Advances in polysaccharide-based hydrogels: Self-healing and electrical conductivity

Neem gum and its derivatives as potential polymeric scaffold for diverse applications: a review

Naturally occurring polymers, particularly polysaccharides, are gaining significant attention for their eco-friendly, non-toxic nature and abundant availability. Neem Gum (NEG), a natural exudate from the neem tree (Azadirachta indica), is secreted as a defense mechanism to protect against microbial invasion and physical damage. Unlike common polysaccharides, NEG exhibits a distinct composition rich in bioactive constituents, including heteropolysaccharides and secondary metabolites, contributing to its diverse functional and therapeutic potential. These unique characteristics make NEG a promising biopolymer for applications in pharmaceuticals, food, cosmetics, and environmental industries, where it serves as a binding, emulsifying, gelling, and stabilizing agent. Recent advancements have focused on developing NEG composites and derivatives with enhanced properties and broader applications. Structural modifications like grafting and carboxymethylation have improved its utility in drug delivery, wound healing, and biodegradable materials. Modified NEG derivatives exhibit superior antimicrobial, anti-inflammatory, and antioxidant effects, expanding their biomedical potential in tissue engineering and controlled drug release. NEG-based hydrogels and films show promise in eco-friendly packaging and self-healing biomaterials. This review compiles NEG's diverse applications, highlighting its role in sustainable technologies and emerging fields like self-healing materials and smart polymers. It addresses challenges in scaling production, regulatory compliance, and technical constraints.

Self-Doped and Biodegradable Glycosaminoglycan-PEDOT Conductive Hydrogels Facilitate Electrical Pacing of iPSC-Derived Cardiomyocytes

Conductive polymers hold promise in biomedical applications owing to their distinct conductivity characteristics and unique properties. However, incorporating these polymers into biomaterials poses challenges related to mechanical performance, electrical stability, and biodegradation. This study proposes an injectable hydrogel scaffold composed of a self-doped conductive polymer, constituted of a sulfated glycosaminoglycan (GAG) with side chains of PEDOT (poly 3,4-ethylenedioxythiophene). This brush copolymer is synthesized via oxidative polymerization from an EDOT monomer grafted onto the backbone of the sulfated GAG. The GAG backbone offers biodegradability, while sulfate groups act as acidic self-doping agents. Conductive hydrogels form through oxime crosslinking, initially existing as a liquid mixture that undergoes gelation within the tissue, allowing for injectability. The conductive hydrogels show tunable stiffness and gelation kinetics influenced by both concentration and pH, and exhibit adhesive properties. They showcase dual ionic and electronic conductivity, where sulfate groups in the GAG backbone act as doping moieties, enhancing conductivity and electrical stability. These properties of conductive hydrogels are associated with the facilitation of electrical pacing of iPSC-cardiomyocytes. Furthermore, hydrogels exhibit biodegradation and show evidence of biocompatibility, highlighting their potential for diverse biomedical applications.

Advancing the design of conductive composite cryogels based on hydroxypropyl cellulose derivatives for improving the compressibility and anti-freezing properties

Conductive hydrogels are an appealing class of "smart" materials with great application potential, as they combine the stimuli-responsiveness of hydrogels with the conductivity of magnetic fillers. However, fabricating multifunctional conductive hydrogels that simultaneously exhibit conductivity, self-healing, adhesiveness, and anti-freezing properties remains a significant challenge. To address this issue, we introduce here a freeze-thawing approach to develop versatile, multiresponsive composite cryogels able to preserve their features under low-temperature conditions. Thus, we engineered robust 3D polymer networks by combining oxidized hydroxypropyl cellulose (HPCox) and polyvinyl alcohol (PVA) in glycerol-water mixtures. The presence of glycerol reduces the water loss by evaporation and prevents elasticity decrease upon storage at -20 °C by forming hydrogen bonds with water, HPCox, and PVA. These interactions result in flexible, stable composite cryogels with an extremely fast shape recovery (few seconds) after 100 % mechanical compression, even after freezing. Additionally, the homogeneous dispersion of magnetite nanoparticles (FeNP) into cryogels imparts both magnetic responsiveness and electrical conductivity. Overall, our innovative strategy generates highly adaptable composite cryogels that retain their properties even after exposure to freezing conditions. This opens new avenues for the development of new functional materials for electronics, sensors, wearable devices, and energy storage systems operating at extremely low temperatures.

A review of self-healing hydrogels for bone repair and regeneration: Materials, mechanisms, and applications

Bone defects, which arise from various factors such as trauma, tumor resection, and infection, present a significant clinical challenge. There is an urgent need to develop new biomaterials capable of repairing a wide array of damage and defects in bone tissue. Self-healing hydrogels, a groundbreaking advancement in the field of biomaterials, displaying remarkable ability to regenerate damaged connections after partial severing, thus offering a promising solution for bone defect repair. This review first presents a comprehensive overview of the progress made in the design and preparation of these hydrogels, focusing on the self-healing mechanisms based on physical non-covalent interactions and dynamic chemical covalent bonds. Subsequently, the applications of self-healing hydrogels including natural polymers, synthetic polymers, and nano-hybrid materials, are discussed in detail, emphasizing their mechanisms in promoting bone tissue regeneration. Finally, the review addresses current challenges as well as future prospects for the use of hydrogels in bone repair and regeneration, identifying osteogenic properties, mechanical performance, and long-term biocompatibility as key areas for further improvement. In summary, this paper provides an in-depth analysis of recent advances in self-healing hydrogels for bone repair and regeneration, underscoring their immense potential for clinical application.

