A review of lignin application in hydrogel dressing

Lignin is the most abundant natural aromatic polymer in the world. Currently, researchers have developed a number of lignin-based composite materials that are widely used in various fields, including industry, agriculture and medicine. Especially in recent years, lignin has attracted great interest as a high-value product for biomedical applications. Due to its antioxidant, antibacterial, adhesive and other properties, lignin is a promising candidate for the development of hydrogel dressings. However, there is no comprehensive overview of the application of lignin-based hydrogel dressings. In this review, lignin-based hydrogel skin dressings were first presented, and the preparation methods of physical and chemical crosslinking in lignin-based hydrogel dressings were discussed. In addition, various functional and environmentally responsive lignin-based hydrogel dressings were primarily reviewed. Finally, the prospects for the development of novel multifunctional lignin-based hydrogel dressings in the future were presented. In conclusion, this review provided a timely and comprehensive summary of the latest advances in the use of lignin as a biomaterial for hydrogel dressings, which would provide valuable guidance for the further development of lignin-based hydrogels.

Fabrication of the SiC/HfC Composite Aerogel with Ultra-Low Thermal Conductivity and Excellent Compressive Strength

Aerogels, as a new type of high-temperature-resistant insulation material, find extensive application in aerospace, high-temperature industrial furnaces, new energy batteries, and various other domains, yet still face some limitations such as inadequate temperature resistance and pronounced brittleness. In this work, SiC/HfC composite aerogels were prepared through a combination of sol-gel method, atmospheric pressure drying technique, and carbothermal reduction reaction. The effects of different molar ratios, calcination time, and temperatures on the microstructural features and physicochemical properties of the resulting SiC/HfC composite aerogels were investigated. The aerogel exhibited an elevated BET-specific surface area of 279.75 m2/g, while the sample displayed an extraordinarily low thermal conductivity of 0.052 W/(m·K). Most notably, the compressive strength reached an outstanding 5.93 MPa after a carbonization temperature of 1500 °C, far exceeding the values reported in prior aerogel studies. This research provided an innovative approach for advancing the development of carbide aerogels in the realm of high-temperature applications.

Preparation and application of curcumin loaded with citric acid crosslinked chitosan-gelatin hydrogels

While oral administration offers safety benefits, its therapeutic efficacy is hindered by various physiological factors within the body. In this study, a novel approach was explored using a matrix consisting of 2 % chitosan and 2 % gelatin, with citric acid (CA) serving as a green cross-linking agent (ranging from 0.4 % to 1.0 %), and curcumin (Cur) as the model drug to formulate hydrogel carriers. The results showed that a 0.4 % CA concentration, the hydrogel (CGA0.4) reached swelling equilibrium in deionized water within 40 min, exhibiting a maximum swelling index was 539 g/g. The addition of Cur to the CGA hydrogel (CGACur) notably enhanced release efficiency, particularly in simulated intestinal fluid, where Cur release rates exceeded 40 % within 100 min compared to below 8 % in other solutions. Among these hydrogels, CGA0.4Cur exhibited the fastest degradation rate in the combined solution, reaching >90 % degradation after 7 days. Additionally, Cur and CA demonstrated positive effects on the tensile strength, antioxidant activity and antibacterial activity of hydrogels. Compare to the bioaccessibility of CGC (27 %), those of CGACur had increased to over 34 %. These findings offer provide theoretical support for CA-crosslinked chitosan/gelatin gels in delivering hydrophobic bioactive molecules and their application in intestinal drug delivery system.

