Adsorption and Assembly of Cellulosic and Lignin Colloids at Oil/Water Interfaces

Recent updates on green synthesis of lignin nanoparticle and its potential applications in modern biotechnology

Lignin is a complex of organic polymers that are abundantly present in the plant cell wall which considered of emerging substrates for various kinds of value-added industrial products. Lignin has potential use for the production of green nanomaterials, which exhibit improved or different properties corresponding to their parent polymers. Nano lignin has received significant interest in recent years due to its applications in numerous fields. Lignin, the abundant and limited functionality has challenges for its potential uses. Creating advanced functional lignin-derived material like lignin nanoparticles (LNPs) which significantly alter the biological process has great potential for its applications. In the fields of biotechnology, several lignin extraction processes from various raw materials and diverse synthesis techniques, including acid precipitation, dialysis, solvent shifting/solvent exchange, antisolvent precipitation, homogenization, water-in-oil (W/O) microemulsion, ultra-sonication, interfacial crosslinking, polymerization, and biological pathway can be employed to produce LNPs. The scientific community has recently become more concerned about the transformation of lignin to lignin nanomaterials, including nanoparticles, nanocapsules, nanofibers, nanotubes, and nanofilms. Recent research has shown that lignin nanoparticles (LNPs) are: non-toxic at adequate amounts (both in vitro and in vivo), are economical, and can be biodegradable by bacteria and fungi. In promising studies, LNPs have been investigated for their potential applications in gene delivery systems, drug carriers, biocatalysts, tissue engineering, heavy metal absorbers, encapsulation of molecules, supercapacitors, hybrid nanocomposites, and other applications. This current review addresses the recent advances in the synthesis of LNPs, their advanced application in different areas, future perspectives, and challenges associated with lignin-based nanomaterials.

Juncus rigidus high biomass and cellulose productivity under wastewater salinity stress - A paradigm shift to the valorization of RO reject water

The use of water purifiers is intensively catching up and disposing of reverse osmosis reject water is of great concern. Reject water management using conventional methods is costly and harmful to the environment. To address this issue, the present study aims to utilize reverse osmosis reject wastewater using an eco-friendly approach. Juncus rigidus was treated with reject wastewater containing different salinity levels. Wastewater-treated plant dry biomass increased with increasing reject water salinity, and 625.3 g dry biomass recovered in treatment-B (~18,520 ppm). However, ~23,220 ppm wastewater salinity was lethal to the plants. The cellulose was extracted by alkali hydrolysis. The cellulose content in the wastewater-treated biomass was significantly higher in Treatment-B compared to both the control and Treatment-A (~12,744 ppm). The water salinity enhanced the cellulose (26.49 %) production in J. rigidus. Cellulose purity was confirmed using spectroscopic and thermogravimetric means. XRD shows highest crystallinity Index (77.29) with a d-spacing of 4.7 Å and 5.7 nm crystallite size in treatment-B. FTIR results reveal well-defined relevant peaks for OH, CH, CO, CH2, C-O-C, CO groups in treatment-B cellulose. Salinity impacts carboxyl groups in treatment B cellulose with a sharper and intense peak at 1644 cm-1 responsible for water absorption. Treatment-B exhibits higher thermal stability due to increased crystallinity. DSC shows endothermic depolymerization of cellulose with distinct peaks for different treatments. Morphological traits got better with increasing salinity with no adverse effect on cellulose. Salinity moderately affected the water absorption capacity of cellulose. All cellulose samples were devoid of gram-negative bacteria known by microbial test. This pioneering work underscores the plant's remarkable capacity not only to accomplish the circular economy by the valorization of wastewater obtained from various water purifiers for Juncus cultivation for cellulose production for diverse applications but also to generate income from wastewater.

Assembly of porous filaments by interfacial complexation of nanochitin-based Pickering emulsion and seaweed alginate

Interfacial polyelectrolyte complexation spinning is an all-water, easy-to-operate method for production of composite filaments. Herein, this concept is extended to interfacial polyelectrolyte-emulsion complexation (IPEC) that better encodes structural and functional attributes of biomass substances into the filaments. This allows for formation of composite filaments by drawing contacting oppositely-charged chitin nanofiber-stabilized Pickering emulsion and seaweed alginate solution. The parameters affecting spinnability of the system including water-to-oil ratio, alginate concentration, and pH are comprehensively elucidated to support the design and application of IPEC. The composite filaments exhibit varied diameters and diverse porous structures that are adjustable by properties of Pickering droplets. The droplet diameter of precursor emulsion and pore size in the filaments are well correlated, revealing controllability of the IPEC spinning. The filaments are mechanically robust in dry condition and show stable performance even in wet condition. The release rate of filaments that is pre-loaded with hydrophilic drug is regulated by the internal pore size, showing capability on sustained release. This study offers a new perspective toward dry spinning via interfacial complexation of complicated nanochitin-based structural building blocks, aiming at developing high-performance fiber materials for advanced applications.

Pickering emulsions stabilized by cellulose nanocrystals extracted from hazelnut shells: Production and stability under different harsh conditions

Cellulose nanocrystals (CNCs) are biodegradable particles that have emerged as promising stabilizers for Pickering emulsions. This study investigated the effectiveness of CNCs in forming the Pickering emulsion from hazelnut shells (HS), an agricultural waste. Following the alkaline and bleaching treatments applied to HS, CNCs were obtained from treated hazelnut shell with acid hydrolysis. The physicochemical characteristics of CNCs were investigated using dynamic light scattering, XRD, FTIR, SEM, and TEM. A high crystalline (69.6 %) CNCs with a spherical shape were obtained. Contact angle and interfacial tension tests were conducted and showed that CNCs had amphiphilic nature. Pickering emulsions were investigated for their size, zeta potential, and stability under varying CNC concentrations. The results showed that when CNCs concentration increased from 0.5 to 2.0 wt%, droplet diameter decreased approximately 1.8 times and zeta potential increased. Creaming was not observed during 28 days of storage in a concentration of 2.0 wt% CNCs. The CNC stabilized emulsions exhibited high stability within a range of pH, temperatures, and salt concentrations. This study demonstrated that CNCs extracted from HS as environmentally friendly and cost-effective materials, could serve as a new stabilizer for Pickering emulsions especially for high temperature and low pH sensitive products such as mayonnaise.

