Search Results (36)

Nanomaterials’ special features enable their extensive application in chemical and biochemical nanosensors for food assays; food packaging; environmental, medicinal, and pharmaceutical applications; and photoelectronics. The analytical strategies based on novel nanomaterials have proved their pivotal role and increasing interest in the assay of key food components. The choice of transducer is pivotal for promoting the performance of electrochemical sensors. Electrochemical nano-transducers provide a large active surface area, enabling improved sensitivity, specificity, fast assay, precision, accuracy, and reproducibility, over the analytical range of interest, when compared to traditional sensors. Synthetic routes encompass physical techniques in general based on top–down approaches, chemical methods mainly relying on bottom–up approaches, or green technologies. Hybrid techniques such as electrochemical pathways or photochemical reduction are also applied. Electrochemical nanocomposite sensors relying on conducting polymers are amenable to performance improvement, achieved by integrating redox mediators, conductive hydrogels, and molecular imprinting polymers. Carbon-based or metal-based nanoparticles are used in combination with ionic liquids, enhancing conductivity and electron transfer. The composites may be prepared using a plethora of combinations of carbon-based, metal-based, or organic-based nanomaterials, promoting a high electrocatalytic response, and can accommodate biorecognition elements for increased specificity. Nanomaterials can function as pivotal components in electrochemical (bio)sensors applied to food assays, aiming at the analysis of bioactives, nutrients, food additives, and contaminants. Given the broad range of transducer types, detection modes, and targeted analytes, it is important to discuss the analytical performance and applicability of such nanosensors. Full article

Hydrogels have emerged as a promising material for the removal of heavy metal ions from contaminated water owing to their high water absorption capacity and biocompatibility. Despite notable advancements in improving the adsorptive capacity of hydrogels, the demand for a more efficient structure persists. Here, we explore the ion adsorption performance of crosslinked hydrogels based on chitosan and sodium alginate with various ratios of carbon nanotubes (CNT) and graphene platelets (GNP). This study highlights the adsorption of chromium ions and the thermal stability of hydrogels for pure, single-particle, and hybrid nanocomposites. The results depict a uniform microstructure attained when CNT, GNP, or both are implemented into the hydrogel due to the strong interaction of functional moieties. The incorporation of CNT and GNP manipulates the crystalline structure of the hydrogels, lowering their crystallinity by around 28% and 13%, respectively. The synergistic effect of CNT and GNP in hybrid hydrogels raises the decomposition temperature by 16%, indicating a favorable interplay interaction between nanoparticles and polymers. Calculations of the adsorption capacity accentuate such a mutual effect between CNT and GNP in various loads of ion capture from aqueous solutions. Kinetic models fitted to the hydrogel nanocomposites reveal that the pseudo-second-order model aligns better with the experimental data in comparison to the pseudo-first-order and intraparticle diffusion models, addressing the adsorption mechanisms while capturing chromium ions. Full article

Bioactive metal and metal oxide-based nanocomposite hydrogels exhibit significant antibacterial properties by interacting with microbial DNA and preventing bacterial replication. They offer potential applications as coating materials for human or animal skin injuries to prevent microbial growth and promote healing. In this study, silver nanoparticles (AgNPs) were synthesized using a chemical reduction method and incorporated into a polymer network to fabricate silver nanocomposite hydrogels (AgNCHGs) through a simple free radical polymerization method. N-isopropylacrylamide (NIPA), which has lower critical solution temperature (LCST) at about body temperature, or acrylamide (AAm) was used as the main monomer, while one or more ionic co-monomers, such as acrylic acid (AAc) and 2-acrylamido-2-methylpropane sulfonic acid (AMPS), were incorporated to obtain AgNCHGs. AgNPs were introduced into the hydrogel network via three different approaches. In the first method, the synthesized hydrogel was immersed in a silver nitrate (AgNO₃) solution and reduced in situ using sodium borohydride (NaBH₄) as a reducing agent. The second method involved mixing AgNO₃ with gel precursors before reduction with NaBH₄ to form AgNPs within the hydrogel. The final approach synthesized the AgNCHGs directly in a dispersion of pre-fabricated AgNPs. The incorporation of AgNPs in different AgNCHGs was confirmed through various characterization techniques. Varying temperature and pH conditions can trigger the release of bioactive AgNPs from the hydrogels. Furthermore, the antimicrobial and wound-healing properties of the AgNCHGs were evaluated against bacteria and fungi, demonstrating their potential in biomedical applications. In addition, AgNCHGs exhibit excellent electrical conductivity. The electrical conductivity of the hydrogels can be finely tuned by adjusting the concentration of AgNPs, making these materials promising candidates for energy, sensor, and stretchable electronics applications. This study presents facile synthesis methods of AgNCHGs, which integrate bioactivity, wound healing, and electrical conductivity in the same matrix, addressing a significant challenge in designing multifunctional hydrogels for next-generation technologies. Full article

