Lignin Nanoparticles Research Articles

Ozonolysis of regular and crosslinked lignin nanoparticles: closing the loop

The oxidative degradation of regular and crosslinked lignin nanoparticles was studied. Despite different solvent stabilities, both degrade at similar rates during ozonolysis, forming smaller oxidized particles and eventually water-soluble molecules.

Self-assembled lignin nanoparticles produced from elephant grass leaves enable selective inactivation of Gram-positive microorganisms

Plant-derived lignin nanoparticles produced through a self-assembly method show selective toxicity against Gram-positive bacteria.

Sprayed water-based lignin colloidal nanoparticle-cellulose nanofibril hybrid films with UV-blocking ability.

In the context of global climate change, the demand for new functional materials that are sustainable and environmentally friendly is rapidly increasing. Cellulose and lignin are the two most abundant raw materials in nature, and are ideal components for functional materials. The hydrophilic interface and easy film-forming properties of cellulose nanofibrils make them excellent candidates for natural biopolymer templates and network structures. Lignin is a natural UV-shielding material, as it contains a large number of phenolic groups. In this work, we have applied two routes for spray deposition of hybrid films with different laminar structures using surface-charged cellulose nanofibrils and water-based colloidal lignin particles. As the first route, we prepare stacked colloidal lignin particles and cellulose nanofibrils hybrid film through a layer-by-layer deposition. As the second route, we spray-deposite premixed colloidal lignin particles and cellulose nanofibrils dispersion to prepare a mixed hybrid film. We find that cellulose nanofibrils act as a directing agent to dominate the arrangement of the colloidal lignin particles in a mixed system. Additionally, cellulose nanofibrils eliminate the agglomerations and thus increase the visible light transparency while retaining the UV shielding ability. Our research on these colloidal lignin and cellulose nanofibril hybrid films provides a fundamental understanding of using colloidal lignin nanoparticles as functional material on porous cellulose-based materials, for example on fabrics.

Hydrophobized lignin nanoparticle-stabilized Pickering foams: building blocks for sustainable lightweight porous materials

CTAB-hydrophobized lignin nanoparticles for durable Pickering foam formation with cellulose nanofibrils as templates for lightweight porous materials.

Preparation of homogeneous lignin nanoparticles by efficient extraction of lignin and modification of its molecular structure using a functional deep eutectic solvent containing γ-valerolactone

A lignin-extractive green reaction medium consisting of choline chloride, 5-sulfosalicylic acid, and γ-valerolactone was designed. Polyphenolic lignin was obtained. The green advancement of DES processing has been enhanced.

Lignin Nanoparticles as Charge Storage Centers in Organic Battery Electrodes

Lignin, the second most abundant biopolymer on Earth, has recently emerged as a promising redox-active material for organic batteries. Different types of lignin have been explored but inherent challenges have remained, i.e., the difficulties of processing kraft lignin and the low charge storage capacity retention of lignosulfonate due to its high water-solubility. In this work, we propose the use of an alternative candidate, lignin nanoparticles (LNPs), which are insoluble, but colloidally stable dispersions in aqueous media, which, can be easily processed using different manufacturing techniques. By combining LNPs with a conducting polymer (PEDOT:PSS), we have successfully prepared a composite that has a charge storage capacity of up to 42.5 mAh/g at a current density of 1 A/g, while its capacity retention shows a good improvement (70% after 1000 cycles) in comparison to the similar systems of lignosulfonate-based electrodes. The morphology and chemical structure of LNPs are tunable, therefore, the effects of particle sizes and the preparation methods of LNPs on the electrode performance were also studied. With the obtained results, this work suggests LNPs as promising materials for the preparation of green and low-cost lignin-based energy storage devices. Keywords: Lignin nanoparticles, Organic batteries, PEDOT:PSS, Electrochemistry.

Lignin Nanoparticles Produced from Wheat Straw Black Liquor Using γ-Valerolactone.