Lignin derivatives-based hydrogels for biomedical applications

Recently, numerous studies have been conducted on renewable polymers derived from different natural sources, exploring their suitability for diverse biomedical applications. Lignin as one of the main components of lignocellulosic has garnered significant attention as a promising alternative to petroleum-based polymers. This interest is primarily due to its cost-effectiveness, biocompatibility, eco-friendly nature, as well as its antioxidant and antimicrobial properties. These characteristics could be more beneficial when incorporating lignin into the formulation of value-added products. Although lignin has a chemical structure that is suitable for various applications, these characteristics require modifications to guarantee that the resultant materials display the desired biological, chemical, and physical properties when applied in the creation of biodegradable hydrogels, particularly for biomedical purposes. This study delineates the recent modification approaches that have been employed in the creation of lignin-based hydrogels. These strategies encompass both chemical and physical interactions with other polymers. Additionally, this review encompasses an examination of the current applications of lignin hydrogels, spanning their use as scaffolds for tissue engineering, carriers for pharmaceuticals, materials for wound dressings and biosensors, and elements in flexible and wearable electronics. Finally, we delve into the challenges and constraints associated with these materials, discuss the necessary steps required to attain the appropriate properties for the development of innovative lignin-based hydrogels, and derive conclusions based on the presented findings.

Multifunctional sodium lignosulfonate/xanthan gum/sodium alginate/polyacrylamide ionic hydrogels composite as a high-performance wearable strain sensor

Recently, conductive hydrogels have shown great promise in flexible electronics and are ideal materials for the preparation of wearable strain sensors. However, developing a simple method to produce conductive hydrogels with excellent mechanical properties, self-adhesion, transparency, anti-freezing, and UV resistance remains a significant challenge. A novel sodium lignosulfonate/xanthan gum/sodium alginate/polyacrylamide/Zn2+/DMSO (SLS/XG/SA/PAM/Zn2+/DMSO) ionic conductive hydrogel was developed using a one-pot method. The resulting ionic conductive hydrogels have excellent mechanical properties (stress: 0.13 MPa, strain: 1629 %), high anti-fatigue properties, self-adhesion properties (iron: 7.37 kPa, pigskin: 4.74 kPa), anti-freezing (freezing point: -33.49 °C) and UV resistance by constructing a chemical and physical hybrid cross-linking network. In particular, the conductivity of G hydrogel reached 6.02 S/m at room temperature and 5.52 S/m at -20 °C. Thus, the hydrogel was assembled into a flexible sensor that could distinguish a variety of large and small scales human movements, such as joint bending, swallowing and speaking in real time with high stability and sensitivity. Moreover, the hydrogel could be used as electronic skin just like human skin and touch screen pen to write.

Lignin Upconversion by Functionalization and Network Formation

Lignin, a complex and abundant biopolymer derived from plant cell walls, has emerged as a promising feedstock for sustainable material development. Due to the high abundance of phenylpropanoid units, aromatic rings, and hydroxyl groups, lignin is an ideal candidate for being explored in various material applications. Therefore, the demand on lignin valorization for development of value-added products is significantly increasing. This mini-review provides an overview of lignin upconversion, focusing on its functionalization through chemical and enzymatic routes, and its application in lignin-based polymer resins, hydrogels, and nanomaterials. The functionalization of lignin molecules with various chemical groups offers tailored properties and increased compatibility with other materials, expanding its potential applications. Additionally, the formation of lignin-based networks, either through cross-linking or blending with polymers, generates novel materials with improved mechanical, thermal, and barrier properties. However, challenges remain in optimizing functionalization techniques, preserving the innate complexity of lignin, and achieving scalability for industrial implementation. As lignin's potential continues to be unlocked, it is poised to contribute significantly to the shift towards more eco-friendly and resource-efficient industries.

Facile Preparation of a Novel HfC Aerogel with Low Thermal Conductivity and Excellent Mechanical Properties

Aerogels emerge as captivating contenders within the realm of high-temperature thermal resistance and thermal insulation. Nevertheless, their practical applications are usually constrained by their inherent brittleness when subjected to rigorous conditions. Herein, employing hafnium dichloride oxide octahydrate (HfOCl2·8H2O) as the hafnium source and resorcinol-formaldehyde (RF) as the carbon precursor, hafnium carbide (HfC) aerogels are fabricated via the sol-gel method complemented with carbothermal reduction reaction. Investigations are conducted into the effects of various molar ratios, duration, and temperatures of calcination on the microstructural features and physico-chemical characteristics of the as-prepared HfC aerogel. The aerogel shows a high BET-specific surface area (601.02 m2/g), which is much larger than those of previously reported aerogels. Furthermore, the HfC aerogel exhibits a low thermal conductivity of 0.053 W/(m·K) and a compressive strength of up to 6.12 MPa after carbothermal reduction at 1500 °C. These excellent thermal insulation and mechanical properties ensure it is ideal for the utilization of high-temperature thermal resistance and thermal insulation in the fields of aerospace.