AK, Yahya EB, Muhammad S, Rizal S, Ahmad MI, Surya I, Abdullah CK. Recent Advances in Nanocellulose Aerogels for Efficient Heavy Metal and Dye Removal

Water pollution is a significant environmental issue that has emerged because of industrial and economic growth. Human activities such as industrial, agricultural, and technological practices have increased the levels of pollutants in the environment, causing harm to both the environment and public health. Dyes and heavy metals are major contributors to water pollution. Organic dyes are a major concern because of their stability in water and their potential to absorb sunlight, increasing the temperature and disrupting the ecological balance. The presence of heavy metals in the production of textile dyes adds to the toxicity of the wastewater. Heavy metals are a global issue that can harm both human health and the environment and are mainly caused by urbanization and industrialization. To address this issue, researchers have focused on developing effective water treatment procedures, including adsorption, precipitation, and filtration. Among these methods, adsorption is a simple, efficient, and cheap method for removing organic dyes from water. Aerogels have shown potential as a promising adsorbent material because of their low density, high porosity, high surface area, low thermal and electrical conductivity, and ability to respond to external stimuli. Biomaterials such as cellulose, starch, chitosan, chitin, carrageenan, and graphene have been extensively studied for the production of sustainable aerogels for water treatment. Cellulose, which is abundant in nature, has received significant attention in recent years. This review highlights the potential of cellulose-based aerogels as a sustainable and efficient material for removing dyes and heavy metals from water during the treatment process.

Nitric oxide releasing polyvinyl alcohol and sodium alginate hydrogels as antibacterial and conductive strain sensors

Conductive hydrogels have promising applications in flexible electronic devices and artificial intelligence, which have attracted much attention in recent years. However, most conductive hydrogels have no antimicrobial activity, inevitably leading to microbial infections during utilization. In this work, a series of antibacterial and conductive polyvinyl alcohol and sodium alginate (PVA-SA) hydrogels were successfully developed with the incorporation of S-nitroso-N-acetyl-penicillamine (SNAP) and MXene through a freeze-thaw approach. Due to the reversibility of hydrogen bonding and electrostatic interactions, the resulting hydrogels had excellent mechanical properties. Specifically, the presence of MXene readily interrupted the crosslinked hydrogel network, but the best stretching can reach up to >300 %. Moreover, the impregnation of SNAP achieved the release of NO over several days under physiological conditions. Due to the release of NO, these composited hydrogels demonstrated high antibacterial activities (> 99 %) against both Gram-positive and negative S. aureus and E. coli bacteria. Notably, the excellent conductivity of MXene endowed the hydrogel with a sensitive, fast, and stable strain-sensing ability, to accurately monitor and distinguish subtle physiological activities of the human body including finger bending and pulse beating. These novel composited hydrogels are likely to have potential as strain-sensing materials in the field of biomedical flexible electronics.

Environmentally adaptive polysaccharide-based hydrogels and their applications in extreme conditions: A review

Polysaccharide hydrogels are one of the most promising hydrogel materials due to their inherent characteristics, including biocompatibility, biodegradability, renewability, and easy modification, and their structure and functional designs have been widely researched to adapt to different application scenarios as well as to broaden their application fields. As typical wet-soft materials, the high water content and water-absorbing ability of polysaccharide-based hydrogels (PHs) are conducive to their wide biomedical applications, such as wound healing, tissue repair, and drug delivery. In addition, along with technological progress, PHs have shown potential application prospects in some high-tech fields, including human-computer interaction, intelligent driving, smart dressing, flexible sensors, etc. However, in practical applications, due to the poor ability of PHs to resist freezing below zero, dehydration at high temperature, and acid-base/swelling-induced deformation in a solution environment, they are prone to lose their wet-soft peculiarities, including structural integrity, injectability, flexibility, transparency, conductivity and other inherent characteristics, which greatly limit their high-tech applications. Hence, reducing their freezing point, enhancing their high-temperature dehydration resistance, and improving their extreme solution tolerance are powerful approaches to endow PHs with multienvironmental adaptability, broadening their application areas. This report systematically reviews the study advances of environmentally adaptive polysaccharide-based hydrogels (EAPHs), comprising anti-icing hydrogels, high temperature/dehydration resistant hydrogels, and acid/base/swelling deformation resistant hydrogels in recent years. First, the construction methods of EAPHs are presented, and the mechanisms and properties of freeze-resistant, high temperature/dehydration-resistant, and acid/base/swelling deformation-resistant adaptations are simply demonstrated. Meanwhile, the features of different strategies to prepare EAPHs as well as the strategies of simultaneously attaining multienvironmental adaptability are reviewed. Then, the applications of extreme EAPHs are summarized, and some meaningful works are well introduced. Finally, the issues and future outlooks of PH environment adaptation research are elucidated.

Novel Trends in Hydrogel Development for Biomedical Applications: A Review

Nowadays, there are still numerous challenges for well-known biomedical applications, such as tissue engineering (TE), wound healing and controlled drug delivery, which must be faced and solved. Hydrogels have been proposed as excellent candidates for these applications, as they have promising properties for the mentioned applications, including biocompatibility, biodegradability, great absorption capacity and tunable mechanical properties. However, depending on the material or the manufacturing method, the resulting hydrogel may not be up to the specific task for which it is designed, thus there are different approaches proposed to enhance hydrogel performance for the requirements of the application in question. The main purpose of this review article was to summarize the most recent trends of hydrogel technology, going through the most used polymeric materials and the most popular hydrogel synthesis methods in recent years, including different strategies of enhancing hydrogels’ properties, such as cross-linking and the manufacture of composite hydrogels. In addition, the secondary objective of this review was to briefly discuss other novel applications of hydrogels that have been proposed in the past few years which have drawn a lot of attention.