Nanoporous Cellulose as Metal Nanoparticles Support

Advances in regenerated cellulosic aerogel from waste cotton textile for emerging multidimensional applications

Rapid development of society and the improvement of people's living standards have stimulated people's keen interest in fashion clothing. This trend has led to the acceleration of new product innovation and the shortening of the lifespan for cotton fabrics, which has resulting in the accumulation of waste cotton textiles. Although cotton fibers can be degraded naturally, direct disposal not only causes a serious resource waste, but also brings serious environmental problems. Hence, it is significant to explore a cleaner and greener waste textile treatment method in the context of green and sustainable development. To realize the high-value utilization of cellulose II aerogel derived from waste cotton products, great efforts have been made and considerable progress has been achieved in the past few decades. However, few reviews systematically summarize the research progress and future challenges of preparing high-value-added regenerated cellulose aerogels via dissolving cotton and other cellulose wastes. Therefore, this article reviews the regenerated cellulose aerogels obtained through solvent methods, summarizes their structure, preparation strategies and application, aimed to promote the development of the waste textile industry and contributed to the realization of carbon neutrality.

Cellulose supported TiO2/Cu2O for highly asymmetric conjugate addition of α,β-unsaturated compounds in aqueous phase

A series of new kind green cellulose-supported bimetallic TiO2/Cu2O (Cell@TiO2/Cu2O) catalytic materials were obtained by in-situ reduction method employing cellulose as the carrier. The effects of metal percentage composition on the morphology and construction of the catalytic materials were systematically investigated. The Cell@TiO2/Cu2O were characterized by FT-IR, TG, XPS, SEM, TEM, EDS, and the element content was obtained by elemental analysis. Then, the achieved catalytic materials were applied to the chiral borylation reaction of α,β-unsaturated compounds, including nitrile compounds, esters, and α,β-unsaturated ketones. Remarkably, this approach provides an efficient strategy to gain an important class of chiral organic boron compounds with target chiral products in high yields as well as enantioselectivities. Besides, the Cell@TiO2/Cu2O could be easily recycled and effectively reused. This work constructed bimetallic TiO2/Cu2O on cellulose as a newly catalyst to obtain chiral boron compounds in aqueous phase.

Synthesis of bacterial cellulose nanofibers/Ag nanoparticles: Structure, characterization and antibacterial activity

The aim of this study was to compare the characterization of bacterial cellulose nanofibers/Ag nanoparticles (BCNs/Ag nanoparticles) obtained by three different pretreatment methods of BCNs (no pretreatment, sodium hydroxide activation pretreatment and TEMPO-mediated oxidation pretreatment), which were recoded as N-BCNs/Ag nanoparticles, A-BCNs/Ag nanoparticles and O-BCNs/Ag nanoparticles, respectively. The results of scanning electron microscopy and transmission electron microscopy showed the prepared Ag nanoparticles by three different pretreatment methods were spherical and dispersed on the surface of BCNs, while the Ag nanoparticles in O-BCNs/Ag nanoparticles displayed the smallest diameter with a value of 20.25 nm and showed the most uniform dispersion on the surface of BCNs. The ICP-MS result showed O-BCNs/Ag nanoparticles had the highest content of Ag nanoparticles with a value of 2.98 wt%, followed by A-BCNs/Ag nanoparticles (1.53 wt%) and N-BCNs/Ag nanoparticles (0.84 wt%). The cytotoxicity assessment showed that the prepared BCNs/Ag nanoparticles were relatively safe. Furthermore, the O-BCNs/Ag nanoparticles had the best antioxidant and antibacterial activities as compared with the other two types of BCNs/Ag nanoparticles, where O-BCNs/Ag nanoparticles destroyed the structure of bacterial cell membranes to lead the leakage of intracellular components. This study showed that O-BCNs/Ag nanoparticles as antibacterial agents have great potential in food packaging.

Antibacterial fibers impregnated with mycosynthetized AgNPs for control of Pectobacterium carotovorum

Using biopolymers functionalized with antibacterial agents to manufacture active packaging is a clean alternative to mitigate food losses due to postharvest plant diseases. In this study, two mycosynthetized AgNPs impregnation methodologies on cotton (cationization and in situ biochemical reduction) were used to obtain the antibacterial fibers (A-AgNPs-C and A-AgNPs-IBR), which, in addition to being characterized by SEM-EDX, XRD, were evaluated as antibacterial materials. The cotton fibers showed growth inhibition of Pectobacterium carotovorum at 48 h. The reuse tests of these cotton fibers showed that the two types of fibers could have up to three successive uses without losing their effectiveness, regardless of the impregnation method used. Is important to highlight that the retention tests indicated that the AgNPs remain attached to the A-AgNPs-C and A-AgNPs-IBR fibers after several successive washes. Finally, the mycosynthesized AgNPs were also impregnated on fique fibers (Fique-AgNPs) by cationization to obtain little antibacterial sacks. Nanostructured materials that in in vivo tests on potatoes showed only 7.8 % of affectation, while the tubers stored in the traditional sacks had an affectation of 25 %. This immobilization of AgNPs in natural fibers will allow the development of a nanobiotechnological application in the storage and transport of potatoes, after performing some additional cytotoxicity tests to guarantee its safety.

