8 research outputs found
Evaluation of Encapsulation Potential of Selected Star-Hyperbranched Polyglycidol Architectures: Predictive Molecular Dynamics Simulations and Experimental Validation
Polymers, including non-linear copolymers, have great potential in the development of drug delivery systems with many advantages, but the design requires optimizing polymerâdrug interactions. Molecular dynamics (MD) simulations can provide insights into polymerâdrug interactions for designing delivery systems, but mimicking formulation processes such as drying is often not included in in silico studies. This study demonstrates an MD approach to model drying of systems comprising either hydrophilic tinidazole or hydrophobic clotrimazole drugs with amphiphilic hyperbranched copolyethers. The simulated drying protocol was critical for elucidating drug encapsulation and binding mechanisms. Experimentally, two polymers were synthesized and shown to encapsulate clotrimazole with up to 83% efficiency, guided by interactions with the hydrophobic core observed in simulations. In contrast, tinidazole is associated with surface regions, indicating capacity differences between drug types. Overall, this work highlights MD simulation of the drying process as an important tool for predicting drugâpolymer complex behaviour. The modelled formulation protocol enabled high encapsulation efficiency and opened possibilities for the design of delivery systems based on computationally derived binding mechanisms. This demonstrates a computationalâexperimental approach where simulated drying was integral to elucidating interactions and developing optimized complexes, emphasizing the value of molecular modelling for the development of drug delivery formulations
Polyglycidol, Its Derivatives, and Polyglycidol-Containing CopolymersâSynthesis and Medical Applications
Polyglycidol (or polyglycerol) is a biocompatible polymer with a main chain structure similar to that of poly(ethylene oxide) but with a âCH2OH 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
Boronic Acid Esters and Anhydrates as Dynamic Cross-Links in Vitrimers
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
Temperature-Induced Changes in the Nanostructure of Hydrogels Based on Reversibly Cross-Linked Hyperbranched Polyglycidol with B(OH)<sub>4</sub><sup>â</sup> Ions
Solid-state boron
nuclear magnetic resonance (<sup>11</sup>B NMR)
and positron annihilation lifetime spectroscopies (PALS) were used
to study the molecular structure of self-healing hydrogels based on
cross-linked hyperbranched polyglycidol (HbPGL) with borax at basic
pH. The lifetime and intensity of orthopositronium allowed characterizing
the micro- and nanostucture of hydrogels at various thermal conditions.
Stepwise changes in the free volume parameters were found in pure
HbPGL as well as in hydrogels based on this polymer. However, the
shift in the phase transition temperature suggests that the important
properties of the hydrogel arise from the water building these systems.
Rheological measurements demonstrated the subsequent reduction of
the average cross-link lifetime within the polymer network under heating.
Composition of boronic species within hydrogel systems also diverged
upon change in temperature range from â10 °C to +70 °C.
The reduced fraction of boronic diester upon heating was quantitatively
rebuilt after cooling to ambient temperature. Heating the hydrogel
at 70 °C launched the irreversible release of a small fraction
of HbPGL macromolecules from the polymer network, generating its defects,
still present after cooling. The structural studies carried out in
a nanoscale facilitated the distinction in cross-linking density of
two analyzed hydrogel systems. The PAL spectroscopy turned out to
be a valuable tool to exclude entanglements between individual macromolecules
of pristine HbPGL
A facile method to control the phase behavior of hydroxypropyl cellulose
Raw data sets in a XLSX file, use for the prepration of 'A facile method to control the phase behavior of hydroxypropyl cellulose' articles.
These include:
FTIR of spectra hydroxypropyl cellulose carbamate;
13C NMR spectra hydroxypropyl cellulose carbamate;
1H NMR spectra hydroxypropyl cellulose carbamate;
Data from the 'kinetics experiment' of the reaction between hydroxypropyl cellulose and N-Methyl Carbamoylimidazole
Transmitace of 0.5% HPC3.4 carbamates solutions in respect to temeprature; 1C/min
Viscosity of 10% HPC3.4 carbamates solutions in respect to temeprature; 1C/min
Determined cloud points for 0.5% HPC carbamates solutions
Surface tension of HPC carbamates solution
Diffusion-Controllable Biomineralization Conducted In Situ in Hydrogels Based on Reversibly Cross-Linked Hyperbranched Polyglycidol
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 <sup>1</sup>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 <sup>1</sup>H HR MAS DOSY NMR is used to monitor diffusion
low-molecular weight compound within hydrogels, whereas <sup>31</sup>P 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/polyÂ(AM-<i>ran</i>-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
Converting Unrefined Birch Suberin Monomers into Vitrimer
Suberin extracted from birch bark, a side product of
the wood industry,
was used as a resin for the synthesis of a biobased vitrimer utilizing
the transesterification reaction. Suberin was extracted by hydrolyzing
the outer bark of birch trees under alkaline conditions and used further
without refining. The resulting resin, natively rich in hydroxyl and
carboxyl groups, was polymerized in the presence of various catalysts
and a small-molecule polyol to provide an excess of primary OH groups.
The study showed that among the catalysts tested, only dibutyltin
dilaurate (DBTDL) promoted the transesterification reaction in the
polymer matrix to the extent that the polymer could be recycled at
elevated temperatures. Furthermore, a chemical recycling route was
successfully tested through alkaline hydrolysis and repolymerization
of the obtained vitrimer. The resulting suberin vitrimer showed elastomer-like
properties with Tg at approximately â20
°C and a Youngâs modulus exceeding 1 MPa. It was also
demonstrated to be hydrolytically stable under moderately alkaline
and acidic conditions