Injectable, self-healing hydrogels with enhanced solubilization of hydrophobic drugs are urgently needed for antimicrobial intravaginal therapies. Here, we report the first hydrogel systems constructed of dynamic boronic esters crosslinking unimolecular micelles, which are a reservoir of antifungal hydrophobic drug molecules. The selective hydrophobization of hyperbranched polyglycidol with phenyl units in the core via ester or urethane bonds enabled the solubilization of clotrimazole, a water-insoluble drug of broad antifungal properties. The encapsulation efficiency of clotrimazole increases with the degree of the HbPGL core modification; however, the encapsulation is more favorable in the case of urethane derivatives. In addition, the rate of clotrimazole release was lower from HbPGL hydrophobized via urethane bonds than with ester linkages. In this work, we also revealed that the hydrophobization degree of HbPGL significantly influences the rheological properties of its hydrogels with poly(acrylamide-ran-2-acrylamidephenylboronic acid). The elastic strength of networks (G N ) and the thermal stability of hydrogels increased along with the degree of HbPGL core hydrophobization. The degradation of the hydrogel constructed of the neat HbPGL was observed at approx. 40 °C, whereas the hydrogels constructed on HbPGL, where the monohydroxyl units were modified above 30 mol %, were stable above 50 °C. Moreover, the flow and selfhealing ability of hydrogels were gradually decreased due to the reduced dynamics of macromolecules in the network as an effect of increased hydrophobicity. The changes in the rheological properties of hydrogels resulted from the engagement of phenyl units into the intermolecular hydrophobic interactions, which besides boronic esters constituted additional cross-links. This study demonstrates that the HbPGL core hydrophobized with phenyl units at 30 mol % degrees via urethane linkages is optimal in respect of the drug encapsulation efficiency and rheological properties including both self-healable and injectable behavior. This work is important because of a proper selection of a building component for the construction of a therapeutic hydrogel platform dedicated to the intravaginal delivery of hydrophobic drugs.

Polyglycidol (or polyglycerol) is a biocompatible polymer with a main chain structure similar to that of poly(ethylene oxide) but with a -CH 2 OH reactive side group in every structural unit. The hydroxyl groups in polyglycidol not only increase the hydrophilicity of this polymer but also allow for its modification, leading to polymers with carboxyl, amine, and vinyl groups, as well as to polymers with bonded aliphatic chains, sugar moieties, and covalently immobilized bioactive compounds in particular proteins. The paper describes the current state of knowledge on the synthesis of polyglycidols with various topology (linear, branched, and star-like) and with various molar masses. We provide information on polyglycidol-rich surfaces with protein-repelling properties. We also describe methods for the synthesis of polyglycidol-containing copolymers and the preparation of nano-and microparticles that could be derived from these copolymers. The paper summarizes recent advances in the application of polyglycidol and polyglycidol-containing polymers as drug carriers, reagents for diagnostic systems, and elements of biosensors.

Growing environmental awareness imposes on polymer scientists the development of novel materials that show a longer lifetime and that can be easily recycled. These challenges were largely met by vitrimers, a new class of polymers that merges properties of thermoplastics and thermosets. This is achieved by the incorporation of dynamic covalent bonds into the polymer structure, which provides high stability at the service temperature, but enables the processing at elevated temperatures. Numerous types of dynamic covalent bonds have been utilized for the synthesis of vitrimers. Amongst them, boronic acid-based linkages, namely boronic acid esters and boroxines, are distinguished by their quick exchange kinetics and the possibility of easy application in various polymer systems, from commercial thermoplastics to low molecular weight thermosetting resins. This review covers the development of dynamic cross-links. This review is aimed at providing the state of the art in the utilization of boronic species for the synthesis of covalent adaptable networks. We mainly focus on the synthetic aspects of boronic linkages-based vitrimers construction. Finally, the challenges and future perspectives are provided.

The design and synthesis of various polymer coreshell particles result from their distinct characteristics, which combine the properties of two or more components into one material. Many accessible synthetic strategies for obtaining polymer core-shell particles lead to the formation of particles for which the internal morphology differs from the ideal coreshell structure. Understanding the precise morphology characteristics is important for mechanistic studies of particle formation, which ultimately results in the design of particles for specific structures and properties. The detailed characteristics of complex polymer particle structures are complicated and require more than one method. This review focuses on imaging methods such as transmission electron microscopy (TEM), cryo-TEM, scanning transmission electron microscopy (STEM) and confocal fluorescence microscopy that reveal the radial redistribution of the components and methods for the quantitative analysis of individual phases (core, shell and interfacial layer), such as small-angle X-ray scattering (SAXS), small-angle neutron scattering (SANS), differential scanning calorimetry (DSC) and nuclear magnetic resonance (NMR). Methods that can determine the surface composition and makeup of the character of interfacial layer (gradient or containing small domains, etc.) were also reviewed.

