Swelling Ability Research Articles

A Deformation–Diffusion-Coupled Constitutive Theory for Hydrogels by Considering the Preparation Conditions

Hydrogels are excellent soft materials that can absorb large amounts of water and have applications ranging from biocompatible sensors to soft robots. Experiments have demonstrated that the equilibrium swelling state of hydrogels strongly depends on their preparation and external conditions, such as the as-prepared water content, cross-linking density, and temperature. However, traditional theories based on Flory’s work have failed to capture these dependence effects. In particular, these theories ignore the existence of solvents in the as-prepared state of hydrogels, making them unable to characterize the sensitivity of the swelling and mechanical behaviors to the as-prepared water content. In this study, we propose a constitutive theory that considers the preparation conditions based on statistical thermodynamics. Our theory can precisely predict the swelling ability of hydrogels under diverse preparation conditions and capture the phase transitions of temperature-sensitive hydrogels. We further derived the governing equations for large deformations and solvent diffusion considering their strong coupling effects. Based on our theory, the inhomogeneous deformation-induced solvent migration and delayed fracture of hydrogels were investigated. From theoretical investigations, we revealed the underlying mechanism of these interesting hydrogel behaviors. The theoretical results were further used to guide the design of diverse intelligent structures that can be applied as soft actuators, flexible robots, and morphing the growth of plants.

The characteristics of swelling and biodegradation tests of bovine amniotic membrane-hydroxyapatite biocomposite

Background: A good biocomposite is a structure that can provide opportunities for cells to adhere, proliferate, and differentiate. It is affected by the characteristics of a material. As bone tissue regeneration occurs, biomaterials must have a high swelling ability and low biodegradability. The high swelling capability will have a larger surface area that can support maximal cell attachment and proliferation on the biocomposite surface, which accelerates the regeneration process of bone defects. Purpose: The study aimed to analyze the characteristics of swelling and biodegradation of bovine amniotic membrane-hydroxyapatite (BAM-HA) biocomposite with various ratios. Methods: The BAM-HA biocomposite with a ratio of 30:70, 35:65, and 40:60 (w/w) was synthesized using a freeze-dry method. The swelling test was done by measuring the initial weight and final weight after being soaked in phosphate-buffered saline for 24 hours and the biodegradation test was done by measuring the initial weight and final weight after being soaked in simulated body fluid for seven days. Results: The swelling percentage of BAM-HA biocomposite at each ratio of 30:70, 35:65, and 40:60 (w/w) was 303.90%, 477.94%, and 574.19%. The biodegradation percentage of BAM-HA biocomposite at each ratio of 30:70, 35:65, and 40:60 was 9.43%, 11.05%, and 12.02%. Conclusion: The BAM-HA biocomposite with a ratio of 40:60 (w/w) has the highest swelling percentage while the 30:70 (w/w) ratio has the lowest percentage of biodegradation.

Alginate/acemannan-based beads loaded with a biocompatible ionic liquid as a bioactive delivery system

Combining biomacromolecules with green chemistry principles and clean technologies has proven to be an effective approach for drug delivery, providing a prolonged and sustained release of the encapsulated material. The current study investigates the potential of cholinium caffeate (Ch[Caffeate]), a phenolic-based biocompatible ionic liquid (Bio-IL) entrapped in alginate/acemannan beads, as a drug delivery system able to reduce local joint inflammation on osteoarthritis (OA) treatment. The synthesized Bio-IL has antioxidant and anti-inflammatory actions that, combined with biopolymers as 3D architectures, promote the entrapment and sustainable release of the bioactive molecules over time. The physicochemical and morphological characterization of the beads (ALC, ALAC0,5, ALAC1, and ALAC3, containing 0, 0.5, 1, and 3 %(w/v) of Ch[Caffeate], respectively) revealed a porous and interconnected structure, with medium pore sizes ranging from 209.16 to 221.30 μm, with a high swelling ability (up 2400 %). Ch[Caffeate] significantly improved the antioxidant activities of the constructs by 95 % and 97 % for ALAC1 and ALAC3, respectively, when compared to ALA (56 %). Besides, the structures provided the environment for ATDC5 cell proliferation, and cartilage-like ECM formation, supported by the increased GAGs in ALAC1 and ALAC3 formulations after 21 days. Further, the ability to block the secretion of pro-inflammatory cytokines (TNF-α and IL-6), from differentiated THP-1 was evidenced by ChAL-Ch[Caffeate] beads. These outcomes suggest that the established strategy based on using natural and bioactive macromolecules to develop 3D constructs has great potential to be used as therapeutic tools for patients with OA.

