Gelation Time Research Articles

Influence of halloysite nanotubes on processing, structural and thermal properties of poly(vinyl chloride)/high-density polyethylene composites with wood flour

ABSTRACT The aim of this work was to investigate the effect of halloysite nanotubes (HNT) on the processing, structural and thermal properties of poly(vinyl chloride) (PVC), high-density polyethylene (HDPE), and PVC–HDPE composites with various proportions of both polymer components containing 30 wt% wood flour (WF) and 5 wt% halloysite processed in the Brabender measuring mixer. The HNT content in the composites leads to a slight increase in the maximum torque and a reduction in the gelation time for PVC and PVC–HDPE matrix composites with the 90:10 component ratio. In addition, microscopic images of these materials showed a homogeneous distribution of HNT in the polymer matrix. The addition of mineral filler to the matrix, regardless of the polymer type, resulted in a slight increase in the torque values at the kneading endpoint. The PVC–HDPE–wood flour composites are characterized by higher thermal stability at processing temperature when HNT is loaded. The introduction of 5 wt% HNT into the PVC–HDPE 90:10 30 wt% WF blend resulted in an increase of the 2% weight loss temperature by 16°C. The simultaneous use of wood flour and halloysite as fillers for PVC–HDPE blends could be an eco-efficient solution for the new composite material sector.

Preparation and Evaluation of Poloxamer/Carbopol In-Situ Gel Loaded with Quercetin: In-Vitro Drug Release and Cell Viability Study.

Periodontitis is a severe chronic inflammatory disease, whose traditional systemic antimicrobial therapy faces great limitations. In-situ gels provide an effective solution as an emerging local drug delivery system. In this study, the novel thermosensitive poloxamer/carbopol in-situ gels loaded with 20μmol/L quercetin for the treatment of periodontitis were prepared by cold method. Thirteen batches of in-situ gels based on two independent factors (X1: poloxamer 407 and X2: carbopol 934P) were designed and optimized by the statistical method of central composite design (CCD). The transparency, pH, injectability, viscosity, gelation temperature, gelation time, elasticity modulus, degradation rate and in-vitro drug release studies of the batches were evaluated, and the percentage of drug release in the first hour, the time required for 90% drug release, gelation temperature, and gelation time were selected as dependent variables. These two independent factors significantly affected the four dependent variables (p < 0.05). The optimization result displayed that the optimized concentration of poloxamer 407 was 20.84% (w/v), and carbopol 934P was 0.5% (w/v). The optimized formulation showed a clear appearance (++), acceptable injectability (Pass), viscosity(151,798mPas), gelation temperature (36°C), gelation time (213s), preferable cell viability and cell proliferation, conformed to first-order release kinetics, and had a significant antibacterial effect. The article demonstrates the great potential of the quercetin in-situ gel as an effective treatment for periodontitis.

FRESH 3D printing of zoledronic acid-loaded chitosan/alginate/hydroxyapatite composite thermosensitive hydrogel for promoting bone regeneration

The aim of this study was to develop a composite thermosensitive hydrogel for bone regeneration applications. This hydrogel consisted of chitosan, alginate and hydroxyapatite, and was loaded with zoledronic acid as a model drug. The feasibility of three-dimensional (3D) printing of the thermosensitive hydrogel using the extrusion technique was investigated. The 3D printing technique called Freeform Reversible Embedded Suspended Hydrogel (FRESH) printing was employed for this purpose. To characterize the composite hydrogels, several tests were conducted. The gelation time, rheological properties, and in vitro drug release were analyzed. Additionally, the cell viability test on human osteosarcoma MG-63 cells for the composite hydrogel was assessed using an MTT assay. The results of the study showed that the zoledronic acid-loaded composite thermosensitive hydrogel was successfully printed using the FRESH 3D printing technique which was not possible otherwise i.e., by using traditional 3D printing techniques. Further examination of the printed constructs using a Scanning Electron Microscope revealed the presence of porous and layered structures. The gelation times of the composite thermosensitive hydrogel was determined to be 10 and 20 min, respectively for scaffolds with and without HA, indicating the successful formation of the gel within a reasonable time to the FRESH technique. The flow behavior of the hydrogel was found to be pseudoplastic, following a non-Newtonian flow pattern with Farrow’s constant (N) values of 1.708 and 1.853 for scaffolds with and without hydroxyapatite, respectively. In terms of drug release, scaffolds prepared with and without hydroxyapatite reached nearly 100% of zoledronic acid release in 360 h and 48 h, respectively. The cell viability test on human osteosarcoma MG-63 cells using MTT assay has shown increased cell viability % in the case of the composite hydrogel, indicating a biocompatible scaffold. Overall, this study successfully developed a composite thermosensitive hydrogel loaded with zoledronic acid for bone regeneration applications and 3D printed using the FRESH 3D printing technique. The results of this study provide valuable insights into the potential use of this composite hydrogel for future biomedical applications.

