Thixotropic Behavior Research Articles

Innovative Epicardial Bigels Containing Amiodarone Hydrochloride: Pharmacotechnical and Analytical Characterization

Background/Objectives: The search for novel ways of providing treatment also targets the development of formulations used in drug delivery. Among the important characteristics of pharmaceutical gels are their ability to penetrate membranes, their capability to offer rapid response, and their capacity to avoid the hepatic metabolization route followed by many drugs. Bigels combine the advantages of both hydrogels and oleogels, creating a biphasic system that might improve the solubility of amiodarone in water, which is otherwise poorly soluble. This study aimed to succeed in formulating stable amiodarone hydrochloride bigels (coded from ABG1-ABG6) destined for atrial application and evaluating them from a pharmacotechnical perspective. Methods: Three of the six initial formulations presented stability and underwent studies of spreadability, rheology, drug content, textural properties, and microbiological activity. A statistical analysis was performed on penetrometry and drug assay data. Results: The spreadability varied from 1734.07 mm2 (ABG1) to 2163.85 mm2 (ABG6), while the drug concentration ranged between 1.35 and 1.49% (w/w). The textural profile analysis highlighted superior hardness, cohesiveness, and resilience for ABG6 and higher adhesion for ABG2. Both presented pseudoplastic thixotropic behavior, while a plastic thixotropic flow was registered in the case of ABG1. Conclusions: All three bigels are suitable for amiodarone incorporation; however, the influence of the type of ingredients chosen on the texture and properties of the formulations was reflected in the data gathered upon evaluation.

Influence of Grinding Aids on the Grinding Performance and Rheological Properties of Cementitious Systems.

The cement industry is of great importance in terms of raw materials consumed, energy consumed, and greenhouse gases emitted. Grinding aids (GA) are used to reduce energy consumption and costs, as well as to reduce the amount of CO2 released into the environment. In this study, the effect of GA-polycarboxylate ether-based water-reducing admixture (PCE) compatibility on some fresh, rheological and hardened state properties of cementitious systems was investigated. In order to investigate the rheological properties and thixotropic behavior of the mixtures, a total of 51 cement paste mixtures were prepared, containing 4 different types (molasses, MEG, DEA and ethanol) and ratios (0.025, 0.05, 0.75 and 0.1) of GAs and 2 different ratios (0.08% and 0.16%) of PCE in addition to the control mixture. In addition, the effect of the used GAs on the grinding efficiency and compressive strength value was investigated. Additionally, the predictability of the type of GA, dosage and cure time using the Taguchi method was investigated. It was determined that the highest grinding performance was obtained in mixtures containing MEG. It was determined that in cement paste mixtures containing GAs, the dynamic yield stress and viscosity values generally decrease with the increase in PCE usage rate up to a certain value, and these values may increase if the PCE usage increases further. It was determined that such behavior is not present in cement paste mixtures containing GAs and that the structural build-up value of the mixtures generally increases with the increase in the PCE admixture usage rate. It was determined that the use of GAs had a positive effect on 28-day compressive strength.

Studies on allantoin topical formulations: in vitro drug release studies and rheological characteristics

The extent and rate of release of active substances from topical products must be sufficient to ensure their effectiveness, which depends on selecting the most appropriate formulation. This study examined allantoin emulsions and gel formulations. In water-in-oil (W/O) and oil-in-water (O/W) emulsions, the main emulsifier was varied, while the same gelling agent was used in all formulations to test the effects of oil phase presence and emulsifier type on allantoin release, as well as the formulations’ rheological and textural characteristics. O/W emulsions exhibited similar release rates and the overall amount released over six hours (11–14.8%), while the highest amount of allantoin (20.9%) was released from the gel formulation. Conversely, the amount of allantoin released from the W/O emulsion (0.77%) was insufficient. Experimental data generally fit best with the Higuchi model kinetics. The formulations demonstrated shear-thinning thixotropic behavior. The greatest deviation from the Newtonian type of flow, with the smallest value of constant n (0.106-0.13) and the largest thixotropic loop area (6602.67-8140 Pas-1) were shown by O/W emulsions. The W/O emulsion exhibited the highest constant n (0.70) and smaller hysteresis area (991.23 Pas-1). Firmness and consistency values increased in the order: gel < W/O emulsion < O/W emulsions. The O/W emulsions showed similarity in microstructure and textural characteristics, likely explaining their similar release behavior.