Nafcillin-Loaded Photocrosslinkable Nanocomposite Hydrogels for Biomedical Applications.

Skin infections are frequently treated via intravenous or oral administration of antibiotics, which can lead to serious adverse effects and may sometimes contribute to the proliferation of resistant bacterial strains. Skin represents a convenient pathway for delivering therapeutic compounds, ensured by the high number of blood vessels and amount of lymphatic fluids in the cutaneous tissues, which are systematically connected to the rest of the body. This study provides a novel, straightforward method to obtain nafcillin-loaded photocrosslinkable nanocomposite hydrogels and demonstrates their performance as drug carriers and antimicrobial efficacy against Gram-positive bacteria. The novel formulations obtained, based on polyvinylpyrrolidone, tri(ethylene glycol) divinyl ether crosslinker, hydrophilic bentonite nanoclay, and/or two types of photoactive (TiO2 and ZnO) nanofillers, were characterized using various analytical methods (transmission electron microscopy (TEM), scanning electron microscopy-energy-dispersive X-ray analysis (SEM-EDX), mechanical tests (tension, compression, and shear), ultraviolet-visible spectroscopy (UV-Vis), swelling investigations, and via specific microbiological assays ("agar disc diffusion method" and "time-kill test"). The results reveal that the nanocomposite hydrogel possessed high mechanical resistance, good swelling abilities, and good antimicrobial activity, demonstrating a decrease in the bacteria growth between 3log10 and 2log10 after one hour of direct contact with S. aureus.

Insights into the aggregation structure and physicochemical properties of heat-moisture treated wheat starch and its associated effects on noodle quality

In this work, impacts of heat moisture treatment (HMT) on the aggregation structure and physicochemical properties of wheat starch were investigated, and relationship between starch physicochemical properties and quality performance of noodles fortified with HMT-treated starches was revealed. Results show that HMT reduced the ordered degree of starch aggregation structures (e.g., crystalline and short-range ordered molecular structures) but increased their rigidity and thermostability, and in turn, retarded starch enzyme hydrolysis, swelling, breakdown, and reassociation during digestion, heating and cooling. Then, the limited swelling and reassociation ability of starch molecules after HMT may contribute to a weaker gel strength and herein a lower absorption, hardness, springiness, and chewiness of noodles. Notably, HMT-30 fortified noodles presented more obvious changes. Hence, it can be concluded that quality attributes of noodles could be tailored by modulating starch gel structure through HMT.

Nasal mucoadhesive in situ gelling liquid crystalline fluid precursor system of polyene antibiotic for potential treatment of localized sinuses aspergillosis post COVID infection

