Search Results (91)

Although publications have documented the osteo-inductive effects of various bioactive materials on tissue sections, the associated morphologic patterns of tissue remodeling pathways at the cellular level have not been detailed. Therefore, we present a comparative histopathological follow-up evaluation of bone defect repair mediated by silica aerogels and methacrylate hydrogels over a 6-month period, which is the widely accepted time course for complete resolution. Time-dependent microscopic analysis was conducted using the “critical size model”. In untreated rat calvaria bone defects (control), re-ossification exclusively started at the lateral regions from the edges of the remaining bone. At the 6th month, only a few new bones were formed, which were independent of the lateral ossification. The overall ossification resulted in a 57% osseous encroachment of the defect. In contrast, aerogels (AE), hydrogels (H), and their β-tricalcium-phosphate (βTCP)-containing counterparts, which were used to fill the bone defects, characteristically induced rapid early ossification starting from the 1st month. This was accompanied by fibrous granulomatous inflammation with multinucleated giant macrophages, which persisted in decreasing intensity throughout the observational time. In addition to lateral ossification, multiple and intense intralesional osseous foci developed as early as the 1st month, and grew progressively thereafter, reflecting the osteo-inductive effects of all compounds. However, both βTCP-containing bone substituents generated larger amounts and more mature new bones inside the defects. Nevertheless, only 72.8–76.9% of the bone defects treated with AE and H and 80.5–82.9% of those treated with βTCP-containing counterparts were re-ossified by the 6th month. Remarkably, by this time, some intra-osseous hydrogels were found, and traces of silica from AE were still detectable, indicating these as the causative agents for the persistent osseous–fibrous granulomatous inflammation. When silica or methacrylate-based bone substituents are used, chronic ossifying fibrous granulomatous inflammation develops. Although 100% re-ossification takes more than 6 months, by this time, the degree of osteo-fibrous solidification provides functionally well-suited bone repair. Full article

UV-cured methacrylated chitosan (MCHIT) hydrogels were achieved in the presence of silanised tellurium-doped silica bioactive glass (BG-Te-Sil) to produce an antimicrobial and osteoconductive scaffold for tissue engineering applications. Methacrylation of chitosan enabled efficient crosslinking, and the curing process was evaluated by means of Fourier-transform infrared spectroscopy (FTIR) and photorheology analyses. Compressive testing on crosslinked hydrogels showed that the silanised, bioactive, doped glass increased the hydrogel’s elastic modulus by up to 200% compared to unreinforced controls. Antibacterial assays against Staphylococcus aureus ATCC 43300 revealed a significant (p < 0.05) reduction in bacterial metabolic activity for hydrogels containing 50 wt% of the Te-doped bioactive glass. In vitro cytocompatibility with human bone-marrow mesenchymal stem cells demonstrated sustained viability and uniform distribution at 72 h (live/dead staining, AlamarBlue). Under H₂O₂-induced oxidative stress, reinforced hydrogels downregulated pro-inflammatory genes (TNF-α, IFN-γ, IL-1β, and PGES-2). These results suggest that the presence of the silanised bioactive glass can significantly enhance mechanical stability, antibacterial properties, and anti-inflammatory responses without affecting cytocompatibility, making these hydrogels promising for tissue engineering applications. Full article

