Acrylic Acid Hydrogel Research Articles

In Vitro Evaluation of Smart and pH-Sensitive Chondroitin Sulfate/Sodium Polystyrene Sulfonate Hydrogels for Controlled Drug Delivery.

Ibuprofen is an antipyretic and analgesic drug used for the management of different inflammatory diseases, such as rheumatoid arthritis and osteoarthritis. Due to a short half-life and rapid elimination, multiple doses of ibuprofen are required in a day to maintain pharmacological action for a long duration of time. Due to multiple intakes of ibuprofen, certain severe adverse effects, such as gastric irritation, bleeding, ulcers, and abdominal pain are produced. Therefore, a system is needed which not only prolongs the release of ibuprofen but also overcomes the drug’s adverse effects. Hence, the authors have synthesized chondroitin sulfate/sodium polystyrene sulfonate–co-poly(acrylic acid) hydrogels by the free radical polymerization technique for the controlled release of ibuprofen. Sol-gel, porosity, swelling, and drug release studies were performed on the fabricated hydrogel. The pH-responsive behavior of the fabricated hydrogel was determined by both swelling and drug release studies in three different pH values, i.e., pH 1.2, 4.6, and 7.4. Maximum swelling and drug release were observed at pH 7.4, as compared to pH 4.6 and 1.2. Similarly, the structural arrangement and crosslinking of the hydrogel contents were confirmed by Fourier transform infrared spectroscopy (FTIR). Scanning electron microscopy (SEM) evaluated the hard and irregular surface with a few macrospores of the developed hydrogel, which may be correlated with the strong crosslinking of polymers with monomer content. Similarly, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) demonstrated the high thermal stability of the formulated hydrogel, as compared to pure polymers. A decrease in the crystallinity of chondroitin sulfate and sodium polystyrene sulfonate after crosslinking was revealed by powder X-ray diffraction (PXRD). Thus, considering the results, we can demonstrate that a developed polymeric network of hydrogel could be used as a safe, stable, and efficient carrier for the controlled release of ibuprofen.

γ-Irradiation crosslinking of graphene oxide/cellulose nanofiber/poly (acrylic acid) hydrogel as a urea sensing patch

Poly (acrylic acid) (PAA) nanocomposite hydrogel was fabricated as a sensing patch for non-invasive dual detection of urea in sweat. The hydrogel was prepared by γ-irradiation crosslinking of PAA solution incorporated with graphene oxide (GO) and cellulose nanofiber (CNF). With high water-sorption capacity and transparency, the hydrogel was suitable to accommodate coloring reagents and enzymes for colorimetric sensing of urea in sweat. The colorimetric sensor exhibited vivid color change towards the increase of urea concentration in a linear range of 40–80 mM covering a cut-off value (60 mM) for chronic kidney disease (CKD) indication. Furthermore, the hydrogel could be directly applied as a substrate for direct quantitation of urea in sweat by laser desorption ionization mass spectroscopy (LDI-MS). While CNF improved the mechanical properties of the hydrogel, GO played a key role in enhancing laser desorption ionization of urea in LDI-MS and increased the hydrogel functionalities. LDI-MS verified that GO/CNF/PAA hydrogel could act as a direct matrix for promoting urea ionization and these results corresponded well with the colorimetric sensor. Hence, this hydrogel patch might be a potential material to be applied in non-invasive and dual-detection of CKD in medical diagnosis.

Nanocellulose fine-tuned poly(acrylic acid) hydrogel for enhanced diclofenac removal

Hydrogel was recognized as one of the most promising materials for adsorption of pharmaceuticals and personal care products (PPCPs). The highly efficient bio-based nanocelluloses fine-tuned poly(acrylic acid) hydrogel (PAA/NC) adsorbent was constructed by adjusting aspect ratio, surface charge and crystallinity of NC. The cross-linked networks were fabricated through a single-step free-radical polymerization via steric effect and hydrogen bonds. The uniform three-dimensional structures with abundant macropores and mesopores were in-situ visualized by the cryogenic-scanning electron microscopy (Cryo-SEM). The diclofenac adsorption capacity of TEMPO oxidized cellulose nanofibers (TCNF) incorporated PAA hydrogel (PAA/TCNF, 559.8 mg·g−1) was circa 2.1 times higher than pristine PAA (293.5 mg·g−1) due to the elevated specific surface area, favorable spatial structure with unimpeded channels and abundant surface-charged carboxylic groups. Moreover, PAA/NC hydrogel exhibited a wide-pH applicability and high salinity tolerance. The adsorption was predominantly determined by hydrogen bonds, validated by XPS and FT-IR analysis. It was demonstrated developed PAA/NC hydrogel with unique porous structure significantly enhanced adsorption capacity for potential application in the purification of refractory organic pollutants-containing wastewater.

