Synthesis of composite hydrogel of glutamic acid, gum tragacanth, and anionic polyacrylamide by electron beam irradiation for uranium (VI) removal from aqueous samples: Equilibrium, kinetics, and thermodynamic studies

Enhanced dye sequestration with natural polysaccharides-based hydrogels: A review

Due to the expansion of industrial activities, the concentration of dyes in water has been increasing. The dire need to remove these pollutants from water has been heavily discussed. This study focuses on the reproducible and sustainable solution for wastewater treatment and dye annihilation challenges. Adsorption has been rated the most practical way of the several decolorization procedures due to its minimal initial investment, convenient utility, and high-performance caliber. Hydrogels, which are three-dimensional polymer networks, are notable because of their potential to regenerate, biodegrade, absorb bulky amounts of water, respond to stimuli, and have unique morphologies. Natural polysaccharide hydrogels are chosen over synthetic ones because they are robust, bioresorbable, non-toxic, and cheaply accessible. This study has covered six biopolymers, including chitosan, cellulose, pectin, sodium alginate, guar gum, and starch, consisting of their chemical architecture, origins, characteristics, and uses. The next part describes these polysaccharide-based hydrogels, including their manufacturing techniques, chemical alterations, and adsorption effectiveness. It is deeply evaluated how size and shape affect the adsorption rate, which has not been addressed in any prior research. To assist the readers in identifying areas for further research in this subject, limitations of these hydrogels and future views are provided in the conclusion.

Removal of diclofenac sodium from aqueous solution using different ionic liquids functionalized tragacanth gum hydrogel prepared by radiation technique

Diclofenac sodium (DCF) was reported as an important emerging environmental pollutant and its removal from wastewater is very urgent. In this study, different alkyl substituted ionic liquids (1-alkyl -3-vinyl- imidazolium bromide [CnVIm]Br, n = 4, 6, 8, 10, 12) functionalized tragacanth gum (TG-CnBr) are prepared by radiation induced grafting and crosslinking polymerization. The adsorption behaviors of ionic liquids functionalized tragacanth gum for diclofenac sodium from aqueous solutions are examined. The adsorption capacity of TG-CnBr for diclofenac sodium increases with the increasing of alkyl chain length of the imidazolium cation and the hydrophobicity of the hydrogels. The maximum adsorption capacity by TG-C12Br for diclofenac sodium at 30, 40 and 50 °C were 327.87, 310.56 and 283.29 mg/g, respectively. The adsorption of TG-C12Br towards diclofenac sodium was little decreased with NaCl increasing. The removal efficiency was still remained 94.55 % within 5 adsorption-desorption cycles by 1 M HCl. Also, the adsorption mechanism including electrostatic attraction, hydrophobic interaction, hydrogen bonding, and π - π interaction was proposed.

Recent advances in biopolymer-based hydrogels and their potential biomedical applications

Hydrogels are three-dimensional networks of polymer chains containing large amounts of water in their structure. Hydrogels have received significant attention in biomedical applications owing to their attractive physicochemical properties, including flexibility, softness, biodegradability, and biocompatibility. Different natural and synthetic polymers have been intensely explored in developing hydrogels for the desired applications. Biopolymers-based hydrogels have advantages over synthetic polymers regarding improved cellular activity and weak immune response. These properties can be further improved by grafting with other polymers or adding nanomaterials, and they structurally mimic the living tissue environments, which opens their broad applicability. The hydrogels can be physically or chemically cross-linked depending on the structure. The use of different biopolymers-based hydrogels in biomedical applications has been reviewed and discussed earlier. However, no report is still available to comprehensively introduce the synthesis, advantages, disadvantages, and biomedical applications of biopolymers-based hydrogels from the material point of view. Herein, we systematically overview different synthesis methods of hydrogels and provide a holistic approach to biopolymers-based hydrogels for biomedical applications, especially in bone regeneration, wound healing, drug delivery, bioimaging, and therapy. The current challenges and prospects of biopolymers-based hydrogels are highlighted rationally, giving an insight into the progress of these hydrogels and their practical applications.