Cellulose Nanofiber-Alginate Biotemplated Cobalt Composite Multifunctional Aerogels for Energy Storage Electrodes

Tunable porous composite materials to control metal and metal oxide functionalization, conductivity, pore structure, electrolyte mass transport, mechanical strength, specific surface area, and magneto-responsiveness are critical for a broad range of energy storage, catalysis, and sensing applications. Biotemplated transition metal composite aerogels present a materials approach to address this need. To demonstrate a solution-based synthesis method to develop cobalt and cobalt oxide aerogels for high surface area multifunctional energy storage electrodes, carboxymethyl cellulose nanofibers (CNF) and alginate biopolymers were mixed to form hydrogels to serve as biotemplates for cobalt nanoparticle formation via the chemical reduction of cobalt salt solutions. The CNF-alginate mixture forms a physically entangled, interpenetrating hydrogel, combining the properties of both biopolymers for monolith shape and pore size control and abundant carboxyl groups that bind metal ions to facilitate biotemplating. The CNF-alginate hydrogels were equilibrated in CaCl2 and CoCl2 salt solutions for hydrogel ionic crosslinking and the prepositioning of transition metal ions, respectively. The salt equilibrated hydrogels were chemically reduced with NaBH4, rinsed, solvent exchanged in ethanol, and supercritically dried with CO2 to form aerogels with a specific surface area of 228 m2/g. The resulting aerogels were pyrolyzed in N2 gas and thermally annealed in air to form Co and Co3O4 porous composite electrodes, respectively. The multifunctional composite aerogel's mechanical, magnetic, and electrochemical functionality was characterized. The coercivity and specific magnetic saturation of the pyrolyzed aerogels were 312 Oe and 114 emu/gCo, respectively. The elastic moduli of the supercritically dried, pyrolyzed, and thermally oxidized aerogels were 0.58, 1.1, and 14.3 MPa, respectively. The electrochemical testing of the pyrolyzed and thermally oxidized aerogels in 1 M KOH resulted in specific capacitances of 650 F/g and 349 F/g, respectively. The rapidly synthesized, low-cost, hydrogel-based synthesis for tunable transition metal multifunctional composite aerogels is envisioned for a wide range of porous metal electrodes to address energy storage, catalysis, and sensing applications.

Advances in preparation, biomedical, and pharmaceutical applications of chitosan-based gold, silver, and magnetic nanoparticles: A review

During the last decades, the ever-increasing incidence of various diseases, like cancer, has led to a high rate of death worldwide. On the other hand, conventional modalities (such as chemotherapy and radiotherapy) have not indicated enough efficiency in the diagnosis and treatment of diseases. Thus, potential novel approaches should be taken into consideration to pave the way for the suppression of diseases. Among novel approaches, biomaterials, like chitosan nanoparticles (CS NPs, N-acetyl-glucosamine and D-glucosamine), have been approved by the FDA for some efficient pharmaceutical applications. These NPs owing to their physicochemical properties, modification with different molecules, biocompatibility, serum stability, less immune response, suitable pharmacokinetics and pharmacodynamics, etc. have received deep attention among researchers and clinicians. More importantly, the impact of CS polysaccharide in the synthesis, preparation, and delivery of metallic NPs (like gold, silver, and magnetic NPs), and combination of CS with these metallic NPs can further facilitate the diagnosis and treatment of diseases. Metallic NPs possess some features, like converting NIR photon energy into thermal energy and anti-microorganism capability, and can be a potential candidate for the diagnosis and treatment of diseases in combination with CS NPs. These combined NPs would be efficient pharmaceuticals in the future.

Size-Controlled Silver Nanoparticles Supported by Pyrolytic Carbon from Microcrystalline Cellulose

A facile method was developed for preparing size-controlled silver nanoparticles supported by pyrolytic carbon from microcrystalline cellulose (MCC). The pyrolysis of cellulose-AgNO3 mixture caused the oxidation of cellulose, resulting in carboxyl groups to which silver ions can bind firmly and act as nuclei for the deposition of silver nanoparticles. The structure and properties of the obtained nanocomposite were characterized by using a scanning electron microscope (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Fourier transform infrared (FT-IR) and X-ray diffraction (XRD). The results suggest that silver nanoparticles were integrated successfully and dispersed uniformly in the pyrolytic carbon matrix. The average particle size varied between 20 nm and 100 nm in correlation to the dose of silver nitrate and temperature of pyrolysis. The products showed high electric conductivity and strong antimicrobial activity against Escherichia coli (E. coli).