Preparation of a self-adhesive hydrogel and research on its flame-retardant properties

The spontaneous combustion of coal restricts the development of green coal mining. Hydrogels are often used to air-leakage blocking and prevent the spontaneous combustion of coal, but traditional hydrogels suffer from poor adhesion. Therefore, to prevent the spontaneous combustion of coal and improve the utilization rate of hydrogels, this study proposes a new type of fire-extinguishing self-adhesive hydrogel, polyacrylic acid-sodium alginate-tannic acid (PAA-SA-TA). The air-leakage blocking efficiency and inhibition rate of the PAA-SA-TA hydrogel were analyzed. The results showed that the air-leakage blocking efficiency and inhibition rate of the PAA-SA-TA hydrogel were 42.90% and 39.53% higher than those of a poly acrylic acid (PAA) hydrogel, respectively. In addition, the fire-extinguishing tests showed that compared with PAA and polyacrylic acid-tannic acid (PAA-TA) hydrogels, PAA-SA-TA evenly covered the surface of the burning coal body, densely wrapped the coal body, filled the cracks, and extinguished the fire without re-ignition. This study provides a new viscous hydrogel for the prevention and control of the spontaneous combustion of coal in mines.

Ammonium removal and recovery from effluent of AnMBR treating real domestic wastewater using polymeric hydrogel

Anaerobic membrane bioreactor (AnMBR) technology has been considered promising to transform domestic wastewater (DWW) treatment as a net energy producer via bioenergy recovery. However, ammonium-nitrogen (NH4+-N) in DWW cannot be removed by anaerobic process, which raises the risk of eutrophication and prevents the wide-scale adoption of AnMBRs. This study proposed adsorption/desorption by poly (acrylic acid) (PAA) hydrogel as the post-treatment of AnMBRs to remove and recover NH4+-N, thus simultaneously promoting AnMBR technology and the circular economy. Batch experiment results showed that NH4+-N could be rapidly adsorbed by PAA hydrogels within 30 min with excellent maximum adsorption capacities of 110.6–120.8 mg N/L (10–50 °C). Furthermore, PAA hydrogels retained 81.1 % of NH4+-N adsorption capacity when treating AnMBR effluent, preliminarily suggesting their practical feasibility in complex water matrix. Thereafter, PAA hydrogels were packed into a bench-scale fixed-bed column. Up to 98.5% of NH4+-N in AnMBR effluent could be captured in the hydrogel column at the breakthrough point at flow rate of 0.5 mL/min, achieving a polished effluent concentration of <1.5 mg N/L and thus meeting the strictest discharge regulations. The hydrogel column could be regenerated for 10 adsorption/desorption cycles with an insignificant decline in adsorption capacity of ∼4.7%, highlighting its excellent reusability. More importantly, we for the first time proposed the strategic recirculation of 1 mol/l HCl solution as eluent and obtained an NH4+-N enrichment factor of ∼10 over four rounds of adsorption/desorption, demonstrating the promise of this strategy to concentrate NH4+-N as resources. The economic analysis based on our experimental results showed that PAA hydrogel-based adsorption/desorption process coupled with eluent recirculation has the potential to remove and recover NH4+-N from AnMBR effluent cost-effectively. Overall, this study could potentially expand the application of AnMBRs and foster innovations in sustainable wastewater treatment.