Effect of Fucoidan on Conformation of Xanthan Gum and Its Tribo-Rheological Properties.

This study sought to explore the rheological and tribological properties of fucoidan-xanthan gum (XG) mixtures at different fucoidan concentrations. A conformational transition of XG from disordered to ordered forms was observed with an increasing fucoidan concentration, as determined by intrinsic viscosity measurements and Fourier transform infrared analysis. All mixtures exhibited non-Newtonian flow behavior with the yield stress. The mixture sample with 0.5% fucoidan displayed higher apparent viscosity at 100 s-1, yield stress, and viscoelastic moduli values than XG alone, suggesting viscoelastic synergism between the two biopolymers. However, these values exhibited a decreasing trend with higher fucoidan concentrations (0.5-2.0%), indicating a nullification of synergism. While XG alone exhibited antithixotropic behavior, fucoidan-XG mixtures showed thixotropic behavior, most pronounced at 1.0% fucoidan. A decreasing trend was observed in the maximum friction coefficient as the fucoidan concentration increased, indicating better lubricant properties. Collectively, our findings may enable widespread adoption and application of fucoidan in various industries.

The impact of 45S5 bioglass vs. β-TCP nanoparticles ratio on rheological behavior of formulated printing inks and 3D printed polycaprolactone-based scaffolds final properties

Extrusion based 3-D printing has been extensively applied to create geometrically complex composite polymer-ceramic structures as bone tissue substitute. The rheological features of the formulated bioink that regulate the printability and resolution of the printed scaffolds, rely on physicochemical properties of ink components, mainly their composition and chemical structure. The aim of this study was to evaluate the effect of different content of 45S5 bioglass (BG) and β-tricalcium phosphate (β-TCP) nanoparticles on the rheological behavior of printing inks and final composite scaffolds based on polycaprolactone (PCL)/BG/β-TCP. Ceramic nano-powders were first characterized and the composite bioinks were prepared by mixing various ratios of BG and β-TCP powders into the 50% w/v of PCL solution (β-TCP/BG: 70/30, 50/50, 30/70, and 10/90 w/w %). All formulated inks showed a thixotropic behavior and viscosity significantly increased by applying higher fraction of BG. Interestingly highly loaded β-TCP ink (β-TCP/BG: 70/30) revealed a rubbery nature with high surface tension which reduced final scaffolds resolution. All printed scaffolds possessed highly porous structure with interconnected pores. However, porosity percentage and shape stability improved by increasing BG content which was accompanied with lower mechanical strength and superior biodegradation and bioactivity of scaffolds. The biological performance of the printed scaffolds was evaluated using osteoblast cell line MG-63. MTT assay and cell attachment observation by SEM confirmed that printed scaffolds are well biocompatible and properly support cell colonization and proliferation. In overall, besides more appropriate materialistic properties, scaffolds with β-TCP/BG: 30/70 composition provided the most favorable microenvironment for cell colonization and growth.

On the thixotropy of cellulose nanofibril suspensions

The thixotropic behavior of mechanically disk refined cellulose nanofibril (CNF) aqueous suspensions with 100% fines content at 1 and 3 wt% concentrations was investigated through creep, shear-recovery, multiple-step oscillation, startup, and flow loop experiments. The CNF suspensions exhibited the key thixotropic characteristics such as reduction in viscosity over time and structure recovery after cessation of flow. The results of shear recovery and multiple-step oscillation experiments suggested that regardless of the CNF concentration, lower extents of deformation impede the ability of the suspension to recover its structure at rest and higher levels of shear rates and strain amplitudes facilitate the structure recovery. Furthermore, the results of the startup experiments indicate that CNF suspensions form structures at two different levels where the flocs erode each other during flow. The different types of loops found in the flow loop experiments performed at different shear rates and time intervals were categorized and analyzed in terms of the effects of erosion of flocs and fiber rearrangement during flow.