In the field of enhanced oil recovery (EOR), particularly for water control in high-temperature reservoirs, there is a critical need for effective in-depth water shutoff and conformance control technologies. Polymer-based in situ-cross-linked gels are extensively employed for enhanced oil recovery (EOR), yet their short gelation time under high-temperature reservoir conditions (e.g., >120 °C) limits effective in-depth water shutoff and conformance control. To address this, we developed a hydrogel system via the in situ cross-linking of polyacrylamide (PAM) with phenolic resin (PR), reinforced by silica sol (SS) nanoparticles. We employed a variety of research methods, including bottle tests, viscosity and rheology measurements, scanning electron microscopy (SEM) scanning, density functional theory (DFT) calculations, differential scanning calorimetry (DSC) measurements, quartz crystal microbalance with dissipation (QCM-D) measurement, contact angle (CA) measurement, injectivity and temporary plugging performance evaluations, etc. The composite gel exhibits an exceptional gelation period of 72 h at 130 °C, surpassing conventional systems by more than 4.5 times in terms of duration. The gelation rate remains almost unchanged with the introduction of SS, due to the highly pre-dispersed silica nanoparticles that provide exceptional colloidal stability and the system’s pH changing slightly throughout the gelation process. DFT and SEM results reveal that synergistic interactions between organic (PAM-PR networks) and inorganic (SS) components create a stacked hybrid network, enhancing both mechanical strength and thermal stability. A core flooding experiment demonstrates that the gel system achieves 92.4% plugging efficiency. The tailored nanocomposite allows for the precise management of gelation kinetics and microstructure formation, effectively addressing water control and enhancing the plugging effect in high-temperature reservoirs. These findings advance the mechanistic understanding of organic–inorganic hybrid gel systems and provide a framework for developing next-generation EOR technologies under extreme reservoir conditions. Full article

Hydrogel-based adsorbents have gained increasing recognition in recent years due to their promising potential for pollutant removal. However, conventional hydrogels often suffer from low mechanical strength over prolonged use. Therefore, this study explores the incorporation of silica extracted from bamboo culm (Dendrocalamus asper) to enhance the mechanical stability of hydrogel beads composed from carboxymethyl cellulose (CMC), chitosan (CS), and magnetite ferrofluid (Fe₃O₄), through cross-linking. We hypothesize that silica enhances the mechanical properties of magnetite hydrogel beads without compromising their adsorption capacity. The extracted silica was confirmed with FTIR and EDS analysis. The synthesized CMC-CS-Fe₃O₄-Si hydrogel beads were characterized using FTIR and SEM. Its stability was assessed through dry weight loss measurements, while its adsorption efficiency was evaluated using batch adsorption experiments. The silica-incorporated hydrogel exhibited enhanced mechanical and thermal stability under various pH and temperature conditions, without negatively affecting its adsorption performance, achieving maximum adsorption capacities of 53.00 mg/g for Cr (VI) and 85.06 mg/g for Cu (II). Desorption and regeneration studies confirmed the reusability of the hydrogel for more than four cycles. Overall, the interaction between the hydrogel and silica resulted in excellent adsorption performance, improved mechanical properties, and long-term reusability, making this a promising hydrogel adsorbent for wastewater remediation. Full article

A sol-gel approach was used to prepare a thin hydrogel membrane based on an organic-inorganic polymer matrix embedded with pre-synthesized gold nanoparticles (AuNPs). The organic polymers utilized were poly(vinyl alcohol) (PVA) and poly(ethylene oxide) 400 (PEO) while tetraethoxysilane (TEOS) served as a precursor for the inorganic silica polymer. AuNPs were synthesized using D-glucose as a reducing agent and starch as a capping agent. A mixture of PVA, PEO, pre-hydrolyzed TEOS, and AuNP dispersions was cast and dried at 50 °C to obtain the hybrid hydrogel membrane. The structure, morphology, and optical properties of the nanocomposite membrane were analyzed using TEM, SEM, XRD, and UV-Vis spectroscopy. The newly designed hybrid hydrogel membrane was utilized as an efficient sorbent for the simultaneous speciation analysis of valence species of chromium and manganese in water samples via solid-phase extraction. This study revealed that Cr(III) and Mn(II) could be simultaneously adsorbed onto the PVA/PEO/SiO₂/AuNP membrane at pH 9 while Cr(VI) and Mn(VII) remained in solution due to their inability to bind under these conditions. Under optimized parameters, detection limits and relative standard deviations were determined for chromium and manganese species. The developed analytical method was successfully applied for the simultaneous speciation analysis of chromium and manganese in drinking water and wastewater samples. Full article