Synthesis and characterization of pH-sensitive glucomannan-poly(acrylic acid) hydrogels for 5-aminosalicylic acid controlled delivery systems

In this study, glucomannan-poly(acrylic acid) hydrogels were synthesized under different conditions. The hydrogels consist of glucomannan and acrylic acid and are crosslinked by N,N-methylene-bis-(acrylamide). The structure and morphology of the hydrogels were investigated by using Fourier-transform infrared spectroscopy (FT-IR) and scanning electron microscope (SEM). The swelling ratio, biodegradation and pH-sensitive properties, relationship between hydrogel swelling rate and 5-ASA adsorption-desorption capacity, influence of medium pH on 5-ASA desorption, and 5-ASA adsorption kinetics were studied. The swelling ratio of the synthesized hydrogel samples is 16.70–56.21 times. This ratio is low in the pH 1.0 media and increases significantly in the pH 7,4 media. The hydrogels are biodegradable in the presence of cellulase (400 U·mg–1) in a pH 7.4 phosphate buffer at 37 °C (69.8% after ten days; the cellulase concentration 1.5 g·L­–1). The hydrogels exhibit high adsorption and desorption capacities for 5-ASA. The adsorption kinetics follows the pseudo-first-order model. These hydrogels can be applied to smart drug delivery systems.

Hydrochar-embedded carboxymethyl cellulose-g-poly(acrylic acid) hydrogel as stable soil water retention and nutrient release agent for plant growth

The cellulose-based hydrogel has been widely applied for soil water retention and nutrient release agents for several decades. Embedding the inorganic materials into hydrogels is an excellent strategy to improve the inherent limits of the cellulose-based hydrogel. Notably, municipal sludge-derived hydrochar (HC) has reduced the environmental burden and offered a potential hydrogel carrier to control water-retention and nutrient-release. However, the above function for plant growth of hydrochar-embedded carboxymethyl cellulose-g-poly(acrylic acid) (CMC-g-PAA/HC) is unknown, and relevant reports are lacking. This study investigated the water retention, nutrient release behavior, and effect of germination and plant growth of CMC-g-PAA/HC hydrogel. Characterization results showed that HC was successfully incorporated into CMC-g-PAA/HC with 6.0% higher thermostability, 7.2–21.0% lower swelling ratio (SR) in water, and substantial SR in phosphate solution (P-solution). The water loss rate of CMC-g-PAA/HC in P-solution or water owned a more significant temperature response (7.9–15.0 folds) than CMC-g-PAA (8.2–10.0 folds). Moreover, 4.0% higher n value and more 18.5% released P for CMC-g-PAA/HC were also observed. These phenomena were due to restricting the polymer chains movement and the water molecules diffusion inside the hydrogels with HC. Phytotoxicity assessments showed that HC in CMC-g-PAA/HC could effectively alleviate the inhibition effects on rape germination retained with 78.3% germination vigor and 80.0% germination ratio, even dramatically improved plant growth to 28 d. The results of this study demonstrated a new route for developing eco-friendly CMC-g-PAA/HC hydrogel, advantageous as a water retention agent and nutrient carrier in arid and semiarid regions.

Starch based mechanically tough hydrogel for effective removal of toxic metal ions from wastewater

Mechanically tough hydrogels have attracted incredible attention in numerous fields owing to their outstanding flexibility with extraordinary fatigue resistance. In this research, a new synthetic strategy was demonstrated to improve mechanical properties of starch grafted poly(acrylic acid) hydrogel by introducing a double cross-linked network. The design strategy includes the introduction of epichlorohydrin cross-linked starch into the poly(acrylic acid) chain. This cross-linked hydrogel possesses mechanical strength of 2.78 ± 0.58 MPa. More impressively, the hydrogel was also manifested noteworthy adsorption capacity for heavy metal ions for wastewater purification. Additionally, the hydrogel showed outstanding reusability due to its excellent mechanical strength. It has also prominent desorption ability to release the adsorbed metal ions from its network under the used condition. Thus, it was used for the subsequent cycles. This kind of mechanically strong bio-based hydrogel is promising as adept toxic heavy metal ions adsorbent, as it meets the demand for soft matter with remarkable mechanical properties to satisfy recyclability. Thus, the developed material may help to remove hazardous metal pollutants from contaminated water.