Selective, rapid extraction of uranium from aqueous solution by porous chitosan-phosphorylated chitosan-amidoxime macroporous resin composite and differential charge calculation

Herein, a new porous chitosan-phosphorylated chitosan-amidoxime macroporous resin composite (PCAR) was designed and synthesized for the rapid and selective extraction of uranium resources from aqueous solution. This study showed that PCAR exhibited excellent adsorption toward uranium in a pH range of 5-9. The dynamic adsorption process aligned with the quasi-second-order kinetic model and corresponded to the chemical adsorption process. The maximum adsorption capacity was 561.28 mg·g-1 at pH 6 and 308 K. Mechanism analysis showed that the synergistic effect of the amidoxime group (-(NH2)C=N-OH), PO, and -NH2 on the PCAR surface improved the uranium adsorption performance. The differential charge density indicated that the amidoxime and phosphate groups provide lone-pair electrons for the adsorption of UO22+ and their synergistic effect improves the UO22+ adsorption performance of PCAR. The uranium distribution coefficients of PCAR and CAR are 4.6 and 2.4 times those of vanadium, respectively. These results indicate that phosphorylation can ameliorate the disadvantage of competitive vanadium adsorption of the amidoxime adsorbent. In addition, PCAR exhibits good reusability and stable adsorption capacity after five adsorption-desorption cycles. Hence, PCAR has excellent potential for uranium extraction from aqueous solution.

Advances in gum-based hydrogels and their environmental applications

Gum-based hydrogels (GBHs) have been widely employed in diverse water purification processes due to their environmental properties, and high absorption capacity. More desired properties of GBHs such as biodegradability, biocompatibility, material cost, simplicity of manufacture, and wide range of uses have converted them into promising materials in water treatment processes. In this review, we explored the application of GBHs to remove pollutants from contaminated waters. Water resources are constantly being contaminated by a variety of harmful effluents such as heavy metals, dyes, and other dangerous substances. A practical way to remove chemical waste from water as a vital component is surface adsorption. Currently, hydrogels, three-dimensional polymeric networks, are quite popular for adsorption. They have more extensive uses in several industries, including biomedicine, water purification, agriculture, sanitary products, and biosensors. This review will help the researcher to understand the research gaps and drawbacks in this field, which will lead to further developments in the future.

Hybrid gum tragacanth/sodium alginate hydrogel reinforced with silver nanotriangles for bacterial biofilm inhibition

Biomaterial associated bacterial infections are indomitable to treatment due to the rise in antibiotic resistant strains, thereby triggering the need for new antibacterial agents. Herein, composite bactericidal hydrogels were formulated by incorporating silver nanotriangles (AgNTs) inside a hybrid polymer network of Gum Tragacanth/Sodium Alginate (GT/SA) hydrogels. Physico-chemical examination revealed robust mechanical strength, appreciable porosity and desirable in vitro enzymatic biodegradation of composite hydrogels. The antibacterial activity of AgNT-hydrogel was tested against planktonic and biofilm-forming Gram-negative (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus) bacteria. For all the strains, AgNT-hydrogel showed a dose-dependent decrease in bacterial growth. The addition of AgNT-hydrogels (40-80 mg ml^-1) caused 87% inhibition of planktonic biomass and up to 74% reduction in biofilm formation. Overall, this study proposes a promising approach for designing antibacterial composite hydrogels to mitigate various forms of bacterial infection.

Surface ion-imprinted brewer's spent grain with low template loading for selective uranyl ions adsorption from simulated wastewater

Efficient removal of uranyl ions from wastewater requires excellent selectivity of the adsorbents. Herein, we report a new strategy using a high monomer/template molar ratio of 500:1 to prepare surface ion-imprinted brewer's spent grain (IIP-BSG) for selective U(VI) removal using binary functional monomers (2-hydroxyethyl methacrylate and diethyl vinylphosphonate) with high site accessibility and easy template removal. IIP-BSG exhibits a maximum U(VI) adsorption capacity of 165.7 mg/g, a high selectivity toward U(VI) in the presence of an excess amount of Eu(III) (Eu/U molar ratio = 20), a good tolerance of salinity, and a high reusability. In addition, mechanism studies have revealed electrostatic interaction and a coordination of uranyl ions by carboxyl and phosphoryl groups, the predominant contribution of high-energy (specific) sites during selective adsorption, and internal mass transfer as the rate-controlling step of U(VI) adsorption. Furthermore, IIP-BSG shows great potentials to separate U(VI) from lanthanides in simulated nuclear wastewater (pH₀ = 3.5) and selectively concentrate U(VI) from simulated mine water (pH₀ = 7.1). This study proves that the ion-imprinting effect can be achieved using a very low template amount with reduced production cost and secondary pollution, which benefits large-scale promotion of the ion-imprinted materials for selective uranyl ions removal.