Sustainable Biomass Lignin-Based Hydrogels: A Review on Properties, Formulation, and Biomedical Applications

Different techniques have been developed to overcome the recalcitrant nature of lignocellulosic biomass and extract lignin biopolymer. Lignin has gained considerable interest owing to its attractive properties. These properties may be more beneficial when including lignin in the preparation of highly desired value-added products, including hydrogels. Lignin biopolymer, as one of the three major components of lignocellulosic biomaterials, has attracted significant interest in the biomedical field due to its biocompatibility, biodegradability, and antioxidant and antimicrobial activities. Its valorization by developing new hydrogels has increased in recent years. Furthermore, lignin-based hydrogels have shown great potential for various biomedical applications, and their copolymerization with other polymers and biopolymers further expands their possibilities. In this regard, lignin-based hydrogels can be synthesized by a variety of methods, including but not limited to interpenetrating polymer networks and polymerization, crosslinking copolymerization, crosslinking grafted lignin and monomers, atom transfer radical polymerization, and reversible addition-fragmentation transfer polymerization. As an example, the crosslinking mechanism of lignin-chitosan-poly(vinyl alcohol) (PVA) hydrogel involves active groups of lignin such as hydroxyl, carboxyl, and sulfonic groups that can form hydrogen bonds (with groups in the chemical structures of chitosan and/or PVA) and ionic bonds (with groups in the chemical structures of chitosan and/or PVA). The aim of this review paper is to provide a comprehensive overview of lignin-based hydrogels and their applications, focusing on the preparation and properties of lignin-based hydrogels and the biomedical applications of these hydrogels. In addition, we explore their potential in wound healing, drug delivery systems, and 3D bioprinting, showcasing the unique properties of lignin-based hydrogels that enable their successful utilization in these areas. Finally, we discuss future trends in the field and draw conclusions based on the findings presented.

Lignin-based nanomaterials for food and pharmaceutical applications: Recent trends and future outlook

Small particles of size ranging from 1 to 100 nm are referred to as nanoparticles. Nanoparticles have tremendous applications in various sectors, including the areas of food and pharmaceutics. They are being prepared from multiple natural sources widely. Lignin is one such source that deserves special mention due to its ecological compatibility, accessibility, abundance, and low cost. This amorphous heterogeneous phenolic polymer is the second most abundant molecule in nature after cellulose. Apart from being used as a biofuel source, lignin is less explored for its potential at a nano-level. In plants, lignin exhibits cross-linking structures with cellulose and hemicellulose. Numerous advancements have taken place in synthesizing nanolignins for manufacturing lignin-based materials to benefit from the untapped potential of lignin in high-value-added applications. Lignin and lignin-based nanoparticles have numerous applications, but in this review, we are mainly focusing on the applications in the food and pharmaceutical sectors. The exercise we undertake has great relevance as it helps scientists and industries gain valuable insights into lignin's capabilities and exploit its physical and chemical properties to facilitate the development of future lignin-based materials. We have summarized the available lignin resources and their potential in the food and pharmaceutical industries at various levels. This review attempts to understand various methods adopted for the preparation of nanolignin. Furthermore, the unique properties of nano-lignin-based materials and their applications in fields including the packaging industry, emulsions, nutrient delivery, drug delivery hydrogels, tissue engineering, and biomedical applications were well-discussed.

Carboxymethyl cellulose based sustainable hydrogel for colon-specific delivery of gentamicin

The current research includes the synthesis, improvement of NaCMC-cl-DMAA/AAc hydrogel and in-situ controlled release of gentamicin within various pH environments. The prepared hydrogel was then modified using boron nitride nanosheets aiming to enhancement in the adsorption rate. The prepared hydrogels were investigated by FTIR, XRD, FESEM, TGA/DSC, swelling and cell viability analysis. Cytotoxicity study indicated that prepared sample has a cytocompatibility nature towards healthy normal human cell line (FR2 cells). By changing the pH environment, the drug release properties of the hydrogels can be controlled. The cumulative rate of release for NaCMC-cl-DMAA/AAc hydrogel was 76.5 % at pH = 2.2 and 87.5 % at pH = 7.4. Whereas drug release rate for NaCMC-cl-DMAA/AAc-BNNSs hydrogel composite was 78.6 % at pH = 2.2 and 97.3 % at pH = 7.4 within 4320 min. Gentamicin release kinetics have been determined using the Korsemeyar-Peppas model, which confirms the drug release mechanism.

