Search Results (267)

Polymeric micelles have the potential to improve the efficacy and safety of drug delivery by improving drug solubility, enhancing bioaccumulation and reducing off-target toxicity. Despite excellent safety profiles, a major limitation with polymeric micelles is their inability to rapidly release their payload once they have reached their target, leading to the inadequate delivery of therapeutic doses. To address this limitation, we have developed a novel strategy to impart pH-responsiveness in non-responsive micelles through the co-encapsulation of oligoelectrolytes with drugs. Herein, we investigate the influence of copolymer composition and drug identity in combination with oligoelectrolyte—oligo(2-vinyl pyridine) (OVP)—loading on pH-triggered drug release from micelles and their cytotoxicity. A library of OVP-loaded micelles was prepared using conventional and well-established non-responsive block copolymers. Dynamic light scattering (DLS) was used to monitor the changes in the micelles as a function of pH. Regardless of the copolymer composition, an abrupt decrease in the hydrodynamic diameter (D_h) was observed as the pH was reduced due to OVP expulsion from the core, which was also confirmed by release studies. In general, co-encapsulation of OVP and model drugs (doxorubicin (DOX), gossypol (GP), paclitaxel (PX), and 7-ethyl-10-hydroxycamptothecin (SN38)) in the micelles provided good to excellent encapsulation efficiency percentage (EE%) values. In vitro studies revealed the pH triggered release of drugs from the OVP-loaded micelles regardless of the drug identity, which increased as the OVP loading increased. This general behaviour was observed in all cases, largely independent of the copolymer composition, albeit with subtle differences in the release profile for different drugs. Compared to their blank counterparts, the drug-loaded micelles displayed a slight increase in cytotoxicity against a panel of cancer cell lines, in a dose dependent manner. However, drug- and OVP-loaded micelles displayed a significant increase in cytotoxicity (up to 8-fold increase) that was independent of the copolymer composition. These results demonstrate the versatility of the oligoelectrolyte-mediated approach to furnish non-responsive micelles with a pH-trigger that allows the rapid release of drugs, regardless of the micelle composition or the drug identity. Full article

Polyelectrolyte-based complexes have attracted attention, as the interaction of the oppositely charged components results in nanoparticle formation through an easy but highly efficient method, avoiding the use of strong solvents, extreme temperatures, and toxic chemicals. Sodium oleate (NaOL) is a widely used surfactant in the pharmaceutical industry due to its availability, eco-friendliness, and low cost. In the present study, the neutral-cationic block copolymer poly(oligo(ethylene glycol) methyl ether methacrylate)–b–quaternized poly(2-(dimethylamino) ethyl methacrylate) (POEGMA-b-Q(PDMAEMA)) is mixed with the anionic surfactant sodium oleate for the formation of nanoscale polyelectrolyte complexes through electrostatic interactions. Different weight ratios of copolymer to surfactant are studied. Then, the co-solvent protocol was implemented, and curcumin is successfully loaded in the formed particles for drug delivery applications. The size and morphology of the macromolecular complexes are examined via Dynamic Light Scattering (DLS) and Cryogenic Transmission Electron Microscopy (cryo-TEM). The methods that we have used have indicated that the polymer–surfactant complexes form spherical complexes, worm-like and vesicle-like structures. When curcumin was introduced, encapsulation was effectively achieved into micelles, giving rise to vesicle-like shapes. The success of curcumin encapsulation is confirmed by Ultraviolet–Visible absorption (UV–Vis) and fluorescence (FS) spectroscopy. POEGMA-b-Q(PDMAEMA)–sodium oleate polyelectrolyte complexes revealed promising attributes as efficient drug carrier systems for pharmaceutical formulations. Full article

Double hydrophilic copolymers (DHCs) can form nano-assemblies such as micelles and vesicles in aqueous media under certain environmental conditions. These assemblies have attracted much attention in both fundamental and applied research. To date, most studies on DHC self-assemblies have focused on block copolymers rather than graft copolymers. In this study, we investigated using Ca²⁺ ions in an aqueous medium to induce the formation of carboxylated polyallylamine-graft-poly(ethylene glycol) (PAA-g-PEG) self-assemblies as a graft-type DHC. Dynamic light scattering measurements conducted under various conditions showed that the carboxylated PAA-g-PEG self-assemblies had a micellar structure with a core of Ca²⁺ ions/carboxylates surrounded by non-ionic poly(ethylene glycol) grafts. Confocal laser scanning microscopy showed that the carboxylated PAA-g-PEG self-assemblies were able to deliver Ca²⁺ ions into cells. These results show that carboxylated PAA-g-PEG self-assemblies formed in the presence of divalent metal ions have potential for future applications in the biomedical field. Full article