Statistical evaluation of liquid phase sequestration of acridine orange and Cr6+ by novel mesoporous glutamic acid-g-polyacrylamide/plaster of paris/riboflavin hydrogel nanocomposite

The adsorption of acridine orange and Cr⁶⁺ ion onto plaster of paris reinforced glutamic acid-grafted-polyacrylamide hydrogel nanocomposite modified with riboflavin, Glu-g-PAM/POP/Rb HNC was studied. The Glu-g-PAM/POP/Rb HNC was physico-chemically characterized by Fourier transform infrared spectroscopy, X-ray diffraction analysis, scanning electron microscopy coupled with energy dispersive X-ray spectroscopy, transmission electron microscopy and Brunauer-Emmett-Teller analysis. The specific surface area, pore volume and pore diameter were 15.48 m²/g, 0.015 cm³/g and 4.23 nm, respectively. Adsorption process was strategized by response surface methodology (RSM) based on a 3-level 5-factor (initial solution pH, contact time, adsorbent dose, initial adsorbate concentration and temperature) central composite design (CCD), and validity of the estimated parameters was statistically evaluated using analysis of variance (ANOVA). The optimized operating variables were: pH (AO = 10; Cr⁶⁺ = 4.15), contact time (AO = 60 min; Cr⁶⁺ = 59 min), adsorbent dose (0.8 g/L), initial adsorbate concentration (60 mg/L) and temperature (298 K). Isotherm results were coincident with Langmuir isotherm model. The experimental kinetic adsorption data was congruous with pseudo-second order model, with the uptake rate controlled by both intraparticle and liquid film diffusions. The relatively high Langmuir saturation capacity of 202.63 mg AO/g and 143.68 mg Cr⁶⁺/g, supported by the decent recyclability up to four times affirmed the promising performance of the adsorbent. The efficacy of the adsorbent for simultaneous removal of AO and Cr⁶⁺ from bi-component system was assessed. The possible adsorption mechanism mainly involved hydrogen bonding, van der Waals forces, electrostatic and π-π interactions. Adsorption of AO and Cr⁶⁺ onto Glu-g-PAM/POP/Rb HNC was feasible and exothermic as revealed by the thermodynamic parameters. The findings demonstrated superior adsorbent efficacy for the seizure of pollutants, particularly AO and Cr⁶⁺ from aqueous solution.

One-pot synthesis of brewer's spent grain-supported superabsorbent polymer for highly efficient uranium adsorption from wastewater

High-efficient and fast adsorption of uranium is important to reduce the hazards caused by the uranium contamination of water environment due to the increased human activities. Herein, brewer's spent grain (BSG)-supported superabsorbent polymers (SAP) with different cross-linking densities are prepared as cheap and eco-friendly adsorbents for the first time via one-pot swelling and graft polymerization. A 7 wt% NaOH solution is used to swell BSG before grafting and subsequently neutralize the acrylic acid to control the reaction rate without producing alkaline wastewater. Compared with the traditional methods, swelling improves the grafting density and the utilization of raw materials due to the increased disorder degree of the BSG fibers. This results in the grafting of abundant carboxyl and amide groups onto the BSG backbone, forming a strongly hydrophilic polymer network of the BSG-SAP. Compared with the reference polymers without BSG, BSG-SAP presents higher adsorption capacity and enhanced reusability. The highly cross-linked BSG-SAP (BSG-SAP-H) shows an outstanding adsorption capacity of U(VI) (1465 mg/g at pH₀ = 4.6), a fast adsorption rate (81% of equilibrium adsorption capacity in 15 min), and a high selectivity in the presence of competing ions. Adsorption mechanism studies reveal the involvement of amide groups, a bidentate binding structure between UO₂²⁺ and the carboxyl groups, and a cation exchange between Na⁺ and UO₂²⁺. More importantly, the adsorption capacity of BSG-SAP-H reaches 254.4 mg/g in the fixed-bed column experiment at a low initial concentration (c₀(U) = 30 mg/L) and keeps 80% of the adsorption capacity after four cycles, indicating a great potential for uranium removal from wastewater. This work shows a suitable approach to explore the untreated biomass to prepare SAP with enhanced adsorption performance via a general and low-cost strategy.