Cellulose-Based Metallogels-Part 2: Physico-Chemical Properties and Biological Stability

Metallogels represent a class of composite materials in which a metal can be a part of the gel network as a coordinated ion, act as a cross-linker, or be incorporated as metal nanoparticles in the gel matrix. Cellulose is a natural polymer that has a set of beneficial ecological, economic, and other properties that make it sustainable: wide availability, renewability of raw materials, low-cost, biocompatibility, and biodegradability. That is why metallogels based on cellulose hydrogels and additionally enriched with new properties delivered by metals offer exciting opportunities for advanced biomaterials. Cellulosic metallogels can be either transparent or opaque, which is determined by the nature of the raw materials for the hydrogel and the metal content in the metallogel. They also exhibit a variety of colors depending on the type of metal or its compounds. Due to the introduction of metals, the mechanical strength, thermal stability, and swelling ability of cellulosic materials are improved; however, in certain conditions, metal nanoparticles can deteriorate these characteristics. The embedding of metal into the hydrogel generally does not alter the supramolecular structure of the cellulose matrix, but the crystallinity index changes after decoration with metal particles. Metallogels containing silver (0), gold (0), and Zn(II) reveal antimicrobial and antiviral properties; in some cases, promotion of cell activity and proliferation are reported. The pore system of cellulose-based metallogels allows for a prolonged biocidal effect. Thus, the incorporation of metals into cellulose-based gels introduces unique properties and functionalities of this material.

A review of important heavy metals toxicity with special emphasis on nephrotoxicity and its management in cattle

Toxicity with heavy metals has proven to be a significant hazard with several health problems linked to it. Heavy metals bioaccumulate in living organisms, pollute the food chain, and possibly threaten the health of animals. Many industries, fertilizers, traffic, automobile, paint, groundwater, and animal feed are sources of contamination of heavy metals. Few metals, such as aluminum (Al), may be eliminated by the elimination processes, but other metals like lead (Pb), arsenic (As), and cadmium (Ca) accumulate in the body and food chain, leading to chronic toxicity in animals. Even if these metals have no biological purpose, their toxic effects are still present in some form that is damaging to the animal body and its appropriate functioning. Cadmium (Cd) and Pb have negative impacts on a number of physiological and biochemical processes when exposed to sub-lethal doses. The nephrotoxic effects of Pb, As, and Cd are well known, and high amounts of naturally occurring environmental metals as well as occupational populations with high exposures have an adverse relationship between kidney damage and toxic metal exposure. Metal toxicity is determined by the absorbed dosage, the route of exposure, and the duration of exposure, whether acute or chronic. This can lead to numerous disorders and can also result in excessive damage due to oxidative stress generated by free radical production. Heavy metals concentration can be decreased through various procedures including bioremediation, pyrolysis, phytoremediation, rhizofiltration, biochar, and thermal process. This review discusses few heavy metals, their toxicity mechanisms, and their health impacts on cattle with special emphasis on the kidneys.

All-cellulose air filter composed with regenerated nanocellulose prepared through a facile method with shear-induced

High-speed shear system is usually used for the dispersion improvement of slurry, nanomaterials preparation, and even two-dimensional materials production. However, there is barely study that focused on the regenerated cellulose (RC) which was coagulated with shear induced. In this work, a new type of all-cellulose air filter was fabricated through high-speed shear in aqueous regeneration system using parenchyma cellulose from corn stalk. The obtained RC were aggregated by ribbon-like fine cellulose and nanocellulose sheets. The study exhibited the micro-structure of RC displayed excellent unidirectional alignment and a relatively high crystallinity. All-cellulose air filter which was produced via RC presented excellent filtration efficiency (PM_2.5 97.3 %, PM_10.0 97.7 %) with slightly pressure drop (19 Pa). Therefore, this work provides a facile method to obtain a novel RC with nanocellulose particles used for air filtration, which gives an effective strategy application in the conversion of all-cellulose materials from agricultural waste.

Insights on Some Polysaccharide Gel Type Materials and Their Structural Peculiarities

Global resources have to be used in responsible ways to ensure the world's future need for advanced materials. Ecologically friendly functional materials based on biopolymers can be successfully obtained from renewable resources, and the most prominent example is cellulose, the well-known most abundant polysaccharide which is usually isolated from highly available biomass (wood and wooden waste, annual plants, cotton, etc.). Many other polysaccharides originating from various natural resources (plants, insects, algae, bacteria) proved to be valuable and versatile starting biopolymers for a wide array of materials with tunable properties, able to respond to different societal demands. Polysaccharides properties vary depending on various factors (origin, harvesting, storage and transportation, strategy of further modification), but they can be processed into materials with high added value, as in the case of gels. Modern approaches have been employed to prepare (e.g., the use of ionic liquids as "green solvents") and characterize (NMR and FTIR spectroscopy, X ray diffraction spectrometry, DSC, electronic and atomic force microscopy, optical rotation, circular dichroism, rheological investigations, computer modelling and optimization) polysaccharide gels. In the present paper, some of the most widely used polysaccharide gels will be briefly reviewed with emphasis on their structural peculiarities under various conditions.

Synthesis and Application of Innovative and Environmentally Friendly Photocatalysts: A Review

Modern society faces two major challenges: removing pollutants from water and producing energy from renewable sources. To do this, science proposes innovative, low-cost, and environmentally friendly methods. The heterogeneous photocatalysis process fits perfectly in this scenario. In fact, with photocatalysis, it is possible both to mineralize contaminants that are not easily biodegradable and to produce hydrogen from the water splitting reaction or from the conversion of organic substances present in water. However, the main challenge in the field of heterogeneous photocatalysis is to produce low-cost and efficient photocatalysts active under visible light or sunlight. The objective of this review is to compare the new proposals for the synthesis of innovative photocatalysts that reflect the requirements of green chemistry, applied both in the removal of organic contaminants and in hydrogen production. From this comparison, we want to bring out the strengths and weaknesses of the proposals in the literature, but above all, new ideas to improve the efficiency of heterogeneous photocatalysis guaranteeing the principles of environmental and economic sustainability.

