10 research outputs found
Кіноніми Кіровоградщини: особливості вибору кличок та способи їх творення
Стаття присвячена вивченню особливостей української кінонімії. Основну увагу зосереджено на дослідженні процесу номінації та способів словотворення кличок собак. Окремо розглянуто офіційні назви тварин, які мають родослівну.Статья посвящена изучению особенностей украинской кинонимии. Основное внимание сосредоточено на изучении процесса номинации и способах словообразования кличек собак. Отдельно рассмотрены официальные названия собак, имеющих родословную.The article is devoted to the research of the peculiarities of Ukrainian cynonymy. Most attention is taid to the research of the process of nomination and to the ways of formation of dogs' names. Special consideration is given to the official names of the animals with genealogy
Synthesis and Characterization of Thermally and Chemically Gelling Injectable Hydrogels for Tissue Engineering
Novel, injectable hydrogels were developed that solidify through a dual-gelation, physical and
chemical, mechanism upon preparation and elevation of temperature to 37°C. A thermogelling,
poly(N-isopropylacrylamide)-based macromer with pendant epoxy rings and a hydrolyticallydegradable
polyamidoamine-based diamine crosslinker were synthesized, characterized, and
combined to produce in situ forming hydrogel constructs. Network formation through the epoxyamine
reaction was shown to be rapid and facile, and the progressive incorporation of the
hydrophilic polyamidoamine crosslinker into the hydrogel was shown to mitigate the often
problematic tendency of thermogelling materials to undergo significant post-formation gel
syneresis. The results suggest that this novel class of injectable hydrogels may be attractive
substrates for tissue engineering applications due to the synthetic versatility of the component
materials and beneficial hydrogel gelation kinetics and stability
Biofabrication of reinforced 3D-scaffolds using two-component hydrogels
Progress in biofabrication technologies is mainly hampered by the limited number of suitable hydrogels that can act as bioinks. Here, we present a new bioink for 3D-printing, capable of forming large, highly defined constructs. Hydrogel formulations consisted of a thermoresponsive polymer mixed with a poly(ethylene glycol) (PEG) or a hyaluronic acid (HA) cross-linker with a total polymer concentration of 11.3 and 9.1 wt% respectively. These polymer solutions were partially cross-linked before plotting by a chemoselective reaction called oxo-ester mediated native chemical ligation, yielding printable formulations. Deposition on a heated plate of 37 degrees C resulted in the stabilization of the construct due to the thermosensitive nature of the hydrogel. Subsequently, further chemical cross-linking of the hydrogel precursors proceeded after extrusion to form mechanically stable hydrogels that exhibited a storage modulus of 9 kPa after 3 hours. Flow and elastic properties of the polymer solutions and hydrogels were analyzed under similar conditions to those used during the 3D-printing process. These experiments showed the ability to extrude the hydrogels, as well as their rapid recovery after applied shear forces. Hydrogels were printed in grid-like structures, hollow cones and a model representing a femoral condyle, with a porosity of 48 +/- 2%. Furthermore, an N-hydroxysuccinimide functionalized thermoplastic poly-epsilon-caprolactone (PCL) derivative was successfully synthesized and 3D-printed. We demonstrated that covalent grafting of the developed hydrogel to the thermoplastic reinforced network resulted in improved mechanical properties and yielded high construct integrity. Reinforced constructs also containing hyaluronic acid showed high cell viability of chondrocytes, underlining their potential for further use in regenerative medicine applications
Thermoresponsive Injectable Hydrogels Cross-Linked by Native Chemical Ligation
Temperature-induced
physical gelation was combined with native chemical ligation (NCL)
as a chemical cross-linking mechanism to yield rapid network formation
and mechanically strong hydrogels. To this end, a novel monomer <i>N</i>-(2-hydroxypropyl)methacrylamide-cysteine (HPMA-Cys) was
synthesized that copolymerizes with <i>N</i>-isopropylacrylamide
(NIPAAm) to yield thermoresponsive polymers decorated with cysteine
functionalities. Triblock copolymers consisting of a poly(ethylene
glycol) (PEG) middle block flanked by random blocks of NIPAAm and
HPMA-Cys were successfully synthesized and characterized. Additionally,
thioester cross-linkers were synthesized based on PEG and hyaluronic
acid, respectively. Upon mixing the thermoresponsive polymer with
PEG or hyaluronic acid cross-linker, cysteine and thioester functionalities
react under physiological conditions to generate a native peptide
bond. An immediate physical network was formed after elevation of
the temperature to 37 °C due to the self-assembly of the pNIPAAm
chains. This network was stabilized in time by covalent cross-linking
due to NCL reaction between thioester and cysteine functionalities,
resulting in hydrogels with up to 10 times higher storage moduli than
without chemical cross-links. Finally, a collagen mimicking peptide
sequence was successfully ligated to this hydrogel using the same
reaction mechanism, showing the potential of this hydrogel for tissue
engineering applications
Thermogelling and Chemoselectively Cross-Linked Hydrogels with Controlled Mechanical Properties and Degradation Behavior
Chemoselectively cross-linked hydrogels
have recently gained increasing
attention for the development of novel, injectable biomaterials given
their limited side reactions. In this study, we compared the properties
of hydrogels obtained by native chemical ligation (NCL) and its recently
described variation termed oxo-ester-mediated native chemical ligation
(OMNCL) in combination with temperature-induced physical gelation.