We present biocompatible hydrogel systems suitable for biomineralization processes based on hyperbranched polyglycidol cross-linked with acrylamide copolymer bearing carbonyl-coordinated boronic acid. At neutral pH, diol functional groups of HbPGL react with boronic acid of polyacrylamide to generate 3D network in water by the formation of boronic ester cross-links. The dynamic associative/dissociative characteristics of the cross-links makes the network reversible. The presented hydrogels display self-healing properties and are injectable, facilitating gap filing of bone tissue. The H HR MAS DOSY NMR studies reveal that acrylamide copolymer plays the role of the network framework, whereas HbPGL macromolecules, due to their compact structure, move between reactive sites of the copolymer. The influence of the copolymer macromolecules entanglements and overall polymer concentrations on macromolecules mobility and stress relaxation processes is investigated. The process of hydrogel biomineralization results from hydrolysis of 1-naphthyl phosphate calcium salt catalyzed by encapsulation in hydrogel alkaline phosphatase. The environment of the hydrogel is entirely neutral toward the enzyme. However, the activity of alkaline phosphatase encapsulated within the hydrogel structure is diffusion-limited. In this article, based on the detailed characteristics of three model hydrogel systems, we demonstrate the influence of the hydrogel permeability on the encapsulated enzyme activity and calcium phosphate formation rate. The H HR MAS DOSY NMR is used to monitor diffusion low-molecular weight compound within hydrogels, whereasP HR MAS NMR facilitates monitoring of the progress of biomineralization in situ within hydrogels. The results show a direct correlation between low molecular diffusivity in hydrogels and network dynamics. We demonstrate that the morphology of in situ-generated calcium phosphate within three model HbPGL/poly(AM-ran-APBA) hydrogels of different low molecular permeability varies substantially from sparsely deployed large, well-defined crystals to an even distribution within the polymers polycrystalline continuous network.

In this paper, we present novel well-defined unimolecular micelles constructed a on poly(furfuryl glycidyl ether) core and highly hydrophilic poly(glyceryl glycerol ether) shell, PFGE-b-PGGE. The copolymer was synthesized via anionic ring-opening polymerization of furfuryl glycidyl ether and (1,2-isopropylidene glyceryl) glycidyl ether, respectively. MTT assay revealed that the copolymer is non-cytotoxic against human cervical cancer endothelial (HeLa) cells. The copolymer thanks to furan moieties in its core is capable of encapsulation of nifuratel, a hydrophobic nitrofuran derivative, which is a drug applied in the gynaecology therapies that shows a broad antimicroorganism spectrum. The study shows high loading capacity of the copolymer, i.e., 146 mg of nifuratel per 1 g of copolymer. The load unimolecular micelles were characterized using DLS and TEM microscopy and compared with the reference glyceryl glycerol ether homopolymer sample. The presence of numerous 1,2-diol moieties in the shell of PFGE-b-PGG macromolecules enabled the formation of reversible cross-links with 2-acrylamidephenylboronic acid-based polyacrylamide. The obtained hydrogels were both injectable and self-healable, which was confirmed with a rheological study.

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This article demonstrates the utility of DOSY NMR for the determination of the optimal conditions for the efficient covalent, reversible cross-linking of macromolecules in water for hydrogel formation. The studied model system was hyperbranched polyglycidol (HbPGL) containing numerous diol groups in peripheral regions and two types of boronic acids, that is, B(OH) 4 § and benzene-1,4-boronic diacid, as crosslinking agents. Diffusion coefficient changes of a polymer in solution, under the influence of various concentrations of cross-linking agent and pH, which influences the equilibrium of the reaction between boronic acids and diols, were recorded.These data are consistent with the rheological properties, namely the G 0 max (x) of hydrogels prepared under analogous conditions, from more concentrated solutions of HbPGL. This approach appears to be promising as it facilitates avoiding the loss of a large amount of polymer that is necessary for the elaboration of appropriate conditions for network formation in aqueous media.