A green route to prepare fluorescent and absorbent nano-hybrid hydrogel for water detection

A Transparent Hydrogel-Ionic Conductor with High Water Retention and Self-Healing Ability

This study presents a transparent and ion-conductive hydrogel with suppressed water loss. The hydrogel comprises agarose polymer doped with sucrose and sodium chloride salt (NaCl-Suc/A hydrogel). Sucrose increases the water retention of the agarose gel, and the Na and Cl ions dissolved in the gel provide ionic conductivity. The NaCl-Suc/A gel shows high retention capability and maintains a 45% water uptake after 4 h of drying at 60 °C without encapsulation at the optimum gel composition. The doped NaCl-Suc/A hydrogel demonstrates improved mechanical properties and ionic conductivity of 1.6 × 10-2 (S/cm) compared to the pristine agarose hydrogel. The self-healing property of the gel restores the electrical continuity when reassembled after cutting. Finally, to demonstrate a potential application of the ion-conductive hydrogel, a transparent and flexible pressure sensor is fabricated using the NaCl-Suc/A hydrogel, and its performance is demonstrated. The results of this study could contribute to solving problems with hydrogel-based devices such as rapid dehydration and poor mechanical properties.

Synthesis of curcuma longa doped cellulose grafted hydrogel for catalysis, bactericidial and insilico molecular docking analysis

Curcumin (diferuloylmethane), the primary curcuminoid in turmeric rhizome, has been acknowledged as a bioactive compound for numerous pharmacological activities. Nonetheless, the hydrophobic nature, rapid metabolism, and physicochemical and biological instability of this phenolic compound correspond to its poor bioavailability. So, recent scientific advances have found many components and strategies for enhancing the bioavailability of curcumin with the inclusion of biotechnology and nanotechnology to address its existing limitations. Therefore, In this study, copolymerized aqua-gel was synthesized by graft polymerization of poly-acrylic acid (P-AA) on cellulose nanocrystals (CNC), after that Curcuma longa (Cur) was incorporated as dopant (5, 10, 15, and 25 mg) in hydrogel (Cur/C-P) as a stabilizing agent for evaluation of bacterial potential and sewage treatment. The antioxidant tendency of 25 mg Cur/C-P was much higher (72.21 %) than other samples and displayed a catalytic activity of up to 93.89 % in acidic conditions and optimized bactericidal inclinations toward gram-positive bacterial strains. Furthermore, ligand binding was conducted against targeted protein enoyl-[acylcarrier-protein] reductase (FabI) enzyme to comprehend the putative mechanism of microbicidal action of CNC-PAA (CP), Cur/C-P, and curcumin. Our outcomes suggest that 25 mg Cur/C-P hydrogels are plausible sources for hybrid, multifunctional biological activity.

Novel Hydrogel Membranes Based on the Bacterial Polysaccharide FucoPol: Design, Characterization and Biological Properties

FucoPol, a fucose-rich polyanionic polysaccharide, was used for the first time for the preparation of hydrogel membranes (HMs) using Fe³⁺ as a crosslinking agent. This study evaluated the impact of Fe³⁺ and FucoPol concentrations on the HMs' strength. The results show that, above 1.5 g/L, Fe³⁺ concentration had a limited influence on the HMs' strength, and varying the FucoPol concentration had a more significant effect. Three different FucoPol concentrations (1.0, 1.75 and 2.5 wt.%) were combined with Fe³⁺ (1.5 g/L), resulting in HMs with a water content above 97 wt.% and an Fe³⁺ content up to 0.16 wt.%. HMs with lower FucoPol content exhibited a denser porous microstructure as the polymer concentration increased. Moreover, the low polymer content HM presented the highest swelling ratio (22.3 ± 1.8 g/g) and a lower hardness value (32.4 ± 5.8 kPa). However, improved mechanical properties (221.9 ± 10.2 kPa) along with a decrease in the swelling ratio (11.9 ± 1.6 g/g) were obtained for HMs with a higher polymer content. Furthermore, all HMs were non-cytotoxic and revealed anti-inflammatory activity. The incorporation of FucoPol as a structuring agent and bioactive ingredient in the development of HMs opens up new possibilities for its use in tissue engineering, drug delivery and wound care management.

