Search Results (517)

Aqueous smectite clay dispersions undergo sol–gel transitions and form three-dimensional networks at relatively low clay concentrations. However, the clay and electrolyte concentrations required for gelation differ markedly among clay species, and the physical origin of these differences remains unclear. In this study, sol–gel state diagrams were constructed for four smectite clays based on rheological measurements, and DLVO analysis was subsequently applied to the experimentally determined sol–gel transition boundaries using the corresponding zeta potentials and Debye lengths. The apparent Hamaker constant, A_H,app, decreased with increasing NaCl concentration for all clays. In addition, ln(A_H,app/10⁻²⁰ J) showed approximately linear relationships with the reciprocal Debye length, 1/L_D, with distinct trends in the low- and high-salt regions. A characteristic interaction distance, H*, was defined as the negative of the fitted slope. H* was larger and more strongly clay-dependent in the low-salt region, whereas it became smaller and less clay-dependent in the high-salt region. The crossover in H*, observed at approximately 0.01–0.03 mol/L NaCl, occurred in the same broad concentration range as the onset of decreased transmittance and previously reported rheological changes. Because these datasets were acquired at non-identical clay volume fractions, this agreement should be regarded as qualitative rather than as a direct one-to-one correspondence. Full article

Background/Objectives: Cervical cancer cells evade chemotherapy by upregulating antioxidant defenses (e.g., glutathione (GSH)). A platform that simultaneously amplifies ROS and suppresses antioxidant defense is a low toxicity strategy. This study presents a local nanoplatform that combines chemodynamic therapy (CDT) with chemotherapy for the localized treatment of cervical cancer. Methods: Diallyl trisulfide (DATS) was loaded into the echinacoside (ECH)-copper metal–phenolic networks (MPNs) nanoparticles (ECD NPs) through a one-step coordination assembly method. The nanoparticles were incorporated into a poloxamer/HPMC thermosensitive hydrogel for vaginal delivery. The formulation was characterized for size, drug loading, sol–gel transition, and pH-responsive release. Antitumor activity was evaluated in SiHa and HeLa cells via Cu²⁺ uptake, GSH depletion, ROS accumulation, apoptosis markers, and viability. In vivo efficacy and biosafety were assessed in an orthotopic cervical cancer model. Results: ECD NPs showed uniform size (~135 nm), high DATS loading (~27.6%). The ECD NPs-loaded hydrogel exhibited a sol–gel transition at 36.7 °C. The ECD NPs-loaded hydrogel released 16.4% of DATS at pH 7.4, 32.4% at pH 4.5, 64.8% at pH 6.5, and 80.9% at pH 5.6 over 24 h. Release was minimal at vaginal pH, clearly triggered at tumor pH, and fastest at lysosomal pH, confirming pH-responsive behavior. The ECD NPs-loaded hydrogel enhanced Cu²⁺ uptake, depleted GSH, elevated ROS, and reduced cell viability to <50% at 80 μg/mL. In the orthotopic model, the ECD NPs hydrogel achieved a tumor inhibition rate of 87.81%, significantly outperforming free DATS (65.3%) and blank MPN (55.62%) hydrogels, with no evident systemic toxicity. Conclusions: The ECD NPs hydrogel triggers a Cu²⁺-driven ROS/GSH cascade that combines copper-mediated oxidative stress with DATS-induced apoptosis for enhanced antitumor activity. Its vaginal localization, pH-responsive release, and biosafety profile support further evaluation for cervical cancer therapy. Full article