A Biomimetic Lignocellulose Aerogel-Based Membrane for Efficient Phenol Extraction from Water

Rapid extraction and concentration systems based on green materials such as cellulose or lignin are promising. However, there is still a need to optimize the material properties and production processes. Unlike conventional cellulose or lignin sorbent materials, aquatic reed root cells can concentrate external organic pollutants in the water and accumulate them in the plant. Inspired by this, a new nanocellulose-lignin aerogel (NLAG) was designed, in which nanocellulose was used as a substrate and lignin and polyamide epoxy chloropropane were used to crosslink cellulose in order to enhance the strength of the NLGA, resulting in good mechanical stability and water-oil amphiphilic properties. In practical applications, the organic membrane on the NLAG can transport organic pollutants from water to the NLAG, where they are immobilized. This is evidenced by the fact that the aerogel can remove more than 93% of exogenous phenol within a few minutes, highly enriching it inside. In addition, the aerogel facilitates filtration and shape recovery for reuse. This work establishes a novel biopolymer-aerogel-based extraction system with the advantages of sustainability, high efficiency, stability, and easy detachability, which are hard for the traditional adsorbent materials to attain.

Antibacterial polylactic acid fabricated via Pickering emulsion approach with polyethyleneimine and polydopamine modified cellulose nanocrystals as emulsion stabilizers

Antibacterial biodegradable plastics are highly demanded for food package and disposable medical plastic consumables. Incorporating antibacterial nanoagents into polymer matrices is an effective method to endow polymers with antibacterial activity. However, synthesis of sustainable antibacterial nanoagents with high antibacterial activity via facile approach and well dispersion of them in polymer matrices are still challenging. In this study, polyethyleneimine (PEI) was grafted on surface of cellulose nanocrystals (CNCs) via the oxidation self-polymerization of dopamine (DA) and the Michael addition/Schiff base reaction between DA and PEI. The resulted PEI and polydopamine modified CNCs (PPCs) showed substantially enhanced antibacterial activity and reduced cytotoxicity for NIH3T3 than PEI due to increased local concentration and anchoring of PEI. The minimum concentration of PPCs to achieve antibacterial rate of 99.99 % against S. aureus and E. coli were about 50 and 20 μg/mL, respectively. PPCs displayed outstanding emulsifying ability, and PPC coated polylactic acid (PLA) microspheres were obtained by drying PPC stabilized PLA Pickering emulsion, leading to a well dispersion of PPCs in PLA. PPC/PLA film prepared by hot-pressing displayed great antibacterial performance and enhanced mechanical properties. Therefore, this study proposed a facile approach to fabricate biocompatible antibacterial nanoagents and plastics.

Sugarcane Light-Colored Lignin: A Renewable Resource for Sustainable Beauty

Lignin has emerged as a promising eco-friendly multifunctional ingredient for cosmetic applications, due to its ability to protect against ultraviolet radiation and its antioxidant and antimicrobial properties. However, its typical dark color and low water solubility limit its application in cosmetics. This study presents a simple process for obtaining light-colored lignin (LCLig) from sugarcane bagasse (SCB) alkaline black liquor, involving an oxidation treatment with hydrogen peroxide, followed by precipitation with sulfuric acid. The physico-chemical characterization, antioxidant and emulsifying potential of LCLig, and determination of its safety and stability in an oil-in-water emulsion were performed. A high-purity lignin (81.6%) with improved water solubility was obtained, as a result of the balance between the total aromatic phenolic units and the carboxylic acids. In addition, the antioxidant and emulsifying capacities of the obtained LCLig were demonstrated. The color reduction treatment did not compromise the safety of lignin for topical cosmetic applications. The emulsion was stable in terms of organoleptic properties (color, pH, and viscosity) and antioxidant activity over 3 months at 4, 25, and 40 °C.

Apparent Failures in Interpretation of Interfacial Characterization When Formulating Emulsions Stabilized by Cellulose Nanocrystals

Cellulose nanocrystals (CNCs) are sustainable particles that are effective at stabilizing emulsions by adsorbing at droplet interfaces and providing a steric barrier to coalescence. However, CNCs have surface charges that reduce the coverage of the emulsion droplets due to the electrostatic repulsion between CNCs. In such cases, adding salt is a typical (and straightforward) way to adjust the formulation so that the charges are screened, allowing increased coverage of the droplets. At the outset of this work, we hypothesized that characterization of the interfacial tension and interfacial shear rheology of the oil-water interface would be correlated to interfacial coverage and therefore predictive of the optimal salt concentration for emulsion stability. Included in the methods section as a useful reference to others is the presentation of a detailed derivation for the equations needed to compute interfacial shear moduli in a custom, double-gap geometry. In contrast to our hypothesis, we found that interfacial tension did not correlate well with emulsion stability and that the native surface-active compounds in corn oil overwhelmed any influence of the CNCs on the interfacial tension. Additionally, we found that interfacial shear rheology (which can be painstakingly difficult to measure) was not a useful tool for formulating these emulsions. This is because at commonly used concentrations of CNCs, the bulk rheology is increased to a much greater degree than that of the interface, making the details of the interfacial rheology unimportant. Finally, we found that at concentrations of CNCs that are typical in industrial processes, characterizing the bulk viscoelastic properties of the aqueous suspending phase without added oil (a relatively simple measurement) is sufficient to predict the influence of NaCl concentration on charge screening between the CNCs and, by extension, increased surface coverage of droplets for greater emulsion stability.

Lignin nanoparticles as co-stabilizers and modifiers of nanocellulose-based Pickering emulsions and foams

Nanocellulose is very hydrophilic, preventing interactions with the oil phase in Pickering emulsions. This limitation is herein addressed by incorporating lignin nanoparticles (LNPs) as co-stabilizers of nanocellulose-based Pickering emulsions. LNP addition decreases the oil droplet size and slows creaming at pH 5 and 8 and with increasing LNP content. Emulsification at pH 3 and LNP cationization lead to droplet flocculation and rapid creaming. LNP application for emulsification, prior or simultaneously with nanocellulose, favors stability given the improved interactions with the oil phase. The Pickering emulsions can be freeze-dried, enabling the recovery of a solid macroporous foam that can act as adsorbent for pharmaceutical pollutants. Overall, the properties of nanocellulose-based Pickering emulsions and foams can be tailored by LNP addition. This strategy offers a unique, green approach to stabilize biphasic systems using bio-based nanomaterials without tedious and costly modification procedures.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10570-023-05399-y.