Nanocellulose as a promising substrate for advanced sensors and their applications

Nanocellulose has broad and promising applications owing to its low density, large specific surface area, high mechanical strength, modifiability, renewability. Recently, nanocellulose has been widely used to fabricate flexible, durable and environmental-friendly sensor substrates. In this contribution, the construction and characteristics of nanocellulose-based sensors are comprehensively reviewed. Various nanocellulose-based sensors are summarized and divided into colorimetric, fluorescent, electronic, electrochemical and SERS types according to the sensing mechanism. This review also introduces the applications of nanocellulose-based sensors in the fields of biomedicine, environmental monitoring, food safety, and wearable devices.

Facile synthesis of nanomaterials as nanofertilizers: a novel way for sustainable crop production

Nutrient fertilization plays a major role in improving crop productivity and maintaining soil fertility. In the last few decades, the productivity of current agricultural practices highly depends on the use of chemical fertilizers. Major drawback of traditional fertilizers is their low crop nutrient use efficiency and high loss into water. Nanomaterial in agriculture is a multipurpose tool for increasing growth, development, and yield of plants. Nanotechnology facilitates the amplifying of agriculture production by reducing relevant losses and improving the input efficiency. Nanotechnology has emerged as an attractive field of research and has various agriculture applications, especially the use of nano-agrochemicals to increase nutrient use efficiency and agricultural yield. Nanofertilizers are more effective as compared to chemical fertilizers due to their cost-efficient, eco-friendly, non-toxic, and more stable in nature. Overall, this chapter focuses on synthesis of nanofertilizers through physical, chemical, and biological methods. This chapter will also explore the use of nano-enabled fertilizers to enhance the nutrient use efficiency for sustainable crop production, and global food safety.

An Overview of Green Synthesis and Potential Pharmaceutical Applications of Nanoparticles as Targeted Drug Delivery System in Biomedicines

Nanotechnology-based nanomedicine offers several benefits over conventional forms of therapeutic agents. Moreover, nanomedicine has become a potential candidate for targeting therapeutic agents at specific sites. However, nanomedicine prepared by synthetic methods may produce unwanted toxic effects. Due to their nanosize range, nanoparticles can easily reach the reticuloendothelial system and may produce unwanted systemic effects. The nanoparticles produced by the green chemistry approach would enhance the safety profile by avoiding synthetic agents and solvents in its preparations. This review encompasses toxicity consideration of nanoparticles, green synthesis techniques of nanoparticle preparation, biomedical application of nanoparticles, and future prospects.

Optically active plasmonic cellulose fibers based on Au nanorods for SERS applications

Cellulose might be a promising material for surface-enhanced Raman scattering (SERS) substrates due to its wide availability, low cost, ease of fabrication, high flexibility and low optical activity. This work shows, for the first time development of the cellulose-based substrate, that owes its SERS activity to the presence of gold nanorods in its internal structure, and not only on the surface, as it is shown elsewhere, thus ensuring superior stability of the obtained material. This flexible cellulose-based substrate exhibiting plasmonic activity, provide easy and reproducible detection of different analytes via SERS technique. The substrate was prepared by introduction of gold nanorods into the cellulose fibers matrix using an eco-friendly process based on N-Methylmorpholine-N-Oxide. Au-modified cellulose fibers were used for the detection of p-Mercaptobenzoic acid and Bovine Serum Albumin by the SERS method. The obtained results show that this substrate offers large signal enhancement of 6-orders of magnitude, and high signal reproducibility with a relative standard deviation of 8.3%. Additionally, washing tests (90 °C, 20 h) showed superior stability of the as prepared plasmonic fibers, thus proving the good reusability of the substrates and the long shelf life.

Cellulose-Silver Composites Materials: Preparation and Applications

Cellulose has received great attention owing to its distinctive structural features, exciting physico-chemical properties, and varied applications. The combination of cellulose and silver nanoparticles currently allows to fabricate different promising functional nanocomposites with unique properties. The current work offers a wide and accurate overview of the preparation methods of cellulose-silver nanocomposite materials, also providing a punctual discussion of their potential applications in different fields (i.e., wound dressing, high-performance textiles, electronics, catalysis, sensing, antimicrobial filtering, and packaging). In particular, different preparation methods of cellulose/silver nanocomposites based on in situ thermal reduction, blending and dip-coating, or additive manufacturing techniques were thoroughly described. Hence, the correlations among the structure and physico-chemical properties in cellulose/silver nanocomposites were investigated in order to better control the final properties of the nanocomposites and analyze the key points and limitations of the current manufacturing approaches.