Nasal mucoadhesive in situ gelling liquid crystalline precursor system (IGFPS) of nystatin was developed for localized treatment of nasal aspergillosis post COVID infection. The stimuli-sensitive sol system comprising of Monoolein (60%w/w), Oleic acid (10%w/w), Dimethyl sulfoxide (15%w/w), Poloxamer 407 (9%w/w), and the drug (2.23%w/w) exhibited a faster sol–gel transformation in situ with good swelling ability. The small angle X-ray scattering study identified the coexistence of Im3m cubic phase with hexagonal closed pack P63/mmc structures. The subzero differential scanning calorimetry studies identified entrapped interphasal water and free water in the gels with confirmation of gelation due to micellization. Mucoadhesive properties of the gel indicate these systems to prolong the residence time at the site of absorption. The gels followed Non-Newtonian flow pattern characteristic of pesudoplastic type. The oscillatory rheology revealed that high complex viscosity and lower tanδ value provided superior adhesiveness and mucoadhesion ability to the gel. The gel exhibited a drug release of 86% at the end of 8h and of Higuchi kinetics with anomalous transport. The IGFPS exhibited better in vitro antifungal activity in comparison to drug solution. The system demonstrated permeation enhancing effect undamaged cilia and no serious histological changes. Post intranasal administration the maximum concentration (11.79 ± 2.31 μg/ml) was realized in 20 min and the curve showed a decline similar to intravenous. The storage stability of the IGFPS was found to be within acceptable limits for stability. Thus, a nasal mucoadhesive in situ gelling fluid liquid crystalline precursor formulation may represent a promising novel alternative for the localized and systemic delivery of nystatin.

Non-toxic chitosan-pyrazole adsorbent enriched with greenly synthesized zinc oxide nanoparticles for dye removal from wastewater

The limited usage of chitosan as a dye adsorbent is attributed to its compact structure and low swelling ability, despite its exceptional properties. The present study aimed to prepare novel chitosan/pyrazole Schiff base (ChS) adsorbents enriched with greenly synthesized zinc oxide nanoparticles. The preparation of ZnO-NPs was carried out through a green approach using the Coriandrum sativum extract. The presence of ZnO-NPs at the nanoscale was validated through TEM, DLS and XRD analyses. FTIR and 1H NMR confirmed the successful preparation of the Schiff base and its ZnO-NPs adsorbents. The incorporation of ZnO-NPs improved the thermal, swelling and antimicrobial properties of the chitosan Schiff base. In addition, a significant improvement in the adsorption of Maxilon Blue dye from its aqueous solution by the Schiff base/ZnO-NPs adsorbent was achived. The prepared ChS/ZnO-NPs adsorbent has the potential to be used as an alternative to conventional adsorbents for the removal of dyes from wastewater.

Drug controlled releasing system based on polypyrrole modified multi-responsive hydrogel constructed from methacrylic acid and N-isopropylacrylamide

Stimuli-responsive hydrogels could effectively solve the problem that traditional drug carriers were difficult to deliver drug on-demand. However, some shortcomings such as complex preparation, single responsiveness, and narrow application still needed to be urgently overcome. In view of this situation, two kinds of hydrogels were elaborately designed in this work. In the unique ethanol/water mixed solvent, a homogeneous reaction system consisting of methacrylic acid (MAA) and N-isopropylacrylamide (NIPAM) was constructed, and a dual-responsive P(MAA-co-NIPAM) hydrogel was successfully synthesized. A near-infrared (NIR) responsive multi-functional PPy/P(MAA-co-NIPAM) hydrogel was subsequently prepared by the introduction of polypyrrole (PPy) via in-situ polymerization. NIR-responsive swelling, photodeformable, and photothermal ability of the hydrogel under NIR light irradiation were explored. It was found that rapid shape and temperature change could be achieved within 60 s for PPy/P(MAA-co-NIPAM) hydrogel. With doxorubicin as a model drug, the drug loading and in vitro controlled releasing behaviors under different conditions were comprehensively investigated. It was confirmed that the multi-responsive hydrogels had controllable drug releasing ability under different stimulations, which would realize potential targeted drug delivery in physiological environment. This work might provide a new synthetic method of hydrogel for drug releasing, which was expected to expand the potential application domain of hydrogel materials in NIR penetration targeted therapy.