Facile synthesis of copolymerized cellulose grafted hydrogel doped calcium oxide nanocomposites with improved antioxidant activity for anti-arthritic and controlled release of doxorubicin for anti-cancer evaluation

The combination treatment is considered an approach to attaining synergistic impact while minimizing applied dosage. Hydrogels are analogous to the tissue environment attributed to hydrophilic and porous structure. Despite extensive study in biological and biotechnological domains, their restricted mechanical strength and limited functionalities impede their potential uses. Emerging strategies are centred on research and developing nanocomposite hydrogels to combat these issues. Herein, we prepared copolymerized hydrogel by grafting poly-acrylic acid P(AA) onto cellulose nanocrystals (CNC) and adding CNC-g-PAA as dopant (2 and 4 wt%) in calcium oxide (CaO) nanoparticles to generate an effective hydrogel doped nanocomposite (NCH) (CNC-g-PAA/CaO) for biomedical applications such as anti-arthritic, anti-cancer, and antibacterial investigations alongside their comprehensive characterization. CNC-g-PAA/CaO (4 %), compared to other samples, had a substantially higher antioxidant potential (72.21 %). Doxorubicin, a potential chemotherapeutic drug, was then effectively loaded into NCH (99 %) via electrostatic interaction, and pH-triggered based release was found to be >57.9 % in 24 h. Furthermore, molecular docking investigation against targeted protein Cyclin-dependent kinase 2 and in vitro cytotoxicity study verified the improved antitumor effectiveness of CNC-g-PAA and CNC-g-PAA/CaO. These outcomes indicated that hydrogels might serve as potential delivery vehicles for innovative multifunctional biomedical applications.

Formation of biocompatible MgO/cellulose grafted hydrogel for efficient bactericidal and controlled release of doxorubicin

In this study, MgO-doped CNC-g-PAA hydrogel was synthesized by grafting poly (acrylic acid) (PAA) onto cellulose nanocrystals (CNC) and then doped Magnesium oxide (MgO) using pH 7.0 and 12.0 to obtain an efficient nanocomposite hydrogel for antibacterial and anti-cancer activities. The synthesized nanocomposite hydrogels were evaluated by detailed characterization and confirmed the formation of a well-interconnected porous structure. MgO/CNC-g-PAA (pH = 12.0) exhibited improved bactericidal tendencies towards gram-negative and gram-positive bacteria, which was further investigated by in-silico molecular docking analyses and also examined the reactive oxygen species production by photocatalysis and free radical-scavenging assay. After this, Doxorubicin (DOX), a model anticancer drug, was successfully loaded into nanocomposites (~79 %) by electrostatic interaction and confirmed pH-triggered based release, which was over 53.7 % in 24 h. Finally, in vitro cytotoxicity-based analysis confirmed the improved antitumor efficacy of nanocomposite hydrogels. These findings revealed that MgO/CNC-g-PAA hydrogels might be prospective carriers for controlled drug delivery.

Novel Fluorescent Nanocellulose Hydrogel Based on Nanocellulose and Carbon Dots for Detection and Removal of Heavy Metal Ions in Water

Water is an important raw material in the food production process. Maintaining the quality and safety of water is very important in the food field. In this study, a simple novel fluorescent nanocellulose hydrogel (FNH) was prepared for the detection and removal of heavy metals (Fe³⁺ and Pb²⁺) in aqueous solutions based on carbon dots (CDs). The CDs were grafted onto the carboxylated nanocellulose (CNC) by the EDC/NHS coupling method, and then the nanocellulose (NC), CNC, and FNH were characterized by FTIR analysis. The effect of adsorption environment on FNH adsorption capacity was also investigated. After carboxylation and grafting of CDs, the adsorption capacity of nanocellulose to Fe³⁺ and Pb²⁺ was greatly improved, and it was also allowed to make fast visual responses to Fe³⁺ as an optical sensor to determine the concentration of Fe³⁺ through the visual signal. Static adsorption experiment demonstrated that the removal rate of Fe³⁺ and Pb²⁺ by FNH exceeded 69.4% and 98.2%, and the adsorption capacity amount reached 98.3 mg/g and 442.0 mg/g. At the same time, due to the fluorescence quenching effect of Fe³⁺, FNH could also be used for the detection of Fe³⁺ concentration in aqueous solution, and the limit of detection (LOD) could reach 62.5 mg/L.

Plant-Based Structures as an Opportunity to Engineer Optical Functions in Next-Generation Light Management

This review addresses the reconstruction of structural plant components (cellulose, lignin, and hemicelluloses) into materials displaying advanced optical properties. The strategies to isolate the main building blocks are discussed, and the effects of fibrillation, fibril alignment, densification, self-assembly, surface-patterning, and compositing are presented considering their role in engineering optical performance. Then, key elements that enable lignocellulosic to be translated into materials that present optical functionality, such as transparency, haze, reflectance, UV-blocking, luminescence, and structural colors, are described. Mapping the optical landscape that is accessible from lignocellulosics is shown as an essential step toward their utilization in smart devices. Advanced materials built from sustainable resources, including those obtained from industrial or agricultural side streams, demonstrate enormous promise in optoelectronics due to their potentially lower cost, while meeting or even exceeding current demands in performance. The requirements are summarized for the production and application of plant-based optically functional materials in different smart material applications and the review is concluded with a perspective about this active field of knowledge.

