Coupling of 3-Aminopropyl Sulfonic Acid to Cellulose Nanofibers for Efficient Removal of Cationic Dyes

Sulfonic acid functionalized cellulose-derived (nano)materials: Synthesis and application

The preparation/application of heterogeneous (nano)materials from natural resources has currently become increasingly fascinating for researchers. Cellulose is the most abundant renewable polysaccharide on earth. The unique physicochemical, structural, biological, and environmental properties of this natural biopolymer have led to its increased application in many fields. The more desirable features of cellulose-based (nano)materials such as biodegradability, renewability, biocompatibility, cost-effectiveness, simplicity of preparation, environmentally friendly nature, and widespread range of applications have converted them into promising compounds in medicine, catalysis, biofuel cells, and water/wastewater treatment processes. Functionalized cellulose-based (nano)materials containing sulfonic acid groups may prove to be one of the most promising sustainable bio(nano)materials of modern times in the field of cellulose science and (nano)technology owing to their intrinsic features, high crystallinity, high specific surface area, abundance, reactivity, and recyclability. In this review, the developments in the application of sulfonated cellulose-based (nano)materials containing sulfonic acid (-SO3H) groups in catalysis, water purification, biological/biomedical, environmental, and fuel cell applications have been reported. This review provides an overview of the methods used to chemically modify cellulose and/or cellulose derivatives in different forms, including nanocrystals, hydrogels, films/membranes, and (nano)composites/blends by introducing sulfonate groups on the cellulose backbone, focusing on diverse sulfonating agents utilized and substitution regioselectivity, and highlights their potential applications in different industries for the generation of alternative energies and products.

Enrichment and immobilization of heavy metal ions from wastewater by nanocellulose/carbon dots-derived composite

Heavy metal ions (HMIs) have been widely applied in various industries because of their excellent physicochemical properties. However, their discharging without appropriate treatment brought about serious pollution problems. So it is desirable but challenging to rapidly and completely clean up these toxic pollutants from water, especially utilizing environmentally friendly and naturally rich biomass materials. In this work, we prepared nanocellulose/carbon dots/magnesium hydroxide (CCMg) ternary composite using cotton via a simple hydrothermal method. The removal mechanism towards Cd2+ and Cu2+ was investigated using a combination of experimental techniques and density functional theory calculations. CCMg shows a good ability to remove HMIs. It is realized that the interaction between each component of CCMg and cadmium nitrate is mainly of hydrogen/dative bonds. Cadmium nitrate is preferentially enriched by the Mg(OH)2 moiety, proved by calculated thermodynamics, interfacial interactions and charges. After transformation, the cadmium carbonate precipitate is fixed on the surface by nanocellulose (NC) via chemical coupling; and of interest is that copper ion precipitates in the form of basic sulfate. Due to its high adsorption effect and simple recovery operation, CCMg is having a wide range of application prospects as a water treatment agent.

Novel cellulose derivative containing aminophenylacetic acid as sustainable adsorbent for removal of cationic and anionic dyes

The synthesis and characterization of a novel cellulose derivative as a potential sustainable adsorbent for cationic and anionic dyes are described through processing in ionic liquids. Cellulose was solubilized in ionic liquid with tosyl chloride to form tosyl cellulose which reacted with 4-aminophenylacetic acid through nucleophilic substitution mechanism. The new cellulose derivative was characterized and explored as an effective adsorbent for methylene blue (MB) and methyl orange (MO) removal, and the adsorption behaviors were investigated with various models. The adsorption behavior of the cellulose derivative followed Langmuir and pseudo-second-order models, and the maximum adsorption efficiency recorded 135 and 106 mg/g for MB and MO, respectively. There is possibility that the enhanced adsorption capacity of the cellulose derivative is due to the carboxylic and amino functional groups that provide sufficient active sites to enhance dye molecule affinity. The adsorption results demonstrate that the cellulose derivative containing aminophenylacetic acid was efficient adsorbent for removals of MB and MO.