Effects of PGPR Bioinoculants, Hydrogel and Biochar on Growth and Physiology of Soybean under Drought Stress

ABSTRACT The drought ameliorative effects of poly(acrylic acid) hydrogel (HG), biochar (BC) and plant growth-promoting rhizobacteria (PGPR) were evaluated on soybean exposed to drought stress. Prior to sowing, soybean seeds were soaked for 3–4 h in the broth culture of Planomicrobium chinense (MF616408) and Pseudomonas putida (KX574857), while BC (5 g/kg soil) and HG (2 g/kg soil) were mixed with autoclaved soil. Plants were well watered and grown under natural conditions for 35 d, followed by 4 d of drought exposure. While drought stress negatively impacted plant growth, effects of individual application of BC, HG and PGPR in combating the drought stress were noteworthy and a predominant increase in plant biomass by BC and plant antioxidant enzymes (superoxide dismutase (SOD) and catalase (CAT)) and elevated soil nutrients by PGPR were observed. PGPR assisted HG in retaining the soil moisture content (SMC) and further elevated the leaf relative water content (LRWC) and fresh weight (FW) root. The combined application of HG and PGPR consortium was most effective in improving photosynthetic pigments, FW shoot and soil fertility status. Likewise, the combined application of BC and PGPR had stimulatory effects on plant osmoregulants, with BC combined with Pseudomonas putida significantly improving soil nutrient retention. It is inferred that HG and BC in combination with PGPR isolates and PGPR consortium are effective drought mitigating strategies.

Modelling viscoelastic relaxation mechanisms in thermorheologically complex Fe(III)-poly(acrylic acid) hydrogels.

Mechanical properties of hydrogels with reversible transition metal-polymer crosslinks can be flexibly tuned depending on the dissociation kinetics of the metal bond. We use rheology to investigate the sol-gel transition of a Fe(III)-poly(acrylic acid) network with varying crosslinker content and model the corresponding mechanical relaxation at different stages of gelation. The system transitions from an unentangled chain regime to a crosslink dissociation dominated regime, where the relaxation is governed by two timescales with different activation energies. To account for the interplay of chain and crosslinker dynamics, a time-temperature-superposition procedure is introduced for both processes separately, thus separating the dynamic processes in these thermorheologically complex dynamic networks. The activation energy of chain relaxation remains unchanged whether or not the chain participates in the network. To model contributions to the dynamic modulus of each process, we combine concepts from fractional viscoelasticity with a generalized Maxwell model, which describes the dynamics of an unentangled chain solution with reversible crosslinks. This allows us to quantify the evolution of viscoelastic parameters in the course of gelation, where we find that the terminal relaxation time of the gels increases less than expected at high crosslinker contents. This result is attributed to a facilitated crosslink exchange mechanism and a lower pH of the gel matrix.

An In Situ Incorporation of Acrylic Acid and ZnO Nanoparticles into Polyamide Thin Film Composite Membranes for Their Effect on Membrane pH Responsive Behavior.

This paper focuses on an in situ interfacial polymerization modification of polyamide thin film composite membranes with acrylic acid (AA) and zinc oxide (ZnO) nanoparticles. Consequent to this modification, the modified polyamide thin film composite (PA–TFC) membranes exhibited enhanced water permeability and Pb (II) heavy metal rejection. For example, the 0.50:1.50% ZnO/AA modified membranes showed water permeability of 29.85 ± 0.06 L·m−2·h−1·kPa−1 (pH 3), 4.16 ± 0.39 L·m−2·h−1·kPa−1 (pH 7), and 2.80 ± 0.21 L·m−2·h−1·kPa−1 1 (pH 11). This demonstrated enhanced pH responsive properties, and improved water permeability properties against unmodified membranes (2.29 ± 0.59 L·m−2·h−1·kPa−1, 1.79 ± 0.27 L·m−2·h−1·kPa−1, and 0.90 ± 0.21 L·m−2·h−1·kPa−1, respectively). Furthermore, the rejection of Pb (II) ions by the modified PA–TFC membranes was found to be 16.11 ± 0.12% (pH 3), 30.58 ± 0.33% (pH 7), and 96.67 ± 0.09% (pH 11). Additionally, the membranes modified with AA and ZnO/AA demonstrated a significant pH responsiveness compared to membranes modified with only ZnO nanoparticles and unmodified membranes. As such, this demonstrated the swelling behavior due to the inherent “gate effect” of the modified membranes. This was illustrated by the rejection and water permeation behavior, hydrophilic properties, and ion exchange capacity of the modified membranes. The pH responsiveness for the modified membranes was due to the –COOH and –OH functional groups introduced by the AA hydrogel and ZnO nanoparticles.