The use of water-efficient soil amendments has gained increasing importance in agriculture, particularly in regions facing water scarcity. So, this study evaluates the impact of silica and nano-silica hydrogels on soil water retention, crop yield, and crop water productivity under variable irrigation regimes. Using a randomized complete block design with furrow irrigation, the experiment tested different hydrogel application rates and irrigation levels in rice (Oryza sativa L.) and clover (Trifolium alexandrinum L.) across two growing seasons. Statistical tests, including ANOVA and t-tests, confirm that nano-silica hydrogel significantly improves soil properties, yield, and crop water productivity (CWP), especially at moderate irrigation levels (70–90% of water requirements). In the first season, nano-silica hydrogel enhanced rice yield, with a maximum yield of 10.76 tons ha⁻¹ with 90% irrigation and 119 kg ha⁻¹ of hydrogel compared with other treatments. In the second season, clover yields were also positively affected, with the highest fresh forage yield of 5.02 tons ha⁻¹ with 90% irrigation and 119 kg ha⁻¹ nano-silica hydrogel. Despite seasonal variation, nano-silica hydrogel consistently outperformed silica hydrogel in terms of improving soil water retention, reducing bulk density, and enhancing hydraulic conductivity across different irrigation levels. Principal Component Analysis (PCA) revealed that nano-silica hydrogel significantly improved soil water retention properties, including the water-holding capacity (WHC), field capacity (FC), and available water (AW), and reduced the wilting point (WP). These improvements, in turn, led to increased crop yield and water productivity, particularly at moderate irrigation levels (70–90% of the crop’s total water requirements. These findings highlight the potential of nano-silica hydrogel as an effective amendment for improving soil water retention, enhancing crop productivity, and increasing crop water productivity under reduced irrigation conditions. Full article

The greenhouse effect and global warming, driven by the accumulation of pollutants, such as sulfur oxides (SOx), nitrogen oxides (NOx), and CO₂, are primarily caused by the combustion of fossil fuels and volcanic eruptions. These phenomena represent an international crisis that negatively impacts human health and the environment. Several studies have reported novel carbon capture, utilization, and storage (CCUS) technologies, promising solutions. Notable methods include chemical absorption using solvents, and the development of functionalized porous materials, such as MCM-41, impregnated with amines like polyethyleneimine. These technologies have demonstrated high capture capacity and thermal stability; however, they face challenges related to recyclability and high operating costs. In parallel, biodegradable polymers and hydrogels present sustainable alternatives with a lower environmental impact, although their industrial scalability remains limited. This review comprehensively analyzes CO₂ capture methods, focusing on silica-based porous supports, polymers, hydrogels, and emerging techniques, like CCUS and MOFs, while including traditional methods and a bibliometric analysis to update the field’s scientific dynamics. With increasing investigations focused on developing new CCUS technologies, this study highlights a growing interest in eco-friendly alternatives. A bibliometric analysis of 903 articles published between 2010 and 2024 provides an overview of current research on environmentally friendly carbon capture technologies. Countries such as the United States, the United Kingdom, and India are leading research efforts in this field, emphasizing the importance of scientific collaboration. Despite these advancements, implementing these technologies in industrial sectors with high greenhouse gas emissions remains scarce. This underscores the need for public policies and financing to promote their development and application in these sectors. Future research should prioritize materials with high capture capacity, efficient transformation, and valorization of CO₂ while promoting circular economy approaches and decarbonizing challenging sectors, such as energy and transportation. Integrating environmentally friendly materials, energy optimization, and sustainable strategies is essential to position these technologies as key tools in the fight against climate change. Full article