Kraft Lignin: A Valuable, Sustainable Resource, Opportunities and Challenges

Kraft lignin, a by-product from the production of pulp, is currently incinerated in the recovery boiler during the chemical recovery cycle, generating valuable bioenergy and recycling inorganic chemicals to the pulping process operation. Removing lignin from the black liquor or its gasification lowers the recovery boiler load enabling increased pulp production. During the past ten years, lignin separation technologies have emerged and the interest of the research community to valorize this underutilized resource has been invigorated. The aim of this Review is to give (1) a dedicated overview of the kraft process with a focus on the lignin, (2) an overview of applications that are being developed, and (3) a techno-economic and life cycle asseeements of value chains from black liquor to different products. Overall, it is anticipated that this effort will inspire further work for developing and using kraft lignin as a commodity raw material for new applications undeniably promoting pivotal global sustainability concerns.

Integral Valorization of Grape Pomace for Antioxidant Pickering Emulsions

Full harnessing of grape pomace (GP) agricultural waste for the preparation of antioxidant Pickering emulsions is presented herein. Bacterial cellulose (BC) and polyphenolic extract (GPPE) were both prepared from GP. Rod-like BC nanocrystals up to 1.5 µm in length and 5-30 nm in width were obtained through enzymatic hydrolysis (EH). The GPPE obtained through ultrasound-assisted hydroalcoholic solvent extraction presented excellent antioxidant properties assessed using DPPH, ABTS and TPC assays. The BCNC-GPPE complex formation improved the colloidal stability of BCNC aqueous dispersions by decreasing the Z potential value up to -35 mV and prolonged the antioxidant half-life of GPPE up to 2.5 times. The antioxidant activity of the complex was demonstrated by the decrease in conjugate diene (CD) formation in olive oil-in-water emulsions, whereas the measured emulsification ratio (ER) and droplet mean size of hexadecane-in-water emulsions confirmed the physical stability improvement in all cases. The synergistic effect between nanocellulose and GPPE resulted in promising novel emulsions with prolonged physical and oxidative stability.

MIL-101(Fe) based biomass as permeable reactive barrier applied to EK-PRB remediation of antimony contaminated soil

Numerous studies have demonstrated that electrokinetic-permeable reactive barrier (EK-PRB) can be used for the remediation of heavy metal contaminated soils, and their remediation efficiency is mainly determined by the filler material selected. By growing MIL-101(Fe) in situ on hollow loofah fiber (HLF), a novel material entitled HLF@MIL-101(Fe) was developed. The morphological characteristics and loading conditions were investigated, the adsorption characteristics were analyzed, and finally the synthesized composite material was applied to treat antimony-contaminated soil with EK-PRB as the reaction medium. The results show that MIL-101(Fe) is stably loaded on HLF. The adsorption capacity of Sb(III) can reach up to 82.31 mg g^-1, and the adsorption is in accordance with the quasi-secondary kinetic model, which indicates that chemisorption is dominant. The isothermal adsorption model indicates that the adsorption form of HLF@MIL-101(Fe) is mainly monolayer adsorption with more uniform adsorption binding energy. In the EK-PRB experiment, when ethylenediaminetetraacetic acid (EDTA) is used as the cathodic electrolyte, it can effectively enhance the electromigration and electroosmotic effects, and the overall remediation efficiency of the soil is increased by 38.12% compared with the citric acid (CA) group. These demonstrate the feasibility of HLF@MIL-101(Fe) in collaboration with EK-PRB in the treatment of antimony-contaminated soil.

Horse manure as resource for biogas and nanolignocellulosic fibres

Nanofibrillated cellulose (NFC) has key applications in composites, water filters and as emulsifiers. The affinity of NFC to water is a challenge, as it negatively influences its integrity. Lignin, a major component of plant biomass, is a natural hydrophobiser. Anaerobic digestion (AD) of biomass to produce biomethane allows to up-concentrate lignin in the fermentation residue containing lignocellulosic fibres. Horse manure was used as substrate for biogas production from which nanolignocellulose fibres (LCNF) were extracted. A biogas yield of 207 L_N kg_VS^-1 with a methane concentration of 65 % was achieved. From the fermentation residue LCNFs, in yields of up to 41 %, with lignin contents between 23 and 29 wt% depending on fermentation time were obtained. Nanopapers produced from LCNFs possessed tensile strengths and moduli of 45 to 91 MPa and 7 to 8 GPa, respectively. The increased lignin content was responsible for decreased water absorption capacity of nanopapers.

Correlation between interfacial layer properties and physical stability of food emulsions: current trends, challenges, strategies, and further perspectives

Emulsions are thermodynamically unstable systems that tend to separate into two immiscible phases over time. The interfacial layer formed by the emulsifiers adsorbed at the oil-water interface plays an important role in the emulsion stability. The interfacial layer properties of emulsion droplets have been considered the cutting-in points that influence emulsion stability, a traditional motif of physical chemistry and colloid chemistry of particular significance in relation to the food science and technology sector. Although many attempts have shown that high interfacial viscoelasticity may contribute to long-term emulsion stability, a universal relationship for all cases between the interfacial layer features at the microscopic scale and the bulk physical stability of the emulsion at the macroscopic scale remains to be established. Not only that, but integrating the cognition from different scales of emulsions and establishing a unified single model to fill the gap in awareness between scales also remain challenging. In this review, we present a comprehensive overview of recent progress in the general science of emulsion stability with a peculiar focus on interfacial layer characteristics in relation to the formation and stabilization of food emulsions, where the natural origin and edible safety of emulsifiers and stabilizers are highly requested. This review begins with a general overview of the construction and destruction of interfacial layers in emulsions to highlight the most important physicochemical characteristics of interfacial layers (formation kinetics, surface load, interactions among adsorbed emulsifiers, thickness and structure, and shear and dilatational rheology), and their roles in controlling emulsion stability. Subsequently, the structural effects of a series of typically dietary emulsifiers (small-molecule surfactants,proteins, polysaccharides, protein-polysaccharide complexes, and particles) on oil-water interfaces in food emulsions are emphasized. Finally, the main protocols developed for modifying the structural characteristics of adsorbed emulsifiers at multiple scales and improving the stability of emulsions are highlighted. Overall, this paper aims to comprehensively study the literature findings in the past decade and find out the commonality of multi-scale structures of emulsifiers, so as to deeply understand the common characteristics and emulsification stability behaviour of adsorption emulsifiers with different interfacial layer structures. It is difficult to say that there has been significant progress in the underlying principles and technologies in the general science of emulsion stability over the last decade or two. However, the correlation between interfacial layer properties and physical stability of food emulsions promotes revealing the role of interfacial rheological properties in emulsion stability, providing guidance on controlling the bulk properties by tuning the interfacial layer functionality.