Molecular Dynamics-Assisted Design of High Temperature-Resistant Polyacrylamide/Poloxamer Interpenetrating Network Hydrogels

Polyacrylamide has promising applications in a wide variety of fields. However, conventional polyacrylamide is prone to hydrolysis and thermal degradation under high temperature conditions, resulting in a decrease in solution viscosity with increasing temperature, which limits its practical effect. Herein, combining molecular dynamics and practical experiments, we explored a facile and fast mixing strategy to enhance the thermal stability of polyacrylamide by adding common poloxamers to form the interpenetrating network hydrogel. The blending model of three synthetic polyacrylamides (cationic, anionic, and nonionic) and poloxamers was first established, and then the interaction process between them was simulated by all-atom molecular dynamics. In the results, it was found that the hydrogen bonding between the amide groups on all polymers and the oxygen-containing groups (ether and hydroxyl groups) on poloxamers is very strong, which may be the key to improve the high temperature resistance of the hydrogel. Subsequent rheological tests also showed that poloxamers can indeed significantly improve the stability and viscosity of nonionic polyacrylamide containing only amide groups at high temperatures and can maintain a high viscosity of 3550 mPa·S at 80 °C. Transmission electron microscopy further showed that the nonionic polyacrylamide/poloxamer mixture further formed an interpenetrating network structure. In addition, the Fourier transform infrared test also proved the existence of strong hydrogen bonding between the two polymers. This work provides a useful idea for improving the properties of polyacrylamide, especially for the design of high temperature materials for physical blending.

Efficient removal of U(VI) in acidic environment with spent coffee grounds derived hydrogel

In this study, humic-like substances (HLSs) was extracted from spent coffee grounds (SCGs), and it together with poly acrylic acid (PAA), was used for the first time to synthesize hydrogel material, namely HLSs/PAA gel, by one-step radical polymerization. Its maximum theoretical sorption capacity toward U(VI) at pH 3.00 was 661.01 mg/g, and it could decrease the concentration of U(VI) in acidic actual groundwater from 0.2537 to 0.0003 mg/L, showing that the gel had excellent U(VI) removal efficiency in acidic environment. The SEM characterization of HLSs/PAA gel showed that its macroporous network structure maintained well after the sorption process, indicating that the gel had excellent acid-resistant property. Moreover, the gel exhibited excellent anti-interference performance in the interfering ions effect experiment. The gel integrates the merits of excellent U(VI) sorption properties, stability and anti-interference performance in acidic environment, and has promising application prospects in the remediation of acidic uranium wastewater.

Deciphering the adsorption potential of a functionalized green hydrogel nanocomposite for aspartame from aqueous phase

Herein, a functionalized green hydrogel nanocomposite based on carboxymethylated gum tragacanth and nanobentonite (GTBCH) was designed via free-radical polymerization approach for the elimination of Aspartame (AS) from wastewater. The GTBCH fabrication was validated by Fourier Transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX) techniques. Central composite design (CCD) was efficaciously applied to determine the quadratic polynomial approach for predicting the adsorption capacity (q_e) of AS. The optimum sequestration conditions were dosage (0.8 g L^‒1), agitation time (35 min) initial AS concentration (60 mg L^-1), pH (6) and temperature (308 K). The CCD results revealed that dosage of GTBCH and initial concentration have greater impact on q_e followed by pH, time, and temperature. The significant adsorption capacity (392.04 mg g^-1), calculated from Langmuir model, could be attributed to the stronger interactions prevalent between AS and GTBCH. Diffusion investigations depicted the uptake of AS via surface adsorption, liquid film and intraparticle diffusion, respectively. Ionic strength and real water have minor effect on the adsorption capacity demonstrating electrostatic interaction has least impact in adsorption process. The pHzpc, FTIR and XPS investigations revealed hydrogen bonding, n-π and van der Waals interactions as the principal removal mechanisms. Robust design, high adsorption capacity, eco-friendly facets along with excellent reusability indicated the GTBCH as a competent adsorbent for AS decontamination from wastewater.