Conductive Hydrogels Based on Industrial Lignin: Opportunities and Challenges

The development of green materials, especially the preparation of high-performance conductive hydrogels from biodegradable biomass materials, is of great importance and has received worldwide attention. As an aromatic polymer found in many natural biomass resources, lignin has the advantage of being renewable, biodegradable, non-toxic, widely available, and inexpensive. The unique physicochemical properties of lignin, such as the presence of hydroxyl, carboxyl, and sulfonate groups, make it promising for use in composite conductive hydrogels. In this review, the source, structure, and reaction characteristics of industrial lignin are provided. Description of the preparation method (physical and chemical strategies) of lignin-based conductive hydrogel is elaborated along with their several important properties, such as electrical conductivity, mechanical properties, and porous structure. Furthermore, we provide insights into the latest research advances in industrial lignin conductive hydrogels, including biosensors, strain sensors, flexible energy storage devices, and other emerging applications. Finally, the prospects and challenges for the development of lignin-conductive hydrogels are presented.

Lignin valorization: Status, challenges and opportunities

As an abundant aromatic biopolymer, lignin has the potential to produce various chemicals, biofuels of interest through biorefinery activities and is expected to benefit the future circular economy. However, lignin valorization is hindered by a series of constraints such as heterogeneous polymeric nature, intrinsic recalcitrance, strong smell, dark colour, challenges in lignocelluloses fractionation and the presence of high bond dissociation enthalpies in its functional groups etc. Nowadays, industrial lignin is mostly combusted for electricity production and the recycling of inorganic compounds involved in the pulping process. Given the research and development on lignin valorization in recent years, important applications such as lignin-based hydrogels, surfactants, three-dimensional printing materials, electrodes and production of fine chemicals have been systematically reviewed. Finally, this review highlights the main constraints affecting industrial lignin valorization, possible solutions and future perspectives, in the light of its abundance and its potential applications reported in the scientific literature.

Lignin-Mediated Silver Nanoparticle Synthesis for Photocatalytic Degradation of Reactive Yellow 4G and In Vitro Assessment of Antioxidant, Antidiabetic, and Antibacterial Activities

This study explored the potential of abundantly available sodium lignosulfonate (LS) as a reducer and fabricating agent in preparing silver nanoparticles (LS–Ag NPs). The operational conditions were optimized to make the synthesis process simpler, rapid, and eco-friendly. The prepared LS–Ag NPs were analyzed via UV–Vis spectroscopy, X-ray diffraction spectroscopy, Fourier transform infrared spectroscopy, and high-resolution transmission electron microscopy. Results demonstrated that LS–Ag NPs were of crystalline structure, capped with LS constituents, and spherical in shape with a size of approximately 20 nm. Under optimized conditions, LS–Ag NPs exhibited significant photocatalytic activity in Reactive Yellow 4G degradation. The effects of photocatalyst (LS–Ag NPs) dosage, dye concentration, and its reusability for dye degradation were studied to make the process practically applicable in textile wastewater treatment. Additionally, the synthesized LS–Ag NPs displayed significant free radical scavenging against 2-diphenyl-1-picrylhydrazyl (DPPH) with an IC₅₀ value of (50.2 ± 0.70 µg/mL) and also exhibited antidiabetic activity in terms of inhibition in the activity of carbohydrate-degrading marker enzyme α-glucosidase with an IC₅₀ value of (58.1 ± 0.65 µg/mL). LS–Ag NPs showed substantial antibacterial potential against pathogenic strains, namely E. coli and S. aureus. In conclusion, LS–Ag NPs can be a reliable and eco-friendly material for their possible application in the treatment of dye-containing wastewater and have a great perspective in the biomedical and pharmaceutical sectors.