This study presents the synthesis, characterization, and evaluation of hybrid hydrogels based on calcium alginate (Ca-Alg) and synthetic nanoclay LaponiteRD (Lap), with an emphasis on their swelling and sorption properties. The motivation behind the development of these hybrid hydrogels stems from the need for sustainable materials with enhanced mechanical strength, swelling properties, and sorption capacity for environmental remediation and controlled-release applications. Synthesis methods for the ionotropically cross-linked Ca-Alg hydrogel and Alg–Lap composite hydrogels, based on Alg and Lap in the form of granules and fibres, have been developed. The Fourier-transform infrared spectroscopy (FTIR), Energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD) analyses of composite hydrogels confirmed the successful incorporation of Lap into the Ca-Alg matrix, indicating strong interactions between the polymer and clay, which enhanced the structural integrity of the hydrogels. The morphology of the surface and pore structure of nanocomposites were studied using Scanning Electron Microscopy (SEM). The swelling behaviour of the nanocomposites was largely dependent on the concentrations of Lap and the cross-linking agent (CaCl₂), with higher concentrations leading to more rigid, less swellable structures due to the increased cross-linking density. The sorption studies, specifically with Fe(II) ions, demonstrated that the hybrid hydrogels possess a large sorption capacity, with Lap contributing to selective sorption at lower Fe(II) ion concentrations and Alg enhancing overall capacity at higher concentrations. This suggests that the synergistic interaction between Alg and Lap not only improves mechanical stability but also tailors the sorption properties of the hydrogels. These findings position the Alg-Lap hydrogels as promising materials for a range of environmental applications, including wastewater treatment, heavy metal ion removal, and the design of advanced filtration systems. The study’s insights into the tunability of these hydrogels pave the way for further research into their use in diverse fields such as biomedicine, agriculture, and industrial water management. Full article

Interfaces between implantable bioelectrodes and tissues provide critical insights into the biological and pathological conditions of targeted organs, aiding diagnosis and treatment. While conventional bioelectronics, made from rigid materials like metals and silicon, have been essential for recording signals and delivering electric stimulation, they face limitations due to the mechanical mismatch between rigid devices and soft tissues. Recently, focus has shifted toward soft conductive materials, such as conductive hydrogels and hydrogel nanocomposites, known for their tissue-like softness, biocompatibility, and potential for functionalization. This review introduces these materials and provides an overview of recent advances in soft hydrogel nanocomposites for implantable electronics. It covers material strategies for conductive hydrogels, including both intrinsically conductive hydrogels and hydrogel nanocomposites, and explores key functionalization techniques like biodegradation, bioadhesiveness, injectability, and self-healing. Practical applications of these materials in implantable electronics are also highlighted, showcasing their effectiveness in real-world scenarios. Finally, we discuss emerging technologies and future needs for chronically implantable bioelectronics, offering insights into the evolving landscape of this field. Full article