The Effectiveness of Residual Soil, Orashi River Sand, and Sombrero River Sand as Stabilizing Agents for Subgrade Soil of Highway Pavement

The study investigated the effect of different stabilization materials, including residual soil and river sands, on the properties of subgrade soil for road and pavement structures. The results showed that the chemical composition of the subgrade soil was dominated by calcium, aluminum, and silicon, indicating a mineral clay soil. The use of stabilization materials led to a decrease in fines content and an increase in maximum dry density. The behavior of optimum moisture content was non-linear, and the liquid limit of the stabilized subgrade soil decreased significantly for all three materials, indicating a decrease in soil swelling ability. The study also revealed that the use of composite materials of cement and residual soil or river sand can improve the properties of subgrade soil and lead to an increase in unconfined compressive strength. The findings of this study can aid in the selection of appropriate stabilization materials and methods, and in the optimization of the use of these materials in road construction for improved strength and durability. Further research is needed to fully understand the characteristics of subgrade soil and determine the most effective methods for its stabilization and management. This study investigates the effects of residual soil and river sands on the mechanical properties of subgrade soil, with a focus on liquid limit, plastic limit, plasticity index, and unconfined compressive strength. The results suggest that residual soil, Orashi River sand, and Sombrero River sand are effective stabilizing agents for subgrade soil, with an increase in strength observed with increasing percentages of stabilizing material. However, there is an optimum content of stabilization material required to achieve maximum strength values, beyond which the strength decreases. The study also highlights the importance of considering the effect of soaking on the strength of subgrade soil and demonstrates the effectiveness of using composite .........

Sustained-Drug-Release, Strong, and Anti-Swelling Water-Lipid Biphasic Hydrogels Prepared via Digital Light Processing 3D Printing for Protection against Osteoarthritis: Demonstration in a Porcine Model.

Osteoarthritis is a serious disease affecting joint cartilage. Owing to poor blood supply, the meniscus and acetabular labrum of joints heal poorly after injury. However, the development of artificial alternatives to these components that have similar mechanical properties and cartilage-protection ability is challenging. In this study, a strong hydrogel with a biomimetic microstructure is prepared with an emulsion-type photosensitive resin, where both hydrophilic and hydrophobic monomers, photo-initiator, and drugs can be adopted. In this system, the hydrophobic monomer forms uniformly dispersed aggregates after curing, improving the mechanical properties of the hydrogel significantly. Furthermore, the coordination bonds between nontoxic Zr4+ cations and sulfonic acid groups prevent hydrogel swelling. In addition, the water-oil biphasic hydrogel ink enables the loading of water- and lipid-soluble drugs, yielding hydrogel scaffolds with sustained dual-drug release ability. Crucially, hydrogel scaffolds having excellent mechanical properties, low swelling, and sustained biphasic drug release ability can be prepared using digital light processing 3D printing technology, owing to the high curing rate of the hydrophobic photo-initiator. These hydrogel scaffolds are applied as meniscal and labral replacements in a porcine model and show great promise for the prevention of secondary osteoarthritis, demonstrating the broad potential clinical applications of this material.

Preparation and Properties of Carboxymethyl Cellulose / β-Cyclodextrin Hydrogel

Carboxymethyl cellulose (CMC) based hydrogels provide superabsorbent properties but show low mechanical properties. In order to overcome this problem, β-cyclodextrin (CD) is added to improve the mechanical strength of hydrogels. Moreover, CD-containing hydrogels have the potential to encapsulate antimicrobial essential oils or drugs and give a sustained release for medical applications to treat a variety of bacterial infectious diseases causing destruction to human health. In this work, the CMC/CD hydrogels were prepared by using epichlorohydrin as a chemical crosslinking agent. The objective of this research was to study the effect of the CMC/CD weight ratio at 6:1, 7:1, and 8:1 on morphology, mechanical properties and swelling ratio in water of the CMC/CD hydrogels compared with CMC hydrogel. The weight ratio of epichlorohydrin and CMC/CD was constant at 6:1. The morphology analysis of the CMC/CD hydrogels showed an irregular porous structure with the presence of -like structure. The addition of CD content led to an increase in compressive strength whereas the swelling ratio of the hydrogel decreased. The CMC/CD hydrogel at weight ratio of 7:1 provided the highest compressive strength and also retained swelling ability.

