hydrogel swelling
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2022 ◽  
Vol 23 (2) ◽  
pp. 971
Author(s):  
Juliana S. Ribeiro ◽  
Eliseu A. Münchow ◽  
Ester A. F. Bordini ◽  
Nathalie S. Rodrigues ◽  
Nileshkumar Dubey ◽  
...  

This study aimed at engineering cytocompatible and injectable antibiotic-laden fibrous microparticles gelatin methacryloyl (GelMA) hydrogels for endodontic infection ablation. Clindamycin (CLIN) or metronidazole (MET) was added to a polymer solution and electrospun into fibrous mats, which were processed via cryomilling to obtain CLIN- or MET-laden fibrous microparticles. Then, GelMA was modified with CLIN- or MET-laden microparticles or by using equal amounts of each set of fibrous microparticles. Morphological characterization of electrospun fibers and cryomilled particles was performed via scanning electron microscopy (SEM). The experimental hydrogels were further examined for swelling, degradation, and toxicity to dental stem cells, as well as antimicrobial action against endodontic pathogens (agar diffusion) and biofilm inhibition, evaluated both quantitatively (CFU/mL) and qualitatively via confocal laser scanning microscopy (CLSM) and SEM. Data were analyzed using ANOVA and Tukey’s test (α = 0.05). The modification of GelMA with antibiotic-laden fibrous microparticles increased the hydrogel swelling ratio and degradation rate. Cell viability was slightly reduced, although without any significant toxicity (cell viability > 50%). All hydrogels containing antibiotic-laden fibrous microparticles displayed antibiofilm effects, with the dentin substrate showing nearly complete elimination of viable bacteria. Altogether, our findings suggest that the engineered injectable antibiotic-laden fibrous microparticles hydrogels hold clinical prospects for endodontic infection ablation.


2021 ◽  
Vol 12 ◽  
pp. 532
Author(s):  
Nancy E Epstein ◽  
John Lancione Esq

Background: The package insert for DuraSeal (Integra LifeSciences, Princeton NJ) states it is Contraindicated for use in the anterior cervical spine (confined space): “Do not apply DuraSeal® hydrogel to confined bony structures where nerves are present since neural compression may result due to hydrogel swelling (…up to 12% of its size in any direction).” Further, it should not be used to treat massive unrepaired cerebrospinal fluid (CSF) leaks in any location; “…(it) is indicated as an adjunct to sutured dural repair during spine surgery to provide watertight closure,” but it is not to be used “...for a gap greater than 2 mm….” Methods: A spinal surgeon interpreted a geriatric patient’s MR as showing severe C3-C4 to C5-C6 anterior cord compression due to disc disease/spondylosis. However, he never reviewed the CT report/images that documented marked ossification of the posterior longitudinal ligament (OPLL) with multiple signs of dural penetrance. Results: The anterior C4, C5 corpectomy, and C3-C6 strut fusion/plating resulted in a massive, irreparable cerebrospinal fluid (CSF) leak. Despite the contraindications, the surgeon mistakenly applied DuraSeal which caused the patient’s postoperative quadriplegia (i.e., as documented on the delayed postoperative MR scan). Following a secondary surgery consisting of a laminectomy/posterior fusion, the patient was still quadriplegic. Further, as he requested no postoperative MR scan and performed no subsequent corrective surgery (i.e., anterior removal of DuraSeal), the patient remained permanently quadriplegic. Conclusion: DuraSeal is directly contraindicated for use in the anterior cervical spine, with/without a CSF leak. Here, utilizing DuraSeal for anterior cervical OPLL surgery resulted in permanent quadriplegia, and was below the standard of care.


2021 ◽  
Author(s):  
Michael M. Lerch ◽  
Ankita Shastri ◽  
Thomas B.H. Schroeder ◽  
Amos Meeks ◽  
Shucong Li ◽  
...  