Physically crosslinked chitosan/αβ–glycerophosphate hydrogels enhanced by surface-modified cyclodextrin: An efficient strategy for controlled drug release

This study reports physically crosslinked chitosan/αβ–glycerophosphate (CS/GP) hydrogels containing surface-modified cyclodextrin for efficient controlled drug release. Highly water-soluble β–cyclodextrin-grafted L–serine (CD–g–Ser) compounds were synthesized, and employed as an effective carrier of berberine hydrochloride (Ber) for CS/GP hydrogels. Various characterizations, including gelation time determination, scanning electron microscopy, and viscosity measurement, indicated that the introduction of CD–g–Ser led to increased crosslinking degree, improved temperature sensitivity, and shortened sol–gel phase transition time of the hydrogel. Meanwhile, the sustained release ability for Ber was achieved due to the hydrophobic association between cyclodextrin and Ber. It was observed that within 4 h, the hydrogel containing CD–g–Ser released 40 % of Ber, while the CS/GP hydrogel without CD–g–Ser released 65 % of Ber. Furthermore, in vitro bacteriostasis experiments confirmed the drug-loaded hydrogel had an excellent antibacterial effect against E. coli and S. aureus (diameter of the inhibition zone up to (16.4 and 34.7) mm, respectively), low hemolysis rate (<2 %), and high cell viability (>90 %). The findings indicate that the physical crosslinked CS hydrogel can be used as a new drug delivery system, and its excellent antibacterial effect makes it a potential wound dressing candidate.

Performance of delaying release and reducing adsorption of polyethyleneimine/poly(vinyl sulfonate) polyelectrolyte complex nanoparticles in polyacrylamide/polyethyleneimine gel system

Polyacrylamide/Polyethyleneimine (HPAM/PEI) is an environmentally friendly and promising gel system. However, inadequate gelation time and retention of the cross-linker (polyethyleneimine, PEI) during migration pose significant challenges for effective water control treatment in deep reservoirs. Polyelectrolyte complex nanoparticles (PECs) have demonstrated the ability to efficiently encapsulate PEI, facilitating for its gradual release. To achieve this, a cost-effective polyanionic complex, poly(vinyl sulfonate) (PVS), was employed to form PECs with PEI. By adjusting the mixing ratio of PEI and PVS, stable PECs suspensions with varying charges were successfully produced. These stable PECs exhibited spherical shapes with a particle size distribution ranging from 127.3–442.71 nm, and an average particle size of approximately 200 nm. The encapsulation efficiency of PEI by PECs varied from 64.56 % to 86.14 %. Under different conditions, 55.12 % to 90.26 % of PEI could be released from PECs. Increased temperatures, higher ionic strengths, and greater deviations in pH from the initial state of the PECs suspension all facilitated the release of PEI. The most stable PECs delayed the gelation time of the HPAM/PEI system to 9.5 days, which is twice the base gelation time of 4.5 days. The strength of mature HPAM/PEI (PECs) gels increased by 8.95 Pa in storage modulus (G′) compared to HPAM/PEI at the same concentration, albeit with a reduced linear viscoelastic region. And, the PECs-based delayed crosslinking method does not negatively affect the mechanical strength of the HPAM/PEI gel system, and thus its water control ability, under reservoir conditions. On the other hand, the static adsorption of PEI encapsulated by anionic PECs on sand decreased to one-fourth of that of free PEI (PEI solution). Additionally, the breakthrough of PEI encapsulated in anionic PECs in fractured sandstone cores was significantly advanced compared to free PEI.