Triblock copolymers consisting of cysteine functionalities, thermoresponsive <i>N</i>-isopropylacrylamide (NIPAAm) units and degradable moieties
were mixed with functionalized poly(ethylene glycol) (PEG) cross-linkers.
Thioester or <i>N</i>-hydroxysuccinimide (NHS) functionalities
attached to PEG reacted with cysteine residues of the triblock copolymers
via either an NCL or OMNCL pathway. The combined physical and chemical
cross-linking resulted in rapid network formation and mechanically
strong hydrogels. Stiffness of the hydrogels was highest for thermogels
that were covalently linked via OMNCL. Specifically, the storage modulus
after 4 h reached a value of 26 kPa, which was over a 100 times higher
than hydrogels formed by solely thermal physical interactions. Endothelial
cells showed high cell viability of 98 ± 2% in the presence of
OMNCL cross-linked hydrogels after 16 h of incubation, in contrast
to a low cell viability (13 ± 7%) for hydrogels obtained by NCL
cross-linking. Lysozyme was loaded in the gels and after 2 days more
than 90% was released, indicating that the cross-linking reaction
was indeed chemoselective as the protein was not covalently grafted
to the hydrogel network. Moreover, the degradation rates of these
hydrogels under physiological conditions could be tailored from 12
days up to 6 months by incorporation of a monomer containing a hydrolyzable
lactone ring in the thermosensitive triblock copolymer. These results
demonstrate a high tunability of mechanical properties and degradation
rates of these in situ forming hydrogels that could be used for a
variety of biomedical applications
Swelling Enhanced Remanent Magnetization of Hydrogels Cross-Linked with Magnetic Nanoparticles
Hydrogels that are pH-sensitive and
partially cross-linked by cobalt
ferrite nanoparticles exhibit remarkable remanent magnetization behavior.
The magnetic fields measured outside our thin disks of ferrogel are
weak, but in the steady state, the field dependence on the magnetic
content of the gels and the measurement geometry is as expected from
theory. In contrast, the time-dependent behavior is surprisingly complicated.
During swelling, the remanent field first rapidly increases and then
slowly decreases. We ascribe the swelling-induced field enhancement
to a change in the average orientation of magnetic dipolar structures,
while the subsequent field drop is due to the decreasing concentration
of nanoparticles. During shrinking, the field exhibits a much weaker
time dependence that does not mirror the values found during swelling.
These observations provide original new evidence for the markedly different spatial profiles of
the pH during swelling and shrinking of hydrogels
Structure–Property Evaluation of Thermally and Chemically Gelling Injectable Hydrogels for Tissue Engineering
Ten-year experience of a national multidisciplinary tumour board for cancer and pregnancy in the Netherlands
Background: Most physicians encounter pregnant women with cancer incidentally, leading to a lack of expertise or confidence to inform and treat these patients based on the most recent guidelines and expert opinions. In the Netherlands, a national multidisciplinary tumour board for cancer, infertility and pregnancy (CIP-MDT) was founded in December 2012, including 35 specialists from a variety of disciplines. This study evaluates the frequency of consultation of the CIP-MDT, the types of questions asked and the satisfaction of consulting physicians with its existence. Methodology: Of all requests to the CIP-MDT between December 2012 and June 2021, tumour type, stage, gestational age at diagnosis and recommendations were collected and analysed. For evaluating the methods of the CIP-MDT, a survey with questions regarding experiences with the CIP-MDT and its impact on treatment decisions was sent out to physicians that consulted the CIP-MDT. Results: Recommendations (n = 213) concerned preferred and safest options for imaging, treatment options during pregnancy, possible effects on the child and fertility preserving options. Most frequently discussed malignancies were breast cancer (n = 66), cervical cancer (n = 34), haematological malignancies (n = 32) and melanoma (n = 21). The questionnaire was completed by 54% of the physicians (n = 50). Satisfaction with the recommendations of the CIP-MDT was high, and 94% of the physicians informed their patients about consulting the CIP-MDT and felt supported by the received recommendations. Discussion: The national Dutch CIP-MDT contributes to a high level of satisfaction among physicians requesting advice. Further research should be executed to confirm that a CIP-MDT improves the outcomes for pregnant women and their children
Thermoresponsive Injectable Hydrogels Cross-Linked by Native Chemical Ligation
Temperature-induced physical gelation was combined with native chemical ligation (NCL) as a chemical cross-linking mechanism to yield rapid network formation and mechanically strong hydrogels. To this end, a novel monomer N-(2-hydroxypropyl)methacrylamide-cysteine (HPMA-Cys) was synthesized that copolymerizes with N-isopropylacrylamide (NIPAAm) to yield thermoresponsive polymers decorated with cysteine functionalities. Triblock copolymers consisting of a poly(ethylene glycol) (PEG) middle block flanked by random blocks of NIPAAm and HPMA-Cys were successfully synthesized and characterized. Additionally, thioester cross-linkers were synthesized based on PEG and hyaluronic acid, respectively. Upon mixing the thermoresponsive polymer with PEG or hyaluronic acid cross-linker, cysteine and thioester functionalities react under physiological conditions to generate a native peptide bond. An immediate physical network was formed after elevation of the temperature to 37 °C due to the self-assembly of the pNIPAAm chains. This network was stabilized in time by covalent cross-linking due to NCL reaction between thioester and cysteine functionalities, resulting in hydrogels with up to 10 times higher storage moduli than without chemical cross-links. Finally, a collagen mimicking peptide sequence was successfully ligated to this hydrogel using the same reaction mechanism, showing the potential of this hydrogel for tissue engineering applications. © 2014 American Chemical Society