Co-Assembly of Biosynthetic Chiral Nematic Adhesive Materials with Dynamic Polarized Luminescence

There is currently an extensive demand for simple and effective synthetic methods to allow the design and fabrication of robust and flexible chiral materials that can generate strong and switchable circularly polarized luminescence (CPL). Herein, biosynthetic light-emitting adhesive materials based upon chiral nematic cellulose nanocrystal-polyelectrolyte complexes with universal high adhesion on both hydrophilic and hydrophobic substrates are reported. Strong and dynamic photoluminescence with highly asymmetric and switchable circular polarization is induced by minute rare earth europium doping without compromising adhesive strength and initial iridescent properties. The photoluminescence can be temporarily quenched with highly volatile acetone vapor and liquid followed by fast recovery after drying with full restoration of initial emission. The unique properties of light-emitting bio-adhesives with universal adhesion, amplified and dynamic photoluminescence, and large and switchable CPL can be utilized for security optical coding, bio-optical memory, hidden communication, and biochemical sensing as wearable stickers, prints, and tattoos to directly adhere to human clothes, gadgets, and skin by using adhesive stickers with bright tailored photoluminescence.

Engineering Carbohydrate-Based Particles for Biomedical Applications: Strategies to Construct and Modify

Carbohydrate-based micro/nanoparticles have gained significant attention for various biomedical applications such as targeted/triggered/controlled drug delivery, bioimaging, biosensing, etc., because of their prominent characteristics like biocompatibility, biodegradability, hydrophilicity, and nontoxicity as well as nonimmunogenicity. Most importantly, the ability of the nanoparticles to recognize specific cell sites by targeting cell surface receptors makes them a promising candidate for designing a targeted drug delivery system. These particles may either comprise polysaccharides/glycopolymers or be integrated with various polymeric/inorganic nanoparticles such as gold, silver, silica, iron, etc., to reduce the toxicity of the inorganic nanoparticles and thus facilitate their cellular insertion. Various synthetic methods have been developed to fabricate carbohydrate-based or carbohydrate-conjugated inorganic/polymeric nanoparticles. In this review, we have highlighted the recently developed synthetic approaches to afford carbohydrate-based particles along with their significance in various biomedical applications.

Vanadium Phosphorus Oxide/Siliceous Mesostructured Cellular Foams: efficient and selective for sustainable acrylic acid production via condensation route

A new type of supported vanadium phosphorus oxide (VPO) with self-phase regulation was simply fabricated (organic solvent free) for the first time by depositing the specific VPO precursor NH₄(VO₂)HPO₄ onto the Siliceous Mesostructured Cellular Foams (MCF) with controlled activation. The resulting materials were found to be highly efficient and selective for sustainable acrylic acid (AA) plus methyl acrylate (MA) production via a condensation route between acetic acid (HAc) and formaldehyde (HCHO). A (AA + MA) yield of 83.7% (HCHO input-based) or a (AA + MA) selectivity of 81.7% (converted HAc-based) are achievable at 360 °C. The systematic characterizations and evaluations demonstrate a unique surface regulation occurring between the MCF and the NH₄(VO₂)HPO₄ precursor. NH₃ release upon activation of NH₄(VO₂)HPO₄ precursor together with adsorption of NH₃ by MCF automatically induces partial reduction of V⁵⁺ whose content is fine-tunable by the VPO loading. Such a functionalization simultaneously modifies phase constitution and surface acidity/basicity of catalyst, hence readily controls catalytic performance.

Anisotropic Diffusion and Phase Behavior of Cellulose Nanocrystal Suspensions

In this paper, we use dynamic light scattering in polarized and depolarized modes to determine the translational and rotational diffusion coefficients of concentrated rodlike cellulose nanocrystals in aqueous suspension. Within the range of studied concentrations (1-5 wt %), the suspension starts a phase transition from an isotropic to an anisotropic state as shown by polarized light microscopy and viscosity measurements. Small-angle neutron scattering measurements also confirmed the start of cellulose nanocrystal alignment and a decreasing distance between the cellulose nanocrystals with increasing concentration. As expected, rotational and translational diffusion coefficients generally decreased with increasing concentration. However, the translational parallel diffusion coefficient was found to show a local maximum at the onset of the isotropic-to-nematic phase transition. This is attributed to the increased available space for rods to move along their longitudinal axis upon alignment. This increased parallel diffusion coefficient thus confirms the general idea that rodlike particles gain translational entropy upon alignment while paying the price for losing rotational degrees of freedom. Once the concentration increases further, diffusion becomes more hindered even in the aligned regions due to a reduction in the rod separation distance. This leads once again to a decrease in translational diffusion coefficients. Furthermore, the relaxation rate for fast mode translational diffusion (parallel to the long particle axis) exhibited two regimes of relaxation behavior at concentrations where significant alignment of the rods is measured. We attribute this unusual dispersive behavior to two length scales: one linked to the particle length (at large wavevector q) and the other to a twist fluctuation correlation length (at low wavevector q) along the cellulose nanocrystal rods that is of a larger length when compared to the actual length of rods and could be linked to the size of aligned domains.