Solar radiation-induced synthesis of bacterial cellulose/silver nanoparticles (BC/AgNPs) composite using BC as reducing and capping agent

In the present work, a simple, novel, and ecofriendly method for synthesis of silver nanoparticles (AgNPs) and BC/AgNP composite using bacterial cellulose (BC) nanofibers soaked in AgNO₃ solution under induction action of solar radiation. The photochemical reduction of silver Ag + ions into silver nanoparticles (Ag^o) was confirmed using UV visible spectra; the surface plasmon resonance of synthesized AgNPs was localized around 425 nm. The mean diameter of AgNPs obtained by DLS analysis was 52.0 nm with a zeta potential value of - 9.98 mV. TEM images showed a spherical shape of AgNPs. The formation of BC/AgNP composite was confirmed by FESEM, EDX, FTIR, and XRD analysis. FESEM images for BC showed the 3D structures of BC nanofibers and the deposited AgNPs in the BC crystalline nanofibers. XRD measurements revealed the high crystallinity of BC and BC/AgNP composite with crystal sizes of 5.13 and 5.6 nm, respectively. BC/AgNP composite and AgNPs exhibited strong antibacterial activity against both Gram-positive and Gram-negative bacteria. The present work introduces a facile green approach for BC/AgNP composite synthesis and its utility as potential food packaging and wound dressings, as well as sunlight indicator application.

Development of implantation substrates for the collection of radionuclides of medical interest produced via ISOL technique at INFN-LNL

Accelerator-based techniques with electromagnetic mass separation are considered among the most innovative and promising strategies to produce non-conventional radionuclides for nuclear medicine. Such approach was successfully used at CERN, where the dedicated MEDICIS facility was built, and at TRIUMF, where the ISAC radioactive beam facility was used to produce unconventional α-emitters. In such framework, the Legnaro National Laboratories of the Italian Institute of Nuclear Physics (INFN-LNL) proposed the ISOLPHARM project (ISOL technique for radioPHARMaceuticals), which will exploit radionuclides producible with the SPES (Selective Production of Exotic Species) ISOL (Isotope Separation On-Line) facility to develop novel radiopharmaceuticals. The ISOL technique utilizes the irradiation with a primary beam of particles/nuclei of a production target where radionuclides are produced. A radioactive ion beam is subsequently extracted from the production target unit, and transported up to an analyzing magnet, where non-isobaric contaminants are filtered out. The so-obtained purified radioactive beam is dumped onto an implantation substrate, referred as collection target. Then, the desired nuclides can be chemically harvested from the collected isobars, and the isotopically pure atom collection can be employed to radiolabel high specific activity radiopharmaceuticals. Metallic deposition targets in the form of coated metal foils were mostly used at TRIUMF and CERN. At ISOLPHARM, a different approach is under investigation which foresees the use of soluble cold-pressed collection targets, possibly facilitating the chemical purification process of the collected radionuclides. In this study, the production and characterization of some of the ISOLPHARM collection targets is presented, in particular, soluble salts (NaCl and NaNO3) and organic materials widely used for pharmaceutical tablets production are considered. All such materials proved to be potentially suitable as collection targets, since solid samples were easily produced and resulted compatible with the vacuum conditions required for the ion implantation process. Furthermore, some of the selected substrates were used for proof-of-concept deposition tests with stable silver, to prove their suitability as ISOLPHARM deposition substrates for silver-111, a promising candidate for radiotherapy. Such tests highlighted possible scenarios useful for the development of new alternative materials, as the use of insoluble organic targets.

Facile Processing of Transparent Wood Nanocomposites with Structural Color from Plasmonic Nanoparticles

Wood is an eco-friendly and abundant substrate and a candidate for functionalization by large-scale nanotechnologies. Infiltration of nanoparticles into wood, however, is hampered by the hierarchically structured and interconnected fibers in wood. In this work, delignified wood is impregnated with gold and silver salts, which are reduced in situ to plasmonic nanoparticles via microwave-assisted synthesis. Transparent biocomposites are produced from nanoparticle-containing wood in the form of load-bearing materials with structural color. The coloration stems from nanoparticle surface plasmons, which require low size dispersity and particle separation. Delignified wood functions as a green reducing agent and a reinforcing scaffold to which the nanoparticles attach, predesigning their distribution on the surface of fibrous "tubes". The nanoscale structure is investigated using scanning transmission electron microscopy (STEM), energy-dispersive spectroscopy (EDS), and Raman microscopy to determine particle size, particle distribution, and structure-property relationships. Optical properties, including response to polarized light, are of particular interest.

Cellulose-based polymers

The presented chapter deals with structure, morphology, and properties aspects concerning cellulose-based polymers in both research and industrial production, such as cellulose fibers, cellulose membranes, cellulose nanocrystals, and bacterial cellulose, etc. The idea was to highlight the main cellulose-based polymers and cellulose derivatives, as well as the dissolution technologies in processing cellulose-based products. The structure and properties of cellulose are introduced briefly. The main attention has been paid to swelling and dissolution of cellulose in order to yield various kinds of cellulose derivatives through polymerization. The main mechanisms and methods are also presented. Finally, the environmental friendly and green cellulose-based polymers will be evaluated as one of the multifunctional and smart materials with significant progress.