The application of nanocomposites based on polyacrylamide hydrogels as well as silica nanoparticles in various tasks related to the petroleum industry has been rapidly developing in the last 10–15 years. Analysis of the literature has shown that the introduction of nanoparticles into hydrogels significantly increases their structural and mechanical characteristics and improves their thermal stability. Nanocomposites based on hydrogels are used in different technological processes of oil production: for conformance control, water shutoff in production wells, and well killing with loss circulation control. In all these processes, hydrogels crosslinked with different crosslinkers are used, with the addition of different amounts of nanoparticles. The highest nanoparticle content, from 5 to 9 wt%, was observed in hydrogels for well killing. This is explained by the fact that the volumes of injection of block packs are counted only in tens of cubic meters, and for the sake of trouble-free workover, it is very important to preserve the structural and mechanical properties of block packs during the entire repair of the well. For water shutoff, the volumes of nanocomposite injection, depending on the well design, are from 50 to 150 m³. For conformance control, it is required to inject from one to several thousand cubic meters of hydrogel with nanoparticles. Naturally, for such operations, service companies try to select compositions with the minimum required nanoparticle content, which would ensure injection efficiency but at the same time would not lose economic attractiveness. The aim of the present work is to develop formulations of nanocomposites with increased structural and mechanical characteristics based on hydrogels made of partially hydrolyzed polyacrylamide crosslinked with resorcinol and paraform, with the addition of commercially available nanosilica, as well as to study their thermal degradation, which is necessary to predict the lifetime of gel shields in reservoir conditions. Hydrogels with additives of pyrogenic (HCSIL200, HCSIL300, RX380) and hydrated (white carbon black grades: ‘BS-50’, ‘BS-120 NU’, ‘BS-120 U’) nanosilica have been studied. The best samples in terms of their structural and mechanical properties have been established: nanocomposites with HCSIL200, HCSIL300, and BS-120 NU. The addition of hydrophilic nanosilica HCSIL200 in the amount of 0.4 wt% to a hydrogel consisting of partially hydrolyzed polyacrylamide (1%), resorcinol (0.04%), and paraform (0.09%) increased its elastic modulus by almost two times and its USS by almost three times. The thermal degradation of hydrogels was studied at 140 °C, and the experimental time was converted to the exposure time at 80 °C using Van’t Hoff’s rule. It was found that the nanocomposite with HCSIL200 retains its properties at a satisfactory level for 19 months. Filtration studies on water-saturated fractured reservoir models showed that the residual resistance factor and selectivity of the effect of nanocomposites with HCSIL200 on fractures are very high (226.4 and 91.6 for fracture with an opening of 0.05 cm and 11.0 for porous medium with a permeability of 332.3 mD). The selectivity of the isolating action on fractured intervals of the porous formation was noted. Full article

Weathering products of sphalerite-bearing ores play an important role in controlling the fate of Zn in the environment. In this framework, the relative stability of Zn carbonates is of special relevance for the common case of ore weathering by carbonated groundwater in the presence of calcium carbonates. We investigated the experimental (co)nucleation and growth of Zn and Ca carbonates at 25 °C in finite double diffusion silica hydrogel media with the purpose of deciphering the system’s reactive pathway and unraveling the major governing factors behind the obtained mineral assemblages. The crystallized solids were carefully extracted two months post-nucleation and studied with micro-Raman spectroscopy, micro X-ray diffraction (XRD), scanning electron microscopy, and electron microprobe (EMP) methods. The obtained results indicate that the grown Zn-bearing phases corresponded to smithsonite and/or Zn hydroxyl carbonate, while CaCO₃ polymorphs aragonite and calcite were also crystallized. Moreover, the observed mineral textural relationships reflected the interplay between supersaturation with respect to CaCO₃/pCO₂ and the grown Zn-bearing carbonate. Experiments conducted in more supersaturated conditions with respect to CaCO₃ polymorphs (higher pCO₂) favored the precipitation of smithsonite, while the opposite was true for the obtained Zn hydroxyl carbonate phase. The gathered Raman, XRD, and EMP data indicate that the latter phase corresponded to a non-stoichiometric, poorly crystalline solid. Full article