Self-assembled/composited lignin colloids utilizing for therapy, cosmetics and emulsification

Lignin, the most abundant source of renewable aromatic compounds on the planet, is attracting more scholarly attention due to its possibility of replacing petroleum-based chemicals and products. However, it remains underutilized because of the heterogeneity of its multi-level structure that prevents homogenization and standardization of derived products. The key to solving these problems lies in finding a general preparation method to achieve the integrated utilization of lignin molecules at all levels. The assembly-mediated granulation methods provide a significant means for the integrated value-added utilization of lignin, and for biomass productization applications, it is significant to understand the molecular mechanisms of lignin nano-colloids (LNCs) formation thus accurately guiding their functionalization. Therefore, a thorough understanding of the assembly morphology and behavior of lignin in different solutions towards colloids is of great scientific importance. In this minireview, we focus on the assembly behavior of lignin in different solvents, specifically in mono-solvent and multi-solvent, and in particular, we review various methods for preparing lignin composite colloids and concentrate on the applications in therapy, cosmetics and emulsification, which are important for guiding the preparation and efficient utilization of LNCs.

Characterization of Polyhydroxybutyrate, PHB, Synthesized by Newly Isolated Haloarchaea Halolamina spp

This work aims to characterize the haloarchaeal diversity of unexplored environmental salty samples from a hypersaline environment on the southern coast of Jeddah, Saudi Arabia, looking for new isolates able to produce polyhydroxyalkanoates (PHAs). Thus, the list of PHA producers has been extended by describing two species of Halolamina; Halolamina sediminis sp. strain NRS_35 and unclassified Halolamina sp. strain NRS_38. The growth and PHA-production were investigated in the presence of different carbon sources, (glucose, sucrose, starch, carboxymethyl cellulose (CMC), and glycerol), pH values, (5-9), temperature ranges (4-65 °C), and NaCl concentrations (100-350 g L-1). Fourier-transform infra-red analysis (FT-IR) and Liquid chromatography-mass spectrometry (LC-MS) were used for qualitative identification of the biopolymer. The highest yield of PHB was 33.4% and 27.29% by NRS_35 and NRS_38, respectively, using starch as a carbon source at 37 °C, pH 7, and 25% NaCl (w/v). The FT-IR pattern indicated sharp peaks formed around 1628.98 and 1629.28 cm-1, which confirmed the presence of the carbonyl group (C=O) on amides and related to proteins, which is typical of PHB. LC-MS/MS analysis displayed peaks at retention times of 5.2, 7.3, and 8.1. This peak range indicates the occurrence of PHB and its synthetic products: Acetoacetyl-CoA and PHB synthase (PhaC). In summary, the two newly isolated Halolamina species showed a high capacity to produce PHB using different sources of carbon. Further research using other low-cost feedstocks is needed to improve both the quality and quantity of PHB production. With these results, the use of haloarchaea as cell factories to produce PHAs is reinforced, and light is shed on the global concern about replacing plastics with biodegradable polymers.

Biocompatible Nanoparticle Heteroaggregates as Stabilizers of Pickering Emulsions for Vitamin D3 Efficient Delivery

Vitamin D3 deficiency is a major public health problem worldwide, and standard cholecalciferol formulations provide poor absorbability of the vitamin. Several biphasic formulas have been proposed to overcome the disadvantages in which Pickering emulsions stand out in particular. This paper describes olive oil-in-water Pickering emulsions stabilized by pseudoboehmite (AlOOH), cellulose nanocrystals (CNC), and their heterocoagulates. Colloidal properties were assessed by laser Doppler microelectrophoresis, potentiometric titration, and rheology. It was shown that the heterocoagulation of CNC and AlOOH led to a drastic change in surface properties (ζ-potential, pKa, and number of active centers), which promoted the formation of more stable emulsions with the smallest size of droplets and the highest viscosity among the studied samples. Simulated digestion studies showed the targeted release in the small intestine medium where cholecalciferol should be delivered. High-performance liquid chromatography showed the efficient encapsulation of cholecalciferol in emulsions (86% of initial concentration). Oral administration to laboratory mice of initial nanoparticles and emulsions stabilized by them showed nontoxicity for all of the components, and they were estimated to be class V materials. The proposed emulsions have great potential as targeted delivery systems of lipophilic drugs.

Nanochitin: Chemistry, Structure, Assembly, and Applications

Chitin, a fascinating biopolymer found in living organisms, fulfills current demands of availability, sustainability, biocompatibility, biodegradability, functionality, and renewability. A feature of chitin is its ability to structure into hierarchical assemblies, spanning the nano- and macroscales, imparting toughness and resistance (chemical, biological, among others) to multicomponent materials as well as adding adaptability, tunability, and versatility. Retaining the inherent structural characteristics of chitin and its colloidal features in dispersed media has been central to its use, considering it as a building block for the construction of emerging materials. Top-down chitin designs have been reported and differentiate from the traditional molecular-level, bottom-up synthesis and assembly for material development. Such topics are the focus of this Review, which also covers the origins and biological characteristics of chitin and their influence on the morphological and physical-chemical properties. We discuss recent achievements in the isolation, deconstruction, and fractionation of chitin nanostructures of varying axial aspects (nanofibrils and nanorods) along with methods for their modification and assembly into functional materials. We highlight the role of nanochitin in its native architecture and as a component of materials subjected to multiscale interactions, leading to highly dynamic and functional structures. We introduce the most recent advances in the applications of nanochitin-derived materials and industrialization efforts, following green manufacturing principles. Finally, we offer a critical perspective about the adoption of nanochitin in the context of advanced, sustainable materials.