In this study, La_1−xCa_xMnO₃ (LCMO) samples (x = 0.3, 0.4 and 0.5) were synthesized using a sol–gel method and their structural, electronic, magnetic and magneto–transport properties were investigated. Structural analysis by XRD confirmed orthorhombic perovskite structure. FTIR studies indicated the changes in bond length and bond angle of Mn–O/Mn–O–Mn bonds; FESEM/EDAX confirmed a polycrystalline nature. Magneto–transport studies revealed a decrease in ferromagnetic metal–paramagnetic semiconductor transition temperature with the increase in Ca²⁺ content. Magneto–transport studies also revealed that the resistivity in the ferromagnetic metallic region was predominantly governed by the extrinsic spin–polarized tunneling (SPT) mechanism along with double-exchange interaction, whereas charge transport in the paramagnetic semiconducting region at higher temperatures was due to variable-range hopping conduction. Magnetoresistance was at its maximum near the transition temperature, but decreased at lower temperature (77 K). XPS and ⁵⁵Mn IFNMR confirmed coexistence of Mn³⁺/Mn⁴⁺, while IFNMR results at 77 K confirmed high-frequency electron exchange among Mn³⁺ and Mn⁴⁺ ions due to double exchange interaction. VSM studies at 300 K showed that the paramagnetic nature of the samples and susceptibility decreased with the increase in Ca²⁺ content. The close agreement between the magnetoresistance behavior and the ⁵⁵Mn IFNMR results confirms the role of the intrinsic DE interaction in governing the magnetotransport properties of LCMO. Full article

Gel-based novel drug delivery systems (NDDS) occupy a mechanistically distinct niche among controlled-release platforms because they decouple three design variablesnetwork cross-link density, continuous-phase polarity, and stimulus sensitivitythat in particulate carriers (liposomes, polymeric nanoparticles) are often interdependent. This critical review synthesizes 102 primary and secondary sources published predominantly between 2010 and 2026 to interrogate, rather than merely catalog, how hydrogels, organogels, aerogels, nanogels, in situ gelling systems, and hydrogel-forming microneedles have been engineered for site-specific pharmacotherapy. Beyond a taxonomic overview, the review quantitatively contrasts formulation parameters sol–gel transition temperatures (typically 32–37 °C for poloxamer 407/188 systems), swelling ratios, mesh sizes, and reported drug-release half-lives across oncology, chronic diabetic wound care, ophthalmic and nasal-to-brain delivery, musculoskeletal (intra-articular) therapy, subunit vaccine depots, periodontal pocket therapy, and glucose-responsive insulin delivery. Particular attention is paid to the mechanistic basis of burst release, the porosity–mechanical-integrity trade-off inherent to interconnected hydrogel networks, and the divergence between preclinical rodent efficacy and the comparatively sparse controlled human trial data available for most gel platforms. The review concludes that while stimuli-responsive and 3D/4D-printed gel architectures have matured substantially as engineering constructs, clinical translation remains bottlenecked less by materials science than by inconsistent characterization standards, unresolved terminal-sterilization compatibility, and a paucity of head-to-head comparative trials against existing standard-of-care formulations. Full article

Cancer remains a major global health concern, driving the search for safe and effective bioactive compounds from natural sources. Jujube peel red pigment (JP), an anthocyanin-rich extract, has shown preliminary bioactivity, yet its antitumor potential and delivery challenges remain underexplored. This study systematically evaluated the in vitro antitumor activity of JP and developed a thermosensitive hydrogel-based local delivery system (JP-H) to overcome its rapid diffusion and poor retention. JP exhibited selective cytotoxicity against HeLa cervical cancer and B16 melanoma cells, with no obvious toxicity to normal L929 and RAW264.7 cells. In HeLa cells, JP exerted antitumor effects by initiating mitochondrial-dependent apoptosis accompanied by elevated expression of Bax and cleaved Caspase-9/-3 as well as decreased Bcl-2 level, and arrested cell cycle at the G1/S phase by regulating CCND1, CDK2, CDK4, PCNA, MYC and TP53. To enable localized delivery, JP was incorporated into an injectable chitosan/gelatin/F127 thermosensitive hydrogel (JP-H), which exhibited rapid sol-gel transition at physiological temperature, shear-thinning behavior, and a porous microstructure. JP-H not only sustained JP release but also significantly enhanced antibacterial activity against E. coli and S. aureus compared to free JP. Furthermore, JP-H markedly inhibited HeLa cell migration and induced superior apoptotic/necrotic cell death in co-culture assays, outperforming free JP. Collectively, this work establishes JP as a multi-target antitumor agent and demonstrates JP-H as a promising local therapeutic platform combining sustained delivery, antibacterial protection, and enhanced anticancer efficacy for cervical cancer treatment. Full article