Carboxylcellulose hydrogel confined-Fe3O4 nanoparticles catalyst for Fenton-like degradation of Rhodamine B

Facile preparation of functional hydrogel materials for environmental catalysis is a hot research topic of soft materials science and green catalysis. In this study, a carboxylcellulose hydrogel confined Fe₃O₄ nanoparticles composite catalyst (Fe₃O₄@CHC) with magnetic recyclability has been synthesized by taking the advantages of the newly developed cellulose solution in tetramethyl guanidine/DMSO/CO₂ through in situ acylation using mixed cyclic anhydrides and ion exchange reaction. The achieved Fe₃O₄@CHC hydrogel catalyst was shown to be an more efficient and better Fenton-like catalyst for decomposition of the organic dye rhodamine B (RhB) in the presence of hydrogen peroxide, with almost complete decomposition occurring within 180 min, in comparison with Fe₃O₄@cellulose hydrogel (CH) with excellent recyclability. This work provided a facile strategy for the preparation of hydrogel-based functional composite green catalytic materials, which has potential applications in green catalysis.

Bifunctional Regenerated Cellulose/Polyaniline/Nanosilver Fibers as a Catalyst/Bactericide for Water Decontamination

For antagonizing urgent water pollution and increasing environmental consciousness, the integration of renewable resources and nanotechnologies has become a trend to improve water quality in the ecosystem. Here, we designed a green route to fabricate regenerated cellulose fibers (CFs) with 3D micro- and nanoporous structures in NaOH/urea aqueous solvent systems via a scalable wet-spinning procedure as support materials for nanoparticles (NPs). Modification of CFs with polyaniline@Ag nanocomposites through in situ reduction of the silver ion with aqueous aniline led to enhanced pollutant removal efficiency of functional cellulose-based fibers (FCFs), demonstrating both rapid hydrogenation catalytic performance for the reduction of p-nitrophenol and high antibacterial properties for in-flow water purification. Most importantly, the hierarchically porous structures of FCFs not only provided carrier space but also formed a limiting domain guaranteeing the homogeneity of FCFs even with a Ag NP content as high as 36.47 wt %. The prepared functional fibers show good behavior in in-flow water purification, representing significant advancement in the use of biomass fibers for catalytic and bactericidal applications in liquid media.

Green Synthesis of Metallic Nanoparticles and Their Potential Applications to Treat Cancer

Nanoparticle synthesis using microorganisms and plants by green synthesis technology is biologically safe, cost-effective, and environment-friendly. Plants and microorganisms have established the power to devour and accumulate inorganic metal ions from their neighboring niche. The biological entities are known to synthesize nanoparticles both extra and intracellularly. The capability of a living system to utilize its intrinsic organic chemistry processes in remodeling inorganic metal ions into nanoparticles has opened up an undiscovered area of biochemical analysis. Nanotechnology in conjunction with biology gives rise to an advanced area of nanobiotechnology that involves living entities of both prokaryotic and eukaryotic origin, such as algae, cyanobacteria, actinomycetes, bacteria, viruses, yeasts, fungi, and plants. Every biological system varies in its capabilities to supply metallic nanoparticles. However, not all biological organisms can produce nanoparticles due to their enzymatic activities and intrinsic metabolic processes. Therefore, biological entities or their extracts are used for the green synthesis of metallic nanoparticles through bio-reduction of metallic particles leading to the synthesis of nanoparticles. These biosynthesized metallic nanoparticles have a range of unlimited pharmaceutical applications including delivery of drugs or genes, detection of pathogens or proteins, and tissue engineering. The effective delivery of drugs and tissue engineering through the use of nanotechnology exhibited vital contributions in translational research related to the pharmaceutical products and their applications. Collectively, this review covers the green synthesis of nanoparticles by using various biological systems as well as their applications.

Fabrication of cellulose carbamate hydrogel-dressing with rarasaponin surfactant for enhancing adsorption of silver nanoparticles and antibacterial activity

Bacterial contamination on external wounds is known to be a factor that prevents wound healing and triggers tissue damage. Hydrogel-dressings with antibacterial activity is a useful medical device to avoid this contamination, wherein the antibacterial activity can be provided via incorporation of silver nanoparticles (AgNPs). Contrary to the conventional two-step preparation of an AgNPs-loaded hydrogel (AgNPs@hydrogel), this work aims to establish a new and facile synthesis method employing the adsorption principle. Once AgNO₃ adsorbed into active sites of the hydrogels, in situ reductions using NaBH₄ was employed to produce AgNPs@hydrogel. The effect of surfactant addition on the AgNO₃ loading and the antibacterial activity of the resulting hydrogel dressing was investigated. The outcome of this work indicates that the addition of rarasaponin not only can increase the loading of AgNPs on cellulose carbamate hydrogel (CCH) but also significantly enhance the antibacterial activity of the resulted hydrogel-dressing. Superior to the other studied surfactant, the loading capacity (LC) of AgNPs is found to be 10.15, 9.94, and 7.53 mg/g for CCH modified with rarasaponin, CTAB, and Tween80, respectively. These findings conclude that the addition of surfactant, especially rarasaponin, can effectively improve the loading of AgNPs onto hydrogel-dressing via adsorption and promote the antibacterial activity. Furthermore, the cytotoxic test shows that the hydrogel-dressings have good biocompatibility toward skin fibroblast cells.