Recent Advances of Stimuli-Responsive Polysaccharide Hydrogels in Delivery Systems: A Review

Hydrogels obtained from natural polymers have received widespread attention for their excellent biocompatible property, nontoxicity, easy gelation, and functionalization. Polysaccharides can regulate the gut microbiota and improve the intestinal microenvironment, thus exerting the healthy effect of intestinal immunity. In an active substance delivery system, the extent and speed of the substance reaching its target are highly dependent on the carrier. Thus, the smart active substance delivery systems are gradually increasing. The smart polysaccharide-hydrogels possess the ability in response to external stimuli through changing their volume phase and structure, which are applied in various fields. Natural polysaccharide-based hydrogels possess excellent characteristics of environmental friendliness, good biocompatibility, and abundant sources. According to the response type, natural polysaccharide-based hydrogels are usually divided into stimulus-responsive hydrogels, including internal response (pH, temperature, enzyme, redox) and external response (light, electricity, magnetism) hydrogels. The delivery system based on polysaccharides can exert their effects in the gastrointestinal tract. At the same time, polysaccharides may also take part in regulating the brain signals through the microbiota-gut-brain axis. Therefore, natural polysaccharide-hydrogels are considered as promising biomaterials, which can be designed as delivery systems for regulating the gut-brain axis. This article reviews the research advance of stimulus-responsive hydrogels, which focus on the types, response characteristics, and applications for polysaccharide-based smart hydrogels as delivery systems.

Surface functionalization and size modulate the formation of reactive oxygen species and genotoxic effects of cellulose nanofibrils

BACKGROUND

Cellulose nanofibrils (CNFs) have emerged as a sustainable and environmentally friendly option for a broad range of applications. The fibrous nature and high biopersistence of CNFs call for a thorough toxicity assessment, but it is presently unclear which physico-chemical properties could play a role in determining the potential toxic response to CNF. Here, we assessed whether surface composition and size could modulate the genotoxicity of CNFs in human bronchial epithelial BEAS-2B cells. We examined three size fractions (fine, medium and coarse) of four CNFs with different surface chemistry: unmodified (U-CNF) and functionalized with 2,2,6,6-tetramethyl-piperidin-1-oxyl (TEMPO) (T-CNF), carboxymethyl (C-CNF) and epoxypropyltrimethylammonium chloride (EPTMAC) (E-CNF). In addition, the source fibre was also evaluated as a non-nanosized material.

RESULTS

The presence of the surface charged groups in the functionalized CNF samples resulted in higher amounts of individual nanofibrils and less aggregation compared with the U-CNF. T-CNF was the most homogenous, in agreement with its high surface group density. However, the colloidal stability of all the CNF samples dropped when dispersed in cell culture medium, especially in the case of T-CNF. CNF was internalized by a minority of BEAS-2B cells. No remarkable cytotoxic effects were induced by any of the cellulosic materials. All cellulosic materials, except the medium fraction of U-CNF, induced a dose-dependent intracellular formation of reactive oxygen species (ROS). The fine fraction of E-CNF, which induced DNA damage (measured by the comet assay) and chromosome damage (measured by the micronucleus assay), and the coarse fraction of C-CNF, which produced chromosome damage, also showed the most effective induction of ROS in their respective size fractions.

CONCLUSIONS

Surface chemistry and size modulate the in vitro intracellular ROS formation and the induction of genotoxic effects by fibrillated celluloses. One cationic (fine E-CNF) and one anionic (coarse C-CNF) CNF showed primary genotoxic effects, possibly partly through ROS generation. However, the conclusions cannot be generalized to all types of CNFs, as the synthesis process and the dispersion method used for testing affect their physico-chemical properties and, hence, their toxic effects.

The Formulation, Development and Application of Oil Dispersants

Oil spills in open waters pose a significant threat to marine life. The application of dispersant as an oil-spill response is a promising approach to minimize the environmental burden caused by these accidental events. Dispersants have been accepted and applied by many countries around the world as a countermeasure in responding to oil spills due to their great success and advancements in recent years. This review covers different approaches for design and development of chemical formulas of oil dispersants with the aim to improve dispersing efficiencies, followed by formulating non-chemical dispersants, which are more environmentally friendly approaches. The encouraging properties motivate scientific communities to research and develop these non-chemical-based dispersants. In general, this review intends to offer a multi-perspective overall picture of progress made in recent years to develop and apply different dispersants suitable for combating oil spills.

Enhanced Interface Properties and Stability of Lignocellulose Nanocrystals Stabilized Pickering Emulsions: The Leading Role of Tannic Acid

Cellulose and tannin are both abundant and biodegradable biopolymers, whose integrations show great potential in the food field due to their nutritional properties and biological activity. Here, lignocellulose nanocrystals (LCNC) isolated from pineapple peel were complexed with tannic acid (TA) through hydrogen-bonding interaction to prepare the LCNC/TA complex for stabilizing Pickering emulsions. Introducing TA decreased the interfacial tension (23.8-20.1 mN/m) and water contact angle (83.2-56.2°) with the LCNC/TA ratio ranging from 1:0 to 1:0.8 (w/w) but increased the size of the LCNC/TA complex. The droplet size of emulsions decreased from 115.0 to 51.3 μm accompanied by improved rheological properties. The emulsions stabilized by the LCNC/TA complex exhibited higher storage and environmental stabilities than those stabilized by LCNC alone. Interestingly, TA effectively promoted the interfacial adsorption of LCNC to build a stronger interfacial layer. The emulsion network structure was enhanced due to the formation of hydrogen-bonding interaction between LCNC and TA in the continuous phase.

Utilization of lignocellulosic biomass: A practical journey towards the development of emulsifying agent

With each passing year, the agriculture and wood processing industries generate increasingly high tonnages of biomass waste, which instead of being burned or left to accumulate should be utilized more sustainably. In parallel, advances in green technology have encouraged large companies and nations to begin using eco-friendly materials, including eco-friendly emulsifiers, which are used in various industries and in bio-based materials. The emulsion-conducive properties of lignocellulosic materials such as cellulose, hemicellulose, and lignin, the building blocks of plant and wood structures, have demonstrated a particular ability to alter the landscape of emulsion technology. Beyond that, the further modification of their structure may improve emulsion stability, which often determines the performance of emulsions. Considering those trends, this review examines the performance of lignocellulosic materials after modification according to their stability, droplet size, and distribution by size, all of which suggest their outstanding potential as materials for emulsifying agents.

