the copolymer molecular weight on the self-assembly properties was thoroughly examined. The encapsulation of curcumin and indomethacin within the dry cores of the micellar structures was conducted in aqueous solutions for all block copolymers at various curcumin/indomethacin-to-polymer mass ratios. UV-Vis spectroscopy was used to evaluate the drug-loading capacity and efficiency (%DLC and %DLE). In several cases, the encapsulation of both hydrophobic drugs was found to be nearly quantitative. Combined with the observed stability of the micellar structures, these findings suggest that the block copolymers demonstrate significant potential as carriers for drug delivery applications. Full article

Background: Encapsulating essential oils in polymer-based nanocarriers can improve their stability, solubility, and bioavailability, while maintaining the biological activity of the oil’s active ingredients. In this contribution, we investigated the antiviral activity of Oregano Essential Oil (OEO) in its pure form and encapsulated into nanosized polymeric micelles, based on a poly(ethylene oxide)-block-poly(ε-caprolactone) diblock copolymer. Methods: The effect of encapsulation was evaluated using three structurally different viruses: herpes simplex virus type 1 (HSV-1) (DNA—enveloped virus), human coronavirus (HCoV OC-43) (RNA—enveloped virus), and feline calicivirus (FCV) (RNA—naked virus). The effect on the viral replicative cycle was determined using the cytopathic effect inhibition (CPE) test. Inhibition of the viral adsorption step, virucidal activity, and protective effect on healthy cells were assessed using the final dilution method and were determined as Δlg compared to the untreated viral control. Results: In both studied forms (pure and nanoformulated), OEO had no significant effect on viral replication. In the remaining antiviral experiments, the oil embedded into nanocarriers showed a slightly stronger effect than the pure oil. When the oil was directly applied to extracellular virions, viral titers were significantly reduced for all three viruses, with the effect being strongest for HSV-1 and FCV (Δlg = 3.5). A distinct effect was also observed on the viral adsorption stage, with the effect being most significant for HSV-1 (Δlg = 3.0). Conclusions: Pretreatment of healthy cells with the nanoformulated OEO significantly protected them from viral infection, with the greatest reduction in viral titer for HCoV OC-43. Full article

Polymeric vesicles, characterized by enhanced colloidal stability, excellent mechanical properties, controllable surface functionality, and adjustable membrane thickness, are extremely useful in nano- and bio-technology for potential applications as nanosized carriers for drugs and enzymes. However, a few preparative steps are necessary to achieve a unilamellar vesicle with a narrow size distribution. Herein, we report the spontaneous formation of unilamellar polymeric vesicles with nanometer sizes (<50 nm), fabricated by simply mixing diblock copolymers (P(EO-AGE)(2K-2K) and P(EO-AGE)(0.75K-2K)) with differing hydrophilic mass fractions in aqueous solutions. Depending on the mixing ratio of block copolymers and the temperature, the block copolymer mixtures self-assemble into various nanostructures, such as spherical and cylindrical micelles, or vesicles. The self-assembled structures of the block copolymer mixtures were characterized by small-angle neutron scattering, resulting in a phase diagram drawn as a function of temperature and the mixing condition. Notably, the critical temperature for the micelle-to-vesicle phase transition can be easily controlled by altering the mixing conditions; it decreases with an increase in the concentration of one of the block copolymers. Full article