Block copolymers with diverse compositions and topologies can self-assemble into multi-hierarchical structures, yielding materials with a wide range of functional properties. By adjusting external stimuli such as temperature, solvent polarity, mechanical force, and light exposure, these polymers form various nanostructures—including nanocrystals, micelles, and vesicles in solution; spherical, cylindrical, and lamellar microphases in bulk; and even “fractal” morphologies at interfaces. These hierarchical materials exhibit tailored functionality based on molecular design, enabling broad applications in nanomedicine, electronic devices, optical elements, and catalytic systems. In this review, we first summarize synthetic strategies for block copolymers with varying compositions and architectures. We then discuss their self-assembly behaviors and resulting nanoscale morphologies in bulk, solution, and interfacial environments. Several representative examples of assembled block copolymer systems and their practical applications are highlighted. Finally, we offer perspectives on future developments in the fabrication and application of block copolymer-based nanomaterials. This review provides an overview of strategies and examples for constructing precision nanostructures via block copolymer self-assembly, aiming to inspire further advances in nanomanufacturing technologies. Full article

Photodynamic therapy (PDT) is a minimally invasive cancer treatment that uses light-activated photosensitizers to selectively kill cancer cells. While effective, residual photosensitizers can cause phototoxicity when exposed to sunlight. To address this, drug delivery systems (DDS) such as polymeric micelles have been explored to improve targeting and reduce side effects. In this study, photosensitizer-loaded block copolymers were synthesized and incorporated into micelles. Their phototoxicity was evaluated using HeLa and MCF−7 cells, showing significant cell death upon light exposure. HT29 cell tests are ongoing, and results will be reported at the time of presentation. 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

The association behavior of amphiphilic block copolymers of N-vinyl pyrrolidone (NVP) and several vinyl esters (Ves) (PNVP-b-PVEs), as exemplified by vinyl butyrate (VBu), vinyl decanoate (VDc), and vinyl stearate (VSt), was studied in tetrahydrofuran (THF), which serves as the selective solvent for the PVE blocks. Static (SLS) and dynamic light scattering (DLS) techniques were adopted as the tools to investigate micellar properties and acquire information regarding the degree of association, the hydrodynamic radii, and the shape of the aggregates. In addition, CONTIN analysis provided insights concerning the association equilibria in THF solutions. The effect of the chemical structure of the corona-forming PVE block on the association process was investigated. Finally, the experimental results were compared with those obtained in previous studies describing the micellization properties of block copolymers consisting of PNVP and polymethacrylate blocks in the same selective solvent. 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 mini-review article is focused on polymeric materials that comprise thermoresponsive and fluorescent organic units. The combination of fluorescent clusters/dots embedded in or grafted with polymers is not considered in this article. Here we review the preparation, characterization, and application of thermoresponsive polymers functionalized covalently with organic fluorescent compounds either compartmentalized or randomly distributed: block-copolymers, self-assembled micelles or vesicles, core–shell nanogels, and their temperature driven self-assembly/shrinkage/expansion and resulting effect in fluorescence: quenching, enhancing, shifting. The applications suggested for these smart-materials are reviewed in the last ten years and range from nanothermometers, drug delivery systems, agents for bioimaging, sensors, and advanced materials for theranostics focused on cancer treatment. This article is organized reviewing the preparation methods, the main characterization techniques, and the application, depending on polymer architecture and the emission wavelength of the fluorophores. Finally, comments, suggestions, and problems to be solved for the advancement of these materials in the future prior to real-life applications are given. Full article

Poly(ε-caprolactone)-b-polysarcosine (PCL-b-PSar) block copolymers (BCPs) emerge as a promising alternative to conventional poly(ε-caprolactone)-b-poly(ethylene oxide) BCPs for biomedical applications, leveraging superior biocompatibility and biodegradability. In this study, we synthesized two series of PCL-b-PSar BCPs with controlled polymerization degrees (DP of PCL: 45/67; DP of PSar: 28–99) and low polydispersity indexes (Đ ≤ 1.1) and systematically investigated their crystallization-driven self-assembly (CDSA) in alcohol solvents (ethanol, n-butanol, and n-hexanol). It was found that the limited solubility of PSar in alcohols resulted in competition between micellization and crystallization during self-assembly of PCL-b-PSar, and thus coexistence of lamellae and spherical micelles. To overcome this morphological heterogeneity, we developed a modified self-seeding method by employing a two-step crystallization strategy (i.e., T_c1 = 33 °C and T_c2 = 8 °C), achieving conversion of micelles into crystals and yielding uniform self-assembled structures. PCL-b-PSar BCPs with short PSar blocks tended to form well-defined two-dimensional lamellar crystals, while those with long PSar blocks induced formation of hierarchical structures in the PCL₄₅ series and polymer aggregation on crystal surfaces in the PCL₆₇ series. Solvent quality notably influenced the self-assembly pathways of PCL₄₅-b-PSar₂₈. Lamellar crystals were formed in ethanol and n-butanol, but micrometer-scale dendritic aggregates were generated in n-hexanol, primarily due to a significant Hansen solubility parameter mismatch. This study elucidated the CDSA mechanism of PCL-b-PSar in alcohols, enabling precise structural control for biomedical applications. Full article