TPZ is a hypoxia-activated anticancer agent that exerts selective cytotoxicity within hypoxic tumor microenvironments. Although intratumoral injection of TPZ can achieve localized antitumor activity, the drug is prone to rapid diffusion and clearance from the injection site, limiting its long-term retention and thereby reducing therapeutic durability and overall efficacy. To achieve sustained release and prolonged retention of TPZ in subcutaneous tumors, a thermosensitive nanogel loaded with TPZ (TPZ@PNA-TNG) was developed. By thoroughly mixing 3 mg/mL TPZ with 6 wt% PNA-TNG, the resulting formulation enabled continuous slow release of TPZ following intratumoral injection, resulting in favorable therapeutic outcomes. The sol–gel phase transition behavior of TPZ@PNA-TNG was investigated using the inverted vial method and rheological measurements. In vivo antitumor studies demonstrated that a single administration of TPZ@PNA-TNG effectively suppressed tumor progression, with tumor volume decreasing to 0.72 ± 0.04 times its initial size over a 14-day period. Mechanistically, TPZ@PNA-TNG markedly enhanced antitumor immune responses, inhibited tumor cell proliferation, promoted apoptosis and anti-angiogenesis, and ultimately induced extensive ischemic necrosis within subcutaneous tumors. In addition, owing to the prolonged intratumoral retention capability of PNA-TNG, TPZ@PNA-TNG enabled sustained local delivery of TPZ, thereby significantly reducing systemic toxicity and adverse effects associated with TPZ while maintaining favorable biocompatibility. These findings highlight the therapeutic potential of TPZ@PNA-TNG for cancer therapy applications. Full article

The viscosity peak phenomenon at the phase inversion point in crude oil emulsions can be understood through the lens of physical gelation. This study employs coarse-grained molecular dynamics (CG-MD) simulations to investigate the gel-like network structures formed at oil–water interfaces across varying water-to-oil particle-number ratios. We reveal that pure water forms a fully connected hydrogen bond network (500 molecules, 313.15 K, 2.68 H-bonds per molecule) behaving as a flexible physical gel scaffold, while pure oil exhibits a dispersed sol-like structure (35.9 clusters average). At the phase inversion point (50% water cut), the water network fragments into 44 gel-like clusters (193 network bonds) while oil forms 76 small clusters acting as physical crosslinking nodes embedded within the water network voids. This creates an interlocked gel structure with a maximum Interlocking Index (LI_CG = 36.67), directly corresponding to the viscosity peak. At 30% water cut, a W/O morphology with (LI_CG = 22.17) represents a weaker gel state. We demonstrate that gel rigidity rather than network existence determines macroscopic viscosity, with $LI$ serving as an effective crosslinking density metric. Model parameters calibrated via differential evolution optimization against experimental data from three oil wells yield $R^2=0.94$. This work provides a molecular mechanism revealing the flexible-network-to-rigid-gel transition as the origin of emulsion viscosity peaks, offering a gel-science perspective on emulsion rheology control in petroleum engineering. Full article