Kaolin-embedded cellulose hydrogel with tunable properties as a green fire retardant

This study reports the synthesis of methylene bisacrylamide (MBA) crosslinked cellulose-kaolin (CMK) composite hydrogels. The internal structures of hydrogels were deduced using network parameters, viz. elastic modulus, average molecular weight, mesh size, and effective crosslink. Meanwhile, combustion behavior was investigated using the cone calorimeter test (CCT), limiting oxygen index (LOI) test, vertical flammability test (VFT), and open fire test (OFT). Our results revealed that kaolin addition improves the fire retardancy of hydrogels but reduces their swelling ability. Hydrogel having cellulose to MBA ratio of 1:2 and 2 % w/v kaolin (CM2K2) produced 63 % wt. char residue and the hydrogel-coated cotton fabric exhibited the lowest heat release rate (HRR) of 26.60 kJ/m2 and total heat release (THR) of 0.9 MJ/m2. The LOI of the cotton fabric surged from 20 % to 34.37 % after hydrogel coating. Kinetic analysis using the isoconversional model yielded the highest activation energy (216 kJ/mol) for the CM2K2 hydrogel, corroborating the increased LOI after kaolin addition. VFT and OFT validated the delay in the burning process and the formation of a char layer, which protected the underlying layer of cotton from burning. Overall, cellulose-kaolin hydrogels developed in this study are effective green fire retardant coatings for flammable materials.

Dual responsive self-healing hydrogels with wide stability and excellent mechanical strength based on aliphatic polycarbonate

The wide development of hydrogels had been used in many filed due to the high water-containing and tough three-dimensional structure, however, the poor mechanical and multi-functional properties of hydrogel can be limited in its applications deeply. Herein, the dual responsive self-healing hydrogels with tough mechanical properties were manufactured by dual-physical cross-linking based on biodegradable aliphatic polycarbonate. Choosing the soft and hard segments to design the polymeric hydrogel not only can facilitate the dual-dynamic bonding interactions but also the resilient hydrogels possess robust and controllable mechanical strength (6.51 MPa). Furthermore, the results of swelling and stability tests of the materials indicated that the swelling ability of the biodegradable hydrogels can be regulated by the hydrophilic group, and the maximal swelling ratio in water and the equilibrium water content is 66% and 40%, respectively. It is worth mentioning that the tough hydrogels embrace dual-responsive high efficiency of self-healing ability, and the self-healing time is 2 h at 50 °C or 10 h under pH = 5, suggesting that the obtained hydrogels can respond to temperature and pH value to drive the fracture interface for fast self-healing, which will offer new opportunities for stimuli-responsive materials and wound healing.

Combinatorial approach to fabricate silica doped polyvinyl alcohol/hydroxyapatite/carrageenan nanocomposite for bone regeneration applications

AbstractBone tissue engineering is a dominating approach for the fabrication of nanocomposite bone implants with superior biocompatibility and low toxicity to the surrounding tissues. Here, in this report ternary nanocomposites integrating nanohydroxyapatite/κ‐carrageenan/silica doped polyvinyl alcohol in three different ratios, that is, 60/30/10 (HCP1), 60/20/20 (HCP2), and 60/10/30 (HCP3) was constructed and a binary system comprised of nanohydroxyapatite and κ‐carrageenan was also prepared for analyzing and comparing their bone regeneration potential. The samples were characterized by various physico‐chemical techniques such as infra‐red spectroscopy, which furnished details about structural functionalities and complex formation. Rough surface morphology and dispersed particle size distribution of developed nanocomposites were revealed by scanning electron microscopy and electron transmission microscopy, respectively. Thermogravimetric analysis and differential temperature analysis revealed higher thermal stability of HCP3 nanocomposite with total weight loss of 10% and X‐ray diffraction analysis revealed average crystallite size of 15 nm for HCP3 nanocomposite. Bioactivity and biocompatibility of fabricated nanocomposites were deduced with the help of biological techniques. HCP3 manifested cell viability above 100% at 2 μg/mL concentration and exhibited hemolysis below 3% at all tested concentration favoring cell growth with minimum cytotoxicity. HCP3 also exhibited efficient apatite layer deposition, optimum swelling ability and improved biodegradability (~30%) and anti‐bacterial activity predicting it as a promising nanocomposite implant for future orthopedic applications.