Robust Conductive Hydrogels with Ultrafast Self-Recovery and Nearly Zero Response Hysteresis for Epidermal Sensors

Robust conductive hydrogels are in great demand for the practical applications of smart soft robots, epidermal electronics, and human–machine interactions. We successfully prepared nanoparticles enhanced polyacrylamide/hydroxypropyl guar gum/acryloyl-grafted chitosan quaternary ammonium salt/calcium ions/SiO₂ nanoparticles (PHC/Ca²⁺/SiO₂ NPs) conductive hydrogels. Owing to the stable chemical and physical hybrid crosslinking networks and reversible non-covalent interactions, the PHC/Ca²⁺/SiO₂ NPs conductive hydrogel showed good conductivity (~3.39 S/m), excellent toughness (6.71 MJ/m³), high stretchability (2256%), fast self-recovery (80% within 10 s, and 100% within 30 s), and good fatigue resistance. The maximum gauge factor as high as 66.99 was obtained, with a wide detectable strain range (from 0.25% to 500% strain), the fast response (25.00 ms) and recovery time (86.12 ms), excellent negligible response hysteresis, and good response stability. The applications of monitoring the human’s body movements were demonstrated, such as wrist bending and pulse tracking.

Synthesis of gum tragacanth-grafted pentapolymer hydrogels for As(III) exclusion: Roles of microwaves, RSM optimization, and DFT studies

Microwave assisted homogeneous heating, selectivity in radical formation, and the faster polymerization facilitate the synthesis, structures, properties, and the higher branching associated stability of multifunctional multipolymers. Thus, the optimum gum tragacanth (GMTR)-grafted pentapolymer hydrogel/ HG2 was synthesized from three monomers, i.e., cis-butenedioic acid (cBDA), N-hydroxymethylacryalamide (NHMAm), and 2-(methacryloyloxy)ethanol (MAOE), and in situ generated 2-(3-((hydroxymethyl)amino)-3-oxopropoxy)ethyl-2-methylbutanoate (CM1) and 2-hydroxyethyl 3-(N-(hydroxymethyl)-2-methylbutanamido)-2-methylpropanoate (CM2) comonomers through microwave assisted facile polymerization in aqueous medium. Here, twenty-one GMTR-grafted-[cBDA-co-CM1-co-NHMAm-co-CM2-co-MAOE/ HG1] hydrogels were prepared by using variable amounts of synthesis parameters, of which the optimum HG2 was chosen for the scale-up repetitive As(III)-exclusion. RSM was used to measure the optimum power-temperature-time of microwave irradiation. The structures of HG1, HG2, and As(III)-adsorbed HG2/ As(III)-HG2, in situ anchored comonomers, GMTR-grafting, reusability, thermostability, and surface phenomena were comprehended by XPS, NMR, UV-vis, FTIR, TG, XRD, DLS, and SEM analyses; pH_PZC; network parameters; and thermodynamic variables. The geometries, electronic structures, and variable coordinations of As(III) with HG2 were investigated through DFT studies of HG2 and As(OH)₃-HG2. The highest exclusion efficiency of 25 mg HG2 within 5-100 mg L^-1 As(III) and at 298 K was 192.91 mg g^-1, which was significantly higher than that of HG1.