Methylcellulose is a thermoresponsive polymer that undergoes thermally induced association and gelation upon heating, with behavior strongly influenced by thermal history, concentration, and ionic environment. In this work, dynamic light scattering (DLS) was used beyond conventional particle size analysis to monitor the temperature-dependent mobility of methylcellulose solutions through the apparent diffusion coefficient, complemented by transmittance and oscillatory rheology. For a 0.1 wt.% methylcellulose solution, rheology showed a sol–gel transition during heating between approximately 50 and 60 °C, but no complete gel–sol transition during cooling, indicating pronounced thermal hysteresis. Transmittance and DLS confirmed this path dependence while revealing different recovery behavior: optical turbidity recovered near 38–40 °C, whereas apparent mobility recovered at slightly lower temperatures, around 30–35 °C. A simple Arrhenius-type model described sol-state mobility but not the full heating cycle. Therefore, a two-state phenomenological model was introduced, representing DLS-derived mobility as weighted sol-like and gel-like contributions. The model captured mobility loss, recovery, and a hysteresis window of about 22 °C. Overall, DLS-derived apparent mobility provides a useful descriptor of methylcellulose association, dissociation, and hysteresis, complementing rheology and turbidity measurements. Full article

Alkali-activated binders (AABs) represent eco-friendly alternatives to ordinary Portland cement. Nevertheless, the synergistic influences of calcium dosage and aluminosilicate stoichiometry on phase assemblage, gel nanostructure, and mechanical properties have not been fully elucidated. Herein, AAB samples with graded CaO contents were fabricated, and the co-regulatory mechanisms of CaO dosage and Si/Al molar ratio on compressive strength and microstructural evolution were systematically explored through compressive strength tests, XRD, TG-DTG, FTIR, and SEM-EDS. In addition, pure reference C-S-H and N-A-S-H gels were synthesized by using the sol–gel method for comparison with AAB pastes. The results reveal that CaO dosage acts as the primary parameter dictating gel phase transition and strength level, categorizing the prepared AABs into three distinct zones: low-calcium region (CaO < 10 wt.%), medium-calcium region (10–20 wt.%), and high-calcium region (CaO > 20 wt.%). Combined grey relational and partial correlation analyses clarify the collinearity-induced false correlations and reveal the stage-dependent independent effects of oxide molar ratios on AABs’ compressive strength. Low-calcium AAB matrices are dominated by N-A-S-H gel networks coexisting with abundant low-strength zeolite crystals, which deteriorate thermal stability and retard strength gain. Increasing CaO content triggers a progressive phase transformation from N-A-S-H gel to high-strength C-(A)-S-H gel. Abundant Ca-rich chabazite and C-S-H gel form in high-calcium systems, which fill internal pores and microcracks and greatly enhance matrix densification and thermal resistance. This work clarifies the multiscale regulatory mechanism of calcium species over gel polycondensation, crystalline phase development, and mechanical performance of AABs, offering fundamental theoretical guidance for the customized design and property optimization of high-strength alkali-activated binders. Full article

Thermosensitive polyurethane (PU) hydrogels were prepared and loaded with meloxicam (MX), a nonsteroidal anti-inflammatory drug (NSAID). The role of different excipients, i.e., eucalyptus essential oil as well as poly(vinylpyrrolidone), poly(ethylene glycol) and their mixture, was highlighted. The sol–gel transition induced by temperature increase was evidenced by rheological measurements in oscillatory shear conditions. The viscoelastic behavior was investigated at 37 °C in various shear conditions, evidencing the network strength and stability of formulations. The structural recovery was monitored after applying high strain values, and the self-healing ability was revealed. Depending on the excipient, the gel samples loaded with MX release between 60% and 90% of the active substance. It was shown that the Fickian and chain relaxation contributions compete during MX release from PU-based hydrogels. In vitro anti-inflammatory activity was evaluated and discussed. Full article