Extrusion bioprinting from a fluid mechanics perspective

Bioprinting is an emerging technology for fabricating intricate and diverse structures that closely mimic natural tissues and organs for such applications as tissue engineering, drug delivery, and cancer research as well. Among the various bioprinting techniques, extrusion-based bioprinting stands out due to its capability to apply a wide range of biomaterials and living cells and its controllability over printed structures. In bioprinting, the bioink stored in a syringe is forced to flow through the nozzle connected to the syringe, and then to exit and deposit onto the printing stage to form three-dimensional (3D) structures. The bioprinting process involves the flow of bioink in both syringe and nozzle and then its flow or spreading on a printing stage. As a result, fluid mechanics plays a crucial role in extrusion bioprinting. Notably, the biomaterials used in bioprinting are typically non-Newtonian fluids, which have complex viscoelastic and thixotropic behaviors; and the influence of these behaviors on the bioprinting process has been drawn considerable attention by employing various methods, including the numerical simulations via computational fluid dynamics (CFD). This paper reviews the latest development in the fluid mechanics aspects of extrusion-based bioprinting to shed light on the challenges and key considerations involved. It covers the topics of extrusion bioprinting (including driving mechanisms, printability, cell viability), biomaterial rheology and its effect on bioprinting, multi-material bioprinting and numerical simulation of bioprinting. Key issues and challenges are also discussed along with the recommendations for future research.

Rheological and tribological properties of xanthan gum-fucoidan mixture: Effect of NaCl, KCl, and CaCl2

This study endeavored to investigate the effects of salts (NaCl, KCl, and CaCl2) on the rheological and tribological properties of xanthan gum (XG)-fucoidan mixtures. With increasing salt concentrations, the intrinsic viscosity (56.1–30.9 dL/g) of mixtures decreased, with pronouncedly lower values (30.9–35.8 dL/g) observed with CaCl2 addition compared to monovalent salts addition (36.4–46.6 dL/g). This indicates a contraction of hydrodynamic size of the polymers due to the charge screening effect of cations and the formation of a more compact conformation in the presence of CaCl2 than with either NaCl or KCl addition. FTIR analysis revealed changes in the interaction between the two polymers in the presence of each salt. All samples exhibited shear-thinning behavior, and their thixotropic behavior increased as the salt concentration increased. The apparent viscosity and viscoelastic moduli decreased in the presence of monovalent salts but were increased in the presence of CaCl2. This was attributed to the crosslinking effect of Ca2+; Na+ and K+ did not induce crosslinking. In addition, the friction coefficient (μ) of mixtures containing salts reached the maximum at a lower entrainment speed (0.08–0.17 mm·s−1) than that without salt (1.54 mm·s−1), and the mixtures containing salts exhibited lower maximum μ values (0.28–0.62) compared to that without salt (0.83), indicating an improvement in the lubricant properties of XG-fucoidan mixtures. Our findings may help broaden the application of fucoidan in the food industry.

Mechanically Flexible Self-Healing Mg(II)-Metallogel: Approach of Triggering the ROS-Induced Apoptosis in Human Breast Cancer Cells.

A self-assembly-directed thixotropic metallohydrogel (i.e., Mg-Tetrakis) of Mg(II)-metal salt and N,N,N',N'-tetrakis(2-hydroxy-ethyl)ethylenediamine (i.e., Tetrakis) was successfully achieved. The organic chemical component N,N,N',N'-tetrakis(2-hydroxy-ethyl)ethylenediamine was used as a low-molecular-weight gelator, and water was employed as the gel-forming solvent. The fabricated supramolecular metallohydrogel promisingly depicted viscoelastic and mechanoelastic behaviors, which are interpreted through various rheological parameters. The thixotropic behavior of the metallohydrogel is also well characterized through this rheological study. Field emission scanning electron microscopy microstructural analyses were performed to visualize the morphological arrangements of the metallohydrogel. The anticancer properties of the synthesized metallogels are investigated through this work. The cytotoxic potential of the metallohydrogel on the MCF-7 breast cancer cell line is critically examined. Reducing the growth of breast cancer cell line MCF-7 through the treatment of gel on the colony formation assay has been explored through the work. The antimigratory potential of the metallohydrogel on the MCF-7 cell was also scrutinized. The anticancer effect of the fabricated metallohydrogel is inspected through various assay formation strategies, like wound healing assay, tumor spheroid inhibition assay, nuclear fragmentation assay, and so on. Quantitative reactive oxygen species analysis of the cancer cells by treatment with the metallohydrogel was also conducted through this study. The mechanistic apoptosis study was executed by studying the expression of various apoptotic markers like BAX, BCL2, PUMA, and NOXA.

