Among the most promising areas of research, cellulose-based electrochemical sensors stand out for their intrinsic properties such as abundance, biocompatibility, and versatility. This review is concerned with the integration and application of cellulose-derived materials in electrochemical sensors, pointing out improvements in sensitivity, selectivity, stability, and functionality for a wide variety of applications. The most relevant developments on cellulose-based sensors have been concentrated on nanocellulose composite synthesis, advanced cellulose modification, and the successful embedding in wearable technologies, medical diagnostics, and environmental monitoring. Considering these, it is worth mentioning that significant challenges still need to be overcome regarding the scalability of production, selectivity improvement, and long-term stability under real operational conditions. Future research efforts will concern the union of cellulose-based sensors with the Internet of Things (IoT) and artificial intelligence (AI) toward wiser and more sustainable health and environmental solutions. Correspondingly, this work puts cellulose in the front line among the most perspective materials for enabling the development of eco-friendly and high-performance sensing technologies.

The search for sustainable and efficient remediation techniques is required to control increasing environmental pollution caused by synthetic dyes, heavy metal ions, and other harmful pollutants. From this point of view, natural polymers like chitosan, cellulose, lignin, and pectin have been found highly promising due to their biodegradability, availability, and possibility of chemical functionalization. Natural polymers possess inherent adsorption properties that can be further enhanced by cross-linking and surface activation. This review discusses the main properties, adsorption mechanisms, and functional groups such as hydroxyl, carboxyl, and amino groups responsible for pollutant sequestration. The paper also emphasizes the effectiveness of natural polymers in removing heavy metals and dyes from wastewater and discusses recent advances in polymer modifications, including ionic crosslinking and grafting. This study underlines the ecological potential of natural polymer-based adsorbents in the treatment of wastewater and the protection of the environment as a sustainable solution to pollution challenges.

Chronic and non-communicable diseases (NCDs) account for a large proportion of global disorders and mortality, posing significant burdens on healthcare systems. Early diagnosis and timely interference are critical for effective management and disease prevention. However, the traditional methods of diagnosis still suffer from high costs, time delays in processing, and infrastructure requirements that are usually unaffordable in resource-constrained settings. Aptamer-based biosensors have emerged as promising alternatives to offer enhanced specificity, stability, and cost-effectiveness for disease biomarker detection. The SELEX (Systematic Evolution of Ligands by Exponential Enrichment) methodology allows developing aptamers with high-affinity binding capabilities to a variety of targets, for instance proteins, cells, or even small molecules, hence rendering them suitable for NCD diagnosis. Aptasensors—recent developments in the electrochemical and optical dominion—offer much enhanced sensitivity, selectivity, and stability of detection across a diverse range of diseases from lung cancer and leukemia to diabetes and chronic respiratory disorders. This study provides a comprehensive review of progress in aptamer-based sensors, focusing on their role in point-of-care diagnostics and adaptability in a real-world environment with future directions in overcoming current limitations.

Clean water and uncontaminated soil are fundamental for sustaining life on Earth and are essential for assuring human health, and the use of sustainable adsorption materials has emerged as an effective strategy to reduce the volume of effluents released into the environment. Cellulose–bentonite composites have shown significant promise in water purification due to their high adsorption capacity, structural stability, and eco-friendly nature, making them an effective material for the removal of a wide range of pollutants from contaminated water. The most commonly employed methods of fabrication of cellulose–bentonite composites include solution casting, in situ polymerization, and electrospinning. Wastewater typically contains a variety of toxic contaminants, including synthetic dyes such as Congo red and methylene blue, heavy metals such as Cu, Pb, Hg, Ni, pesticides, and oils. Cellulose–bentonite composites offer an economical and efficient solution for the removal of these pollutants, owing to their synergistic properties—especially when compared to other adsorbents such as activated carbon, nanographene oxide, and metal–organic frameworks (MOFs). However, a systematic evaluation of their fabrication strategies, adsorption mechanisms, and application-related studies remains lacking. Also, there is an urgent need for a comprehensive review that consolidates recent findings on the removal of environmental contaminants and highlights both individual and combined adsorption efficiencies. Therefore, this work focuses on cellulose–bentonite composites as highly promising materials for developing sustainable, high-performance adsorbents tailored for advanced water treatment technologies.

In this study, the fabrication of magnetic hemicellulosic composite microspheres and the adsorption of copper ions are explored. The microspheres were prepared by the micro-emulsion technique, using Fe₃O₄ nanoparticles and hemicellulose extracted from wheat straw with the ionic liquid B[mim]Cl as a solvent. Fe₃O₄ nanoparticles, synthesized through coprecipitation, were evenly encapsulated within the hemicellulosic microspheres. The Fe₃O₄ nanoparticles measured 10–15 nm in size, while the microspheres had an average diameter of about 20 μm and displayed a saturation magnetization of 35.95 emu/g. The optimal conditions for copper adsorption by the microspheres were found to be a pH of 5.0, a temperature of 323 K, and an initial copper ion concentration of 80 mg/L, resulting in an adsorption capacity of 85.65 mg/g after 24 h. The adsorption kinetics followed a pseudo-second-order model, and the Langmuir isotherm suggested a monomolecular layer adsorption mechanism, with a theoretical maximum capacity of 149.25 mg/g. In summary, the magnetic hemicellulosic microspheres exhibited considerable adsorption potential and favorable recycling capabilities for copper ions.

Lignin-based hydrogels represent a new generation of bio-composite materials that utilize environmentally sustainable resources and exhibit significantly advanced functional properties. As a highly abundant yet underutilized natural polymer, lignin imparts hydrogels with exceptional mechanical strength, biocompatibility, and responsiveness to environmental stimuli. This review discusses various synthetic approaches that harness lignin’s unique properties for hydrogel synthesis, including graft polymerization, crosslinking copolymerization, and interpenetrating polymer networks. Each strategy offers distinct advantages and enables the customization of physicochemical properties to meet specific application requirements. The multifunctional nature of lignin-based hydrogels has proven valuable in a range of fields. In biomedicine, they are explored for applications such as wound healing, drug delivery, and tissue engineering. In environmental remediation, they show strong potential for the adsorption of heavy metals and dyes. Despite their promise, challenges remain in the synthesis of lignin-based hydrogels due to the structural heterogeneity and variable chemical reactivity of lignin. Ongoing developments in chemical modification and hybrid hydrogel systems aim to overcome these limitations. Overall, lignin-based hydrogels offer a promising, eco-friendly alternative that supports the green materials agenda across both healthcare and environmental sectors.