Gum Tragacanth (GT): A Versatile Biocompatible Material beyond Borders

The use of naturally occurring materials in biomedicine has been increasingly attracting the researchers’ interest and, in this regard, gum tragacanth (GT) is recently showing great promise as a therapeutic substance in tissue engineering and regenerative medicine. As a polysaccharide, GT can be easily extracted from the stems and branches of various species of Astragalus. This anionic polymer is known to be a biodegradable, non-allergenic, non-toxic, and non-carcinogenic material. The stability against microbial, heat and acid degradation has made GT an attractive material not only in industrial settings (e.g., food packaging) but also in biomedical approaches (e.g., drug delivery). Over time, GT has been shown to be a useful reagent in the formation and stabilization of metal nanoparticles in the context of green chemistry. With the advent of tissue engineering, GT has also been utilized for the fabrication of three-dimensional (3D) scaffolds applied for both hard and soft tissue healing strategies. However, more research is needed for defining GT applicability in the future of biomedical engineering. On this object, the present review aims to provide a state-of-the-art overview of GT in biomedicine and tries to open new horizons in the field based on its inherent characteristics.

Fast photothermal poly(NIPAM-co-β-cyclodextrin) supramolecular hydrogel with self-healing through host-guest interaction for intelligent light-controlled switches

A graphene oxide/poly(N-isopropylacrylamide-co-β-cyclodextrin) (GO/poly(NIPAM-co-β-CD)) hydrogel has been synthesized through host-guest interaction between β-cyclodextrin (β-CD) and the isopropyl group of N-isopropylacrylamide (NIPAM). The product exhibits rapid responses to the stimuli of temperature and near-infrared (NIR) irradiation, self-healing properties, and excellent mechanical properties. The host-guest interaction serves as the main physical cross-linker, while a hydrogen bond between the hydroxyl group of β-CD, GO sheets and amide group of NIPAM acts as a secondary cross-linker. The volume phase transition temperature and NIR response rate of such a hydrogel are controlled by its contents of β-CD and GO. The obtained hydrogels showing excellent properties might be applied in remote contactless control devices in advanced smart technologies. Based on the excellent characteristics of the hydrogels, remote light-controlled switches have been designed, and more applications will be explored, such as intelligent light-controlled drivers and soft robots.

Design of a pseudo stir bar sorptive extraction using graphenized pencil lead as the base of the molecularly imprinted polymer for extraction of nabumetone

Molecularly imprinted polymer (MIP) was synthesized through the coprecipitation method on the graphene oxide anchored pencil lead as a substrate for the first time and applied as an efficient sorbent for pseudo stir bar sorptive extraction of nabumetone. The extracted analyte was determined by a novel spectrophotometric method based on the aggregation of silicate sol-gel stabilized silver nanoparticles in the presence of the analyte. The synthesized polymer was characterized using Fourier transform infrared spectroscopy and field emission scanning electron microscopy. Optimization of important parameters affecting the extraction efficiency was done using central composite design whereas the spectrophotometric method was optimized via one at a time variable. Under the optimal conditions, the calibration curve exhibited linearity in the concentration range of 1.5-20.0 μg L^-1. A limit of detection of 0.20 μg L^-1, an enhancement factor of 393 and relative standard deviations (at 10 μg L^-1, n = 6) of 4.6% and 8.1% for intra- and inter-day analysis were obtained. The developed procedure was successfully utilized for the quantification of traces of nabumetone in tap water and biological samples with the complex matrix including human urine and serum.

Microwave-Assisted Rapid Synthesis of Reduced Graphene Oxide-Based Gum Tragacanth Hydrogel Nanocomposite for Heavy Metal Ions Adsorption