Preparation, optimization, and modification of urea‐formaldehyde resin for used as a plugging agent in fractured and caved oil and gas reservoirs

AbstractBased on the requirements of resin‐based plugging agents on initial viscosity, gel time and cost, the urea‐formaldehyde resin Poly‐UF was synthesized via aqueous solution polymerization. Subsequently, the Poly‐UF was further modified by using melamine, polyvinyl alcohol (PVA), and oxidized starch to enhance its application performances, which were marked by Poly‐UF‐M, Poly‐UF‐PVA and Poly‐UF‐OS, respectively. Simultaneously, the relationship between the preparation process, structural, and performance characteristics of the different resin types was investigated using a single‐factor experimental approach, specifically, the solid content, viscosity, and free formaldehyde content were evaluated to gauge its application performance. In this study, the chemical structure, thermal stability and microscopic morphology of Poly‐UF‐M, Poly‐UF‐PVA and Poly‐UF‐OS were studied by using FTIR, TG‐DTG and SEM. As a result, it was confirmed that the Poly‐UF was successfully modified, and the thermal stability was obviously improved, and the microstructure was further enhanced by melamine, PVA and oxidized starch. The outcomes revealed a notable reduction in free formaldehyde content and a significant increase in solid content for Poly‐UF‐M, Poly‐UF‐PVA, and Poly‐UF‐OS, specifically, the free formaldehyde content decreased by 47.15%, 36.59%, and 32.52%, respectively, while the solid content increased by 3.47%, 1.62%, and 1.39%, respectively. Moreover, the acid and alkali solubility, mechanical strength of cured Poly‐UF‐M, Poly‐UF‐PVA and Poly‐UF‐OS were improved attribute to excellent membrane‐forming performance. The innovation of this study is that the systematic investigation and optimization of urea‐formaldehyde resin are presented, providing technical insights on its utilization as a plugging agent in fractured and caved oil and gas reservoirs.

Chitosan Nanoparticles Embedded in In Situ Gel for Nasal Delivery of Imipramine Hydrochloride: Short-Term Stage Development and Controlled Release Evaluation

Imipramine hydrochloride (IMP), a tricyclic antidepressant used for major depression, enuresis, and neuropathic pain, is limited by gastrointestinal complications, low oral bioavailability (44%), and complex dosing requirements. This study aimed to explore a novel non-invasive nasal delivery system using chitosan nanoparticles (Cs NPs) embedded in an in situ gel to address the limitations of oral IMP administration. Cs NPs loaded with IMP were synthesized via ionic gelation and assessed for precision in drug concentration using a validated HPLC method. The particles were integrated into a thermoresponsive polymer, Pluronic F127, to form an in situ gel suitable for nasal administration. The formulation was characterized for gelation temperature, duration, viscosity, mucoadhesive strength, and overall gel robustness. Drug release kinetics and the controlled release mechanism were studied using ex vivo permeation tests with Franz diffusion cells and nasal sheep mucosa. The optimized nanoparticle formulation (F4-50) exhibited a consistent PS of 141.7 ± 2.2 nm, a zeta potential (ZP) of 16.79 ± 2.1 mV, and a high encapsulation efficiency of 67.71 ± 1.9%. The selected in situ gel formulation, F4-50-P1, demonstrated a gelation temperature of 33.6 ± 0.94 °C and a rapid gelation time of 48.1 ± 0.7 s. Transform-attenuated total reflectance infrared spectroscopy (ATR-IR) confirmed the compatibility and effective encapsulation of IMP within the formulation. The release profile of F4-50 included an initial burst release followed by a sustained release phase, with F4-50-P1 showing improved control over the burst release. The flux rates were 0.50 ± 0.01 mg/cm2/h for F4-50 and 0.33 ± 0.06 mg/cm2/h for F4-50-P1, indicating effective permeation. The developed chitosan nanoparticle-based in situ gel formulation provides a promising approach for the controlled release of IMP, enhancing therapeutic efficacy and patient compliance while mitigating the disadvantages associated with oral delivery.