Facile Obtainment of Fluorescent PEG Hydrogels Bearing Pyrene Groups by Frontal Polymerization.

Frontal polymerization (FP) was used to prepare poly(ethylene glycol) methyl ether acrylate (PEGMA) fluorescent polymer hydrogels containing pyrenebutyl pendant groups as fluorescent probes. The polymerization procedure was carried out under solvent-free conditions, with different molar quantities of pyrenebutyl methyl ether methacrylate (PybuMA) and PEGMA, in the presence of tricaprylmethylammonium (Aliquat 336®) persulfate as a radical initiator. The obtained PEGPy hydrogels were characterized by FT-IR spectroscopy, confirming the effective incorporation of the PybuMA monomer into the polymer backbone. The thermal properties of the hydrogels were determined using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). After immersing the hydrogels in deionized water at 25 °C and pH = 7, their swelling behavior was investigated by mass gain at different pH and temperature values. The introduction of PybuMA comonomer into the hydrogel resulted in a decreased swelling ability due to the hydrophobicity of PybuMA. The optical properties of PEGPy were determined by UV-visible absorption and fluorescence spectroscopies. Both monomer and excimer emission bands were observed at 379-397 and 486 nm, respectively, and the fluorescence spectra of the PEGPy hydrogel series were recorded in different solvents to explore the coexistence of monomer and excimer emissions.

Microporous Hemostatic Sponge Based on Silk Fibroin and Starch with Increased Structural Retentivity for Contact Activation of the Coagulation Cascade.

Hemostatic agents with diverse forms and materials are necessitated to control excessive bleeding to improve surgical site visibility during operation. The adequate use of hemostatic agents dramatically reduces the chance of dehydration, absence of oxygen, and, in severe cases, death. Polysaccharide-based hemostatic agents are widely used as they are safe for the human body. Among diverse polysaccharides, starch has exhibited a high swelling ability, but its powder formulation is limited during incompressible bleeding. Herein, starch was blended with silk protein and crosslinked using glycerol to improve structural integrity. The silk/starch solution was lyophilized to be a sponge with interconnected pores, which is beneficial to blood coagulation by increased swelling ratio and underwater retentivity to absorb blood plasma. The surface contact between the blood component and the sponge initiates clotting by intrinsic pathway activation and platelet activation without the hemolytic effect or cytotoxicity. The clinical effectiveness of the sponges as topical hemostatic agents was confirmed by animal bleeding model tests.

Advanced Polymeric Membranes as Biomaterials Based on Marine Sources Envisaging the Regeneration of Human Tissues.

The self-repair capacity of human tissue is limited, motivating the arising of tissue engineering (TE) in building temporary scaffolds that envisage the regeneration of human tissues, including articular cartilage. However, despite the large number of preclinical data available, current therapies are not yet capable of fully restoring the entire healthy structure and function on this tissue when significantly damaged. For this reason, new biomaterial approaches are needed, and the present work proposes the development and characterization of innovative polymeric membranes formed by blending marine origin polymers, in a chemical free cross-linking approach, as biomaterials for tissue regeneration. The results confirmed the production of polyelectrolyte complexes molded as membranes, with structural stability resulting from natural intermolecular interactions between the marine biopolymers collagen, chitosan and fucoidan. Furthermore, the polymeric membranes presented adequate swelling ability without compromising cohesiveness (between 300 and 600%), appropriate surface properties, revealing mechanical properties similar to native articular cartilage. From the different formulations studied, the ones performing better were the ones produced with 3 % shark collagen, 3% chitosan and 10% fucoidan, as well as with 5% jellyfish collagen, 3% shark collagen, 3% chitosan and 10% fucoidan. Overall, the novel marine polymeric membranes demonstrated to have promising chemical, and physical properties for tissue engineering approaches, namely as thin biomaterial that can be applied over the damaged articular cartilage aiming its regeneration.