The valorization of the black liquor produced during the chemical pulping of wheat straw is the key to the sustainable use of this abundant agricultural waste. However, the silica problem has hampered the recovery process. Herein, nanoprecipitation technology was used to produce lignin nanoparticles (LNPs) from wheat straw black liquor using γ-valerolactone (GVL) as a solvent and water as an anti-solvent. The results showed that a uniform, well-dispersed, and stable LNP was produced. The particle size and Zeta potential of 161 nm and -24 mV of the LNP suspension were obtained at a GVL concentration of 87%. The chemical structure and bonding of the lignin were adequately preserved after nanoprecipitation based on two-dimensional heteronuclear single quantum coherence nuclear magnetic resonance (2D-HSQC NMR) spectroscopy, Fourier transform infrared (FTIR) analysis, and thermal stability was improved based on thermogravimetric analysis. In addition, the abundant phenolic hydroxyl groups of LNP quantified by 31P-NMR analysis are beneficial for chemical cross-linking and modification. This work not only achieved the valorization of wheat straw black liquor but also opened up a new avenue for advanced nanomaterials.

Sustainable lignin nanoparticles from coconut fiber waste for enhancing multifunctional properties of macroalgae biofilms

Multifunctional and sustainable packaging biofilms felicitous to changeable conditions are in large demand as substitutes to petroleum-derived synthetic films. Macroalgae with noticeable film-formation, abundant, low-cost, and edible properties is a promising bioresource for sustainable and eco-friendly packaging materials. However, the poor hydrophobicity and mechanical properties of sustainable macroalgae biofilms seriously impede their practical applications. Herein, lignin nanoparticles (LNPs) produced by a sustainable approach from black liquor of coconut fiber waste were incorporated in the macroalgae matrix to improve the water tolerance and mechanical characteristics of the biofilms. The effect of different LNPs loadings on the performance of biofilms, such as physical, morphological, surface roughness, structural, water resistance, mechanical, and thermal behaviors, were systematically evaluated and found to be considerably improved. Biofilm with 6 % LNPs presented the optimum enhancement in most ultimate performances. The optimized biofilm exhibited great hydrophobic features with a water contact angle of over 100° and high enhancement in the tensile strength of >60 %. This study proposes a facile and sustainable approach for designing and developing LNPs-macroalgae biofilms with excellent and multifunctional properties for sustainable high-performance packaging materials.

Release behavior of natural antimicrobial agents with lignin nanoparticles from Poly(butylene succinate) films in vapor phase application

Polybutylene succinate (PBS) film containing spherical lignin nanoparticles (LNP) and natural agents (NA) such as vanillin (VAN), trans-cinnamaldehyde (CIN), and citral (CIT) was produced via blown film extrusion. The effect of the substance on controlled release qualities and inhibitory action against tropical fruit diseases in the vapor phase was investigated. Solvent extraction results revealed that PBS/LNP/NA composite films have a greater remaining content of each active agent than PBS/NA films. The morphology, mechanical properties, and barrier properties of the PBS/LNP/NA composite films were influenced by the lignin and natural agents. The release behavior of natural agents released into the headspace was appropriately described by mathematical models, with diffusion mainly dependent on NA concentration. According to the diffusion coefficient, PBS/LNP/NA films have a slow and steady constant release into a food matrix. Trans-cinnamaldehyde exhibited the fastest migration, followed by vanillin and citral, with diffusion coefficients ranging from 10−9 to 10−13 m2/s. Furthermore, the composite films were found to exhibit improved antifungal efficacy against Colletotrichum gloeosporioides in the vapor phase. The results show that the biodegradable PBS/LNP/NA film could potentially be used as active packaging to extend the shelf life of tropical fruits.

