Agnieszka Kowalczuk

The development of straightforward and efficient strategies for the preparation of polymer-functionalized mesoporous silica remains an important challenge in the design of advanced hybrid materials. Herein, we report a novel and simplified approach to the covalent functionalization of mesoporous silica particles (MSP) with poly(2-ethyl-2-oxazoline) (PEtOx), based on the direct termination of living cationic polymer chains by amino groups immobilized on the silica surface. In contrast to conventional grafting-to methods, the proposed strategy eliminates the need for polymer end-group functionalization while avoiding the synthetic complexity associated with surface-initiated polymerization. Well-defined PEtOx chains with number-average molar masses of 5000 and 7500 g mol⁻¹ were synthesized by cationic ring-opening polymerization (CROP) and subsequently grafted onto amino-functionalized MSP. Successful covalent immobilization of the polymer was confirmed by Fourier-transform infrared spectroscopy (FT-IR), elemental analysis, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), contact angle measurements, and nitrogen adsorption–desorption studies. The modification preserved the ordered mesoporous architecture while increasing particle hydrophilicity and decreasing the specific surface area and pore volume due to polymer incorporation. Shorter polymer chains exhibited higher grafting efficiency than higher-molar-mass analog, indicating that steric hindrance is an important factor influencing the grafting process. The presented methodology provides a versatile and experimentally accessible platform for the preparation of well-defined poly(2-oxazoline)-functionalized mesoporous silica with tunable physicochemical properties. Owing to the combination of a porous inorganic framework and a polymer shell, the obtained hybrid materials represent promising candidates for drug delivery, adsorption technologies, and other advanced biomedical and environmental applications.

We report di- and triblock copolymers that combine hydrophilic polyethers—poly(ethylene glycol) monomethyl ether (mPEG) and polyglycidol (PGl)—with a hydrophobic, degradable polyester, poly(β-butyrolactone) (P(β-BL)). A mild hydrolysis method was developed to selectively remove acetal protecting groups from poly(ethoxy ethyl glycidyl ether) (PEEGE) without cleaving the β-butyrolactone polyester backbone, enabling the preparation of PGl-b-P(β-BL) and mPEG-b-PGl-b-P(β-BL) block copolymers. Thermal analysis revealed that the glass transition temperatures (T_g) of the copolymers could be tuned by varying block composition and length. Diblock copolymers containing the PGl segment were amorphous, with T_g values ranging from −2.7 to −19.9 °C. The presence of an mPEG segment in the triblock copolymers resulted in a further decrease in T_g, reaching values between −32.3 and −38.9 °C. Solubility and water affinity studies demonstrated that incorporation of hydrophilic polyether blocks enhances copolymer–solvent interactions, leading to increased wettability of the polymer-coated surface. The water contact angle for films formed from PGl-b-P(β-BL) decreased to 53 °C, while for mPEG-b-PGl-b-P(β-BL) copolymers, it was further reduced to 43 °C compared with the hydrophobic P(β-BL) film. Hydrolytic degradation experiments showed accelerated cleavage of the P(β-BL) segment in copolymers containing hydrophilic blocks compared to the P(β-BL) homopolymer, which is attributed to increased water accessibility and surface hydrophilicity. The most pronounced decrease in molar mass, reaching at least 50% relative to the initial non-degraded sample, was observed for the diblock copolymers, whereas the P(β-BL) sample showed only a marginal weight reduction of a few percent. Overall, this study demonstrates that the combination of hydrophilic mPEG and PGl blocks with P(β-BL) enables the design of block copolymers with tunable thermal properties, solubility, and degradation behavior, offering potential for a wide range of applications.

Recent advancements in soft nanomaterials have positioned nanogels at the interface of polymer chemistry and biomedicine, as they combine the physicochemical features of nanoparticles with the three‐dimensional, water‐swollen architecture of hydrogels. This study explored the formation and properties of degradable nanogels from thermoresponsive poly[oligo(ethylene glycol) methacrylates] (POEGMA), indicating their potential as drug carriers. The research underscored the importance of biologically relevant conditions, as nanogel formation and degradation were more challenging in buffer solutions (citrate and PBS) than in water. During synthesis through dual thermal and chemical crosslinking, aggregation occurred when the milieu temperature exceeded the polymers’ cloud point temperature ( T _CP ), revealing a medium and temperature‐dependent processing regime. Obtaining nanogels of suitable size required an appropriate temperature gap between the polymer's T _CP and the temperature of the biological medium. Nanogel degradation in citrate buffer and PBS was followed by dynamic light scattering and cryogenic transmission electron microscopy, and encapsulation and release of doxorubicin hydrochloride were demonstrated. Our findings highlight that translation from simplified aqueous solutions to biological media fundamentally alters nanogel formation, stability and degradation pathways. By identifying temperature‐medium interdependencies as a key design parameter, this work provides chemically grounded guidelines for the rational development of nanogels made of thermoresponsive polymers intended for future applications.