Aerogels from copper (II)-cellulose nanofibers and carbon nanotubes as absorbents for the elimination of toxic gases from air

A novel deodorizer that is capable of selectively eliminating the odorous chemicals, such as ammonia, trimethylamine, hydrogen sulfide and methyl mercaptan, is described. The deodorizer is a nanostructured aerogel by nature, consisting of 2,2-6,6-tetramethylpiperidine-1-oxyl (TEMPO) oxidized cellulose nanofibrils (CNF), transition metal divalent cations (M²⁺), and multi-walled carbon nanotubes (CNT) as the constitutive elements. CNF are firstly mixed with M²⁺ (M²⁺, in this paper, typifies Ni²⁺, Co²⁺ and Cu²⁺) to form CNF-M²⁺ complexes, monodispersed CNT is then mixed to prepare CNT/CNF-M²⁺ waterborne slurries; CNT/CNF-M²⁺ hybridized aerogels are finally obtained via freezing-drying of the CNT/CNF-M²⁺ waterborne slurries. The CNT/CNF-M²⁺ aerogels are a foam-like structure consisting of CNF and CNT as backbones and M²⁺ as linkers. The aerogels show higher capabilities (in comparison with activated carbon) for selectively adsorbing ammonia, trimethylamine, hydrogen sulfide and methyl mercaptan. Computing simulations suggest a theoretical conclusion that the odorous chemicals are absorbed in a preferring manner of bimolecular absorptions via the M²⁺ moieties. The CNT/CNF-M²⁺ hybridized aerogels are lightweight, eco-friendly, and easy to produce in industrial scales. Our new finding, as is described in this paper, demonstrates potential applications of the TEMPO-oxidized CNF to the field of deodorizations.

Supercritical Fluid Applications in the Design of Novel Antimicrobial Materials

Bacterial resistance to antibiotics is one of the biggest problems in the modern world. The prevention of bacterial spreading from hospitals to the community and vice versa is an issue we have to deal with. This review presents a vast potential of contemporary high-pressure techniques in the design of materials with antimicrobial activity. Scientists from all over the world came up with ideas on how to exploit extraordinary properties of supercritical fluids in the production of advantageous materials in an environmentally friendly way. The review summarizes reported methods and results.

Advances in nanotechnology and antibacterial properties of biodegradable food packaging materials

A large number of non-biodegradable and non-renewable materials are produced daily for application as food packaging materials. These waste materials have a greatly negative effect on our health and the ecosystem. The idea of a bio-based economy is steadily gaining attention from the scientific, societal, and financial communities, so there are several areas in which the intended approaches can be improved for this reason. Therefore, creating biopolymer-based materials from natural sources, including polysaccharides and proteins, is a good alternative to non-renewable fossil resources. In the current review paper, we plan to summarize the major recent findings in food biodegradable packaging materials that include nanotechnology either directly or indirectly. Several natural nano-materials applied in food packaging applications such as polymers, polysaccharides, and protein-based nano-materials have been included in order to make special biopolymer hosts for nanocomposites. Finally, this review will highlight the antibacterial properties of commonly used nanoparticles or nanomaterials.

Preparation, Characterization, and In Vitro Evaluation of Resveratrol-Loaded Cellulose Aerogel

Resveratrol is a natural active ingredient found in plants, which is a polyphenolic compound and has a variety of pharmaceutical uses. Resveratrol-loaded TEMPO-oxidized cellulose aerogel (RLTA) was prepared using a freeze-drying method, employing high speed homogenization followed by rapid freezing with liquid nitrogen. RLTAs were designed at varying drug-cellulose aerogel ratios (1:2, 2:3, 3:2, and 2:1). It could be seen via scanning electron microscopy (SEM) that Res integrated into TEMPO-oxidized cellulose (TC) at different ratios, which changed its aggregation state and turned it into a short rod-like structure. Fourier transform infrared (FTIR) spectra confirmed that the RLTAs had the characteristic peaks of TC and Res. In addition, X-ray diffraction (XRD) demonstrated that the grain size of RLTA was obviously smaller than that of pure Res. RLTAs also had excellent stability in both simulated gastric fluid and phosphate buffer solution. The drug release rate was initially completed within 5 h under a loading rate of 30.7 wt%. The results of an MTT assay showed the low toxicity and good biocompatibility of the RLTAs. TC aerogel could be a promising drug carrier that may be widely used in designing and preparing novel biomedicine.