Woody biomass derived nano lignin-enabled membrane with high structural stability for efficient wastewater treatment

The application of renewable and functional group-enriched lignin has recently gained massive popularity in wastewater treatment applications. Herein, woody biomass-derived organosolv lignin nanoparticles (LNPs) with uniform colloidal spherical morphology and average particle size (⁓150 nm) were synthesized via a simple and facile anti-solvent nanoprecipitation technique and used for the fabrication of ultrafiltration nanocomposite membrane. Upon the addition of LNPs to polyether sulfone (PES) matrix, the LNPs-impregnated membrane exhibited a thinner surface layer that induced low resistance to water flow, high pore density (83.2 ± 0.9%) with uniformly distributed pores, wider and well-connected internal macrovoids with higher sub-layer porosity, and a higher negative surface charge (−29.8 mV). These structural features hence contributed to high stable permeation flux (92.3 L m−2 h−1) and higher removal efficiencies (> 95%) for treating cationic (methylene blue) and anionic (methylene orange) dyes over a wide range of environmentally relevant pH conditions. The electrostatic interactions between the charged membrane surface and dye species revealed the underlying mechanism for higher dye rejection through the PES-LNP membrane. Finally, the structural stability analysis confirmed the complete incorporation/immobilization of LNPs within the PES matrix, making it ready for real-world applications in wastewater treatment.

Preparation of Lignin-Based Nanoparticles with Excellent Acidic Tolerance as Stabilizer for Pickering Emulsion.

In this work, novel lignin-based nanoparticles (LβNPs) with high acidic tolerance were successfully prepared via electrostatic interaction between β-alanine and lignin nanoparticles. The effects of the mass ratio of lignin nanoparticles to β-alanine and pH value on the morphology and particle sizes of LβNPs were investigated with the aim of obtaining the ideal nanoparticles. The optimized LβNPs were spherical in shape with an average particle size of 41.1 ± 14.5 nm and exhibited outstanding structure stability under high acidic conditions (pH < 4). Subsequently, Pickering emulsions stabilized by LβNPs were prepared using olive oil as the oil phase. Additionally, the effects of pH value, droplet size, morphology, and storage stability on Pickering emulsions were also analyzed. The emulsions displayed excellent stability, and were stable against strongly acidic conditions (pH < 4) after 30 days of storage. The study presented a promising approach to preparing lignin-based nanoparticles with high acidic tolerance (an ideal type of stabilizer to prepare emulsions), and exhibited extremely high potential application values in the fields of drug delivery, food additives, and oily wastewater treatment.

Production of highly antioxidant lignin nanoparticles from a hardwood technical lignin

Eucalypt kraft lignin isolated in a LignoBoost™ pilot plant was characterized by GC–MS, ICP-OES, DSC, HPSEC, 31P NMR, and HSQC 2D-NMR to be used without any further processing to produce lignin nanoparticles (LNPs) by nanoprecipitation. Tetrahydrofuran (THF) was used as a solvent, and water as a non-solvent. Microscopic analysis (TEM) showed that LNPs were regularly spherical with some hollow particles dispersed in-between, and sizes were tunable by changing the solvent dripping rate onto the non-solvent. LNP particle sizes had a bimodal distribution, with the largest population having an average apparent hydrodynamic diameter ranging from 105.6 to 75.6 nm. Colloidal dispersions of LNPs in water presented good stability in different dilutions without significant size changes upon storage at pH close to neutral for as long as 45 days. Zeta potentials around −40 mV were obtained for LNP suspensions at pH ranging from 7 to 9. The high carbohydrate content (circa 10 % on a dry basis, mostly xylans) of the lignin precursor did not interfere in LNP formation, whose antioxidant activity was expressive as demonstrated by the ABTS assay at pH 7.4, with an EC50 of 4.04 μg mL−1. Also, the Trolox® equivalent antioxidant capacity (TEAC) of LNPs reached 1.90 after 40 min reaction time.

ROS-Scavenging Lignin-Based Tolerogenic Nanoparticle Vaccine for Treatment of Multiple Sclerosis.