Highly sensitive and wearable self-powered sensors based on a stretchable hydrogel comprising dynamic hydrogen bond and dual coordination bonds

Most of the reported hydrogel-based strain sensors need an external power supply to translate mechanical deformations into detectable electrical signals. Herein, we prepare a gelatin-graphene oxide-ferric ion cross-linked poly(acrylic acid) (Gel-GO-PAA-Fe 3+ ) hydrogel for constructing a self-powered strain sensor. The hydrogel exhibit favorable self-healing, stretchable and resilient properties due to the formation of dynamic hydrogen bond and dual coordination bond within the gel matrix. With a constant elongation of 400% and high conductivity of 0.50 S/m, the hydrogel-based sensor can monitor various human movements. Interestingly, the hydrogel electrolyte integrating zinc anode and MnO 2 /graphite air cathode are developed into a flexible zinc-air battery, and then connected to a fixed resistor to achieve the self-powered strain sensor. By transforming the resistance variations caused by applied strain into voltage output signals, the integrated system could monitor human activities in a wide range without external power, demonstrating its huge practical application in wearable electronics for sensing.

Polymeric Hydrogels for Controlled Release of Black Tea and Coffee Extracts for Topical Applications.

Tea and coffee are popular beverages. Both are also used in topical applications, such as ultraviolet (UV) protection, anti-aging, and wound healing. However, the impact of tea and coffee extract on skin cells is minimally explored. This study investigated the direct exposure of tea and coffee extract on skin cells using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. It was found that direct exposure of tea and coffee to skin cells can be toxic at a high dose on prolonged exposure (72 h). Therefore, it was hypothesized that a formulation providing a controlled release of tea and coffee could improve their skin compatibility. Thermally cross-linked poly(acrylic acid) hydrogels loaded with tea and coffee extracts (with and without milk) were formulated and optimized. The release profiles of these hydrogels were studied at varying loading efficiency. Milk addition with tea extract retarded the tea extract release from hydrogel while minimally affecting the coffee release. This effect was due to the molecular interaction of tea with milk components, showing changes in size, zeta potential, and polydispersity index. The release study best fitted the Korsmeyer–Peppas release model. Skin cells exposed to tea or coffee-loaded hydrogel showed normal skin cell morphology under fluorescence microscopic analysis. In conclusion, the hydrogels controlled the tea and coffee release and showed biocompatibility with skin cells. It can potentially be used for skin applications.

Synthesis, Characterization, In-Vitro and In-Vivo Evaluation of Ketorolac Tromethamine-Loaded Hydrogels of Glutamic Acid as Controlled Release Carrier.

Glutamic acid-co-poly(acrylic acid) (GAcPAAc) hydrogels were prepared by the free radical polymerization technique using glutamic acid (GA) as a polymer, acrylic acid (AAc) as a monomer, ethylene glycol dimethylacrylate (EGDMA) as a cross-linker, and ammonium persulfate (APS) as an initiator. Increase in gel fraction was observed with the increasing concentration of glutamic acid, acrylic acid, and ethylene glycol dimethylacrylate. High percent porosity was indicated by developed hydrogels with the increase in the concentration of glutamic acid and acrylic acid, while a decrease was seen with the increasing concentration of EGDMA, respectively. Maximum swelling and drug release was exhibited at high pH 7.4 compared to low pH 1.2 by the newly synthesized hydrogels. Similarly, both swelling and drug release increased with the increasing concentration of glutamic acid and acrylic acid and decreased with the increase in ethylene glycol dimethylacrylate concentration. The drug release was considered as non-Fickian transport and partially controlled by viscoelastic relaxation of hydrogel. In-vivo study revealed that the AUC0–∞ of fabricated hydrogels significantly increased compared to the drug solution and commercial product Keten. Hence, the results indicated that the developed hydrogels could be used as a suitable carrier for controlled drug delivery.