Functionalized cellulose nanofibril aerogels as cooperative acid-base organocatalysts for liquid flow reactions

Cellulose nanomaterial aerogels are macroscopic porous solids with relatively high surface areas and are thus an interesting basis for renewable catalyst materials. Cross-linked acid-base bifunctional catalyst aerogels are produced here from TEMPO-oxidized cellulose nanofibrils (TOCNF) and demonstrated in both batch and flow catalysis. Recently established acid-base modification for catalysis is expanded upon for chemical or physical cross-linking with small molecules and polymers. Low density and relatively high surface area (up to 74 m² g^-1) aerogel catalysts are produced with a variety of processing approaches and then freeze-dried from water or tert-butyl alcohol/water mixtures. Finer pore structure and increased surface area are achieved with tert-butyl alcohol as co-solvent. Chemical cross-linking improved aerogel stability to solvents. Homogeneous and aerogel TOCNF catalysts are shown to be effective acid-base cooperative catalysts for aldol condensation reactions in batch reactions. Continuous flow reactions are performed with glass column reactors packed with aerogel catalysts that showed improved rates relative to batch experiments, while also demonstrating physical stability. Catalyst deactivation in flow reactions is observed and observations of deactivation support previously reported mechanisms of site poisoning by competitive chemisorption of reactants in analogous acid-base catalysts. This report is a key demonstration of cellulose nanofibril aerogels for catalysis in continuous liquid flow reactions.

Cellulose from sources to nanocellulose and an overview of synthesis and properties of nanocellulose/zinc oxide nanocomposite materials

Recently, environmental and ecological concerns are increasing due to the usage of petroleum-based products so the synthesis of ultra-fine chemicals and functional materials from natural resources is drawing a tremendous level of attention. Nanocellulose, a unique and promising natural material extracted from native cellulose, may prove to be most ecofriendly materials that are technically and economically feasible in modern times, minimizing the pollution generation. Nanocellulose has gained tremendous attention for its use in various applications, due to its excellent special surface chemistry, physical properties, and remarkable biological properties (biodegradability, biocompatibility, and non-toxicity). Various types of nanocellulose, viz. cellulose nanofibrils (CNFs), cellulose nanocrystals (CNCs), and bacterial nanocellulose (BNC), are deeply introduced and compared in this work in terms of sources, production, structures and properties. The metal and metal oxides especially zinc oxide nanoparticles (ZnO-NPs) are broadly used in various fields due to the diversity of functional properties such as antimicrobial and ultraviolet (UV) properties. Thus, the advancement of nanocellulose and zinc oxide nanoparticles (ZnO-NPs)-based composites materials are summarized in this article in terms of the preparation methods and remarkable properties with the help of recent knowledge and significant findings (especially from the past six years reports). The nanocellulose materials complement zinc oxide nanoparticles, where they impart their functional properties to the nanoparticle composites. As a result hybrid nanocomposite containing nanocellulose/zinc oxide composite has shown excellent mechanical, UV barrier, and antibacterial properties. The nanocellulose based hybrid nanomaterials have huge potential applications in the area of food packaging, biopharmaceuticals, biomedical, and cosmetics. Thus the functional composite materials containing nanocellulose and zinc oxide will determine the potential biomedical application for nanocellulose.

Loading of Iron (II, III) Oxide Nanoparticles in Cryogels Based on Microfibrillar Cellulose for Heavy Metal Ion Separation

Cryogels based on microfibrillar cellulose (MFC) and reinforced with chitosan to endow water resistance were loaded with magnetite nanoparticles (MNPs) and characterized by TEM, XRD, and TGA. The MNP-loaded cryogels were tested for heavy metal ion removal from aqueous matrices. The adsorption capacity under equilibrium conditions for Cr(VI), Pd(II), Cd(II), and Zn(II) was measured to be 2755, 2155, 3015, and 4100 mg/g, respectively. The results indicate the potential of the introduced bicomponent cryogels for nanoparticle loading, leading to a remarkably high metal ion sorption capacity.

Hybrid Plasmonic-Aerogel Materials as Optical Superheaters with Engineered Resonances

Solar radiation is a versatile source of energy, convertible to different forms of power. A direct path to exploit it is the generation of heat, for applications including passive building heating, but it can also drive secondary energy-conversion steps. We present a novel concept for a hybrid material which is both strongly photo-absorbing and with superior characteristics for the insulation of heat. The combination of that two properties is rather unique, and make this material an optical superheater. To realize such a material, we are combining plasmonic nanoheaters with alumina aerogel. The aerogel has the double function of providing structural support for plasmonic nanocrystals, which serve as nanoheaters, and reducing the diffusion rate of the heat generated by them, resulting in large local temperature increases under a relatively low radiation intensity. This work includes theoretical discussion on the physical mechanisms impacting the system's balanced thermal equilibrium.

Cellulose Nanocrystal and Silver Nanobelt Gel: Cooperative Interactions Enabling Dispersion, Colloidal Gels, and Flexible Electronics

Using cellulose nanocrystals (CNCs) as a dispersant and cross-linker, we sought to enable the dispersion of silver nanobelts (AgNBs) in water for use in the manufacture of flexible electronics. In this work, we obtained a colloidal gel relying on contributions from both particles. When dried, particle interactions during gel collapse induced cooperative buckling of the AgNBs, obtaining a desirable spring-like conductive network that was not seen without the presence of CNCs. Thus, exploiting the collapse of bonded colloidal gels may represent a novel method to obtain desirable network buckling behavior for use in flexible electronics, which previously has only been obtained through printing on prestrained substrates.