Reduced graphene oxide (RGO) was synthesized in this research via Tour's method for the use of filler in the hydrogel matrix. The copolymerization of N,N-dimethylacrylamide (DMA) onto the gum tragacanth (GT) was carried out to develop gum tragacanth-cl-N,N-dimethylacrylamide (GT-cl-poly(DMA)) hydrogel using N,N'-methylenebisacrylamide (NMBA) and potassium persulfate (KPS) as cross-linker and initiator correspondingly. The various GT-cl-poly(DMA) hydrogel synthesis parameters were optimized to achieve maximum swelling of GT-cl-poly(DMA) hydrogel. The optimized GT-cl-poly(DMA) hydrogel was then filled with RGO to form reduced graphene oxide incorporated gum tragacanth-cl-N,N-dimethylacrylamide (GT-cl-poly(DMA)/RGO) hydrogel composite. The synthesized samples were used for competent adsorption of Hg²⁺ and Cr⁶⁺ ions. Fourier transform infrared, X-ray powder diffraction, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy were used to characterize the gum tragacanth-cl-N,N-dimethylacrylamide hydrogel and reduced graphene oxide incorporated gum tragacanth-cl-N,N-dimethylacrylamide hydrogel composite. The experiments of adsorption-desorption cycles for Hg²⁺ and Cr⁶⁺ ions were carried out to perform the reusability of gum tragacanth-cl-N,N-dimethylacrylamide hydrogel and reduced graphene oxide incorporated gum tragacanth-cl-N,N-dimethylacrylamide hydrogel composite. From these two samples, reduced graphene oxide incorporated gum tragacanth-cl-N,N-dimethylacrylamide exhibited high adsorption ability. The Hg²⁺ and Cr⁶⁺ ions adsorption by gum tragacanth-cl-N,N-dimethylacrylamide and reduced graphene oxide incorporated gum tragacanth-cl-N,N-dimethylacrylamide were best suited for pseudo-second-order kinetics and Langmuir isotherm. The reported maximum Hg²⁺ and Cr⁶⁺ ions adsorption capacities were 666.6 mg g^-1 and 473.9 mg g^-1 respectively.

Nanoscale Pisum sativum pods biochar encapsulated starch hydrogel: A novel nanosorbent for efficient chromium (VI) ions and naproxen drug removal

Assembly of novel ecofriendly and sustainable (N-PSPB/SHGL) nanosorbent was fabricated based on encapsulation of derived nanoscale spherical biochar from Pisum sativum pods (N-PSPB) with starch hydrogel (SHGL). The mass ratio between starch and N-PSPB was examined and 2% (w/w) was selected as the optimum percentage for fabrication of the assembled hydrogel. High swelling capacity was characterized by N-PSPB/SHGL nanosorbent (500.0%) at room temperature (25 °C), excellent stability for ten cycles with respect to regeneration by 0.1 mol L-1 HCl. Additionally, characterizations of N-PSPB/Starch nanosorbent were established by SEM and BET measurement to characterize surface area (226.94 m2/g) and pore volume (9.88 cm3/g). The N-PSPB/SHGL nanosorbent was subjected to extensive investigations to evaluate its efficiency for removal of naproxen drug (NAP) and chromium (VI). The Cr(VI) and NAP drug adsorptions were fitted to pseudo-second kinetic and correlated with Langmuir isotherm. The adsorption processes were spontaneous and endothermic based on thermodynamic study.

Synthesis of chemically cross-linked hydrogel films based on basil seed (Ocimum basilicum L.) mucilage for wound dressing drug delivery applications

The present study aims toward the preparation of pH-sensitive hydrogel films based on basil seed mucilage (OBM) biopolymer as a novel drug delivery system for wound dressing. Various contents of polyvinyl alcohol (PVA), glutaraldehyde (GA) as cross-linker, and glycerol as a plasticizer were incorporated to have an optimal combination of softness and resilience. OBM hydrogel films characterized by FT-IR, thermogravimetric analysis (TGA), morphological analysis by scanning electron microscope (SEM) and their physical properties were discussed on the reportage of the results of several tests: rheology, mechanical tests (stress at maximum load and Young's modulus), O₂ permeability and water vapor permeability, gel fraction, water retention capacity and swelling degree measurements. The best results for this work were Mu-Gly2, which has the acceptable swelling degree and gel fraction leading to functional water retention capacity, as well as the selected formulations, which were non-toxic and biocompatible according to the result of cytotoxicity test. The optimized formulations of films were used for loading of Tetracycline hydrochloride (TH) as a model drug, and the release studies showed better results at pH = 8.5 and pH = 7.4 rather than acidic pH.

