Biodegradable-stimuli sensitive xanthan gum based hydrogel: Evaluation of antibacterial activity and controlled agro-chemical release

Polysaccharide-based sustainable hydrogel spheres for controlled release of agricultural inputs

Producing food in quantity and quality to meet the growing population demand is a challenge for the coming years. In addition to the need to improve the use and efficiency of conventional agricultural inputs, we face climate change and disparity in access to food. In this context, creating innovative, efficient, and ecologically approaches is necessary to transform this global scenario. Several delivery systems are being developed to encapsulate agrochemicals, aiming to improve the controlled release of active ingredients and protect them against environmental biotic and abiotic factors. Among these systems, hydrogel spheres are particularly notable for their ability to be fabricated from biodegradable materials, allowing the encapsulation of molecules, nanomaterials, and even organisms (e.g., bacteria and fungi). This review provides an overview of the latest progress in developing polysaccharide-based hydrogel spheres for agriculture. In addition, we describe methods for preparing hydrogel spheres and discuss the encapsulation and release of agricultural inputs in the field. Finally, we put hydrogel spheres into perspective and seek to highlight some current challenges in the field to spark new inspiration and improve the development of environmentally friendly and cost-effective delivery systems for the agricultural sector.

Review on emerging trends and challenges in the modification of xanthan gum for various applications

This review explores the realm of structural modifications and broad spectrum of their potential applications, with a special focus on the synthesis of xanthan gum derivatives through graft copolymerization methods. It delves into the creation of these derivatives by attaching functional groups (-OH and -COOH) to xanthan gum, utilizing a variety of initiators for grafting, and examining their diverse applications, especially in the areas of food packaging, pharmaceuticals, wastewater treatment, and antimicrobial activities. Xanthan gum is a biocompatible, biodegradable, less toxic, bioactive, and cost-effective natural polymer derived from Xanthomonas species. The native properties of xanthan gum can be improved by cross-linking, grafting, curing, blending, and various modification techniques. Grafted xanthan gum has excellent biodegradability, metal binding, dye adsorption, immunological properties, and wound healing ability. Owing to its remarkable properties, such as biocompatibility and its ability to form gels resembling the extracellular matrix of tissues, modified xanthan gum finds extensive utility across biomedicine, engineering, and the food industry. Furthermore, the review also covers various modified derivatives of xanthan gum that exhibit excellent biodegradability, metal binding, dye adsorption, immunological properties, and wound healing abilities. These applications could serve as important resources for a wide range of industries in future product development.

Bioinspired Freeze-Tolerant Soft Materials: Design, Properties, and Applications

In nature, many biological organisms have developed the exceptional antifreezing ability to survive in extremely cold environments. Inspired by the freeze resistance of these organisms, researchers have devoted extensive efforts to develop advanced freeze-tolerant soft materials and explore their potential applications in diverse areas such as electronic skin, soft robotics, flexible energy, and biological science. Herein, a comprehensive overview on the recent advancement of freeze-tolerant soft materials and their emerging applications from the perspective of bioinspiration and advanced material engineering is provided. First, the mechanisms underlying the freeze tolerance of cold-enduring biological organisms are introduced. Then, engineering strategies for developing antifreezing soft materials are summarized. Thereafter, recent advances in freeze-tolerant soft materials for different technological applications such as smart sensors and actuators, energy harvesting and storage, and cryogenic medical applications are presented. Finally, future challenges and opportunities for the rapid development of bioinspired freeze-tolerant soft materials are discussed.

Recent insights into polysaccharide-based hydrogels and their potential applications in food sector: A review

Hydrogels are ideal for various food applications because of their softness, elasticity, absorbent nature, flexibility, and hygroscopic nature. Polysaccharide hydrogels are particularly suitable because of the hydrophilic nature, their food compatibility, and their non-immunogenic character. Such hydrogels offer a wide range of successful applications such as food preservation, pharmaceuticals, agriculture, and food packaging. Additionally, polysaccharide hydrogels have proven to play a significant role in the formulation of food flavor carrier systems, thus diversifying the horizons of newer developments in food processing sector. Polysaccharide hydrogels are comprised of natural polymers such as alginate, chitosan, starch, pectin and hyaluronic acid when crosslinked physically or chemically. Hydrogels with interchangeable, antimicrobial and barrier properties are referred to as smart hydrogels. This review brings together the recent and relevant polysaccharide research in these polysaccharide hydrogel applications areas and seeks to point the way forward for future research and interventions. Applications in carrying out the process of flavor carrier system directly through their incorporation in food matrices, broadening the domain for food application innovations. The classification and important features of polysaccharide-based hydrogels in food processing are the topics of the current review study.