Synthesis of Superabsorbent Polymer Hydrogels with Rapid Swelling: Effect of Reaction Medium Dosage and Polyvinylpyrrolidone on Water Absorption Rate

A superabsorbent polymer (SAP) was synthesized by solution polymerization. The influence of synthesis technology was studied and optimized, and FTIR, SEM, and TGA were used to characterize the structure and morphology of the material. Under the optimal synthesis conditions, the water absorption of the material can achieve about 80% of the saturation value in the first 20 min, and the material absorbs distilled water up to 2013 g/g. The SAP also has remarkable water retention and reswelling capability. The excellent performance makes it have a promising application in agriculture. In addition, the results show that the dosage of the reaction medium is a major factor for performance. Under the condition of the optimum value of other factors, the influence of the dosage of the reaction medium on water absorption can reach about 1000 g in distilled water.

Recent advances in lignin-based porous materials for pollutants removal from wastewater

Water pollution is one of the most serious threats facing mankind today and has obtained widespread attention. Significant advances have been made in the past decades to apply porous materials in wastewater treatment, due to their large specific surface areas (S_BET) for interaction with the aimed ions or molecules. However, the majority of porous materials are prepared from fossil-based resources and still possess some drawbacks, such as high cost and non-degradability, which inevitably cause secondary pollution to the environment from their production to disposal. Lignin is the most abundant and the only scalable renewable aromatic resource on earth. Due to its unique physicochemical properties including high carbon content, plentiful functional groups and environmental friendliness, the lignin-based porous materials (LPMs) have shown promising prospects in efficient removal of soluble pollutants from wastewater. In this review, we firstly described the structural and chemical basis of LPMs, following presented the recent progress in the decontamination of heavy metal ions, organic dyes, antibiotics, anions and radionuclides from aqueous systems. Additionally, the outlook was provided to promote more practical implementation of LPMs in the near future.

Deposition behavior of lignin on solid surfaces assessed by stagnation point adsorption reflectometry

The deposition behavior of lignin on a solid surface was studied using stagnation point adsorption reflectometry (SPAR) comprehensively. In this study, the light absorption coefficient of lignin (τ = 20 476 m-1) at 633 nm wavelength was considered to define a new imaginary refractive index (k) used in the SPAR technique for adsorption analysis. The inclusion of k in the adsorption model yielded an adsorbed amount (Γ) of 1.11 mg m-2, leading to the quality factor (Q f) of 31.71 mg m-2. At a lower concentration, the deposition of lignin on the surface was increased, and it generated a maximum sticking coefficient of β = 0.71 at 25 mg L-1 on the surface. At the concentration range of 35 and 45 mg L-1, lignin formed clusters and its deposition dropped. The use of Quartz crystal microbalance (QCM) and SPAR techniques also confirmed that the proportion of water in the deposited lignin adlayer was greater when a lower concentration (5-25 mg L-1) of lignin solution was used for adsorption. The findings of this study revealed the potential use of the SPAR technique for evaluating the deposition performance of lignin-based materials on varied surfaces, which would facilitate the development of coating and composite applications for lignin.

Preparation, Characterization and Antioxidant Activities of Kelp Phlorotannin Nanoparticles

Phlorotannins are a group of major polyphenol secondary metabolites found only in brown algae and are known for their bioactivities and multiple health benefits. However, they can be oxidized due to external factors and their bioavailability is low due to their low water solubility. In this study, the potential of utilizing nanoencapsulation with polyvinylpyrrolidone (PVP) to improve various activities of phlorotannins was explored. Phlorotannins encapsulated by PVP nanoparticles (PPNPS) with different loading ratios were prepared for characterization. Then, the PPNPS were evaluated for in vitro controlled release of phlorotannin, toxicity and antioxidant activities at the ratio of phlorotannin to PVP 1:8. The results indicated that the PPNPS showed a slow and sustained kinetic release of phlorotannin in simulated gastrointestinal fluids, they were non-toxic to HaCaT keratinocytes and they could reduce the generation of endogenous reactive oxygen species (ROS). Therefore, PPNPS have the potential to be a useful platform for the utilization of phlorotannin in both pharmaceutical and cosmetics industries.