Phenolic aerogels, owing to their low density, high char yield, large specific surface area, and well-defined three-dimensional topological networks, hold considerable promise for applications in extreme thermal protection and multifunctional material systems. The sol–gel process, a cornerstone methodology for constructing the three-dimensional nanoporous architecture of these materials, critically governs the resulting microstructural topology and macroscopic performance through its reaction kinetics, phase-separation behavior, and drying dynamics. This review systematically surveys recent advances in the sol–gel synthesis of phenolic aerogels, focusing on the polycondensation mechanisms operative under acidic and basic catalytic conditions, nucleation-and-growth kinetics, and strategies for tailoring multiscale pore structures. It further provides a comparative analysis of interfacial regulation mechanisms for capillary-stress elimination across supercritical drying, freeze-drying, and ambient-pressure drying routes. We also dissect the structure–property relationships underpinning Knudsen-effect-mediated gaseous thermal insulation, multi-scale hybrid network toughening, and inorganic phase-transition-induced in situ ceramization for thermal protection, demonstrating the synergistic optimization of thermal insulation, structural load-bearing, and ablation resistance. Finally, we summarise current applications in extreme thermal protection, environmental adsorption, electromagnetic interference shielding, and electrochemical energy storage and highlight future directions towards green, scalable manufacturing and intelligent materials design. Full article

Wound management continues to represent a major global healthcare challenge, with the wound care market growing each year and a rising incidence of chronic wounds worldwide. Effective wound healing requires dressings that protect injured tissue, prevent infection, and actively modulate the wound microenvironment to promote tissue regeneration. In recent years, smart polymeric wound dressings have emerged as a functional, more advanced class of wound dressings, engineered from materials capable of responding to stimuli. Physically responsive systems include moisture-adaptive dressings that prevent wound dryness or maceration, pressure-sensitive dressings incorporating flexible capacitive sensors for high mechanical stress mapping, thermoresponsive dressings exploiting sol–gel transitions for temperature-controlled drug release, light-responsive dressings enabling photothermal and photodynamic therapy, and electro-responsive dressings integrating conductive polymers for self-powered electrical stimulation or closed-loop wound monitoring. Chemically responsive systems exploit endogenous biochemical signals, including pH shifts for wound monitoring, reactive oxygen species-cleavable bonds for on-demand drug release, and glucose-responsive platforms for autonomous glycemic regulation in diabetic wounds. Biologically responsive dressings use enzymatic triggers, such as matrix metalloproteinases, hyaluronidase, and bacterial proteases, to achieve autonomous drug delivery. Film-forming sprays further expand the versatility of smart polymeric dressings by enabling contactless application adaptable to irregular wound shapes. In this review, we summarize recent advances in the design, stimuli-responsive mechanisms, characterization methods, and therapeutic outcomes of smart polymeric dressings for wound treatment. Despite promising preclinical results, challenges related to clinical translation, regulatory standardization, and scalable production remain and must be addressed to facilitate widespread clinical adoption. Future directions include multi-stimuli responsive platforms, artificial intelligence-guided wound monitoring, bioprinting of specific dressings, and environmentally sustainable biomaterial design. Full article

Recently, gel coatings have been studied as a promising method that can provide electrochemical corrosion protection. This review presents a comprehensive analysis of advanced gels such as sol–gel coatings, hybrid organic–inorganic, self-healing, and crack repair gels. These gels employ different mechanisms for corrosion protection, from passive barrier formation to active self-healing and corrosion inhibition. Their performance can be influenced by gel chemistry, microstructure, and the incorporation of functional additives. Recent studies have shown that gel coatings can achieve promising corrosion resistance. This high efficiency can be attributed to the formation of dense barrier layers that restrict the mobility of attacking ions. The incorporation of functional additives such as silica nanoparticles can enhance mechanical characteristics for gels. In the field of crack-repair, bio-gels based on microbially induced calcium carbonate precipitation show acceptable sealing capability. Additionally, the evolution of polarization resistance and corrosion current suggests the sustained protective performance of these gels. Multifunctional gels extend this concept by combining crack sealing, alkalinity restoration, and steel re-passivation. Gel coatings are transitioning from simple barrier coatings to multifunctional smart inhibition capable of self-healing, corrosion sensing, and long-term durability. This review highlights the relationship between gel chemistry, microstructure, and corrosion resistance for the development of next-generation gel coatings. Full article