Obtaining and characterization of natural extracts from mango (Mangifera Indica) peel and its effect on the rheological behavior in new mango kernel starch hydrogels

Hydrogels based on natural polymers have aroused interest from the scientific community. The aim of this investigation was to obtain natural extracts from mango peels and to evaluate their addition (1, 3, and 5%) on the rheological behavior of mango starch hydrogels. The total phenolic content, antioxidant activities, and phenolic acid profile of the natural extracts were evaluated. The viscoelastic and thixotropic behavior of hydrogels with the addition of natural extracts was evaluated. The total phenol content and antioxidant activity of the extracts increased significantly (p<0.05) with the variation of the ethanol-water ratio; the phenolic acid profile showed the contain of p-coumaric, ellagic, ferulic, chlorogenic acids, epicatechein, catechin, querecetin, and mangiferin. The viscoelastic behavior of the hydrogels showed that the storage modulus G′ is larger than the loss modulus G′′ indicating a viscoelastic solid behavior. The addition of extract improved the thermal stability of the hydrogels. 1% of the extracts increase viscoelastic and thixotropic properties, while concentrations of 3 to 5% decreased. The recovery percentage (%Re) decreases at concentrations from 0% to 1% of natural extracts, however, at concentrations from 3% to 5% increased.

Low-calorie functional dairy dessert enriched by prebiotic fibers and high antioxidant herbal extracts: A study of optimization and rheological properties.

The formulations of functional low-calorie dairy dessert, enriched with inulin/polydextrose (as a starch substitute), and ginger/cinnamon extract (as a flavor component and natural antioxidants), were developed and optimized by the D-optimal mixed design method. In the first stage, using the hedonic sensory evaluation and syneresis data, the optimal concentrations of inulin and polydextrose were obtained as 2.49% inulin and 1.51% polydextrose, respectively. The steady shear rheological test showed that the replacement of starch with inulin and polydextrose caused a decrease in apparent viscosity in all dessert samples. This decrease was higher in the samples containing polydextrose than those containing inulin. The replacement of starch with inulin and polydextrose also reduced the hysteresis loop area and thixotropic behavior. In the second stage, 0-0.4% of ginger and cinnamon extracts were added to the optimum sample and then the antioxidant and color properties of dessert samples were evaluated. The lightness (L*) Hunter parameter decreased by adding extracts and the samples containing cinnamon extract showed a higher a* parameter than the control and ginger-incorporated samples. The result of the 2,2-diphenyl 1-picrylhydrazyl (DPPH) antioxidant assay showed that the antioxidant capacity of ginger extract was significantly higher than that of cinnamon extract. The half-maximal inhibitory concentration (IC50) value of dessert samples decreased by adding 0.4% cinnamon and ginger extracts from 88.30 mg/mL to 77.04 and 31.94 mg/mL, respectively.

3D printed subcutaneous implant for prolonged delivery of tenofovir with desired release capability, biocompatibility, and viability

This study introduced a progressive approach to address the challenges associated with drug delivery in hepatitis B by developing a 3D printed subcutaneous implant. The implant, composed of a polymer-reinforced bovine serum albumin hydrogel crosslinked with glutaraldehyde, exhibited shear thinning and thixotropic behavior. This allows it to undergo transformation into an implant using a semisolid extrusion-based 3D printing technique. Thorough analysis encompassing physical, thermal, and spectroscopy assessments ensured thermal and chemical stability of the implant. Scanning electron microscopy revealed the highly porous microstructures of the hydrogel implant, enhancing its suitability for drug encapsulation. Swelling study showed only 7.88 % swelling of the implant after 28 days, suggesting restricted water movement into the implant matrix, leading to a gradual release of the encapsulated drug. The biodegradable nature of the implant was confirmed using an enzyme degradation study. Notably, the hydrogel implant exhibited sustained release of tenofovir of approximately 63 % over a 28-day period, presenting a promising avenue for prolonged therapeutic interventions in both hepatitis B. Furthermore, the crosslinked hydrogel was found to be cytocompatible in human kidney and dermal fibroblast cells. Overall, this work signifies a notable advancement in implantable drug delivery systems utilizing both hydrogel and the emerging 3D printing technique, offering a potential solution for sustained and localized treatment of chronic viral infections.