New Developments in Medical Applications of Hybrid Hydrogels Containing Natural Polymers

New trends in biomedical applications of the hybrid polymeric hydrogels, obtained by combining natural polymers with synthetic ones, have been reviewed. Homopolysaccharides, heteropolysaccharides, as well as polypeptides, proteins and nucleic acids, are presented from the point of view of their ability to form hydrogels with synthetic polymers, the preparation procedures for polymeric organic hybrid hydrogels, general physico-chemical properties and main biomedical applications (i.e., tissue engineering, wound dressing, drug delivery, etc.).

Lignin-Based Hydrogels: Synthesis and Applications

Polymers obtained from biomass are an interesting alternative to petro-based polymers due to their low cost of production, biocompatibility, and biodegradability. This is the case of lignin, which is the second most abundant biopolymer in plants. As a consequence, the exploitation of lignin for the production of new materials with improved properties is currently considered as one of the main challenging issues, especially for the paper industry. Regarding its chemical structure, lignin is a crosslinked polymer that contains many functional hydrophilic and active groups, such as hydroxyls, carbonyls and methoxyls, which provides a great potential to be employed in the synthesis of biodegradable hydrogels, materials that are recognized for their interesting applicability in biomedicine, soil and water treatment, and agriculture, among others. This work describes the main methods for the preparation of lignin-based hydrogels reported in the last years, based on the chemical and/or physical interaction with polymers widely used in hydrogels formulations. Furthermore, herein are also reviewed the current applications of lignin hydrogels as stimuli-responsive materials, flexible supercapacitors, and wearable electronics for biomedical and water remediation applications.

Lignin-based hydrogels: A review of preparation, properties, and application

Lignin as the second most abundant and the only polyaromatics-contained bio-polymer in plant has been most studied for various applications. In the past decade, the utilization of lignin for value-added materials has been extensively sought after since lignin valorization represents one of the main challenging issues of the paper industry and lignocellulosic biorefinery. Among these researches, making lignin into hydrogels has great potential for upgrading lignin into functional materials. In this review, lignin hydrogel is wrapped up with preparation strategies, properties and applications. The major cross-linking strategies to synthesize lignin-based hydrogels were reviewed first, including monomers copolymerization, crosslinking of monomers with reactive polymer precursors and polymer-polymer crosslinking. Two most important properties of mechanical and porous structures of lignin hydrogel were then discussed. More importantly, we extensively reviewed current applications of lignin hydrogel, including absorption, controlled release, smart materials for stimuli sensitive, biosensors and electrodes. These applications have paved avenues for lignin valorization. Overall, this paper covers recent advancements regarding lignin-based hydrogel and represents a timely review of this promising material.

Super-swelling lignin-based biopolymer hydrogels for soil water retention from paper industry waste

Sources of pulping red liquor, which is produced by acidic sulfite cooking in paper industry, consisted of lignosulphonate and polysaccharide, commonly considered as waste or byproducts and used in low value, such as surfactant and adhesive are wide and its price is low. Here a novel method for high value-added utilization of the pulp and paper industry waste for fabricating super-swelling biopolymer hydrogels is introduced. In contrast to other costly utilizations, which are needed to separate red liquor or purify hemicellulose and lignin before using, it is first time to directly utilize red liquor to prepare hydrogels without pretreatment. FT-IR, SEM, TGA and XRD are used to determine structure and morphology of hydrogels. It is excited the hydrogels fabricated from acrylic (AA) and industry waste exhibit super-swelling and slow release behaviors in water. Compared with synthetic materials, the hydrogels are at low price to be chosen as candidates for water retention agent for agriculture.