Hydrogels are gaining popularity for use in wearable electronics owing to their inherent biomimetic characteristics, flexible physicochemical properties, and excellent biocompatibility. Among various hydrogels, conductive polymer-based hydrogels (CP HGs) have emerged as excellent candidates for future wearable sensor designs. These hydrogels can attain desired properties through various tuning strategies extending from molecular design to microstructural configuration. However, significant challenges remain, such as the limited strain-sensing range, significant hysteresis of sensing signals, dehydration-induced functional failure, and surface/interfacial malfunction during manufacturing/processing. This review summarizes the recent developments in polymer-hydrogel-based wearable electrochemical biosensors over the past five years. Initially serving as carriers for biomolecules, polymer-hydrogel-based sensors have advanced to encompass a wider range of applications, including the development of non-enzymatic sensors facilitated by the integration of nanomaterials such as metals, metal oxides, and carbon-based materials. Beyond the numerous existing reports that primarily focus on biomolecule detection, we extend the scope to include the fabrication of nanocomposite conductive polymer hydrogels and explore their varied conductivity mechanisms in electrochemical sensing applications. This comprehensive evaluation is instrumental in determining the readiness of these polymer hydrogels for point-of-care translation and state-of-the-art applications in wearable electrochemical sensing technology. Full article

The three-dimensional (3D) printing of biomaterials, cells, and bioactive components, including growth factors, has gained interest among researchers in the field of tissue engineering (TE) with the aim of developing many scaffolds to sustain size, shape fidelity, and structure and retain viable cells inside a network. The biocompatible hydrogel employed in 3D printing should be soft enough to accommodate cell survival. At the same time, the gel should be mechanically strong to avoid the leakage of cells into the surrounding medium. Considering these basic criteria, researchers have developed nanocomposite-based printable inks with suitable mechanical and electroconductive properties. These nanomaterials, including carbon family nanomaterials, transition metal dichalcogenides, and polymeric nanoparticles, act as nanofillers and dissipate stress across polymeric networks through their electroactive interactions. Nanofiber-reinforced printable ink is one kind of nanocomposite-based ink that comprises dispersed nanofiber components in a hydrogel matrix. In this current review, we compile various TE applications of nanofiber-reinforced printable ink and describe the 3D-printing parameters, classification, and impact of cross-linkage. Furthermore, we discuss the challenges and future perspectives in this field. Full article

A disposable electrochemical sensor based on silver nanoparticle-embedded cellulose hydrogel composites was developed for sensitive detection of sulfamethoxazole residues in meat samples. Scanning electron microscopy confirmed the porous structure of the cellulose matrix anchored with 20–50 nm silver nanoparticles (AgNPs). Fourier transform infrared spectroscopy and X-ray diffraction verified that the metallic AgNPs coordinated with the amorphous cellulose chains. At an optimum 0.5% loading, the nanocomposite sensor showed a peak-to-peak separation of 150 mV, diffusion-controlled charge transfer kinetics, and an electron transfer coefficient of 0.6 using a ferro/ferricyanide redox probe. Square-wave voltammetry was applied for sensing sulfamethoxazole based on its two-electron oxidation peak at 0.72 V vs. Ag/AgCl in Britton–Robinson buffer of pH 7.0. A linear detection range of 0.1–100 μM sulfamethoxazole was obtained with a sensitivity of 0.752 μA/μM and limit of detection of 0.04 μM. Successful recovery between 86 and 92% and less than 6% RSD was achieved from spiked meat samples. The key benefits of the proposed disposable sensor include facile fabrication, an antifouling surface, and a reliable quantification ability, meeting regulatory limits. This research demonstrates the potential of novel cellulose–silver nanocomposite materials towards developing rapid, low-cost electroanalytical devices for decentralized on-site screening of veterinary drug residues to ensure food safety. Full article

Wound management heavily relies on the vital contribution of wound dressings, emphasizing the significance of finding an ideal dressing that can fulfill the intricate requirements of the wound healing process with multiple functions. A promising strategy is combining several materials and therapies to create multifunctional wound dressings. Nanocomposite hydrogel dressings based on nanomaterials, combining the advantages of nanomaterials and hydrogels in wound treatment, can significantly improve their respective performance and compensate for their shortcomings. A variety of nanocomposite wound dressings with diverse structures and synergistic functions have been developed in recent years, achieving ideal results in wound management applications. In this review, the multiple functions, advantages, and limitations of hydrogels as wound dressings are first discussed. Additionally, the application of inorganic nanomaterials in wound healing is also elaborated on. Furthermore, we focused on summarizing and analyzing nanocomposite hydrogel dressings for wound healing, which contain various inorganic nanomaterials, including metals, metal oxides, metal sulfides, carbon-based nanomaterials, and silicon-based nanoparticles. Finally, prospects for nanocomposite hydrogel wound dressings are envisaged, providing insights for further research in wound management. Full article