Functional Nanostructured Lipid Carrier-Enriched Hydrogels Tailored to Repair Damaged Epidermal Barrier.

In this study, a functional nanostructured lipid carriers (NLCs)-based hydrogel was developed to repair the damaged epidermal skin barrier. NLCs were prepared via a high-energy approach, using argan oil and beeswax as liquid and solid lipids, respectively, and were loaded with ceramides and cholesterol at a physiologically relevant ratio, acting as structural and functional compounds. Employing a series of surfactants and optimizing the preparation conditions, NLCs of 215.5 ± 0.9 nm in size and a negative zeta potential of -42.7 ± 0.9 were obtained, showing acceptable physical and microbial stability. Solid state characterization by differential scanning calorimetry and X-ray powder diffraction revealed the formation of imperfect crystal NLC-type. The optimized NLC dispersion was loaded into the gel based on sodium hyaluronate and xanthan gum. The gels obtained presented a shear thinning and thixotropic behavior, which is suitable for dermal application. Incorporating NLCs enhanced the rheological, viscoelastic, and textural properties of the gel formed while retaining the suitable spreadability required for comfortable application and patient compliance. The NLC-loaded gel presented a noticeable occlusion effect in vitro. It provided 2.8-fold higher skin hydration levels on the ex vivo porcine ear model than the NLC-free gel, showing a potential to repair the damaged epidermal barrier and nourish the skin actively.

Performance Requirements and Optimum Mix Proportion of High-Volume Fly Ash 3D Printable Concrete

In this study, a procedure for mixture design was proposed with the aim of meeting the requirements of extrudability, buildability, and shape stability in 3D printable concrete. Optimum water/binder ratio, sand/binder ratio, binder type, utilization ratio, aggregate particle distribution and quantity, and type and utilization ratio of chemical admixtures were determined for 3D printable concrete in terms of print quality and shape stability criteria. A total of 32 different mixtures were produced. It was determined that mixtures produced using a binder content with approximately 40% fly ash, a w/b ratio of 0.35, and aggregates with Dmax of 1 mm exhibit acceptable characteristics. Investigations were also conducted into the thixotropic behavior, rheological characteristics, and mechanical properties of the mixes that were deemed acceptable. As a result, it was determined that the increase in the amount of fly ash usage positively affected the buildability of the printed layers. Additionally, the dynamic yield stress ranging from 114 to 204 Pa, viscosity ranging from 22 to 43 Pa.s, and structural build-up value ranges suitable for the production of 3D printable concrete mixtures were determined.

3D printing of glycerol-mediated alginate hydrogels with high strength and stiffness

As a biomass material with biodegradability and biocompatibility, sodium alginate (SA) is a good candidate for constructing hydrogels for tissue-mimicking and biomedical scaffold fabricating through extrusion-based 3D printing technology. However, the mechanical strength and stiffness of alginate hydrogels are still not comparable with biological tissues such as tendons and the printability of SA solutions is often poor. Here, a novel strategy for 3D printing of alginate hydrogels with high mechanical performance is developed by using glycerol as a co-solvent for SA solutions. The addition of glycerol (GL) enables the formation of a homogenous SA/GL solution with a high solid content of 12–20 wt.% and endows crosslinked SA hydrogels with high stretchability. By applying uniaxial stretches, hydrogel filaments prepared with concentrated SA/GL solutions reveal a high tensile strength of 36.6–161.3 MPa, Young's modulus of 59.2–1964.2 MPa, and elongation at break of 8.5 %–106.2 % due to the high orientated and closely packed SA chains. SA/GL solutions become more solid-like with increasing SA concentration, and the solution with a solid content of 16 wt.% exhibits optimal 3D printability because of the appropriate rheological properties and thixotropic behavior. By designing the deforming-and-fixing process, 3D printed high-strength alginate hydrogels with complex structures are prepared, broadening the application of alginate hydrogels in load-bearing and biomedical fields.