Multiple sclerosis (MS) is a demyelinating autoimmune disease, in which the immune system attacks myelin. Although systemic immunosuppressive agents have been used to treat MS, long-term treatment with these drugs causes undesirable side effects such as altered glucose metabolism, insomnia, and hypertension. Herein, we propose a tolerogenic therapeutic vaccine to treat MS based on lignin nanoparticles (LNP) with intrinsic reactive oxygen species (ROS)-scavenging capacity derived from their phenolic moieties. The LNP loaded with autoantigens of MS allowed for inducing tolerogenic DCs with low-level expression of costimulatory molecules while presenting antigenic peptides. Intravenous injection of an LNP-based tolerogenic vaccine into an experimental autoimmune encephalomyelitis (EAE) model led to durable antigen-specific immune tolerance via inducing regulatory T cells (Tregs). Autoreactive T helper type 1 cells, T helper type 17 cells, and inflammatory antigen presentation cells (APCs) were suppressed in the central nervous system (CNS), ameliorating ongoing MS in early and late disease states. Additionally, the incorporation of dexamethasone into an LNP-based tolerogenic nanovaccine could further improve the recovery of EAE mice in the severe chronic stage. As lignin is the most abundant biomass and waste byproduct in the pulping industry, a lignin-based tolerogenic vaccine could be a novel, cost-effective, high-value vaccine platform with potent therapeutic efficiency in treating autoimmune diseases.

Towards a deep understanding of the biomass fractionation in respect of lignin nanoparticle formation

Towards a deep understanding of the biomass fractionation in respect of lignin nanoparticle formation

Influence of nanoprecipitation techniques on lignin nanoparticle structure

Lignin nanoparticles (LNPs) have garnered significant interest as sustainable and bioactive materials, finding promising applications across diverse fields. In this study, we synthesized LNPs using four nanoprecipitation methods: dialysis, evaporation, dilution, and acidic dilution. Our investigation delved into how these methods affect LNP morphology and properties. Results unequivocally demonstrate the profound impact of the chosen nanoprecipitation method on LNP characteristics. Dialysis and dilution methods yielded LNPs distinguished by their pronounced hollowness, with an average diameter of 330 nm and 430 nm, whereas the evaporation and acidic dilution methods resulted in less hollow structures with average diameter of 270 nm and 800 nm. The duration of unstable conditions during synthesis significantly influenced particle aggregation, giving rise to a broad size distribution. Furthermore, our prepared LNPs showcased exceptional antioxidant activity (>80 % radical scavenging activity at 0.05 mg/mL of LNPs) and potent antibacterial efficacy against gram-positive bacteria Staphylococcus aureus. This study not only offers crucial insights into optimizing LNP synthesis but also elucidates the nexus between different nanoprecipitation methods and resulting morphology and functionality. The findings provide a fundamental framework for tailoring LNP properties to specific applications, advancing sustainable and eco-friendly technologies within the biomedical, nanotechnology, and materials science domains.

Strong, UV-blocking, and hydrophobic PVA composite films containing tunable lignin nanoparticles

In the present work, hollow and solid lignin nanoparticles (LNPs) were synthesized through a self-assembling process using the organosolv pretreatment of lignin from the eucalyptus and willow byproducts. The SEM, TEM, and zeta potential establish the LNPs of a uniform spherical morphology, and the hollow lignin nanoparticles (HLNPs) display the inner cavity and shell. The polyvinyl alcohol (PVA) nanocomposite films containing the LNPs suggest that the presence of HLNPs results in a “room” like network structure in the films and differs from the solid lignin nanoparticles (SLNPs) induced structural changes. The LNPs inclusion increases the mechanical properties. The films with solid eucalyptus lignin nanoparticles showed excellent tensile strength (132 MPa), while those with hollow eucalyptus lignin nanoparticles resulted in exceptional elongation at break (324%). Hydrophobicity tests revealed that both LNPs incorporation in the PVA film results in a water contact angle of more than 90°. The outcome promises novel opportunities for LNPs in the designing and development of plastic replacement packaging films.