Formulation and In-Vitro Characterization of pH-Responsive Semi-Interpenetrating Polymer Network Hydrogels for Controlled Release of Ketorolac Tromethamine

Ketorolac tromethamine is a non-steroidal anti-inflammatory drug used in the management of severe pain. The half-life of Ketorolac tromethamine is within the range of 2.5–4 h. Hence, repeated doses of Ketorolac tromethamine are needed in a day to maintain the therapeutic level. However, taking several doses of Ketorolac tromethamine in a day generates certain complications, such as acute renal failure and gastrointestinal ulceration. Therefore, a polymeric-controlled drug delivery system is needed that could prolong the release of Ketorolac tromethamine. Therefore, in the current study, pH-responsive carbopol 934/sodium polystyrene sulfonate-co-poly(acrylic acid) (CP/SpScPAA) hydrogels were developed by the free radical polymerization technique for the controlled release of Ketorolac tromethamine. Monomer acrylic acid was crosslinked with the polymers carbopol 934 and sodium polystyrene sulfonate by the cross-linker N’,N’-methylene bisacrylamide. Various studies were conducted to evaluate and assess the various parameters of the fabricated hydrogels. The compatibility of the constituents used in the preparation of hydrogels was confirmed by FTIR analysis, whereas the thermal stability of the unreacted polymers and developed hydrogels was analyzed by TGA and DSC, respectively. A smooth and porous surface was indicated by SEM. The crystallinity of carbopol 934, sodium polystyrene sulfonate, and the prepared hydrogels was evaluated by PXRD, which revealed a reduction in the crystallinity of reactants for the developed hydrogels. The pH sensitivity of the polymeric hydrogel networks was confirmed by dynamic swelling and in vitro release studies with two different pH media i.e., pH 1.2 and 7.4, respectively. Maximum swelling was exhibited at pH 7.4 compared to pH 1.2 and, likewise, a greater percent drug release was perceived at pH 7.4. Conclusively, we can demonstrate that the developed pH-sensitive hydrogel network could be employed as a suitable carrier for the controlled delivery of Ketorolac tromethamine.

Grafting mechanism of poly(acrylic acid) from silica particles during the gelation process

This study explores particle behaviors with regard to crosslinking mechanisms in an effort to understand the characteristics of hybrid gels. We focus on how particles provide a polymer grafting platform through radical polymerization, through interrogation at different gelation times. Silica-poly(acrylic acid) hydrogels were prepared by introducing γ-ray-treated silica particles, which serve as both crosslinkers and initiators. The gelation and structural characteristics were investigated using dynamic light scattering, small-angle neutron scattering, microscopy, and spectroscopy measurements. We found that the incipient gels contain various types of particles stemming from the irregularity of polymer grafting. The particle sub-units were separated by pH controls from the other components generated from the gelation. In particular, the sub-units of core-shell particles were observed from the stage, which is close to the gel threshold. Polymer layers grafted to silica surface through chemical bonds show Si–O–C bonds, and they supported solution stability with stretched chains in aqueous solutions of high pH. The results suggest that sporadic grafting generates multiple components during gelation and could establish inhomogeneities in the consequent gels. This study provides details regarding the behavior of the silica particles during gelation and improves the understanding of the crosslinking process of nanocomposites.

Stretchable, rapid self-healing guar gum-poly(acrylic acid) hydrogels as wearable strain sensors for human motion detection based on Janus graphene oxide

Wearable strain sensors have received widespread attention in research fields due to their applications in human motion detection. In this manuscript, the fabrication of functionalized Janus graphene oxide (GO) nanosheets were used by Pickering emulsion template. Polypyrrole (PPy) and poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) were asymmetrically grafted on the two sides of GO (GO@PPy/PDMAEMA Janus NS), which successfully applied to synthesize Janus NS/guar gum-poly(acrylic acid) (GG-PAA) self-healing nanocomposite hydrogels. The outstandingly improved self-healing efficiency (92.8% for 2 h) and mechanical properties (strength of 4.12 MPa and toughness of 873.8%) of nanocomposite hydrogels were mainly supported by the collaborative effect of reversible electrostatic interactions, multiple hydrogen bonds and metal-ligand coordination. Moreover, the hydrogels exhibited strain sensitivity and could be able to monitor a variety of human motions, which have outstanding application prospects in wearable flexible sensors.

Fabrication and In Vitro Evaluation of pH-Sensitive Polymeric Hydrogels as Controlled Release Carriers.