There is currently a critical need for understanding how the response and activity of whole-cell bacterial reporters positioned in a complex biological or environmental matrix are impacted by the physicochemical properties of their micro-environment. Accordingly, a comprehensive analysis of the bioluminescence response of Cd(II)-inducible PzntA-luxCDABE Escherichia coli biosensors embedded in silica-based hydrogels is reported to decipher how metal bioavailability, cell photoactivity and ensuing light bioproduction are impacted by the hydrogel environment and the associated matrix effects. The analysis includes the account of (i) Cd speciation and accumulation in the host hydrogels, in connection with their reactivity and electrostatic properties, and (ii) the reduced bioavailability of resources for the biosensors confined (deep) inside the hydrogels. The measurements of the bioluminescence response of the Cd(II) inducible-lux biosensors in both hydrogels and free-floating cell suspensions are completed by those of the constitutive rrnB P1-luxCDABE E. coli so as to probe cell metabolic activity in these two situations. The approach contributes to unraveling the connections between the electrostatic hydrogel charge, the nutrient/metal bioavailabilities and the resulting Cd-triggered bioluminescence output. Biosensors are hosted in hydrogels with thickness varying between 0 mm (the free-floating cell situation) and 1.6 mm, and are exposed to total Cd concentrations from 0 to 400 nM. The partitioning of bioavailable metals at the hydrogel/solution interface following intertwined metal speciation, diffusion and Boltzmann electrostatic accumulation is addressed by stripping chronopotentiometry. In turn, we detail how the bioluminescence maxima generated by the Cd-responsive cells under all tested Cd concentration and hydrogel thickness conditions collapse remarkably well on a single plot featuring the dependence of bioluminescence on free Cd concentration at the individual cell level. Overall, the construction of this master curve integrates the contributions of key and often overlooked processes that govern the bioavailability properties of metals in 3D matrices. Accordingly, the work opens perspectives for quantitative and mechanistic monitoring of metals by biosensors in environmental systems like biofilms or sediments. Full article

Natural opal is a widespread mineral formed by the aqueous alteration of silicate rocks. It occurs as a mixture of silica nano-to-micro-structures (e.g., nanograins, spheres) and silica hydrogel cement, with variations in the proportions of these components leading to significant differences in the physico-chemical properties of opals. However, the detailed process of their formation in nature and the influence of the mixing ratio are not fully understood, as opal has not been yet synthesized under geologically relevant conditions. This study aims to develop a method of opal synthesis in conditions close to continental weathering conditions (<50 °C, ambient pressure) using relevant chemicals that could be employed to gain insight into the processes that give rise to opal on Earth and Mars. Our synthesis method enabled us to synthesize opal-A with different mixing ratios, of which four were then studied to determine the effect on the material’s properties. Changes in the proportion of the hydrogel cement affect the porosity and the total water content, as well as the proportion of “water” species (H₂O and OH). Moreover, the synthetic opal obtained with a 1:1 ratio shows the closest similarity to natural opal-AG. Finally, our results support the hypothesized multistage process for opal formation in nature. Full article

The growing use of glass in architecture has driven research into reducing its energy consumption. Thermochromic (TC) glass technology shows promise for enhancing building energy efficiency by regulating solar heat dynamically. Although TC glass helps reduce heat radiation, additional solutions like Low-E or vacuum glass are needed to control heat convection and conduction. Low-E glass, while effective in lowering heat transfer, may increase surface temperature. Thermo-sensitive hydrogels, known for their light-scattering properties at high temperatures, have been explored to complement TC glass. However, their stability at elevated temperatures remains a challenge, especially for applications requiring durability under varying weather conditions. This study proposes enhancing the adhesion between hydrogel and glass by introducing silica–oxygen bonds. As a result, TC glass demonstrates stable performance over 100 cycles within temperature ranges from 85 °C to 30 °C in summer and 40 °C to −20 °C in winter. Furthermore, by incorporating ethylene glycol, the freezing point of TC glass is reduced to −26 °C, rendering it suitable for use in colder regions. The implementation of TC glass effectively addresses the dual requirements of summer shading and winter heating in areas with both cold winters and hot summers, significantly reducing building energy consumption. This study contributes substantially to developing advanced intelligent building materials, paving the way for more sustainable architectural designs. Full article