Variables Affecting In-Vitro Evaluation of Loxoprofen Sodium Topical Emulgel

Although topical preparations like creams, ointments, and gels were used for many years to achieve local or sometimes systemic effects, they have many limitations mostly the inability to control the release of medications. In this research, a new emulgel preparation of loxoprofen sodium was formulated as a suitable alternative possessing the properties of both emulsion and gel preparation making it suitable to prolong the release of the hydrophilic drug. For this reason, five different emulgel formulas were prepared using different percentages of liquid paraffin (5%,10%), tween 80 &amp; span 80 emulsifier mixture (2.5%, 5%), and xanthan gum (1%, 2%). The formulations were evaluated for their physicochemical, rheological, and spreading properties, in addition to content uniformity and in-vitro release properties. Furthermore, the optimum selected emulgel formula was subjected to a skin irritation test, stability, and compatibility study besides an in-vitro release comparison with the marketed Loxonin® gel. The result of all formulated emulgels showed excellent homogeneity, consistency with no phase separation and accepted pH (6.12±0.76 to 6.51±0.92), and content uniformity (99.02±0.45 to 99.48±1.49). Moreover, all the formulas showed a thixotropic shear-thinning behavior with the optimum formula F3 exhibiting the highest spreadability value of (8.3±0.1 cm), and the highest extent of drug liberated after 6 hours (94.81±1.30 %). Additionally, the selected loxoprofen emulgel F3 showed no irritation to human skin, and no significant change upon storage at 4±2°C and 25±2°C with acceptable compatibility. Eventually, the selected formula displayed a slower rate of loxoprofen release than the marketed gel, a result that proves the effectiveness of the newly formulated loxoprofen emulgel for a prolonged release giving better patient compliance.

High Added Value Products from Agroindustrial Residues: Study on Microfibrillated Cellulose for Food Applications

Waste composition range from simple sugars to complex polysaccharides such as starch, cellulose, and hemicellulose, including more complex sources such as lignin, lipids, and proteins. This composition suggests its use as raw materials that can potentially be valued by different techniques and used as resources for new food additives, leading to economic and environmental benefits. In this work, the extraction and production of microfibrillated cellulose (MFC) as the way forward to valorise agroindustrial residues. The high surface area and aspect ratio, rheological behaviour, water absorption and absence of cytotoxic and genotoxic properties of MFC studied in the present study facilitate its use in food applications as stabilizing and texturizer agent. This work has two main goals: The first goal is the production of MFC using a method based on the combination of green chemical and mechanical pre-treatment of the feedstock followed by a disintegration process of the cellulose obtained from agroindustrial residues. The results revealed that the different MFC obtained have a quality comparable with commercial MFC, which is reported by the determination of the Quality Index (QI). QI values between 50 and 63 are obtained with the agroindustrial subproducts tested. The MFC was also characterized using several techniques such as FTIR, SEM and TGA. The second goal is the MFC validation as thickener agent in food (mayonnaise, peach nectar, strawberry syrup and puree apple). First, a rheological study was carried out to observe the MFC thixotropic behaviour. Second, to evaluate techno-functional properties in-vivo, MFC was compared in terms of functionality with the seven additives commonly used in the industry: tare gum, xanthan gum, guar gum, carrageenan, pectin, agar and gelatine. The results revealed that the sample with 0.1% MFC exhibited a reduced thixotropic behavior compared to the other samples (1, 1.5 and 2%). Compared with commercial gums, MFC exhibits the highest water activity (0.87 ± 0.00) and the most alkaline pH value (10.10 ± 0.01). In the in vivo dietary models, thermal stabilization values after 15 min at 85 °C indicate that gums perform better than MFC and carrageenan in mayonnaise stabilization. This study also reveals that gums are more effective in stabilizing the cloud, while gelatine or MFC-containing samples exhibit a higher cloud volume after 30 min of stabilization. Notably, the cloud suspension of peach nectar with MFC-containing samples compares favorably to the control without gums (20 to 40%). This comprehensive study underscores the potential of MFC as a versatile and eco-friendly alternative in food applications, aligning with the broader goals of sustainable waste management and environmentally conscious practices in the agroindustrial sector.Graphical

Mixed-Micelle in Situ Gel as a Candidate for Oral Inflammatory Ulcerative Diseases.