Microwave assisted κ-carrageenan capped silver nanocomposites for eradication of bacterial biofilms

Maturation of bacterial biofilms and their resistance to recurrent antimicrobial agents results in convoluted infectious diseases. In the current study, kappa-Carrageenan (κ-Carrageenan/CRG), was used to formulate CRG-silver nanocomposites through a facile microwave green synthesis approach. CRG-Ag nanoparticles of size 50 ± 10 nm were obtained by using CRG as a reducing and stabilizing agent. CRG-Ag nanoparticles were highly effective against both S. aureus and P. aeruginosa mediated biofilms and acted as a broad spectrum antibacterial agent even after six months. CRG-Ag nanoparticles encapsulated in KCl cross-linked hydrogel also exhibited excellent thermal stability, and antimicrobial potency. All these results depict that CRG-Ag nanocomposites appear as a promising approach to eradicate bacterial biofilms in food packaging and biomedical applications.

Nanostructured Functional Hydrogels as an Emerging Platform for Advanced Energy Technologies

Nanostructured materials are critically important in many areas of technology because of their unusual physical/chemical properties due to confined dimensions. Owing to their intrinsic hierarchical micro-/nanostructures, unique chemical/physical properties, and tailorable functionalities, hydrogels and their derivatives have emerged as an important class of functional materials and receive increasing interest from the scientific community. Bottom-up synthetic strategies to rationally design and modify their molecular architectures enable nanostructured functional hydrogels to address several critical challenges in advanced energy technologies. Integrating the intrinsic or extrinsic properties of various functional materials, nanostructured functional hydrogels hold the promise to break the limitations of current materials, improving the device performance of energy storage and conversion. Here, the focus is on the fundamentals and applications of nanostructured functional hydrogels in energy conversion and storage. Specifically, the recent advances in rational synthesis and modification of various hydrogel-derived functional nanomaterials as core components in batteries, supercapacitors, and catalysts are summarized, and the perspective directions of this emerging class of materials are also discussed.

Electrostatically Interactive Injectable Hydrogels for Drug Delivery

BACKGROUND

Several injectable hydrogels have been developed extensively for a broad range of biomedical applications. Injectable hydrogels forming in situ through the change in external stimuli have the distinct properties of easy management and minimal invasiveness, and thus provide the advantage of bypassing surgical procedures for administration resulting in better patient compliance.

METHODS

The injectable in situ-forming hydrogels can be formed irreversibly or reversibly under physiological stimuli. Among several external stimuli that induce formation of hydrogels in situ, in this review, we focused on the electrostatic interactions as the most simple and interesting stimulus.

RESULTS

Currently, numerous polyelectrolytes have been reported as potential electrostatically interactive in situ-forming hydrogels. In this review, a comprehensive overview of the rapidly developing electrostatically interactive in situ-forming hydrogels, which are produced by various anionic and cationic polyelectrolytes such as chitosan, celluloses, and alginates, has been outlined and summarized. Further, their biomedical applications have also been discussed.

CONCLUSION

The review concludes with perspectives on the future of electrostatically interactive in situ-forming hydrogels.

A photo-switchable and thermal-enhanced fluorescent hydrogel prepared from N-isopropylacrylamide with water-soluble spiropyran derivative

Herein, a photo-switchable and thermal-enhanced fluorescent hydrogel has been fabricated from N-isopropylacrylamide (NIPAAm) with a mixture of water-soluble acryloyl-α-cyclodextrin/acryloyl-α-cyclodextrin-spiropyran (acryloyl-α-CD/ acryloyl-α-CD-SP) as cross-linkers. The physical properties, photochromic properties, and fluorescent behavior of the hydrogel were characterized. The fluorescence emission of the hydrogel can be reversibly switched 'on/off' by UV/visible light irradiation, and meanwhile the fluorescence intensity can be enhanced by increasing the temperature above the volume phase transition temperature (VPTT) of the hydrogel. The hydrogel also shows spatiotemporal fluorescent behavior, excellent cytocompatibility, and fatigue resistance in photochromic and photo-switchable fluorescent behaviors.

Chitosan hydrogelation with a phenothiazine based aldehyde: a synthetic approach toward highly luminescent biomaterials

Hydrogelation of chitosan with a photoactive aldehyde via covalent dynamic chemistry proved an original approach towards efficient luminescent biomaterials.