The purpose of the current investigation was to develop chondroitin sulfate/carbopol-co-poly(acrylic acid) (CS/CBP-co-PAA) hydrogels for controlled delivery of diclofenac sodium (DS). Different concentrations of polymers chondroitin sulfate (CS), carbopol 934 (CBP), and monomer acrylic acid (AA) were cross-linked by ethylene glycol dimethylacrylate (EGDMA) in the presence of ammonium peroxodisulfate (APS) (initiator). The fabricated hydrogels were characterized for further experiments. Characterizations such as Scanning electron microscopy (SEM), Thermogravimetric analysis (TGA), Differential scanning calorimetry (DSC), Powder X-ray diffractometry (PXRD), and Fourier transform infrared spectroscopy (FTIR) were conducted to understand the surface morphology, thermodynamic stability, crystallinity of the drug, ingredients, and developed hydrogels. The swelling and drug release studies were conducted at two different pH mediums (pH 1.2 and 7.4), and pH-dependent swelling and drug release was shown due to the presence of functional groups of both polymers and monomers; hence, greater swelling and drug release was observed at the higher pH (pH 7.4). The percent drug release of the developed system and commercially available product cataflam was compared and high controlled release of the drug from the developed system was observed at both low and high pH. The mechanism of drug release from the hydrogels followed Korsmeyer–Peppas model. Conclusively, the current research work demonstrated that the prepared hydrogel could be considered as a suitable candidate for controlled delivery of diclofenac sodium.

Scalable Wood Hydrogel Membrane with Nanoscale Channels.

Many efforts have been dedicated to exploring nanofluidic systems for various applications including water purification and energy generation. However, creating robust nanofluidic materials with tunable channel orientations and numerous nanochannels or nanopores on a large scale remains challenging. Here, we demonstrate a scalable and cost-effective method to fabricate a robust and highly conductive nanofluidic wood hydrogel membrane in which ions can transport across the membrane. The ionically conductive balsa wood hydrogel membrane is fabricated by infiltrating poly(vinyl alcohol) (PVA)/acrylic acid (AA) hydrogel into the inherent bimodal porous wood structure. The balsa wood hydrogel membrane demonstrates a 3 times higher strength (52.7 MPa) and 2 orders of magnitude higher ionic conductivity compared to those of natural balsa both in the radial direction (coded as R direction) and along the longitudinal direction (coded as L direction). The ionic conductivity of the balsa wood hydrogel membrane is 1.29 mS cm-1 along the L direction and nearly 1 mS cm-1 along the R direction at low salt concentrations (up to 10 mM). In addition, the surface-charge-governed ion transport also renders the balsa wood hydrogel membrane able to harvest electrical energy from salinity gradients. A current density of up to 17.65 μA m-2 and an output power density of 0.56 mW m-2 are obtained under a 1000-fold salt concentration gradient, which can be further improved to 2.7 mW m-2 by increasing the AA content from 25 wt % to 50 wt %. These findings make contributions to develop energy-harvesting systems and other nanofluidic devices from sustainable wood materials.

Impact of Hydrogels on Early Growth of Maize in Sandy Regosols: Progress towards Improving Growth Performance by Enhancing Water and Nutrients Retention Capacity of the Soil

Super Absorbent Polymers or hydrogels are known for enhancing the water-holding properties of soils. This experiment was conducted to evaluate the influence of four different locally-produced hydrogels and one commercially available hydrogel on the early growth of maize in sandy Regosols. Maize variety, Pacific 984 was tested with six treatments in Randomized Complete Block Design. T1 - Reference hydrogel (Sodium polyacrylate-based), T2 - Acrylic acid and acrylamide-based hydrogel where urea has incorporated chemically up to 11.08% (g/g), T3 - without urea incorporating to the hydrogel used in T2, T4 - similar to T2, but urea incorporated only up to 6.17% (g/g), T5- agriculture grade commercial hydrogel (Potassium polyacrylate-based) and T6 - control (without hydrogel) were used for the study. Soil properties and plant growth parameters were quantified. A significant difference was observed in soil pH, total N and available P among treatments after one month of application. Treatment 2 showed the highest total N (0.19%) while T4 showed the highest P (18.94 ppm). The highest growth performances were given by locally produced hydrogels over commercial hydrogel and control treatments. Treatment 2 recorded the highest leaf area (1153.3 cm2/plant), plant height (128.90 cm) and total dry mass production (49.36 g/plant) while T4 has recorded the highest stem girth (4.87 cm). It was observed that locally produced hydrogels including the hydrogel without incorporating urea, have given superior performance over commercial hydrogels. Therefore, it can be concluded that locally produced hydrogel-formulations can enhance the growth of maize effectively than imported commercial hydrogels.