Deconstruction and Reassembly of Renewable Polymers and Biocolloids into Next Generation Structured Materials

This review considers the most recent developments in supramolecular and supraparticle structures obtained from natural, renewable biopolymers as well as their disassembly and reassembly into engineered materials. We introduce the main interactions that control bottom-up synthesis and top-down design at different length scales, highlighting the promise of natural biopolymers and associated building blocks. The latter have become main actors in the recent surge of the scientific and patent literature related to the subject. Such developments make prominent use of multicomponent and hierarchical polymeric assemblies and structures that contain polysaccharides (cellulose, chitin, and others), polyphenols (lignins, tannins), and proteins (soy, whey, silk, and other proteins). We offer a comprehensive discussion about the interactions that exist in their native architectures (including multicomponent and composite forms), the chemical modification of polysaccharides and their deconstruction into high axial aspect nanofibers and nanorods. We reflect on the availability and suitability of the latter types of building blocks to enable superstructures and colloidal associations. As far as processing, we describe the most relevant transitions, from the solution to the gel state and the routes that can be used to arrive to consolidated materials with prescribed properties. We highlight the implementation of supramolecular and superstructures in different technological fields that exploit the synergies exhibited by renewable polymers and biocolloids integrated in structured materials.

Recent Developments in the Formulation and Use of Polymers and Particles of Plant-based Origin for Emulsion Stabilizations

The main scope of this Review was the recent progress in the use of plant-based polymers and particles for the stabilization of Pickering and non-Pickering emulsion systems. Due to their availability and promising performance, it was discussed how the source, modification, and formulation of cellulose, starch, protein, and lignin-based polymers and particles would impact their emulsion stabilization. Special attention was given toward the material synthesis in two forms of polymeric surfactants and particles and the corresponding formulated emulsions. Also, the effects of particle size, degree of aggregation, wettability, degree of substitution, and electrical charge in stabilizing oil/water systems and micro- and macro-structures of oil droplets were discussed. The wide range of applications using such plant-based stabilizers in different technologies as well as their challenge and future perspectives were described.

Influence of a Non-Ionic Surfactant in the Microstructure and Rheology of a Pickering Emulsion Stabilized by Cellulose Nanofibrils

Emulsion stabilization is a broad and relevant field with applications in oil, polymer and food industries. In recent years, the use of solid particles to stabilize emulsions or Pickering emulsions have been studied for their kinetic and physical properties. Nanomaterials derived from natural sources are an interesting alternative for this application. Cellulose nanofibrils (CNFs) have been widely explored as a Pickering emulsifier with potential food applications, however, in some cases the presence of surfactants is unavoidable, and the literature is devoid of an evaluation of the effect of a non-ionic food-grade surfactant, such as polysorbate 80, in the stabilization of a vegetable oil by CNFs. To better assess the possible interactions between CNFs and this surfactant emulsions containing coconut oil, an emerging and broadly used oil, were processed with and without polysorbate 80 and evaluated in their qualitative stability, morphological and physical properties. Fluorescence microscopy, dynamic light scattering and rheology were used for this assessment. Results indicate in absence of the surfactant, emulsion stability increased at higher CNFs content, creaming was observed at 0.15 and 0.3 wt.% of CNFs, while it was not evidenced when 0.7 wt.% was used. After the addition of surfactant, the droplets are covered by the surfactant, resulting in particles with a smaller diameter, entrapped in the cellulosic structure. Rheology indicates a lower network stiffness after adding polysorbate 80.

Basic Amino Acid-Modified Lignin-Based Biomass Adjuvants: Synthesis, Emulsifying Activity, Ultraviolet Protection, and Controlled Release of Avermectin

Avermectin (AVM) is a highly effective and safe biopesticide but is very sensitive to ultraviolet (UV) light and exhibits poor water solubility. Developing green and multifunctional adjuvants is important for the protection and controlled release of AVM. In this work, a number of water-soluble enzymatic hydrolysis lignins (W-EHLs) were prepared via grafting basic amino acids and used as emulsifiers with co-surfactants to prepare high-internal phase emulsions (HIPEs). The results showed that W-EHLs with co-surfactants could be prepared with HIPEs that contained 90 vol % green oil phases such as turpentine, and the stability of the HIPEs first increased and then decreased when the rate of grafting of basic amino acids on lignin increased from 0.26 to 1.46 mmol/g. The more polar oil droplets were less deformable due to their higher viscosity, thereby affording a stability advantage to HIPEs. Subsequently, the relations between the stability and interfacial viscoelasticity of the emulsion were effectively correlated by interfacial rheology, droplet size, and physical stability tests. The results showed that HIPEs with smaller droplets had poor fluidity and strong interfacial viscoelasticity due to their higher droplet packing density, which resulted in good macroscopic stability. Like the AVM carrier, the retention rate of AVM in HIPEs was 80.1% after UV radiation for 72 h, which represented the highest UV protection efficiency in AVM delivery systems. The release curves showed that the rate of release of AVM from HIPEs was adjusted by controlling the pH value of the medium. In addition, the release of HIPEs is completely in accord with both diffusion and the matrix erosion mechanism. The strategy could be extended to other sensitive pesticides and used to promote the development of sustainable agriculture.

Multifunctional lignin-based nanocomposites and nanohybrids

Significant progress in lignins valorization and development of high-performance sustainable materials have been achieved in recent years. Reports related to lignin utilization indicate excellent prospects considering green chemistry, chemical engineering, energy, materials and polymer science, physical chemistry, biochemistry, among others. To fully realize such potential, one of the most promising routes involves lignin uses in nanocomposites and nanohybrid assemblies, where synergistic interactions are highly beneficial. This review first discusses the interfacial assembly of lignins with polysaccharides, proteins and other biopolymers, for instance, in the synthesis of nanocomposites. To give a wide perspective, we consider the subject of hybridization with metal and metal oxide nanoparticles, as well as uses as precursor of carbon materials and the assembly with other biobased nanoparticles, for instance to form nanohybrids. We provide cues to understand the fundamental aspects related to lignins, their self-assembly and supramolecular organization, all of which are critical in nanocomposites and nanohybrids. We highlight the possibilities of lignin in the fields of flame retardancy, food packaging, plant protection, electroactive materials, energy storage and health sciences. The most recent outcomes are evaluated given the importance of lignin extraction, within established and emerging biorefineries. We consider the benefit of lignin compared to synthetic counterparts. Bridging the gap between fundamental and application-driven research, this account offers critical insights as far as the potential of lignin as one of the frontrunners in the uptake of bioeconomy concepts and its application in value-added products.