The present study showcases a series of crystallization experiments using a specially designed double diffusion system to grow crystals belonging to the calcium carbonate–phosphate system. The experimental U-shaped device comprised two vertical solution containers, separated by a horizontal column of silica hydrogel. Each container was filled with 0.5 M CaCl₂ and 0.5 M Na₂CO₃ solutions, which diffused through the gel column over time. Na₃PO₄ solutions, with 50 and 500 ppm concentrations, were incorporated into the gel in different experiments, resulting in a homogeneous distribution of phosphate concentrations within the diffusion column. After 15- and 30-day incubation periods post-nucleation, the crystals formed in different sections of the gel were carefully extracted and studied with scanning electron microscopy and electron microprobe. Additionally, Raman spectra were collected from the samples using a confocal Raman microscope, providing further insights into their molecular composition and structural properties. The obtained results show that under the induced experimental conditions (i) phosphate incorporates into calcite’s structure, and (ii) the growth of calcium phosphates in the presence of carbonate ions involves the sequential, heterogeneous nucleation of CO₃-bearing OCP/HAP-like phases, with Raman spectral characteristics very similar to those of bioapatites. Full article

Fluoropyrimidine (FP) drugs are central components of combination chemotherapy regimens for the treatment of colorectal cancer (CRC). FP-based chemotherapy has improved survival outcomes over the last several decades with much of the therapeutic benefit derived from the optimization of dose and delivery. To provide further advances in therapeutic efficacy, next-generation prodrugs and nanodelivery systems for FPs are being developed. This review focuses on recent innovative nanodelivery approaches for FP drugs that display therapeutic promise. We summarize established, clinically useful FP prodrug strategies, including capecitabine, which exploit tumor-specific enzyme expression for optimal anticancer activity. We then describe the use of FP DNA-based polymers (e.g., CF10) for the delivery of activated FP nucleotides as a nanodelivery approach with proven activity in pre-clinical models and with clinical potential. Multiple nanodelivery systems for FP delivery show promise in CRC pre-clinical models and we review advances in albumin-mediated FP delivery, the development of mesoporous silica nanoparticles, emulsion-based nanoparticles, metal nanoparticles, hydrogel-based delivery, and liposomes and lipid nanoparticles that display particular promise for therapeutic development. Nanodelivery of FPs is anticipated to impact CRC treatment in the coming years and to improve survival for cancer patients. Full article

Mesoporous silica nanoparticles (MSNs) are inorganic nanocarriers presenting versatile properties and the possibility to deliver drug molecules via different routes of application. Their modification with lipids could diminish the burst release profile for water-soluble molecules. In the case of oleic acid (OA) as a lipid component, an improvement in skin penetration can be expected. Therefore, in the present study, aminopropyl-functionalized MSNs were modified with oleic acid through carbodiimide chemistry and were subsequently incorporated into a semisolid hydrogel for dermal delivery. Doxorubicin served as a model drug. The FT-IR and XRD analysis as well as the ninhydrin reaction showed the successful preparation of the proposed nanocarrier with a uniform particle size (352–449 nm) and negative zeta potential. Transmission electron microscopy was applied to evaluate any possible changes in morphology. High encapsulation efficiency (97.6 ± 1.8%) was achieved together with a sustained release profile over 48 h. The composite hydrogels containing the OA-modified nanoparticles were characterized by excellent physiochemical properties (pH of 6.9; occlusion factor of 53.9; spreadability of factor 2.87 and viscosity of 1486 Pa·s) for dermal application. The in vitro permeation study showed 2.35 fold improvement compared with the hydrogel containing free drug. In vitro cell studies showed that loading in OA-modified nanoparticles significantly improved doxorubicin’s cytotoxic effects toward epidermoid carcinoma cells (A431). All of the results suggest that the prepared composite hydrogel has potential for dermal delivery of doxorubicin in the treatment of skin cancer. Full article