Multi-scale utilization of lignin: A catalytic hydrogenation strategy based on catechyl lignin nanoparticles

With an abundance of oxygen-containing groups on the hydrophilic shell of lignin nanoparticles (LNPs), this biomaterial can serve as a catalytic support to adsorb and load metals. Herein, catechyl lignin oligomers from castor seed coats (Cas) were extracted via solvothermal pretreatment and prepared as LNPs using the solvent shifting method. Pd2+ ions were then stabilized and reduced in situ on the surface of LNPs, which were further utilized for the catalyzed hydrogenation of lignin-derived aldehydes. Due to the homogeneous building units and linear linkages, the lignin oligomers from Cas exhibited superior self-assembly capacity with a lower π-π interaction energy than those from conventional lignocelluloses, resulting in a high yield of LNPs with a smooth surface. The high content of phenolic hydroxyl groups in catechyl-dominant LNPs resulted in efficient Pd2+ ions adsorption via chemisorption of monomolecular layer and a partial reduction of the Pd2+ ions into metallic states. In addition, the Cas-derived Pd/LNPs exhibited exceptional catalytic activity for the hydrogenation of lignin-derived aldehydes with high selectivity to alcohols under mild conditions. This could be attributed to the interaction preference of the reaction substrate according to the construction of LNPs: strong hydrogen bond between the aldehyde group of the substrate and the hydrophilic shell of LNPs, as well as the hindered π-π interactions between the benzene ring of the substrate and the hidden hydrophobic core of LNPs. This study, therefore, successfully employed lignin with a broad range of molecular weights from oligomers to monomers, paving the way for a comprehensive lignin biorefining industry.

An ultraviolet shielding material based on lignin nanoparticles engineered with deep eutectic solvents for long-term outdoor application

Ultraviolet radiation (UV) has a significant effect on the wood, and the commonly used UV shielding agents are easily degraded. Lignin is a bio-based UV screening agent and tuning of its nanoparticles is meaningful for realizing the UV shielding properties and stability of composites. With the modification of the deep eutectic solvents based on sulfamic acid and urea, lignin nanoparticles with amino functional groups were prepared, and a protective layer with UV shielding properties was constructed on the surface of the poplar veneer. The phenolic hydroxyl groups, carbonyl groups, and conjugated structure of lignin nanoparticles endowed the composites with the properties of UV shielding, photothermal conversion, and photothermal de-icing. The results of this study provide a benchmark for realizing the low-cost and sustainable preparation of wood composites with UV shielding and are conducive to promoting the high-value application of lignin nanoparticles.

Phospholipase D Immobilization on Lignin Nanoparticles for Enzymatic Transformation of Phospholipids.

Lignin nanoparticles (LNPs) are promising components for various materials, given their controllable particle size and spherical shape. However, their origin from supramolecular aggregation has limited the applicability of LNPs as recoverable templates for immobilization of enzymes. In this study, we show that stabilized LNPs are highly promising for the immobilization of phospholipase D (PLD), the enzyme involved in the biocatalytic production of high-value polar head modified phospholipids of commercial interest, phosphatidylglycerol, phosphatidylserine and phosphatidylethanolamine. Starting from hydroxymethylated lignin, LNPs were prepared and successively hydrothermally treated to obtain c-HLNPs with high resistance to organic solvents and a wide range of pH values, covering the conditions for enzymatic reactions and enzyme recovery. The immobilization of PLD on c-HLNPs (PLD-c-HLNPs) was achieved through direct adsorption. We then successfully exploited this new enzymatic preparation in the preparation of pure polar head modified phospholipids with high yields (60-90 %). Furthermore, the high stability of PLD-c-HLNPs allows recycling for a number of reactions with appreciable maintenance of its catalytic activity. Thus, PLD-c-HLNPs can be regarded as a new, chemically stable, recyclable and user-friendly biocatalyst, based on a biobased inexpensive scaffold, to be employed in sustainable chemical processes for synthesis of value-added phospholipids.

Evaluation of cardioprotective effect of naringin loaded lignin nanoparticles against isoproterenol induced myocardial infarction

Evaluation of cardioprotective effect of naringin loaded lignin nanoparticles against isoproterenol induced myocardial infarction