Eco-friendly whey/polysaccharide-based hydrogel with poly(lactic acid) for improvement of agricultural soil quality and plant growth

A set of renewable and biodegradable hydrogels based on acid whey and cellulose derivatives blended with poly(lactic acid) (PLA) were designed as eco-friendly biopolymeric material for sustainable agricultural applications. The physico-chemical properties of the hydrogel were evaluated using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and rheological measurements. The effect of the whey/polysaccharide/PLA hydrogel on soil quality improvement (water retention study, biodegradability, loading capacity and release of the fertilizers) and the growth pattern of Raphanus sativus and Phaseolus vulgaris has been also studied. The addition of PLA has been found to improve mechanical properties of the hydrogel. The introduction of 20% wt PLA extended decomposition time of hydrogels by 25% which makes the material more stable in the environment and maintaining the soil humidity for longer. The increasing the amount of PLA led to a rise in hydrogel viscosity brought about better entrapment efficiency of the fertilizers (86-92% for KNO₃ and 87-96% for urea, resp.) compared to control (82% for KNO₃ and 85% for urea, resp.). The novel hydrogels with swelling ratio of up to 500% showed potential as a sustainable water reservoir for plants improving water retention capacity of the soil by 30%.

Use of xanthan gum for whole cell immobilization and its impact in bioremediation - a review

Xanthan gum is one of the exo-polysaccharides produced by bacteria and is characterized by unique non-Newtonian properties. Its structure and conformation strongly depend on the fermentation conditions and such factors as temperature and ions concentration. The properties of the xanthan gum were appreciated in the controlled drug delivery but in the crosslinked form. Due to its ability to enhance the survival rate of immobilized bacteria, the potential of a crosslinked form is promising. Unfortunately, xanthan gum crosslinking procedures often require toxic substances or harsh environmental conditions, which cannot be used in the entrapment of living cells. In this study, we summarised a crosslinking method that could potentially be modified to reduce its toxicity to living cells. Moreover, this review also includes using xanthan gum in bioremediation studies and possible utilization methods to avoid carrier accumulation in the environment.

Green antimicrobial adsorbent containing grafted xanthan gum/SiO2 nanocomposites for malachite green dye

Recently, removal of synthetic dyes, especially cationic dye of malachite green (MG), and inhibition of the growth of pathogenic microorganism from drinking water have gained much interest due to their high toxic potency for aquatic biosystems. Herein, a new dye adsorbent with outstanding antibacterial activity was fabricated based on xanthan gum (XG) and SiO₂ nanoparticles through ultrasonication followed by the crosslinking polymerization with vinyl imidazole monomer. The nano adsorbents were characterized with various techniques such as FTIR, XRD, SEM, EDX, and TEM. The nanocomposites were applied as a filter for discarding MG dye and killing the growth of bacterial strains such as E.coli and S.aureus which are considered as the common impurities for drinking water. The data revealed that a maximum adsorption capacity was recorded as 99.5% (Q_max = 588.2 mg/g) at optimum conditions including 10 mg nanocomposite, 10 mL of MG dye (450 ppm), pH = 7, the temperature of 30 °C, and the adsorption time was adjusted within 6 h. The process of dye adsorption was applied to the common isotherm models of Langmuir, Temkin, and Freundlich, and the findings showed that the adsorption behavior was well fitted with the Langmuir one (R² = 0.9983). Moreover, different adsorption kinetic models such as pseudo-first order, pseudo-second order, and intra-particle diffusion were studied for understanding the mechanism of MG adsorption onto nanocomposite surface. It was found that both intraparticle diffusion and pseudo-first-order have participated evenly in the adsorption mechanism of MG dye. Ultimately, the as-prepared nanocomposites were tested against the growth of S. aureus, and E.coli manifesting a superior inhibition diameter as 23.5 ± 0.50, and 25.33 ± 0.47 mm against E.coli, and S. aureus, respectively. Therefore, our new XG-g-PVI/SiO₂ adsorbent is a very promising adsorbent for the fast and efficient capture of dyes from aqueous solutions.