Enhancing the gel properties of soy protein isolate: the role of oxidized konjac glucomannan in acid-induced gelation.

Soy protein isolate (SPI) gels formed using a single coagulant often have poor water-holding capacity (WHC) and low hardness, making them fragile and unsuitable for transportation and storage. Adding compound coagulants or polysaccharides can improve the gelation properties of SPI gels induced by gluconolactone (GDL). This study explores the impact of oxidized konjac glucomannan (OKGM) on the physicochemical and structural properties of GDL-induced SPI gels, with the aim of evaluating the potential of OKGM for enhancing the overall quality and stability of these gels. In this study, the composite gels demonstrated a significant increase in whiteness (69.02% to 70.59%) compared with the SPI gel (67.41%). Key physicochemical properties, such as water-holding capacity (WHC), textural characteristics, viscoelasticity, and thermal stability, were notably improved. Scanning electron microscopy (SEM) revealed a reduction in the average pore diameter of the composite gels from 70.57 ± 4.13 μm to 37.19 ± 0.24 μm when the oxidation degree of OKGM was kept at or below 60 min, contributing to a more compact and orderly microstructure. Enhanced hydrophobic and electrostatic interactions within the composite gels also accelerated the gelation process, shortening the gelation time from 15.77 ± 0.37 min to 12.45 ± 0.18 min. The results demonstrate that OKGM acts effectively as a gel enhancer, improving the physicochemical and structural properties of SPI gels significantly. © 2024 Society of Chemical Industry.

Engineering water-shut-off operations: Application of rheological time-temperature superposition approach for organically-crosslinked polymer gel systems

Polymer-based gels have been extensively utilized in reservoirs to prevent excessive water production and improve oil recovery. In this study, a sulfonated-hydrolyzed polyacrylamide polymer (HPAM-S) and low-toxic organic crosslinkers (hydroquinone and hexamethylenetetramine) were mixed in brine at specified concentrations to formulate the polymer-crosslinker fluid system. The quantitative rheological analysis, along with the TTS (Time-Temperature Superposition) approach, was examined for the first time to achieve the water shut-off operations in high-temperature reservoirs (90 °C–150 °C). The TTS approach was defined as modelling of the viscosity vs. time data obtained at various temperatures using an appropriate empirical shift factor (at) such that a single master curve is established for the viscosity evolution of the given fluid system. This approach facilitates the prediction of the gelation behavior of polymer-crosslinker fluid systems as a function of time at varied reservoir temperatures especially over time scales that are not experimentally accessible. The time-dependent rheological evolution of the fluid system was experimentally investigated using batch-wise bottle testing methods as well as viscosity and viscoelastic measurements by employing an advanced rheometer. The TTS approach was applied to the obtained rheological data at varied temperatures. The model was validated for an unknown set of temperature vs. viscosity data. Based on the TTS approach, the term ‘gelation time’ was defined as the time required to reach a pre-specified viscosity to signify a transition from the liquid-like state to the solid-like state. The gelation time decreases with increasing temperatures. After the gelation time, at each temperature, a swift increase in the fluid viscosity was observed, indicating the initiation of the rapid crosslinking in the fluid systems. It was found that beyond the gelation time, the batch-wise bottle testing showed (G-I) gel strength (qualitative). Analogously, the visco-elasticity test demonstrated a rapid rise in elastic modulus (G′) beyond the gelation time. An underlying mechanism based on polymer hydrolysis was utilized to explain the evolution of distinct viscous and viscoelastic properties as a function of temperature. Moreover, the modeling predictions for the fluid systems were examined for in-situ rock plugging with the help of core-flood equipment. The core-flooding tests confirmed a 99% reduction in the rock permeability beyond the gelation time. The gelation time values obtained from both the batch-wise bottle testing method and rheological tests for the polymer-crosslinker fluid systems were found in agreement with each other, with a tolerance of (±5%).