This study focuses on the synthesis and characterization of thermoresponsive hydrogels of poly(lactic acid) (PLA) and poly(ethylene glycol) (PEG), PLA–PEG copolymers, aiming at the targeted and controlled release of deferoxamine (DFO), a clinically applied iron-chelating drug. Triblock (PLA-PEG-PLA) and diblock (mPEG-PLA) copolymers were synthesized using ring-opening polymerization (ROP) with five different PEGs with molecular weights of 1000, 1500, 2000, 4000, and 6000 g/mol and two types of lactide (L-lactide and D-lactide). Emulsions of the polymers in phosphate-buffered saline (PBS) were prepared at concentrations ranging from 10% to 50% w/w to study the sol–gel transition properties of the copolymers. Amongst the synthesized copolymers, only those that demonstrated thermoresponsive sol-to-gel transitions near physiological temperature (37 °C) were selected for further analysis. Structural and molecular confirmation was performed by Nuclear Magnetic Resonance (NMR) and Fourier-transform infrared spectroscopy (FTIR), while the molecular weights were determined via Gel Permeation Chromatography (GPC). The thermal transitions were studied by calorimetry (DSC) and crystallinity via X-ray diffraction (XRD) analysis. DFO-loaded hydrogels were prepared, and their drug release profiles were investigated under simulated physiological conditions (37 °C) for seven days using HPLC analysis. The thermoresponsive characteristics of these systems can offer a promising strategy for injectable drug delivery applications, where micelles serve as drug carriers and undergo in situ gelation, enabling controlled release. This alternative procedure may significantly improve the bioavailability of DFO and enhance patient compliance by addressing key limitations of conventional administration routes. Full article

Polymers and polymer composites offer versatile possibilities for engineering the physico-chemical properties of materials on micro- and macroscopic scales. This review provides an overview of polymeric and polymer-decorated particles that can serve as drug-delivery vectors: linear polymers, star polymers, diblock-copolymer micelles, polymer-grafted nanoparticles, polymersomes, stealth liposomes, microgels, and biomolecular condensates. The physico-chemical interactions between the delivery vectors and biological cells range from chemical interactions on the molecular scale to deformation energies on the particle scale. The focus of this review is on the structure and elastic properties of these particles, as well as their circulation in blood and cellular uptake. Furthermore, the effects of polymer decoration in vivo (e.g., of glycosylated plasma membranes, cortical cytoskeletal networks, and naturally occurring condensates) on drug delivery are discussed. Full article

In this article, we present a nonlocal Cahn–Hilliard (nCH) equation incorporating a space-dependent parameter to model microphase separation phenomena in diblock copolymers. The proposed model introduces a modified formulation that accounts for spatially varying average volume fractions and thus captures nonlocal interactions between distinct subdomains. Such spatial heterogeneity plays a critical role in determining the morphology of the resulting phase-separated structures. To efficiently solve the resulting partial differential equation, a Fourier spectral method is used in conjunction with a linearly stabilized splitting scheme. This numerical approach not only guarantees stability and efficiency but also enables accurate resolution of spatially complex patterns without excessive computational overhead. The spectral representation effectively handles the nonlocal terms, while the stabilization scheme allows for large time steps. Therefore, this method is suitable for long-time simulations of pattern formation processes. Numerical experiments conducted under various initial conditions demonstrate the ability of the proposed method to resolve intricate phase separation behaviors, including coarsening dynamics and interface evolution. The results show that the space-dependent parameters significantly influence the orientation, size, and regularity of the emergent patterns. This suggests that spatial control of average composition could be used to engineer desirable microstructures in polymeric materials. This study provides a robust computational framework for investigating nonlocal pattern formation in heterogeneous systems, enables simulations in complex spatial domains, and contributes to the theoretical understanding of morphology control in polymer science. Full article

Amphiphilic diblock copolymers comprising polyethylene glycol (PEG) and 1-vinyl imidazole (VIM) were synthesized using reversible addition–fragmentation chain transfer (RAFT) polymerization. The study focused on the synthesis of well-defined nanostructures with tunable composition and their functional modification for biomedical applications. The successful polymerization of PEG-b-PVIM diblock copolymers was confirmed via ¹H NMR spectroscopy, and their molecular weights were analyzed using gel permeation chromatography (GPC). The copolymers exhibited pH-responsive behavior, with effective pK values of approximately 4.2. To facilitate radiolabeling and in vivo tracking, a post-polymerization modification enabled the conjugation of a 1,4,7-Triazacyclononane-1,4,7-triacetic acid (NOTA) chelator via aminolysis. The final conjugates were purified and characterized, confirming successful functionalization. These findings highlight the potential of PEG_x-b-PVIM_y diblock copolymers for biomedical applications. Full article