The current treatment for oral inflammatory ulcerative diseases has limitations. In situ forming hydrogels have shown great potential to deliver therapeutic substances for drug delivery to the buccal cavity. This study aimed to prepare and characterize lipid- and surfactant-based mixed micelle in situ gel (MIG) and evaluate whether it can offer more favorable properties than the in situ gel for effective treatment of the disease. Dexamethasone was incorporated into the MIGs particles, based on Poloxamer 407 and chitosan. The lower gelation time at 37 ℃ was considered a criterion to select superior formulations among the different lipid- and surfactant-based candidates. Further characterization was performed to evaluate the opted formulations regarding morphology, physical stability, rheology, texture, and release profile. All formulations were thermoresponsive and had a shorter gelation time as the temperature increased. Dexamethasone was released in a highly controlled manner, and morphological evaluation revealed that the mixed micellein situ gels had spherical nanoparticles. Thixotropic behavior was observed in all MIGs, indicating a prolonged retention time of the formulation after oral administration. This study has shown that among different MIGs, the one with oleic acid is a more promising candidate than the in situ gel and other MIGs for drug delivery to the buccal cavity.

Thixotropic Composite Hydrogel Electrode Composed of a Polymer Hydrogelator and Water-Dispersive Tungsten Oxide Flat Microparticles.

Here, we introduce an organic/inorganic composite hydrogel as a versatile gel electrode material. This composite hydrogel was formed by simply mixing an aqueous solution of flat microparticles of tungsten oxide, exhibiting superior water dispersibility, with a hydrogel composed of a water-soluble polyaramide-based polymer hydrogelator. The resulting composite hydrogel exhibited uniform dispersion of tungsten oxide flat particles throughout the hydrogel matrix, supplementing the structure formed by the polymer hydrogelator. It maintained the gel-forming capability and thixotropic behavior inherent to the polymer hydrogelator while showcasing the electrochemical characteristics of tungsten oxide. With its spreadability and applicability to various electrode shapes, a composite hydrogel is presented as a potential spreadable gel electrode material.

Comparative Vision of Nonlinear Thermo-Optical Features and Third-Order Susceptibility of Mechanically Flexible Metallosupramolecular Self-Repairing Networks with Isomeric Organic Acids.

Two self-healing-type supramolecular Ni(II)-metallogels are achieved. The choice of proper low-molecular-weight organic gelators such as trans-butenedioic acid (i.e., trans-BDA) and cis-butenedioic acid (i.e., cis-BDA) and triethylamine in N,N'-dimethylformamide solvent facilitates the metallogelation process. Through rheological investigations the mechanical robustness and viscoelastic properties of synthesized metallogels are explored. An in-depth exploration of thixotropic behavior also supports their self-healing features. Notably, distinct variations in morphologies of metallogels are also ascertained through field emission scanning electron microscopy studies. Furthermore, the existence of versatile noncovalent supramolecular interactions operating throughout the metallogel network is clearly revealed via Fourier transform infrared spectroscopy. Electrospray ionization-mass studies also explore the construction protocol of individual Ni(II)-metallogels. The Z-scan measurements with a 532 nm continuous wave laser were employed to unveil the nonlinear thermo-optical response of two synthesized self-healing metallogels, i.e., trans-BDA-TEA@Ni(II) and cis-BDA-TEA@Ni(II). Crucial parameters like the nonlinear refractive index, nonlinear absorption coefficient, thermo-optical coefficient, and third-order susceptibility of these metallogels are obtained. Metallogels show negative signs for the nonlinear refractive index and the nonlinear absorption coefficient. The real parts of the third-order susceptibility for these metallogels are much greater than the imaginary parts (i.e., χR(3) > χI(3)), making such metallogels very promising for all optical-switching applications.