Stomach-Specific Drug Delivery of Clarithromycin Using a Semi Interpenetrating Polymeric Network Hydrogel Made of Montmorillonite and Chitosan: Synthesis, Characterization and In Vitro Drug Release Study

Purpose: In this study, we aimed to prepare an extended drug delivery formulation of clarithromycin (CAM) based on a semi-interpenetrating polymer network (semi-IPN) hydrogel. Methods: Synthesis of semi-IPN hydrogel nanocomposite made of chitosan (CS), acrylic acid (AA), acrylamide (AAm), polyvinylpyrrolidone (PVP), and montmorillonite (MMT) was performed by free radical graft copolymerization method. Swelling kinetic studies were done in acidic buffer solutions of hydrochloric acid (pH = 1.2), acetate (pH = 4), and also distilled water. Also, the effects of MMT on the swelling kinetic, thermal stability, and mechanical strength of the hydrogels were evaluated. Moreover, in vitro release behavior of CAM and its release kinetics from hydrogels were studied in a hydrochloric acid buffer solution. Results: Fourier transform infrared spectroscopy (FTIR) results revealed that synthesis of semi- IPN superabsorbent nanocomposite and CAM incorporation into hydrogel was performed, successfully. Introducing MMT into hydrogel network not only improved its thermal stability but also increased mechanical strength of the final hydrogel product. Also, in comparison with neat hydrogel (1270 g/g), hydrogel nanocomposite containing 13 wt% MMT exhibited greater equilibrium swelling capacity (1568 g/g) with lower swelling rate. In vitro drug release experiments showed that CS-g-poly(AA-co-AAm)/PVP/MMT/CAM formulation possesses a sustained release character over extended period of time compared with CS-g-poly(AA-co- AAm)/PVP/CAM formulation. Conclusion: In the presence of MMT, the effective life time of drug is prolonged, demonstrating a sustained release property. The reason is that interlinked porous channels within superabsorbent nanocomposite network hinder penetration of aqueous solutions into hydrogel and subsequently cause a slower drug release.

A synthesis and performance evaluation of a highly efficient ecological dust depressor based on the sodium lignosulfonate–acrylic acid graft copolymer

In this paper, a highly efficient and environmentally-friendly dust depressor was developed based on the sodium lignosulfonate–acrylic acid graft copolymer. Using the grafting ratio as an index, a three-factor and four-level orthogonal experiment was conducted to optimize the fabrication conditions of the graft copolymer. At a reaction temperature of 60 °C, feed ratio m_SLS–AA of 1 : 3, and FeSO₄·7H₂O content of 2.5%, the prototype produced the highest grafting ratio. The microstructure of the graft copolymer was measured using Fourier transform infrared spectrometry (FTIR) and nuclear magnetic resonance (¹H-NMR). Furthermore, the influence of glycerol and the JFC penetrant on the contact angle between the compound solution and coal powder was investigated. Finally, four formulas of dust depressor were selected based on the experimental results. The dust-control performance of the four dust depressors was then tested on a large-scale spray dust suppression simulation platform. The results show that after applying formula 1 at various distances from the spray field, the average dust reduction rates of the total dust (respirable dust) at each point increased. Compared to the water-spraying dust suppression technique, the dust concentration is significantly reduced after the graft copolymer dust depressor is applied.

In this paper, a highly efficient and environmentally-friendly dust depressor was developed based on the sodium lignosulfonate–acrylic acid graft copolymer.

pH Sensitive Hydrogels in Drug Delivery: Brief History, Properties, Swelling, and Release Mechanism, Material Selection and Applications

Improving the safety efficacy ratio of existing drugs is a current challenge to be addressed rather than the development of novel drugs which involve much expense and time. The efficacy of drugs is affected by a number of factors such as their low aqueous solubility, unequal absorption along the gastrointestinal (GI) tract, risk of degradation in the acidic milieu of the stomach, low permeation of the drugs in the upper GI tract, systematic side effects, etc. This review aims to enlighten readers on the role of pH sensitive hydrogels in drug delivery, their mechanism of action, swelling, and drug release as a function of pH change along the GI tract. The basis for the selection of materials, their structural features, physical and chemical properties, the presence of ionic pendant groups, and the influence of their pKa and pKb values on the ionization, consequent swelling, and targeted drug release are also highlighted.

Cisplatin and doxorubicin dual-loaded mesoporous silica nanoparticles for controlled drug delivery

Multicomponent therapeutic platforms have been proposed to minimize dosage of each drug and reduce toxicity, leading to achieving a synergistic effect and maximizing therapeutic efficacy.