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Cationic nanomaterials are promising candidates for the development of effective antibacterial agents by taking advantage of the nanoscale effects as well as other exceptional physicochemical properties of nanomaterials. In this study, carboxylated cellulose nanocrystals (cCNCs) derived from softwood pulp were coated with cationic poly(diallyldimethylammonium chloride) of varying molecular weights. The resulting cationic carboxylated cellulose nanocrystals coated with poly(diallyldimethylammonium chloride) (cCNCs–PDDA) nanomaterials were characterized for their structural and morphological properties using Fourier transform infrared spectroscopy, dynamic light scattering, zeta potential, elemental analysis, transmission electron microscopy, and thermogravimetric analysis. Cationic cCNCs–PDDA were investigated for their antibacterial properties against Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli 23934 and Pseudomonas aeruginosa using a bacterial lawn growth inhibition assay. cCNC–PDDA materials displayed marked antibacterial activity, particularly against Gram-positive Staphylococcus aureus. Overall, our results indicated that cCNCs–PDDA could be a potential candidate for antibacterial applications such as antibacterial surfaces or coatings. [ABSTRACT FROM AUTHOR]

To unlock nature's potential for functional biomaterials, many efforts have been devoted to isolating the nanocrystalline domains within the supramolecular structure of polysaccharides. Yet, low reactivity and yield in aqueous systems along with excessive solvent usage hinders its development. In this report, the first solvent‐free pathway to access carboxylated chitin and cellulose nanocrystals with excellent mass balance is described, relying on a new method coined high‐humidity shaker aging (HHSA). The method involves a mild grinding of the polysaccharide with ammonium persulfate followed by an aging phase under high‐humidity and on a shaker plate. Insights into the mechanism were uncovered, which highlighted the unique role of high humidity to afford a gradual uptake of water by the material up to deliquescence when the reaction is complete. This process was then validated for direct synthesis of nanocrystals from biomass sources including crab and soft wood pulp. [ABSTRACT FROM AUTHOR]

Over the past five years, there has been growing interest in the design of modified cellulose nanocrystals (CNCs) as nanoscale antimicrobial agents in potential end-user applications such as food preservation/packaging, additive manufacturing, biomedical and water purification. The interest of applying CNCs-based antimicrobial agents arise due to their abilities to be derived from renewable bioresources and their excellent physicochemical properties including rod-like morphologies, large specific surface area, low toxicity, biocompatibility, biodegradability and sustainability. The presence of ample surface hydroxyl groups further allows easy chemical surface modifications for the design of advanced functional CNCs-based antimicrobial materials. Furthermore, CNCs are used to support antimicrobial agents that are subjected to instability issues. The current review summarizes recent progress in CNC-inorganic hybrid-based materials (Ag and Zn nanoparticles, other metal/metal oxide) and CNC-organic hybrid-based materials (polymers, chitosan, simple organic molecules). It focuses on their design, syntheses and applications with a brief discussion on their probable modes of antimicrobial action whereby the roles of CNCs and/or the antimicrobial agents are highlighted. [Display omitted] [ABSTRACT FROM AUTHOR]

In recent years, cellulose nanocrystals (CNCs) have emerged as a leading biomass-based nanomaterial owing to their unique functional properties and sustainable resourcing. Sulfated cellulose nanocrystals (sCNCs), produced by sulfuric acid-assisted hydrolysis of cellulose, is currently the predominant form of this class of nanomaterial; its utilization leads the way in terms of CNC commercialization activities and industrial applications. The functional properties, including high crystallinity, colloidal stability, and uniform nanoscale dimensions, can also be attained through carboxylated cellulose nanocrystals (cCNCs). Herein, we review recent progress in methods and feedstock materials for producing cCNCs, describe their functional properties, and discuss the initial successes in their applications. Comparisons are made to sCNCs to highlight some of the inherent advantages that cCNCs may possess in similar applications. [ABSTRACT FROM AUTHOR]

Removal of toxic organic cationic dye, Auramine O (AO), is critical prior to its discharge to the environment. In this work, wood-based colloidal cellulose nanocrystals (CNCs) in their anionic forms (sulfated and carboxylated) were examined as nanoadsorbents for the effective removal of cationic toxic AO. Both sulfated and carboxylated CNCs were characterized by FTIR, DLS, zeta potential, AFM and XRD techniques. The impact of both surface functionalities (half-ester sulfate and carboxylate) of CNCs were studied in relation to the adsorption of AO. The batch adsorption experiments were performed at 0 and 25 °C at different contact time and the highest removal percentage (82 %) and adsorption capacity (20 mg g−1) were obtained for the sulfated CNCs for an equilibrium contact time of 30 min. The kinetic data was fitted to the pseudo-second-order adsorption model, with the highest rate constant (0.55 g mg-1. min−1) related to the sulfated CNCs for the adsorption at 0 °C. The calculated thermodynamics parameters indicated that AO adsorption on both CNC samples was a spontaneous exothermic process with a decrease in the entropy of the system for the sulfated CNCs and an increase in entropy for the carboxylated CNCs. Fitting equilibrium data to four different types of isotherms (Henry, Freundlich, Langmuir and Temkin) showed that Freundlich isotherm was the most suitable to describe the adsorption behavior of AO at either 0 or 25 °C. Overall, this study demonstrated the potential application of sustainable and biodegradable wood-based CNCs as green bioadsorbents for the adsorption of toxic cationic AO dye. [ABSTRACT FROM AUTHOR]