This study presents a novel synthetic strategy for the preparation of antibacterial poly(2-oxazoline)-based (POx) conjugates with chelating agents.

In this work, we designed non-viral gene delivery vector systems based on three poly(2-ethyl-2-oxazoline)-ran-poly[2-(3-butenyl)-2-oxazoline] copolymers functionalized by primary, secondary, and tertiary amino groups. The impact of copolymer structure and composition was sought through the examination of basic physicochemical and biological parameters. The complexation ability of copolymers with plasmid DNA was studied by ethidium bromide quenching assay. The polyplex particles size and ζ-potential were determined by dynamic and electrophoretic light scattering. The release ability of copolymers was assessed by competitive displacement of DNA using dextran sulfate. The biological performance of amino-functionalized poly(2-ethyl-2-oxazoline)-ran-poly[2-(3-butenyl)-2-oxazoline] based gene delivery systems was evaluated, and their behavior under various environmental conditions, such as pH and ionic strength, was investigated. Cytotoxicity was assessed in two human lung-derived cell lines, and the ability of the copolymers to mediate plasmid DNA delivery and expression was examined. The resulting polyplex nanoparticles exhibited the ability to release DNA molecules and sensitivity to alterations in pH and ionic strength. All systems showed high biocompatibility and were able to mediate plasmid DNA delivery, resulting in detectable EGFP expression in vitro. The vector properties were found to be driven by a multifactorial interplay among hydrophobic character, thermoresponsive behavior, polymer mobility, charge accessibility, intracellular environmental responsiveness, secondary structure effects, etc. The copolymer bearing primary amino groups displayed a distinct balance between DNA binding and release, characterized by moderate complex stability and enhanced sensitivity to environmental changes. These findings provide mechanistic insight into how amino functionality and polymer structure influence the structure–property–behavior relationships of polyoxazoline-based non-viral gene delivery systems.

This study reports the synthesis of core crosslinked star-shaped poly(2-oxazoline)s (CC-sPOxs) via an “arm first” approach combining cationic ring opening polymerization (CROP) with a thiol–ene click reaction. The resulting polymers consist of hydrophilic poly(2-ethyl-2-oxazoline) (PEtOx) arms and a poly(2-(3-butenyl)-2-oxazoline) (PButEnOx) core. First, a series of linear block copolymers PEtOx-b-PButEnOx was synthesized by CROP. These copolymers were subsequently crosslinked through a thiol–ene reaction using the crosslinker 2,2′-(ethylenedioxy)diethanethiol, yielding CC-sPOxs. To optimize the formation of star-shaped polymers, the thiol–ene reaction was carried out with varying amounts of the crosslinking agent and different amounts of comonomers. The resulting polymers were characterized in terms of their molar mass, composition, and solution behaviour and their cytotoxicity was assessed, confirming their potential suitability in biology and medicine. A novel method for synthesizing non-toxic poly(2-oxazoline)s with a non-linear macromolecular topology, with a precisely defined molar mass and number of arms, is presented in this work.

Star-shaped POEGMA- b -P3HT exhibits isotropic behavior, phase-separated nanostructures with ambipolar characteristics.

In this work, we propose a new synthetic pathway to obtain conjugates of poly(2-oxazoline)s (POx) and chelating agents (CA) with antibacterial activity, applying a triazine-based coupling compound. The copolymers based on 2-ethyl-2-oxazoline (EtOx) and 2-(3-butenyl)-2-oxazoline (ButEnOx) were coupled with acyclic and macrocyclic chelating compounds, i.e., diethylenetriaminepentaacetic acid (DTPA) and 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA). The obtained systems were named as POx-DTPA and POx-DOTA, respectively. This modification provided an opportunity to impart to the designed macromolecules the ability for complexation of ions, which stabilize the membrane of bacterial cell. We present, for the first time, studies on the uptake of various cations, including those stabilizing the membrane of Gram-negative bacteria at different environmental pH values for POx-DTPA and POx-DOTA macromolecules, where the increase in the efficiency of conjugate ion trapping is possible owing to the ionization of the functional groups of CA coupled to POx. The antibacterial properties of the designed systems were also confirmed by assessing their minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) with the use of Gram-negative strains of E. coli and P. aeruginosa. Using cytometric analysis, we further investigated the ability of the obtained systems to disrupt the bacterial cell membrane, demonstrating the permeability of the outer bacterial membrane (OM) after POx-DOTA treatment, and the disruption of the OM and the inner membrane (IM) after POx-DTPA treatment. The designed macromolecular systems also remained non-toxic to human skin fibroblasts in a wide range of concentrations, making them promising candidates for further studies on antibacterial biomaterials.

This study highlights new trends in the preparation and development of poly(2-oxazoline)-based systems exhibiting antimicrobial activity.

An interdisciplinary team of Polish scientists has developed innovative “smart” biomaterials to aid in the treatment of painful burn wounds.