Development and Characterization of Thermal Protection Gels for Steel Pipelines Transporting Combustible Materials

Due to low costs, pipelines are commonly used for transporting hazardous substances such as combustible liquids and gasses. Currently, chemical industrial parks and gas production stations have dense pipeline networks. In the case of a pipeline leakage and subsequent fire accident, the adjacent pipelines could be directly impinged by the flame or engulfed in hot smoke, with the potential to result in a chain of accidents and catastrophic consequences. It is thus of practical importance to develop an efficient thermal protection material for pipelines. In this study, a new type of bio-based gel material was prepared for pipeline thermal protection, using guar gum (GG) as the gelling agent, sodium tetraborate (B) as the crosslinking agent and magnesium chloride (MgCl2) as the fire retardant. Firstly, orthogonal experiments were conducted to examine the gelling time of the gel and determine the optimal formulations that meet the protection requirements. Subsequently, water retention, thermal stability and the microstructure of these formulations were analyzed. Finally, the thermal protection performance of the gel formulations was evaluated under the direct impingement of flames or high-temperature smoke. The results indicated that the best performance was achieved by the formulation with GG, B and MgCl2 mass fractions of 2.5, 0.6 and 0.5 wt%, respectively. This formulation also exhibited the best water retention capacity and thermal stability. In the pipeline thermal protection experiments, this formulation achieved effective protection times of 216 s (for a 90 mm diameter) and 312 s (for a 120 mm diameter) for the lower part of the pipeline under direct flame impingement. Under high-temperature smoke impingement, this formulation also showed excellent performance. These research and findings can provide an important foundation for the further development of thermal protection materials for pipelines under fire conditions.

Insight into structural changes in heat-induced whey protein-fucoidan hydrogel by SR-IR and molecular docking techniques

This study aimed to investigate the structural changes in heat-induced polymerized whey protein (PWP)-fucoidan (FCN) hydrogels with different FCN concentration (0 % to 0.75 %, w/v). The interaction of PWP and FCN were traced by simultaneous rheology and Fourier transform infrared spectroscopy spectra (SR-IR) technology. The particle size and absolute zeta potential of PWP-FCN increased significantly (p < 0.05) with higher FCN concentrations, indicating that the formation of PWP-FCN enhanced the stability of the system. The gelation time of PWP-FCN was shortened from 1328 s to 881 s as the FCN concentration increased from 0 to 0.75 % (w/v) paralleled the increased apparent viscosity. The endothermic peak temperature of the hydrogels increased from 95.28 °C to 102.26 °C demonstrating the improved thermal stability due to FCN. The intrinsic fluorescence, surface hydrophobicity, and free thiol groups of PWP-FCN all indicated that FCN could interact with PWP through hydrophobic interactions, which changed the tertiary structure of PWP, and increased the density of PWP-FCN network. Cryogenic scanning electron microscopy (Cryo-SEM) and SEM images showed that the interactions between PWP and FCN resulted to rough and wrinkled microstructure of samples. Results of SR-IR and molecular docking assay both indicated that FCN could also interact with PWP through hydrogen bonds. In summary, FCN could promote the gelation process and the physicochemical properties of PWP-FCN hydrogel. Results of this study could provide theoretical basis for the application of protein–polysaccharide hydrogels in food field.

Process Mapping of the Sol-Gel Transition in Acid-Initiated Sodium Silicate Solutions.

Fabricating large-scale porous bioactive glass bone scaffolds presents significant challenges. This study aims to develop formable, in situ setting scaffolds with a practical gelation time of about 10 min by mixing 45S5 bioactive glass with sodium silicate (waterglass) and an acid initiator. The effects of pH (2-11), waterglass concentration (15-50 wt.%), and acid initiator type (phosphoric or boric acid) were examined to optimize gelation kinetics and microstructure. A 10 min gelation time was achieved with boric acid and phosphoric acid at various pH levels by adjusting the waterglass concentration. Exponential and polynomial models were proposed to predict gelation times in basic and acidic environments, respectively. The optical properties of the gels were studied qualitatively and quantitatively, providing insights into gelation kinetics and structure. Acidic gels formed smaller particles in a dense network (pores < 550 nm) with higher light transmittance, while basic gels had larger aggregates (pores ~5 µm) and lower transmittance. As the waterglass concentration decreased, pore size and transmittance converged in both groups. The onset of gelation was detected around 8 min using the derivative of light transmittance. This work identifies the key factors controlling waterglass gelation and their impact on gel structure, enabling the tailored creation of formable, in situ setting bioactive glass bone scaffolds.