Heavy metal wastewater, characterized by high toxicity, poor biodegradability, and strong bioaccumulation potential, poses a serious threat to the ecological environment and human health. Conventional chemical treatment methods are costly and prone to secondary pollution. In contrast, using solid waste to prepare environmental functional materials for “waste control by waste” has emerged as a research hotspot in the field of synergistic water pollution control and resource recovery. This review systematically consolidates the sources, physicochemical properties, and compositional characteristics of typical industrial solid wastes—including red mud, electroplating sludge, fly ash, copper slag, and blast furnace slag—and elucidates how compositional variations constrain the selection of functionalization pathways. On this basis, key preparation techniques, namely hydrothermal synthesis, surface modification/impregnation, thermal treatment, geopolymerization, and sol–gel/polymerization, are critically reviewed and compared in terms of product structural regulation, process complexity, and engineering scale-up potential. Subsequently, the adsorption performance of the resultant materials toward heavy metals such as Pb²⁺, Cu²⁺, Cr(VI), As(VI), Cd²⁺, Ni^2+, and Zn²⁺ is discussed, with particular emphasis on the pronounced effects of pH, temperature, initial concentration, coexisting ions, and adsorbent dosage on adsorption capacity. Notably, Pb²⁺ exhibits the highest adsorption capacity, whereas the removal of Cr(VI) and As(V) is strongly governed by the positive charge density and reduction efficiency of the material surface. In quinary heavy metal competitive systems, marked differences in the affinity of adsorption sites toward distinct metal ions have been observed. Mechanistic analysis identifies ion exchange, surface complexation, electrostatic attraction, and redox reactions as the predominant removal pathways. This review further incorporates engineering-oriented assessments, including multi-component competitive adsorption, fixed-bed column operation, and regeneration stability, and identifies the critical bottlenecks currently impeding the transition from laboratory-scale research to practical implementation—namely, performance instability arising from feedstock variability, attenuation of adsorption capacity during prolonged operation (with a 10–40% decline over 5–10 cycles), underdeveloped regeneration and recovery routes, and a systemic deficiency in techno-economic analysis and life-cycle assessment data. Finally, future research directions are proposed, emphasizing the development of low-carbon and energy-efficient preparation technologies, the promotion of synergistic valorization of multiple solid wastes alongside critical metal recovery, and the advancement of this field toward engineering applications through artificial intelligence-assisted design and life-cycle assessment, thereby furnishing theoretical references and technical support for the integrated management of industrial solid waste resource utilization and heavy metal wastewater treatment. Full article

This study proposes a process combining alkali-activated potassium feldspar, acid leaching, and sol–gel coupling with supercritical drying to prepare high-performance silica–alumina composite aerogel. The optimal parameters for potassium feldspar alkali-melt activation are a calcination temperature of 350 °C, mass ratio of potassium feldspar to sodium hydroxide of 1:1.2, and calcination time of 120 min, achieving an acid-leaching efficiency of 97.3% for the activated potassium feldspar. The acid leachate, using propylene oxide as a gelling promoter, was processed through aging, solvent exchange, and supercritical drying to yield SiO₂-Al₂O₃ aerogel with typical three-dimensional nanoporous network structure. EDS spectroscopy revealed that the spatial distributions of aluminum and silicon elements were highly coincident and uniformly dispersed. XPS and FTIR further confirmed the formation of Si-O-Al bonds, indicating that aluminum atoms were successfully incorporated into the silico-aluminate tetrahedral network, constructing silicon–aluminum composite framework. The SiO₂-Al₂O₃ aerogel exhibits specific surface area of 660.841 m²/g and a pore volume of 1.321 cm³/g. Its mass loss within the 0–1000 °C range is only 9.55%, far lower than the 28% mass loss of pure aluminum oxide aerogel, indicating that the silicon–aluminum composite structure effectively suppresses high-temperature phase transitions and framework collapse. Full article