Preparation, characterization, and evaluation of tamarind seed polysaccharide-carboxymethylcellulose buccal films loaded with soybean peptides-chitosan nanoparticles

A novel buccal film based on tamarind seed polysaccharide (TSP) and carboxymethylcellulose (CMC) was developed for mucosal delivery of soybean peptides. Soybean peptides-chitosan nanoparticles (SP-CS) were prepared and incorporated into TSP-CMC film to improve the release behavior of soybean peptides in the oral cavity. The introduction of SP-CS enhanced the flexibility of TSP-CMC film and decreased its rigidity. The surfaces of composite films containing SP-CS were hydrophobic with water contact angles ranging from 101° to 114°. Structural characterization showed that the impregnation of SP-CS disrupted the hydrogen bonding between the film matrices, resulting in the loose internal structure of the films. For this reason, the composite films containing SP-CS exhibited good swelling ability and were easily eroded by saliva. Moreover, the results of release test showed that the initial burst release of soybean peptides was suppressed when the concentrations of SP-CS in the films exceeded 1%. The addition of low levels of SP-CS (1%–3%) increased the cumulative release of soybean peptides from the films compared to the film incorporating soybean peptides directly. This study suggested that the TSP-CMC films containing SP-CS displayed positive properties and could be promising candidates for the efficient delivery of soybean peptides.

Portable Nanocomposite System for Wound Healing in Space.

It is well known that skin wound healing could be severely impaired in space. In particular, the skin is the tissue at risk of injury, especially during human-crewed space missions. Here, we propose a hybrid system based on the biocompatible poly 2-hydroxyethyl methacrylate (pHEMA) to actively support a nanocontainer filled with the drug. Specifically, during the cryo-polymerization of HEMA, halloysite nanotubes (HNTs) embedded with thymol (Thy) were added as a component. Thy is a natural pharmaceutical ingredient used to confer wound healing properties to the material, whereas HNTs were used to entrap the Thy into the lumen to ensure a sustained release of the drug. The as-obtained material was characterized by chemical-physical methods, and tests were performed to assess its ability for a prolonged drug release. The results showed that the adopted synthetic procedure allows the formation of a super absorbent system with good swelling ability that can contain up to 5.5 mg of Thy in about 90 mg of dried sponge. Releasing tests demonstrated the excellent material's ability to perform a slow controlled delivery of 62% of charged Thy within a week. As humans venture deeper into space, with more extended missions, limited medical capabilities, and a higher risk of skin wounds, the proposed device would be a versatile miniaturized device for skin repair in space.

Phase separation on giant liposomes prepared by gel-assisted swelling.

Giant unilamellar vesicles (GUVs) are often used as models to study lipid membrane structure and function. The most common method for GUV formation is electroformation, though this technique has its own inherent drawbacks such as low yield in ionic solutions or in the presence of charged lipids. In recent years, the method of gel-assisted swelling has been explored as an alternative for electroformation and has been reported to overcome some of the limitations of this technique. This study aims to assess the ability of gel-assisted swelling to form GUVs of ternary lipid compositions that are known to undergo phase separation. To this end, we utilize different ratios of a 3-component mixture of DOPC/DPPC/Cholesterol to form vesicles capable of separating into phases of liquid-ordered (Lo) and liquid-disordered (Ld). This lipid composition was chosen as previous studies have shown that at room temperature, many of its possible compositions exhibit distinct phase separation. We apply confocal fluorescence microscopy to evaluate the resultant GUVs, in terms of yield, size, and phase behavior. We compare the results of this method to that of electroformation with a focus on GUV size and quantity, as well as formation of lipid domains, their number and area fraction on GUVs. Ultimately, the results show that agarose gel-assisted swelling can parallel electroformation in forming phase-separating GUVs over a series of ternary lipid compositions.