Surfactants are widely utilized in agriculture as emulsifying, dispersing, anti-foaming, and wetting agents. In these adjuvant roles, the inherent biological activity of the surfactant is secondary to the active ingredients. Here, the hydrophilic non-ionic surface-active tri-block copolymer Pluronic^® F68 is investigated for direct biological activity in wheat. F68 binds to and inserts into lipid membranes, which may benefit crops under abiotic stress. F68’s interactions with Triticum aestivum (var Juniper) seedlings and a seed-borne Bacillus spp. endophyte are presented. At concentrations below 10 g/L, F68-primed wheat seeds exhibited unchanged emergence. Root-applied fluorescein-F68 (fF68) was internalized in root epidermal cells and concentrated in highly mobile endosomes. The potential benefit of F68 in droughted wheat was examined and contrasted with wheat treated with the osmolyte, glycine betaine (GB). Photosystem II activity of droughted plants dropped significantly below non-droughted controls, and no clear benefit of F68 (or GB) during drought or rehydration was observed. However, F68-treated wheat exhibited increased transpiration values (for watered plants only) and enhanced shoot dry mass (for watered and droughted plants), not observed for GB-treated or untreated plants. The release of seed-borne bacterial endophytes into the spermosphere of germinating seeds was not affected by F68 (for F68-primed seeds as well as F68 applied to roots), and the planktonic growth of a purified Bacillus spp. seed endophyte was not reduced by F68 applied below the critical micelle concentration. These studies demonstrated that F68 entered wheat root cells, concentrated in endosomes involved in transport, significantly promoted shoot growth, and showed no adverse effects to plant-associated bacteria. Full article

Objectives: Nanosized polymeric micelles (PMs) with an average size of about 80 nm and moderately positive ζ potential, based on an amphiphilic poly(4-methyl-piperazin-1-yl)-propenone)-b-polylactide (PMPP-PLA) block copolymer, were prepared. They were used as platforms for the delivery of bioactive sesquiterpene lactones from Inula helenium L. root extract. Methods: The PMs were characterized with good encapsulation efficiency as a maximum value of 72% was reached at a polymer-to-extract mass ratio of 10:1. The loaded micelles exhibited good colloidal stability. An in vitro release was performed showing a burst release profile. The biocompatibility of the resulting PMs was confirmed by assessing their cytotoxic effect on human keratinocytes in vitro by colorimetric assay and flow cytometry. Results: The systems demonstrated the capability to reduce the biomass of pre-formed Gram-positive and Gram-negative bacterial biofilms. Conclusions: The obtained data clearly determine a trend for a strong combined effect between the PMs and the root extract, distinguishing them with an excellent anti-biofilm potential and prospects for future applications in medical practice. Full article

Delivering of hydrophobic drugs by polymeric nanoparticles is an intensively investigated research and development field worldwide due to the insufficient solubility of many existing and potential new drugs in aqueous media. Among polymeric nanoparticles, micelles of biocompatible amphiphilic block copolymers are among the most promising candidates for solubilization, encapsulation, and delivery of hydrophobic drugs to improve the water solubility and thus the bioavailability of such drugs. In this study, amphiphilic ABA triblock copolymers containing biocompatible hydrophilic hyperbranched (dendritic) polyglycerol (HbPG) outer and hydrophobic poly(tetrahydrofuran) (PTHF) inner segments were synthesized using amine-telechelic PTHF as a macroinitiator for glycidol polymerization. These hyperbranched–linear–hyperbranched block copolymers form nanosized micelles with 15–20 nm diameter above the critical micelle concentration. Coagulation experiments proved high colloidal stability of the aqueous micellar solutions of these block copolymers against temperature changes. The applicability of block copolymers as drug delivery systems was investigated using curcumin, a highly hydrophobic, water-insoluble, natural anti-cancer agent. High and efficient drug solubilization up to more than 3 orders of magnitude to that of the water solubility of curcumin (>1500-fold) is achieved with the HbPG-PTHF-HbPG block copolymer nanomicelles, locating the drug in amorphous form in the inner PTHF core. Outstanding stability of and sustained curcumin release from the drug-loaded block copolymer micelles were observed. The in vitro bioactivity of the curcumin-loaded nanomicelles was investigated on U-87 glioblastoma cell line, and an optimal triblock copolymer composition was found, which showed highly effective cellular uptake and no toxicity. These findings indicate that the HbPG-PTHF-HbPG triblock copolymers are promising candidates for advanced drug solubilization and delivery systems. 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