Innovative bactericidal adsorbents containing modified xanthan gum/montmorillonite nanocomposites for wastewater treatment

Herein, we reported the preparation of novel antibacterial nanocomposites based on biodegradable polymers. The nanocomposites were applied as capable adsorbent for removing of malachite green (MG) dye, as well as inhibiting of E. coli and S. aureus growth as the most common pollutants for water. The grafted xanthan gum with poly(vinylimidazole) (XG-g-PVI) nanocomposites were synthesized in the presence of different Montmorillonite (MMT) nanoclays concentrations (1%, 3% and 5%). The prepared modified XG nanocomposites were detected through XRD, SEM-EDX, FTIR and TEM. The maximum adsorption MG capacity was determined as 99.99% (909.1 mg/g) in basic medium at 30 °C for 90 min. The adsorption isotherm for removal of MG dye was studied against different models like Langmuir, Freundlich, Temkin, FloryHuggins isotherm models, however, the adsorption results were good fitted with Langmuir isotherm model (R² = 0.9942). Additionally, various adsorption kinetic models: pseudo-first order, second order, pseudo-second order, and intra-particle diffusion models were studied for adsorption mechanism of MG dye on top of prepared nanocomposite surface. Finally, the antibacterial activity outcomes displayed that the prepared XG-g-PVI/MMT nanocomposites had excellent inhibition growth for bacteria and the antibacterial activity increased abruptly with the increased of MMT nanoclay concentrations.

Synergic effect of Guggul gum based hydrogel nanocomposite: An approach towards adsorption-photocatalysis of Magenta-O

The article is related to sunlight and UV-visible mineralization of harmful magenta-O (FB) dye. The nanocomposite used is a cross linked network of acrylic acid synthesized inside poly(acrylamide) grafted Guggul gum in the presence of UV-visible respondent bismuth ferrite nanoparticles. The synthesis of poly(acrylamide) grafted Guggul gum (Sample I) and synthesizing a crosslinked network inside it (Sample II) involved a two-step synthesis for optimizing various reaction parameters. The maximum % water uptake obtained for polymeric samples I and II was calculated as 1227.78% and 387.97%, respectively. Average particle size of bismuth ferrite nanoparticles was 47.34 nm. The nanocomposite could maximum uptake-mineralize FB dye as 97.3% and 98.8% under sunlight and photochemical reactor, respectively for 500 mg nanocomposite dose in 10 mg/L concentrated FB solution. Dye uptake occurs through ionic interactions. However, mineralization is a consequence of advanced oxidation process involving free radical species (OH and O₂^-.). The overall process of uptake-mineralization resembled second order kinetics and Langmuir theorem (monolayer adsorption). Intraparticle diffusion model gave an idea about the multistep (three steps) process of adsorption. Physico-chemical properties of FB dye got changed after mineralization except for the pH. The maximum uptake-mineralization was observed to be 76.2% after consecutive reuse of the nanocomposite hydrogel for five cycles.

A novel xanthan gum-based conductive hydrogel with excellent mechanical, biocompatible, and self-healing performances

Tough and conductive hydrogels are promising materials for various applications. However, it remains a great challenge to develop an integrated hydrogel combining outstanding mechanical, conductive, and self-healing performances. Herein, we prepared a conductive, self-healing, and tough hydrogel by constructing synergistic multiple interaction among montmorillonite (MMT), Poly (acrylamide-co-acrylonitrile) (P(AAm-co-AN)), xanthan gum (XG) and ferric ion (Fe³⁺). The obtained xanthan gum/montmorillonite/Poly (acrylamide-co-acrylonitrile) (XG/MMT/PAAm) hydrogels showed high strain stress (0.48 MPa) and compressive stress (5.9 MPa) as well as good shape recovery after multiple loading-unloading cycle tests. Moreover, the XG/MMT/PAAm hydrogels have distinctive features such as remarkable resistance to fatigue and harsh environments, insensitivity to notch, conductive, biocompatible, pH-dependent swelling behaviors and self-healing. Therefore, the as-fabricated hydrogel delivers a new prospect for its applications in various fields, such as flexible conductive device and tissue engineering.