Evaluation of Mucoadhesive Nano-Bilosomal In Situ Gels Containing Anti-Psychotic Clozapine for Treatment of Schizophrenia: In Vitro and In Vivo Studies

Background/Objectives: Patients with schizophrenia have significant challenges in adhering to and complying with oral medicines, resulting in adverse consequences such as symptom worsening and psychotic relapse. Methods: This study aimed to develop clove oil-based bilosomes using definitive screening design (DSD) to maximize the anti-schizophrenic action of clozapine and promote its nose-to-brain delivery. The target was to optimize the physicochemical properties of bilosomes and incorporate them into mucoadhesive intranasal in situ gels, searching for augmented ex vivo and in vivo clozapine delivery. Results: The bilosomes’ particle size was decreased by increasing the span, SDC, and clove oil amounts. In addition to using a high lipid amount, the aforementioned components also helped increase the entrapment efficiency values. Increased zeta potential was only observed by increasing surfactant amount and reducing clozapine concentration. After incorporation of optimized liquid clove oil-based bilosomes, which had a spherical nano-sized vesicular shape, into P 407-dependent gels, an HPMC (2% w/w)/P 407 (20% w/w)-containing formulation (G6) was selected as an optimized gel owing to its acceptable gelation time (13.28 s), gel strength (27.72 s), viscosity (12,766.67 cP), and mucoadhesive strength (4273.93 dyne/cm2). The optimized G6 exhibited higher Jss (50.86 μg/cm2·h−1) through the nasal mucosa compared to the control gel (23.03 μg/cm2·h−1). Compared to the control gel, G6 displayed higher relative bioavailability (491.37%) than a commercial tablet (264.46%). Following ELISA analysis, dopamine and serotonin were significantly reduced, while BDNF was remarkably increased after administration of optimized G6 into schizophrenic rats. Conclusions: Our study indicates the potential of intranasal bilosomal gels in upgrading the anti-schizophrenic and neuroprotective activity of clozapine.

Accelerated Nanocomposite Hydrogel Gelation Times Independent of Gold Nanoparticle Ligand Functionality.

The expansive use of hydrogels in healthcare relies on carefully tuned properties in dynamic environments with predictable behavior, including time sensitive biological systems and biomedical applications. To meet demands in these settings, nanomaterials are often introduced to a hydrogel matrix which simultaneously elevates potential applications while adding complexity to fundamental characteristics. With respect to drug delivery, gold nanoparticles have modifiable surfaces to carry an array of targeted drug treatments. However, different molecules acting as capping ligands possess different chemical structures that can impact gelation times. To understand the influence of capping ligand chemistry on polyacrylamide (PAM) based nanocomposite hydrogel radical gelation time, gold nanoparticle (Au NP) capping ligands were selected to encompass varying functional groups and molecular weights: citrate, cetyltrimethylammonium bromide, polyvinylpyrrolidone, and poly(acrylic acid). Gelation times were quantified as the storage-loss moduli crossover point in rheological time sweeps at constant strain and frequency. The dominating factor for gelation time was the presence of Au NPs, independent of a diverse range of capping ligand structures. The gelation times were also markedly faster than the same capping ligand structures used as stand-alone molecular additives. The accelerated Au NP gelation times, under 2 min, are attributed to the Au NPs acting as a cross-linker, promoting gelation. These results bolster the potential implementation of Au NP nanocomposite hydrogels in time-sensitive biomedical applications as robust drug carriers.