New antibacterial hydrogels based on sodium alginate

Nowadays, the combined knowledge and experience in biomedical research and material sciences results in the innovation of smart materials that could efficiently overcome the problems of microbial contaminations. Herein, a new drug delivery platform prepared by grafting sodium alginate with β-carboxyethyl acrylate and acrylamide was described and characterized. 9-Aminoacridine (9-AA), and kanamycin sulfate (KS) were separately loaded into the hydrogel in situ during graft polymerization. The grafting efficiency for the resulting hydrogels was 70.01-78.08 %. The chemical structure of the hydrogels, thermogravimetric analysis, and morphological features were investigated. The swelling study revealed that the hydrogel without drugs achieved a superior swelling rate compared to drug-loaded hydrogels. The hydrogel tuned the drug-release rate in a pH-dependent manner. Furthermore, the antibacterial study suggested that the hydrogels encapsulating 9-AA (88.6 %) or KS (89.3 %) exhibited comparable antibacterial activity against Gram-positive and Gram-negative bacterial strains. Finally, the cytocompatibility study conducted on normal lung cell line (Vero cells) demonstrated neglectable to tolerable toxicity for the drug-loaded hydrogel. More interestingly, the cell viability for the blank hydrogel was 92.5 %, implying its suitability for biomedical applications.

Bacterial Cellulose/Cellulose Imidazolium Bio-Hybrid Membranes for In Vitro and Antimicrobial Applications

In biomedical applications, bacterial cellulose (BC) is widely used because of its cytocompatibility, high mechanical properties, and ultrafine nanofibrillar structure. However, biomedical use of neat BC is often limited due to its lack of antimicrobial properties. In the current article, we proposed a novel technique for preparing cationic BC hydrogel through in situ incorporation of cationic water-soluble cellulose derivative, cellulose bearing imidazolium tosylate function group (Cell-IMD), in the media used for BC preparation. Different concentrations of cationic cellulose derivative (2, 4, and 6%) were embedded into a highly inter-twined BC nanofibrillar network through the in situ biosynthesis until forming cationic cellulose gels. Cationic functionalization was deeply examined by the Fourier transform infrared (FT-IR), NMR spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) methods. In vitro studies with L929 cells confirmed a good cytocompatibility of BC/cationic cellulose derivatives, and a significant increase in cell proliferation after 7 days, in the case of BC/Cell-IMD3 groups. Finally, antimicrobial assessment against Staphylococcus aureus, Streptococcus mutans, and Candida albicans was assessed, recording a good sensitivity in the case of the higher concentration of the cationic cellulose derivative. All the results suggest a promising use of cationic hybrid materials for biomedical and bio-sustainable applications (i.e., food packaging).

Polysaccharides-Based Injectable Hydrogels: Preparation, Characteristics, and Biomedical Applications

Polysaccharides-based injectable hydrogels are a unique group of biodegradable and biocompatible materials that have shown great potential in the different biomedical fields. The biomolecules or cells can be simply blended with the hydrogel precursors with a high loading capacity by homogenous mixing. The different physical and chemical crosslinking approaches for preparing polysaccharide-based injectable hydrogels are reviewed. Additionally, the review highlights the recent work using polysaccharides-based injectable hydrogels as stimuli-responsive delivery vehicles for the controlled release of different therapeutic agents and viscoelastic matrix for cell encapsulation. Moreover, the application of polysaccharides-based injectable hydrogel in regenerative medicine as tissue scaffold and wound healing dressing is covered.

One-Step Synthesis of Nitrogen-Doped Porous Biochar Based on N-Doping Co-Activation Method and Its Application in Water Pollutants Control

In this work, birch bark (BB) was used for the first time to prepare porous biochars via different one-step methods including direct activation (BBB) and N-doping co-activation (N-BBB). The specific surface area and total pore volume of BBB and N-BBB were 2502.3 and 2292.7 m²/g, and 1.1389 and 1.0356 cm³/g, respectively. When removing synthetic methyl orange (MO) dye and heavy metal Cr⁶⁺, both BBB and N-BBB showed excellent treatment ability. The maximum adsorption capacities of BBB and N-BBB were 836.9 and 858.3 mg/g for MO, and 141.1 and 169.1 mg/g for Cr⁶⁺, respectively, which were higher than most previously reported biochar adsorbents. The probable adsorption mechanisms, including pore filling, π-π interaction, H-bond interaction, and electrostatic attraction, supported the biochars' demonstrated high performance. In addition, after five recycles, the removal rates remained above 80%, which showed the high stability of the biochars. This work verified the feasibility of the one-step N-doping co-activation method to prepare high-performance biochars, and two kinds of biochars with excellent performance (BBB and N-BBB) were prepared. More importantly, this method provides new directions and ideas for the development and utilization of other biomasses.