One-pot green synthesis of polymeric nanocomposite: Biodegradation studies and application in sorption-degradation of organic pollutants

The research work proposes the synthesis of a nanocomposite hydrogel which is a dual combination of binary interpenetrating network (BIPN) and bismuth ferrite nanoparticles. BIPN synthesized from binary graft copolymer (BGC) used as starting material. The cross-linked network of BGC is interpenetrating the newly synthesized cross-linked network of poly(acrylic acid) and the product is named as BIPN. Binary graft copolymer had been synthesized from grafting of guggul aqueous extract with copolymeric chains of acrylamide (primary monomer) and acrylic acid (secondary monomer) crosslinked by N,N'-methylene bisacrylamide (MBA). The maximum percentage swelling was evaluated for BGC through optimization of various reaction parameters: amount of water, binary ratio of acrylamide to acrylic acid, concentrations of MBA, ammonium persulphate, pH, temperature and time. Considering pre-optimized parameters for BGC synthesis, BIPN formation required optimization of only acrylic acid. Maximum percentage swelling obtained was 1497.79% and 308.15% for BGC and BIPN, respectively. Maximum percentage biodegradation of 90.64% and 82.38% were calculated for BGC and BIPN, respectively using composting method. Degradation efficiency of brilliant blue (BB) and fuchsin basic (FB) dyes was in the order: Nanocomposite ≫ BIPN > BGC. Maximum percentage degradation observed in case of nanocomposite was 94.1% and 99.3% in sunlight for BB and FB, respectively. The interaction of dyes with the nanocomposite involved mainly ionic interactions. The adsorption models Freundlich and Langmuir were applicable to overall adsorption and degradation process of BB and FB, respectively. Maximum adsorption capacities corresponding to minimum concentration i.e. 10 mg L^-1 for BB and FB were calculated as 0.409 mg g^-1 and 0.439 mg g^-1, respectively. Second order and first order kinetics were found to be suitable for BB and FB adsorption-degradation pathways, respectively. Intraparticle diffusion mechanism was favorable to both dyes and adsorption followed three steps. Gas chromatography coupled with mass spectrometric analysis could give the degraded products which was helpful in drawing degradation pathway. The degradation process involved active radical species (O₂^-., OH^.) and they carry out oxidation-reduction reactions on dyes to give decolorized solution containing mineral ions.

Slow release fertilizer hydrogels: a review

Slow release fertilizer hydrogels combine fertilizer and hydrogel into one system.

Gum xanthan-psyllium-cl-poly(acrylic acid-co-itaconic acid) based adsorbent for effective removal of cationic and anionic dyes: Adsorption isotherms, kinetics and thermodynamic studies

The present work highlights the synthesis of the adsorbent based on Gum xanthan-psyllium hybrid backbone graft co-polymerized with polyacrylic acid-co-polyitaconic acid chains for the rapid sequestration of auramine-O (Aur-O) and eriochrome black-T (EBT) dyes from the aqueous fluid. The excellent dye removal efficiency of 90.53% for EBT and 95.63% for Aur-O was found at initial dye concentration of 30mgL^-1 (EBT) and 15 mgL^-1 (Aur-O) 40mL^-1 with an adsorbent dose of 600mg within time duration of 5h and 323K temp. The adsorption isotherm data fitted well with Langmuir isotherm and Freundlich isotherm for Aur-O and EBT dyes (R² ≥ 0.90), respectively. The adsorption kinetics depicted that pseudo-second order kinetics was followed simultaneously with intra-particle diffusion for both the dyes. Thermodynamic parameters such as ΔG°, ΔH° and ΔS° were also calculated and confirmed the spontaneity, randomness and endothermic nature of the adsorption process. Further, the adsorbent exhibited good recyclability efficiency for the capture of Aur-O and EBT from aqueous solution with minimal activity decline after six and three cycles, respectively. So, the synthesized adsorbent could be used successfully by the textile industries for the treatment of dye contaminated water with excellent competency.