Recent Innovations in Emulsion Science and Technology for Food Applications

Emulsion technology has been used for decades in the food industry to create a diverse range of products, including homogenized milk, creams, dips, dressings, sauces, desserts, and toppings. Recently, however, there have been important advances in emulsion science that are leading to new approaches to improving food quality and functionality. This article provides an overview of a number of these advanced emulsion technologies, including Pickering emulsions, high internal phase emulsions (HIPEs), nanoemulsions, and multiple emulsions. Pickering emulsions are stabilized by particle-based emulsifiers, which may be synthetic or natural, rather than conventional molecular emulsifiers. HIPEs are emulsions where the concentration of the disperse phase exceeds the close packing limit (usually >74%), which leads to novel textural properties and high resistance to gravitational separation. Nanoemulsions contain very small droplets (typically d < 200 nm), which leads to useful functional attributes, such as high optical clarity, resistance to gravitational separation and aggregation, rapid digestion, and high bioavailability. Multiple emulsions contain droplets that have smaller immiscible droplets inside them, which can be used for reduced-calorie, encapsulation, and delivery purposes. This new generation of advanced emulsions may lead to food and beverage products with improved quality, health, and sustainability.

Preparation of palm (Elaeis oleifera) pressed fibre cellulose nanocrystals via cation exchange resin: characterisation and evaluation as Pickering emulsifier

BACKGROUND

Palm pressed fibre (PPF) is a cellulose-rich biomass residue produced during palm oil extraction. Its high cellulose content allows the isolation of cellulose nanocrystal (CNC). CNC has attracted scientific interest due to its biodegradability, biocompatibility and low cost. The present study isolated CNC from PPF using a cation exchange resin, which is an environmentally friendly and less harsh hydrolysis method than conventional mineral acid hydrolysis. Isolated CNC was used to stabilise an oil-in-water emulsion and the emulsion stability was evaluated in terms of droplet size, morphology and physical stability.

RESULTS

PPF was subjected to alkali and bleach treatment prior to hydrolysis, which successfully removed 54% and 75% of non-cellulosic components (hemicellulose and lignin, respectively). Hydrolysis conditions of 5 h, 15:1 (w/w) resin-to-pulp ratio and 50 °C produced CNC particles of 50-100 nm in length. CNC had a crystallinity index of 42% and appeared rod-like morphologically. CNC-stabilised emulsion had better stability when used in combination with soy lecithin (SL), a well-established, commonly used food stabiliser. Emulsion stabilised by the binary mixture of CNC and SL had droplet size, morphology and physical stability comparable to those of emulsion stabilised using SL.

CONCLUSIONS

CNC was successfully isolated from PPF through a cation exchange resin. This offers an alternative usage for the underutilised PPF to be converted into value-added products. Isolated CNC was also found to have promising potential in the stabilisation of Pickering emulsions. These results provide useful information indicating CNC as a natural and sustainable stabiliser for food, cosmeceutical and pharmaceutical applications. © 2021 Society of Chemical Industry.

Bioethanol Production and Alkali Pulp Processes as Sources of Anionic Lignin Surfactants

Lignin is an abundant biopolymer with potential value-added applications that depend on biomass source and fractioning method. This work explores the use as emulsifiers of three native lignin-rich product coming from industrial bioethanol production and alkali or Kraft pulping. In addition to their distinctive characteristics, the different molecular organization induced by emulsification pH is expected to interact in various ways at the water-oil interface of the emulsion droplets. Initially, model oil-in-water (O/W) emulsions of a silicone oil will be studied as a function of lignin source, disperse phase concentration and emulsification pH. Once stablished the effect of such variables, emulsion formulations of three potential bitumen rejuvenators (waste vegetable cooking oil, recycled lubricating oil and a 160/220 penetration range soft bitumen). Droplet size distribution, Z-potential and viscous tests conducted on model emulsions have shown that emulsification pH strongly affects stabilization ability of the lignins tested. Regarding bitumen rejuvenators, lignin emulsification capability will be affected by surfactant source, pH and, additionally, by the dispersed phase characteristics. Lower Z-potential values shown by KL at pH 9 and 11 seem to facilitate emulsification of the less polar disperse phases formed by RLUB and bitumen. In any case, lower particle size and higher yield stress values were found for both bioethanol-derived lignins emulsifying RVO and RLUB at pH 13, which are expected to exhibit a longer stability.

Plant Nanomaterials and Inspiration from Nature: Water Interactions and Hierarchically Structured Hydrogels

Recent developments in the area of plant-based hydrogels are introduced, especially those derived from wood as a widely available, multiscale, and hierarchical source of nanomaterials, as well as other cell wall elements. With water being fundamental in a hydrogel, water interactions, hydration, and swelling, all critically important in designing, processing, and achieving the desired properties of sustainable and functional hydrogels, are highlighted. A plant, by itself, is a form of a hydrogel, at least at given states of development, and for this reason phenomena such as fluid transport, diffusion, capillarity, and ionic effects are examined. These aspects are highly relevant not only to plants, especially lignified tissues, but also to the porous structures produced after removal of water (foams, sponges, cryogels, xerogels, and aerogels). Thus, a useful source of critical and comprehensive information is provided regarding the synthesis of hydrogels from plant materials (and especially wood nanostructures), and about the role of water, not only for processing but for developing hydrogel properties and uses.

Pickering emulsion stabilized by cellulosic fibers: Morphological properties-interfacial stabilization-rheological behavior relationships

This work aimed to study the stabilization mechanism induced by different morphologies of cellulosic fiber in O/W emulsion. Three types of cellulosic fibers were named squashed cellulose, incompletely nanofibrillated cellulose, and completely nanofibrillated cellulose, respectively. Squashed cellulose acted as barriers between the droplets to stabilize emulsion via depletion flocculation, whereas incompletely nanofibrillated and completely nanofibrillated cellulose formed covering layer via interfacial adsorption and connected adjacent droplets to create the droplet-fiber network structure via bridging flocculation. Differently, completely nanofibrillated cellulose formed the denser covering layer leading to a more stability of droplet. Importantly, it had the higher capacity of bridging flocculation, which can tightly connect the adjacent droplets to form a stronger droplet-fiber 3D network structure. Consequently, in rheological analysis including creep compliance, and dynamic modulus, the corresponding emulsions showed excellent anti-deformation ability and dynamic stability. This study provides practical guidance on the productions of foodstuff and cosmetic.