Bacterially produced poly[(R)-3-hydroxybutyrate] (P3HB) was subjected to an alcoholysis reaction to produce low-molecular-weight (M_n ≈ 10,000 g mol⁻¹) hydroxy-terminated P3HB (LMPHB). Using diethyl zinc as a catalyst, LMPHB was reacted with the cyclic monomers ε-caprolactone and l-lactide in separate ring-opening polymerization (ROP) reactions to produce PHB-b-PCL (PHBCL) and PHB-b-PLA (PHBLA) AB-type crystalline–crystalline diblock copolymers with varying PCL and PLA block lengths. ¹H NMR and GPC were used to confirm the structure of the polymers. DSC was used to measure the thermal properties as well as assessing crystallization. A single-shifting T_g for PHBLA showed the two blocks to be miscible in the melt. The TGA results indicate enhanced thermal stability over the homopolymer P3HB. A study of the crystallization was undertaken by combining WAXD, a second DSC heating regime, and POM. POM showed that the crystallization in PHBCL to be dependent on the crystallization temperature more so than PHBLA, whose composition appeared to be the more definitive factor determining the spherulitic morphology. The results informed the crystallization temperatures used in the production of the melt-crystallized thin films that were imaged using AFM. AFM images showed unique surface morphologies dependent on the diblock copolymer composition, block length, and crystallization temperature. Finally, the enzymatic degradation studies showed these unique surface morphologies to influence how these block copolymers were degraded by enzymes. Full article

By developing and making use of the multi-scale theoretical approach, we identify the main factors that affect the conductivity of a composite composed of a diblock copolymer (DBC) system and conductive particles. This approach relies on the consistent phase-field model of DBC, Monte-Carlo simulations of the filler localization in DBC, and the resistor network model that mimics the conductive filler network formed in DBC. Based on the described approach, we thoroughly explore the relation among the morphological state of the microphase-separated DBC, localization of fillers in DBC, and the electrical response of the composite. Good agreement with experimental results confirms the accuracy of our theoretical predictions regarding the localization of fillers in the DBC microphases. The main factors affecting the composite conductivity are found to be: (i) affinities of fillers for copolymer blocks; (ii) degree of the segregation of a host DBC system, driven by external stimuli; (iii) geometry of the microphases formed in the microphase-separated DBC; and (iv) interactions between fillers. The conductor-insulator transition in the filler network is found to be caused by the order-disorder transition in the symmetric DBC. The order-order transition between the ordered lamellae and cylindrical microphases of asymmetric DBC causes a spike in the composite conductivity. Full article

Nanotechnology offers alternative approaches to the discovery of anticancer drugs. Hydrophobic bioactive components can be included in the cores of amphiphilic nanocarriers, which leads to the formation of a water-dispersible product with improved bioavailability, facilitated excretion, and reduced systemic toxicity in the treated organisms. This study was aimed at the formation of polymer nanocarriers, loaded with anticancer drug precursor podophylotoxin (PPT) or PPT-containing juniper leaf extracts, seeking to study their antineoplastic activity in A-431 epidermoid carcinoma cells and HaCaT normal keratinocytes. The amphiphilic, biodegradable, and biocompatible MPEG-b-PLA diblock copolymer was self-assembled in aqueous media into nanosized particles, whose physicochemical characteristics were studied by dynamic light scattering, transmission electron microscopy, and other methods. High encapsulation efficiency was determined for the PPT component-loaded micelles. DNA fragmentation, cell cycle arrest, nuclear condensation, membrane lipid order assessment, reactive oxygen species, and apoptosis induction by the loaded nanocarriers in A-431 or HaCaT cells were analyzed by the comet assay, FACS, Hoechst DNA staining, Laurdan generalized polarization, and other methods. As a result of various cellular processes induced by the PPT component-loaded nanoparticles, effector caspase-3 and caspase-7 activation showed selectivity towards tumor cells compared to the normal cells. The newly obtained PPT-containing nanoparticles have applications as potential drugs in the prospective nanomedicine. Full article