Evaluation of multifunctional properties of gallic acid crosslinked Poly (vinyl alcohol)/Tragacanth Gum blend films for food packaging applications

The natural polymer Tragacanth Gum is less explored as a supporting matrix, there are very less studies conducted using this polymer in literature. So the present study aims to explore the consequences of different weight percent (wt.%) of gallic acid (GA) on physicochemical properties of Poly (vinyl alcohol)/Tragacanth Gum blend films. The incorporation of GA resulted in more strengthened but less flexible films as confirmed by tensile tests. DSC studies confirmed the miscibility of composite films in the given composition range and TGA studies revealed increased thermal stability. The morphological studies revealed a homogeneous distribution of GA at lower wt.% in the blend system. X-Ray Diffraction study depicted; the added GA lost crystalline structure after incorporating it into the blend. The Water Vapor Transmission Rate (WVTR) was improved after the incorporation of GA into the blend system. Overall migration studies revealed the limited release of GA from the matrix into food simulants. Soil degradation rate increased as the wt.% of GA increased. The composite films presented strong antioxidant activity; therefore, prepared composite films could be used as an alternative to current packaging materials.

Doxycycline drug delivery using hydrogels of O-carboxymethyl chitosan conjugated with caffeic acid and its composite with polyacrylamide synthesized by electron beam irradiation

Two hydrogels of O-carboxymethyl chitosan conjugated with caffeic acid and its composite with polyacrylamide were synthesized using electron beam irradiation. The synthesized hydrogels were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, and mechanical properties studies. The hydrogels were loaded with doxycycline by swelling and its release was investigated in various media. The effect of the dose of electron beam irradiation and PAAm amount on the properties of hydrogels including swelling, drug loading, drug release, mechanical properties, and gel content were studied. The release of doxycycline form hydrogels in different media obeyed the mechanism of non-Fickian diffusion and best fitted to the Higuchi model and Korsmeyer-Peppas. In-vitro doxycycline release consideration indicated that the drug's release from composite hydrogel occurs with higher amounts than the other one. The cytotoxic study confirmed the non-toxicity of the prepared hydrogels dressing. Moreover, the growth inhibition of permissive bacteria against Staphylococcus aureus and Escherichia coli were observed for doxycycline-loaded hydrogels. So, the synthesized hydrogels are appropriate for practical application as a new antibacterial wound dressing.

An Ion-Crosslinked Supramolecular Hydrogel for Ultrahigh and Fast Uranium Recovery from Seawater

Large-scale uranium extraction from seawater is a crucial but challenging part of nuclear power generation. In this study, a new ion-crosslinked supramolecular Zn²⁺ -poly(amidoxime) (PAO) hydrogel that can super-efficiently adsorb uranium from seawater is explored. By simply mixing two solutions of zinc chloride and PAO, a supramolecular Zn²⁺ -PAO hydrogel is achieved via the interaction between zinc cations and amidoxime anions. In contrast with existing amidoxime-functionalized hydrogel-based adsorbents having low PAO contents and fiber-based adsorbents with weak hydrophilicity, the PAOs can be directly crosslinked using a small quantity of superhydrophilic zinc ion. Thus, a supramolecular hydrogel is formed, having both a high content of well-dispersed PAOs and good hydrophilicity. Relative to reported adsorbents, this low-cost hydrogel membrane exhibits outstanding uranium adsorption performance, reaching 1188 mg g^-1 of M_U /M_{dry gel} in 32 ppm uranium-spiked water. More importantly, after immersion in natural seawater for only 4 weeks, the uranium extraction capacity of the Zn²⁺ -PAO hydrogel membrane reaches 9.23 mg g^-1 of M_U /M_{dry gel} . This work can provide a general strategy for designing a new type of supramolecular hydrogel, crosslinked by various bivalent/multivalent cation-crosslinkers and even many other superhydrophilic supramolecular crosslinkers, for the high-efficient and massive extraction of uranium from seawater.

Recent progress in the industrial and biomedical applications of tragacanth gum: A review

Natural polymers have distinct advantages over synthetic polymers because of their abundance, biocompatibility, and biodegradability. Tragacanth gum, an anionic polysaccharide, is a natural polymer which is derived from renewable sources. As a biomaterial, tragacanth gum has been used in industrial settings such as food packaging and water treatment, as well as in the biomedical field as drug carriers and for wound healing purposes. The present review provides an overview on the state-of-the-art in the field of tragacanth gum applications. The structure, properties, cytotoxicity, and degradability as well as the recent advances in industrial and biomedical applications of tragacanth gum are reviewed to offer a backdrop for future research.