Stimuli-responsive materials typically contain responsive molecular units that couple an external trigger to a defined macroscale response. Ongoing efforts to boost the versatility and complexity of these responses increasingly focus on multi-stimuli-responsive molecular units and crosslinkers, as these bear the potential to impart self-regulatory behaviors building on cooperative effects and feedback mechanisms. Herein, we study a stimuli-responsive platform consisting of polyacrylamide-based hydrogels with well-known multi-responsive spiropyrans covalently bound as pendant groups or ´non-innocent´ crosslinkers. Surprisingly, as compared to their appended counterparts, spiropyran crosslinkers cause up to two-fold larger hydrogel swelling in methylenebisacrylamide-crosslinked poly(acrylamide-co-acrylic acid) hydrogels, despite their increased relative crosslinking density. We seek the origin of this unexpected behavior by employing nanoindentation, swelling studies, and UV-vis spectroscopy to study changes in mechanical properties and in spiropyran isomer distribution as a function of solution pH, co-monomer chemistry, and swelling-induced polymer strain. We then estimate the osmotic counterion pressures as a function of spiropyran isomer distribution but find that such pressures alone are insufficient to explain the observed behavior. Charge complexation, cooperative effects between the hydrogel´s mechanics and chemistry, and aggregate formation may all be invoked to explain features of the observed ´non-innocence´ of spiropyran crosslinkers. Taken together, these insights will aid rational implementation of such responsive crosslinkers in materials design and extend the functionality of existing polymeric materials towards more complex and better tunable behaviors.


MRS Advances ◽  
2021 ◽  
Author(s):  
Axel T. Neffe ◽  
Candy Löwenberg ◽  
Andreas Lendlein

AbstractFunctionalization of gelatin with glycidylmethacrylate (GMA-gelatin) enables network formation employing the double bond, so that the reaction is orthogonal to the inherent functional groups in the biomacromolecule. Here, network formation by crosslinking of GMA-gelatin with hexane 1,6-dithiol or nonane 1,9-dithiol to tailor properties and enable a shape-memory effect is shown by 1H NMR and FT-IR spectroscopy. Hydrogel swelling (460–1900 vol%) and mechanical properties (Young’s modulus E = 59–512 kPa, elongation at break εb = 44–127%) depended on the molecular composition of the networks and temperature. Increased crosslinker length, thiol:methacrylate molar ratio, and precursor concentrations led to denser networks. Change of properties with temperature suggested adoption of triple helices by gelatin chains, forming physical netpoints at lower temperatures (< 20 °C). However, the limited freedom of the gelatin chains to move allowed only a minimal extent of triple helices formation, as it became apparent from the related signal in wide-angle X-ray scattering and the thermal transition associated to triple helices in some networks by DSC. The presented strategy is likely transferable to other biomacromolecules, and the results suggest that too short crosslinkers may result in a significant amount of grafting rather than network formation. Graphic abstract


Author(s):  
Hamimullah Watandost ◽  
Jailani Achak ◽  
Abdullah Haqmal

In this study, first a hydrogel based on sodium alginate and acrylamide was prepared by radical polymerization method and then manganese oxide was formed in its lattice structure and nanocomposite hydrogels were obtained. In the next step, Nanocomposite hydrogels were used as catalysts for the oxidation of alcohols. To evaluate the physical properties and confirm the structure of nanocomposite hydrogels, Hydrogel swelling tests, FT-IR infrared conversion spectroscopy, TGA Thermal gravimetric, SEM Scanning electron microscopy and TEM Transmission electron microscopy were used. The amount of manganese was measured using an atomic absorption spectrometer. Also, factors affecting oxidation reactions such as reaction temperature, amount of catalyst and reaction time were optimized to achieve the highest percentage of conversion of alcohols to aldehydes. Under optimal conditions, the highest conversion percentage of benzyl alcohol was 79% for Benz aldehyde at 80 °C for 24 hours.


Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1219
Author(s):  
Yuchen Jiang ◽  
Guihua Li ◽  
Chenyu Yang ◽  
Fangong Kong ◽  
Zaiwu Yuan

Multiresponsive hydrogels have attracted tremendous interest due to their promising applications in tissue engineering, wearable devices, and flexible electronics. In this work, we report a multiresponsive upper critical solution temperature (UCST) composite hydrogel based on poly (acrylic acid-co-acrylamide), PAAc-co-PAAm, sequentially cross-linked by acid-hydrolysis cellulose nanocrystals (CNCs). Scanning electron microscopy (SEM) observations demonstrated that the hydrogels are formed by densely cross-linked porous structures. The PAAc/PAAm/CNC hybrid hydrogels exhibit swelling and shrinking properties that can be induced by multiple stimuli, including temperature, pH, and salt concentration. The driving force of the volume transition is the formation and dissociation of hydrogen bonds in the hydrogels. A certain content of CNCs can greatly enhance the shrinkage capability and mechanical strength of the hybrid hydrogels, but an excess addition may impair the contractility of the hydrogel. Furthermore, the hydrogels can be used as a matrix to adsorb dyes, such as methylene blue (MB), for water purification. MB may be partly discharged from hydrogels by saline solutions, especially by those with high ionic strength. Notably, through temperature-controlled hydrogel swelling and shrinking, doxorubicin hydrochloride (DOX-HCl) can be controllably adsorbed and released from the prepared hydrogels.


Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 703
Author(s):  
Rebeca Leu Alexa ◽  
Horia Iovu ◽  
Bogdan Trica ◽  
Catalin Zaharia ◽  
Andrada Serafim ◽  
...  

The present study investigated the possibility of obtaining 3D printed composite constructs using biomaterial-based nanocomposite inks. The biopolymeric matrix consisted of methacrylated gelatin (GelMA). Several types of nanoclay were added as the inorganic component. Our aim was to investigate the influence of clay type on the rheological behavior of ink formulations and to determine the morphological and structural properties of the resulting crosslinked hydrogel-based nanomaterials. Moreover, through the inclusion of nanoclays, our goal was to improve the printability and shape fidelity of nanocomposite scaffolds. The viscosity of all ink formulations was greater in the presence of inorganic nanoparticles as shear thinning occurred with increased shear rate. Hydrogel nanocomposites presented predominantly elastic rather than viscous behavior as the materials were crosslinked which led to improved mechanical properties. The inclusion of nanoclays in the biopolymeric matrix limited hydrogel swelling due the physical barrier effect but also because of the supplementary crosslinks induced by the clay layers. The distribution of inorganic filler within the GelMA-based hydrogels led to higher porosities as a consequence of their interaction with the biopolymeric ink. The present study could be useful for the development of soft nanomaterials foreseen for the additive manufacturing of customized implants for tissue engineering.


2021 ◽  
Vol 7 (7) ◽  
pp. eabd2711
Author(s):  
Jean-François Louf ◽  
Nancy B. Lu ◽  
Margaret G. O’Connell ◽  
H. Jeremy Cho ◽  
Sujit S. Datta

Hydrogels hold promise in agriculture as reservoirs of water in dry soil, potentially alleviating the burden of irrigation. However, confinement in soil can markedly reduce the ability of hydrogels to absorb water and swell, limiting their widespread adoption. Unfortunately, the underlying reason remains unknown. By directly visualizing the swelling of hydrogels confined in three-dimensional granular media, we demonstrate that the extent of hydrogel swelling is determined by the competition between the force exerted by the hydrogel due to osmotic swelling and the confining force transmitted by the surrounding grains. Furthermore, the medium can itself be restructured by hydrogel swelling, as set by the balance between the osmotic swelling force, the confining force, and intergrain friction. Together, our results provide quantitative principles to predict how hydrogels behave in confinement, potentially improving their use in agriculture as well as informing other applications such as oil recovery, construction, mechanobiology, and filtration.


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