Study on increasing polymer gel strength with Janus nanoparticles and its feasibility in profile control and water plugging

In formations subjected to prolonged flooding, dominant channels are formed in high permeability layers, thereby reducing the displacement efficiency in medium- and low-permeability layers. In this study, the Janus synthesis method was employed to produce Janus Nano-TiO2 with a particle size range of 60–120 nm and superior dispersion properties. These nanoparticles were subsequently combined with polyacrylamide to formulate a high-strength polymer nano-gel for water plugging applications. The successful synthesis of the material was confirmed through FTIR and TGA. Gelation experiments indicated that the gelation strength and time augmented significantly with the increased addition of Janus-T6. Conversely, an increase in temperature or salinity resulted in a reduction of both gelation strength and time. Rheological experiments demonstrated a decrease in polymer viscosity with rising shear rates or temperatures, revealing significant shear thinning behavior in the water-plugging agent solution. System viscosity increased with more Janus-T6. Flow experiments revealed decreasing resistance coefficients at higher permeabilities, while all cores exhibited plugging rates above 85%. Additionally, the breakthrough pressure continuously rose with the increased addition of Janus-T6. Ultimately, displacement experiments indicated a 22.83% increase in the recovery rate after employing PNG plugging followed by secondary water flooding, compared to primary water flooding alone.

Kinetic study of paraquat adsorption on alginate beads loaded with montmorillonite using shrinking core model

Water contamination by pesticides threatens clean water availability, highlighting the need for advanced sustainable sanitation systems. Adsorption using biopolymers and minerals is prominent. Understanding process kinetics and influencing parameters is crucial for optimizing contaminant-adsorbent contact time for safe water disposal. The adsorption kinetics of Paraquat (PQ) at three initial concentrations (C0 = 19, 38, and 50 ppm) were studied using alginate-montmorillonite (Alg-Mt) beads with varying clay contents and a 30-min gelation time. The beads were characterized by elemental analysis, TG/DTG, FTIR, XRD, SEM, and EDX. The Shrinking Core Model (SCM) was applied to the experimental data to determine if the diffusion of PQ within the beads depended on clay content. The effective diffusion coefficient (Dp) in the adsorbent increased from 7 × 10−12 to 1 × 10−10 m2 s−1 with increasing clay content, suggesting that diffusion into the interior depended on interaction with the mineral.This investigation also demonstrated that the synthesis of beads at different gelation times does not impact either the adsorption capacity or the adsorption rate of the herbicide on the materials. These results indicate that diffusion depends solely on the interaction of the cationic herbicide with the clay encapsulated within the bead hydrogel.

Formulation-Property Effects in Novel Injectable and Resilient Natural Polymer-Based Hydrogels for Soft Tissue Regeneration

The development of injectable hydrogels for soft tissue regeneration has gained significant attention due to their minimally invasive application and ability to conform precisely to the shape of irregular tissue cavities. This study presents a novel injectable porous scaffold based on natural polymers that undergoes in situ crosslinking, forming a highly resilient hydrogel with tailorable mechanical and physical properties to meet the specific demands of soft tissue repair. By adjusting the formulation, we achieved a range of stiffness values that closely mimic the mechanical characteristics of native tissues while maintaining very high resilience (&gt;90%). The effects of gelatin, alginate, and crosslinker concentrations, as well as porosity, on the hydrogel’s properties were elucidated. The main results indicated a compression modulus range of 2.7–89 kPa, which fits all soft tissues, and gelation times ranging from 5 to 30 s, which enable the scaffold to be successfully used in various operations. An increase in gelatin and crosslinker concentrations results in a higher modulus and lower gelation time, i.e., a stiffer hydrogel that is created in a shorter time. In vitro cell viability tests on human fibroblasts were performed and indicated high biocompatibility. Our findings demonstrate that these injectable hydrogel scaffolds offer a promising solution for enhancing soft tissue repair and regeneration, providing a customizable and resilient framework that is expected to support tissue integration and healing with minimal surgical intervention.

Dual-Self-Crosslinking Effect of Alginate-Di-Aldehyde with Natural and Synthetic Co-Polymers as Injectable In Situ-Forming Biodegradable Hydrogel.