Diblock copolymers (BCP) consisting of poly(methyl methacrylate) (PMMA) and poly(1H,1H,2H,2H-perfluorodecyl methacrylate) (PsfMA) blocks are employed as templates for controlled dispersion and localization of multi-walled carbon nanotubes (MWCNT). Short MWCNT are modified with perfluoroalkyl groups to increase the compatibility between MWCNT and the semifluorinated (PsfMA) phase and to promote a defined arrangement of MWCNT in the BCP morphology. Thin BCP and BCP/MWCNT composite films are prepared by dip-coating using tetrahydrofuran as solvent with dispersed MWCNT. Atomic force microscopy, scanning and transmission electron microscopy reveal a strong tendency of the BCP to form micelle-like domains consisting of a PMMA shell and a semifluorinated PsfMA core, embedded in a soft phase, containing also semifluorinated blocks. MWCNT preferentially localized in the embedding phase outside the micelles. Perfluoroalkyl-modification leads to significant improvement in the dispersion of MWCNT, both in the polymer solution and the resulting nanocomposite film due to increased interaction of MWCNT with the semifluorinated side chains in the soft phase outside the micelle domains. As a result, reliable electrical conductivity is observed in contrast to films with non-modified MWCNT. Thus, well-dispersed, modified MWCNT provide a defined electrical conduction path at the micrometer level, which is interesting for applications in electronics and vapor sensing. Full article

The kinetic model is a crucial tool for optimizing polymer synthesis protocols and facilitating the scaled-up production processes of the CO₂-responsive polymer poly(N-[3-(dimethylamino)propyl]-acrylamide)-b-poly(methyl methacrylate)(PDMAPAm-b-PMMA), which is supposed to be implemented in direct air capture (DAC) technology. This study presents a simulation of the kinetic model developed for the Reversible Addition−Fragmentation Chain-Transfer (RAFT) polymerization of N-[3-(dimethylamino)propyl]-acrylamide (DMAPAm), alongside an investigation into the kinetics of this polymerization using the simulation as an analytical tool, as well as the application of the simulation for the upscaling of RAFT polymerization. Ultimately, the kinetic model was validated through two kinetic experiments, confirming its reliability. It was subsequently employed to optimize the synthesis recipe and to predict the properties of PDMAPAm homopolymers, thereby supporting the upscaling of PDMAPAm-b-PMMA diblock copolymer synthesis. In the end, the preliminary results of the CO₂-responsiveness of the diblock copolymer were determined with a simple experiment. Full article

This study explored the formation of soft colloidal particles from a diblock ionomer (DI) with the monomeric composition (acrylonitrile)_x-co-(glycidyl methacrylate)_y-b-(3-sulfopropyl methacrylate potassium)_z—abbreviated as (A_xG_y)S_z, where x >> z > y. A colloidal dispersion was generated by introducing water into the pre-prepared DMSO solutions of DI, which led to micelle formation and subsequent coagulation. The assembly of the hydrophobic (A_xG_y) blocks was influenced by water content and chain conformational flexibility (the ability to adopt various forms of conformation). The resulting microgel structure (in particle form) consists of coagulated micelles characterized by discrete internal hydrophobic gel domains and continuous external hydrophilic gel layers. Characterization methods included light scattering, zeta potential analysis, and particle size distribution measurements. In contrast, the copolymer (A_xG_y) chains form random coil aggregates in DMSO–H₂O mixtures, displaying a chain packing state distinct from the hydrophobic gel domains as aforementioned. Additionally, the amphiphilic glycidyl methacrylate (G) units within the (A_xG_y) block were found to modulate the microgel dimensions. Notably, the nanoscale hydrogel corona exhibits high accessibility to reactive species in aqueous media. The typical microgel has a spherical shape with a diameter ranging from 50 to 120 nm. It exhibits a zeta potential of −65 mV in a neutral aqueous medium; however, it may precipitate if the metastable colloidal dispersion state cannot be maintained. Its properties could be tailored through adjusting the internal chain conformation, highlighting its potential for diverse applications. Full article