This study investigates the development of polyvinyl alcohol (PVA) gel matrices for biomass immobilization in wastewater treatment. The PVA hydrogels were prepared through a freezing–thawing (F-T) cross-linking process and reinforced with high surface area nanoparticles to improve their mechanical stability and porosity. The PVA/nanocomposite hydrogels were prepared using two different nanoparticle materials: iron oxide (Fe₃O₂) and titanium oxide (TiO₂). The effects of the metal oxide nanoparticle type and content on the pore structure, hydrogel bonding, and mechanical and viscoelastic properties of the cross-linked hydrogel composites were investigated. The most durable PVA/nanoparticles matrix was then tested in the bioreactor for the biological treatment of wastewater. Morphological analysis showed that the reinforcement of PVA gel with Fe₂O₃ and TiO₂ nanoparticles resulted in a compact nanocomposite hydrogel with regular pore distribution. The FTIR analysis highlighted the formation of bonds between nanoparticles and hydrogel, which caused more interaction within the polymeric matrix. Furthermore, the mechanical strength and Young’s modulus of the hydrogel composites were found to depend on the type and content of the nanoparticles. The most remarkable improvement in the mechanical strength of the PVA/nanoparticles composites was obtained by incorporating 0.1 wt% TiO₂ and 1.0 wt% Fe₂O₃ nanoparticles. However, TiO₂ showed more influence on the mechanical strength, with more than 900% improvement in Young’s modulus for TiO₂-reinforced PVA hydrogel. Furthermore, incorporating TiO₂ nanoparticles enhanced hydrogel stability but did not affect the biodegradation of organic pollutants in wastewater. These results suggest that the PVA-TiO₂ hydrogel has the potential to be used as an effective carrier for biomass immobilization and wastewater treatment. Full article

Hydrogels are three-dimensional (3D) water-swellable polymeric matrices that are used extensively in tissue engineering and drug delivery. Hydrogels can be conformed into any desirable shape using 3D bio-printing, making them suitable for personalized treatment. Among the different 3D bio-printing techniques, digital light processing (DLP)-based printing offers the advantage of quickly fabricating high resolution structures, reducing the chances of cell damage during the printing process. Here, we have used DLP to 3D bio-print biocompatible gelatin methacrylate (GelMA) scaffolds intended for bone repair. GelMA is biocompatible, biodegradable, has integrin binding motifs that promote cell adhesion, and can be crosslinked easily to form hydrogels. However, GelMA on its own is incapable of promoting bone repair and must be supplemented with pharmaceutical molecules or growth factors, which can be toxic or expensive. To overcome this limitation, we introduced zinc-based metal-organic framework (MOF) nanoparticles into GelMA that can promote osteogenic differentiation, providing safer and more affordable alternatives to traditional methods. Incorporation of this nanoparticle into GelMA hydrogel has demonstrated significant improvement across multiple aspects, including bio-printability, and favorable mechanical properties (showing a significant increase in the compressive modulus from 52.14 ± 19.42 kPa to 128.13 ± 19.46 kPa with the addition of ZIF-8 nanoparticles). The designed nanocomposite hydrogels can also sustain drug (vancomycin) release (maximum 87.52 ± 1.6% cumulative amount) and exhibit a remarkable ability to differentiate human adipose-derived mesenchymal stem cells toward the osteogenic lineage. Furthermore, the formulated MOF-integrated nanocomposite hydrogel offers the unique capability to coat metallic implants intended for bone healing. Overall, the remarkable printability and coating ability displayed by the nanocomposite hydrogel presents itself as a promising candidate for drug delivery, cell delivery and bone tissue engineering applications. Full article