Injectable, in situ-forming hydrogels, both biocompatible and biodegradable, have garnered significant attention in tissue engineering due to their potential for creating adaptable scaffolds. The adaptability of these hydrogels, made from natural proteins and polysaccharides, opens up a world of possibilities. In this study, sodium alginate was used to synthesize alginate di-aldehyde (ADA) through periodate oxidation, resulting in a lower molecular weight and reduced viscosity, with different degrees of oxidation (54% and 70%). The dual-crosslinking mechanism produced an injectable in situ hydrogel. Initially, physical crosslinking occurred between ADA and borax via borax complexation, followed by chemical crosslinking with gelatin through a Schiff's base reaction, which takes place between the amino groups of gelatin and the aldehyde groups of ADA, without requiring an external crosslinking agent. The formation of Schiff's base was confirmed by Fourier-transform infrared (FT-IR) spectroscopy. At the same time, the aldehyde groups in ADA were characterized using FT-IR, proton nuclear magnetic resonance (¹H NMR), and gel permeation chromatography (GPC), which determined its molecular weight. Furthermore, borax complexation was validated through boron-11 nuclear magnetic resonance (¹¹B NMR). The hydrogel formulation containing 70% ADA, polyethylene glycol (PEG), and 9% gelatin exhibited a decreased gelation time at physiological temperature, attributed to the increased gelatin content and higher degree of oxidation. Rheological analysis mirrored these findings, showing a correlation with gelation time. The swelling capacity was also enhanced due to the increased oxidation degree of PEG and the system's elevated gelatin content and hydrophilicity. The hydrogel demonstrated an average pore size of 40-60 µm and a compressive strength of 376.80 kPa. The lower molecular weight and varied pH conditions influenced its degradation behavior. Notably, the hydrogel's syringeability was deemed sufficient for practical applications, further enhancing its potential in tissue engineering. Given these properties, the 70% ADA/gelatin/PEG hydrogel is a promising candidate and a potential game-changer for injectable, self-crosslinking applications in tissue engineering. Its potential to revolutionize the field is inspiring and should motivate further exploration.

Calcium-Based Mineralized Hydrogels for Temporary Reinforcement and Conservation of Ancient Ivory Relics.

Ancient ivory serves as an important witness of time and historical events, offering highly significant insights into the fields of paleontology, mineralogy, materials science, and geochemistry. However, ancient ivory has undergone groundwater corrosion and has a loose porous structure and reduced mechanical strength due to being buried for a long time. Therefore, the temporary reinforcement and preservation of ancient ivory artifacts are a well-known challenge. A methodology was presented in this article for the synthesis of calcium-based mineralized hydrogels (Ca-gel), which possess controllable adhesive strength, beneficial compatibility, environmentally friendly and noninvasive protection, as well as efficient and rapid adhesion for ancient ivory cultural relics. By manipulating the various components of Ca-gel, it was possible to achieve a controllable gel time and gel state. Additionally, the hydrogel possessing a substantial water content has the potential to establish a humid environment suitable for the preservation of ancient ivory, thereby overcoming the challenges associated with water loss and weathering that may arise during excavation processes. It is noteworthy that Ca-gel possessed universality and temporary adhesive properties that could be employed in the temporary reinforcement of cultural relics from different materials. A method has been proposed in this study to facilitate the temporary reinforcement process while ensuring the protection of authenticity, integrity, and continuity for cultural relics.

Strategic Approaches in Generation of Robust Microphysiological 3D Musculoskeletal Tissue System

AbstractSkeletal muscle plays a vital role in maintaining the body's shape and regulating various physiological processes. Its function is influenced by a multitude of factors. Given the lack of uniformity in prior research regarding the size and placement of structural pillars within the chip, as well as the choice of cell‐laden hydrogel components with various densities of extracellular matrix, in different gelation times, and cell densities, a meticulous investigation is conducted to enhance the robustness of 3D in vitro musculoskeletal tissues. This study provides guidance on how to optimize the design parameters of skeletal muscle‐on‐a‐chip and hydrogel recipe by evaluating the impact of design elements and hydrogel fabrication conditions on tissue formation and musculoskeletal differentiation. This research reports the direct evidence of mechanical properties of hydrogels are critical in influencing cellular differentiation and tissue functionality through the process of mechanotransduction. The study highlights the importance of standardizing experimental conditions in 3D in vitro musculoskeletal research, and presents a validated framework as a foundation to aid in the development of functional musculoskeletal tissue for clinical and research applications, including disease modeling and regenerative therapies.