Enhancing the Radical Scavenging Activity and UV Resistance of Lignin Nanoparticles via Surface Mannich Amination toward a Biobased Antioxidant

In recent years, lignin specific activities, such as antioxidation and antibacterial and anti-ultraviolet performance, have drawn more and more attention. Nevertheless, the insufficient radical scavenging (antioxidation) activity has become one of the main drawbacks that limits its high-value application. In this study, lignin nanoparticles (LNPs) were prepared via a facile acid treatment strategy. Subsequently, surface amination of LNPs (a-LNPs) was carried out through the Mannich reaction. Specifically, the antioxidant behavior of LNPs and modified LNPs was evaluated by DPPH/DMPO radical scavenging and in vitro HeLa cell reactive oxygen species (ROS) scavenging tests, which demonstrated that the antioxidation activity of a-LNPs was more evident than that of both LNPs and butylated hydroxytoluene (BHT) commercial antioxidant. The mechanism of the radical scavenging ability of aminated LNPs was elucidated and proved to be related to the bond dissociation enthalpy of Ar-O···H, determined by the electron-donating effect of the substituted groups in the ortho-position. Meanwhile, the morphologies, solubilities, and UV-absorbing and antibacterial behavior of LNPs and a-LNPs were also studied, and the results showed that a-LNP sample exhibited higher UV resistance performance than LNPs. We expected that the modified LNPs with high antioxidation activity can serve as a safe and lower-cost biobased antioxidant.

Polysaccharide-Based Materials Created by Physical Processes: From Preparation to Biomedical Applications

Polysaccharide-based materials created by physical processes have received considerable attention for biomedical applications. These structures are often made by associating charged polyelectrolytes in aqueous solutions, avoiding toxic chemistries (crosslinking agents). We review the principal polysaccharides (glycosaminoglycans, marine polysaccharides, and derivatives) containing ionizable groups in their structures and cellulose (neutral polysaccharide). Physical materials with high stability in aqueous media can be developed depending on the selected strategy. We review strategies, including coacervation, ionotropic gelation, electrospinning, layer-by-layer coating, gelation of polymer blends, solvent evaporation, and freezing-thawing methods, that create polysaccharide-based assemblies via in situ (one-step) methods for biomedical applications. We focus on materials used for growth factor (GFs) delivery, scaffolds, antimicrobial coatings, and wound dressings.

Interfacial and Emulsion Characteristics of Oil-Water Systems in the Presence of Polymeric Lignin Surfactant

It is hypothesized that polymeric lignin surfactants have different affinities for stabilizing oil-water emulsions and that the emulsifying performance of these surfactants is highly affected by their adsorption performance at the oil-water interface. To validate this hypothesis, the adsorption performance of sulfethylated lignin (SEKL) surfactant at different oil-water interfaces was examined by assessing the contact angle, dynamic interfacial tension, and surface loading (Γ). Moreover, the interfacial adsorption kinetics of SEKL was comprehensively assessed in different oil-water systems to reveal the mechanisms of the SEKL adsorption at the interface. Also, the impacts of SEKL concentration and ionic strength on the performance of SEKL as an effective emulsifier for the emulsions were assessed. Furthermore, the droplet size and instability index of the emulsions were systematically correlated with the adsorption performance of SEKL at the interface of oil and water. For the first time, by implementing a modified Ward Toradai diffusion model, two distinct early stages of the adsorption of SEKL at the oil interface were identified. Interestingly, the second stage was the determining stage of adsorption with the diffusion-controlled mechanism when polymers reconfigured at the oil-water interface. Salt screening facilitated the clustering of SEKL upon charge repulsion elimination, which removed the energy barrier in the first stage of adsorption (ΔE_p→0 = 0), but it introduced a steric barrier upon the reconfiguration of polymers at the oil interfaces in the second stage of adsorption. In addition to the kinetics of adsorption, satisfactory correlations were observed between surface pressure (Δγ = γ_∞ - γ₀), surface loading (Γ) of polymers, and contact angle at oil interfaces on one hand and the oil droplet size and emulsion stability on the other hand.

Tuning the functional properties of lignocellulosic films by controlling the molecular and supramolecular structure of lignin

This study investigated the relationships between lignin molecular and supramolecular structures and their functional properties within cellulose-based solid matrix, used as a model biodegradable polymer carrier. Two types of derivatives corresponding to distinct structuration levels were prepared from a single technical lignin sample (PB1000): phenol-enriched oligomer fractions and colloidal nanoparticles (CLP). The raw lignin and its derivatives were formulated with cellulose nanocrystals or nanofibrils to prepare films by chemical oxidation or pressure-assisted filtration. The films were tested for their water and lignin retention capacities, radical scavenging capacity (RSC) and antimicrobial properties. A structural investigation was performed by infrared, electron paramagnetic resonance spectroscopy and microscopy. The composite morphology and performance were controlled by both the composition and structuration level of lignin. Phenol-enriched oligomers were the compounds most likely to interact with cellulose, leading to the smoothest film surface. Their RSC in film was 4- to 6-fold higher than that of the other samples. The organization in CLP led to the lowest RSC but showed capacity to trap and stabilize phenoxy radicals. All films were effective against S. aureus (gram negative) whatever the lignin structure. The results show the possibility to tune the performances of these composites by exploiting lignin multi-scale structure.

Pickering Emulsions via Interfacial Nanoparticle Complexation of Oppositely Charged Nanopolysaccharides

We consider the variables relevant to adsorption of renewable nanoparticles and stabilization of multiphase systems, including the particle's hydrophilicity, electrostatic charge, axial aspect, and entanglement. Exploiting the complexation of two oppositely charged nanopolysaccharides, cellulose nanofibrils (CNFs) and nanochitin (NCh), we prepared CNF/NCh aqueous suspensions and identified the conditions for charge balance (turbidity and electrophoretic mobility titration). By adjusting the composition of CNF/NCh complexes, below and above net neutrality conditions, we produced sunflower oil-in-water Pickering emulsions with adjustable droplet diameters and stability against creaming and oiling-off. The adsorption of CNF/NCh complexes at the oil/water interface occurred with simultaneous partitioning (accumulation) of the CNF on the surface of the droplets in net negative or positive systems (below and above stochiometric charge balance relative to NCh). We further show that the morphology of the droplets and size distribution were preserved during storage for at least 6 months under ambient conditions. This long-term stability was held with a remarkable tolerance to changes in pH (e.g., 3-11) and ionic strength (e.g., 100-500 mM). The mechanism explaining these observations relates to the adsorption of the CNF in the complexes, counteracting the charge losses resulting from the deprotonation of NCh or charge screening. Overall, CNF/NCh complexes and the respective interfacial nanoparticle exchange greatly extend the conditions, favoring highly stable, green Pickering emulsions that offer potential in applications relevant to foodstuff, pharmaceutical, and cosmetic formulations.