Due to increasing health and environmental issues, indoor air quality (IAQ) has garnered much research attention with regard to incorporating advanced clean air technologies. Various physicochemical air treatments have been used to monitor, control, and manage air contaminants, such as monitoring devices (gas sensors and internet of things-based systems), filtration (mechanical and electrical), adsorption, UV disinfection, UV photocatalysts, a non-thermal plasma approach, air conditioning systems, and green technologies (green plants and algae). This article reviews presently viable technologies for cleaning indoor air and enhancing IAQ. However, regarding the integration of each technology, there are certain limitations to these methods, including the types of pollutants released. As a result, advanced nanomaterials have been applied to monitoring sensors, filtration and adsorption media, and UV photocatalysts to improve IAQ values. The most important nanomaterials used in this regard include polymeric nanofibrous membranes, nanoporous nanomaterials, nanocomposite hydrogels, polymer/nanocarbon nanocomposite, polymer/metal oxide nanocomposite, polymeric nanohybrids, etc. Accordingly, through the use of nanotechnology, optimal solutions linking IAQ regulation techniques to novel nanomaterials can be achieved to attain safe IAQ levels. Full article

Nanocomposite hydrogels are highly porous colloidal structures with a high adsorption capacity, making them promising materials for wastewater treatment. In particular, magnetic nanoparticle (MNP) incorporated hydrogels are an excellent adsorbent for aquatic pollutants. An added advantage is that, with the application of an external magnetic field, magnetic hydrogels can be collected back from the wastewater system. However, magnetic hydrogels are quite brittle and structurally unstable under compact conditions such as in fixed-bed adsorption columns. To address this issue, this study demonstrates a unique hydrogel composite bead structure, providing a good adsorption capacity and superior compressive stress tolerance due to the presence of hollow cores within the beads. The gel beads contain alginate polymer as the matrix and MNP-decorated cellulose nanofibres (CNF) as the reinforcing agent. The MNPs within the gel provide active adsorption functionality, while CNF provide a good stress transfer phenomenon when the beads are under compressive stress. Their adsorption performance is evaluated in a red mud solution for pollutant adsorption. Composite gel beads have shown high performance in adsorbing metal (aluminium, potassium, selenium, sodium, and vanadium) and non-metal (sulphur) contaminations. This novel hybrid hydrogel could be a promising alternative to the conventionally used toxic adsorbent, providing environmentally friendly operational benefits. Full article

Nanomaterials have demonstrated a wide range of applications and recently, novel biomedical studies are devoted to improving the functionality and effectivity of traditional and unmodified systems, either drug carriers and common scaffolds for tissue engineering or advanced hydrogels for wound healing purposes. In this regard, metal oxide nanoparticles show great potential as versatile tools in biomedical science. In particular, iron oxide nanoparticles with different shape and sizes hold outstanding physiochemical characteristics, such as high specific area and porous structure that make them idoneous nanomaterials to be used in diverse aspects of medicine and biological systems. Moreover, due to the high thermal stability and mechanical strength of Fe₂O₃, they have been combined with several polymers and employed for various nano-treatments for specific human diseases. This review is focused on summarizing the applications of Fe₂O₃-based nanocomposites in the biomedical field, including nanocarriers for drug delivery, tissue engineering, and wound healing. Additionally, their structure, magnetic properties, biocompatibility, and toxicity will be discussed. Full article

Innovative and facile methods for the preparation of metal nanoparticles (MNPs) with A highly uniform distribution and anchored on a unique substrate are receiving increasing interest for the development of efficient and low-cost catalysts in the field of alternative and sustainable energy technologies. In this study, we report a novel and facile metal-ions adsorption-pyrolysis method based on a hydrogel nanocomposite for the preparation of well-distributed nickel nanoparticles on 3D porous carbon frameworks (Ni@PCFs). The pyrolysis temperature effect on electrocatalytic activity toward methanol oxidation and catalyst stability was investigated. Physicochemical characterizations (SEM, TEM, and XRD) were used to determine the morphology and composition of the prepared electrocatalyst, which were then linked to their electrocatalytic activity. The experimental results indicate that the catalyst synthesized by pyrolysis at 800 °C (Ni@PCFs-8) exhibits the highest electrocatalytic activity for oxidation of methanol in alkaline media. Additionally, prepared Ni@PCFs-8 displays a remarkable increase in electrocatalytic activity after activation in 1 M KOH and excellent stability. The adsorption-pyrolysis pathway ensures that the Ni NPs are trapped in the PCFs, which can provide highly reactive surface sites. This work may provide a facile and effective strategy for preparing uniformly distributed metallic NPs on a 3D PCF substrate with high catalytic activity for energy applications. Full article