Green assembly of high-density and small-sized silver nanoparticles on lignosulfonate-phenolic resin spheres: Focusing on multifunction of lignosulfonate

Organic acid-fractionated lignin silver nanoparticles: Antimicrobial, anticancer, and antioxidant characteristics

Bioactive substances are utilized to treat a variety of diseases. Green lignin-mediated silver nanoparticles (L-Ag-NPs) have significant promise as a building block in the production of bio-renovation materials. The work optimized organic acid extraction to remove lignin from residual fermented hybrid Napier grass byproducts. We subsequently produced L-Ag-NPs. FTIR, XRD, DLS, and STEM characterized the sample. L-Ag-NPs were tested for antioxidant activity with the DPPH, DMPD, FRAP, and ABTS assays, as well as antibacterial activities. Antimicrobial activity was evaluated using four pathogenic bacteria (Klebsiella pneumonia, Pseudomonas aeruginosa, Staphylococcus aureus, and Escherichia coli). In contrast, cytotoxicity and ROS production assays were carried out using the HeLa cell line. The findings showed that L-Ag-NPs had high antioxidant efficiency. For each bacteria isolate, the antimicrobial activity showed favorable growth inhibition, with significant variations in L-Ag-NPs. L-Ag-NPs were reported to have an IC50 of 43.61 g/mL in the cytotoxicity test, and a significant increase in ROS generation was seen. In conclusion, L-Ag NPs have an excellent prospect in the pharmaceutical and biomedical industries and can be a dependable and environmentally safe material for their potential use.

Perforin-Mimicking Molecular Drillings Enable Macroporous Hollow Lignin Spheres for Performance-Configurable Materials

Despite the first observations that the perforin can punch holes in target cells for live/dead cycles in the human immune system over 110 years ago, emulating this behavior in materials science remains challenging. Here, a perforin-mimicking molecular drilling strategy is employed to engineer macroporous hollow lignin spheres as performance-configurable catalysts, adhesives, and gels. Using a toolbox of over 20 molecular compounds, the local curvature of amphiphilic lignin is modulated to generate macroporous spheres with hole sizes ranging from 0 to 100 nm. Multiscale control is precisely achieved through noncovalent assembly directing catalysis, synthesis, and polymerization. Exceptional performance mutations correlate with the changes in hole size, including an increase in catalytic efficiency from 50% to 100%, transition from nonstick synthetics to ultrastrong adhesives (adhesion ≈18.3 MPa, exceeding that of classic epoxies), and transformation of viscous sols to tough nanogels. Thus, this study provides a robust and versatile noncovalent route for mimicking perforin-induced structural variations in cells, representing a significant stride toward the exquisite orchestration of assemblies over multiple length scales.

Ultrasonic-assisted synthesis of lignin-based ultrasmall silver nanoparticles for photothermal-mediated sterilization

Lignin-based silver nanoparticles have been considered a promising antimicrobial material. However, it remains challenging to prepare ultra-small size silver nanoparticles sustainably with superior antibacterial performance. In this work, we modified ethanol-extracted lignin (EL) with carboxymethyl groups and further synthesized ultra-small particle size (3.8 ± 0.1 nm) nanosilver incorporated carboxymethyl lignin complexes (AgNPs@CEL) using ultrasonic technology. Due to the outstanding antibacterial properties of the ultra-small size nanosilver, AgNPs@CEL could cause 5.3 and 5.4 log10 CFU/mL reduction against E. coli and S. aureus in 5 min. Meanwhile, AgNPs@CEL exhibited remarkable photothermal antibacterial performance, which caused 6.2 and 6.1 log10 CFU/mL reduction of E. coli and S. aureus, with NIR irradiation for 5 min. Furthermore, the composite films prepared by doping only 0.5 wt% AgNPs@CEL into ethyl cellose could achieve a bactericidal rate more than 99.99 %. This study provides a new insight into design of controlled particle size lignin-based antibacterial nanosilver materials in a sustainable manner and holds promise for applications in antibacterial fields.

A novel oyster shell biocomposite for the efficient adsorptive removal of cadmium and lead from aqueous solution: Synthesis, process optimization, modelling and mechanism studies

This study highlights the effectiveness of oyster shell biocomposite for the biosorption of Cd(II) and Pb(II) ions from an aqueous solution. The aim of this work was to modify a novel biocomposite derived from oyster shell for the adsorption of Cd(II) and Pb(II) ions from aqueous solution. The studied revealed the specific surface BET surface area was 9.1476 m2/g. The elemental dispersive x-ray analysis (EDS) indicated that C, O, Ag, Ca were the predominant elements on the surface of the biocomposite after which metals ions of Cd and Pb were noticed after adsorption. The Fourier transform Irradiation (FT-IR) revealed the presence of carboxyl and hydroxyl groups on the surface. The effect of process variables on the adsorption capacity of the modified biocomposite was examined using the central composite design (CCD) of the response surface methodology (RSM). The process variables which include pH, adsorbent dose, the initial concentration and temperature were the most effective parameters influencing the uptake capacity. The optimal process conditions of these parameters were found to be pH, 5.57, adsorbent dose, 2.53 g/L, initial concentration, 46.76 mg/L and temperature 28.48°C for the biosorption of Cd(II) and Pb(II) ions from aqueous solution at a desirability coefficient of 1. The analysis of variance (ANOVA) revealed a high coefficient of determination (R2 > 0.91) and low probability coefficients for the responses (P < 0.05) which indicated the validity and aptness of the model for the biosorption of the metal ions. Experimental isotherm data fitted better to the Langmuir model and the kinetic data fitted better to the pseudo-second-order model. Maximun Cd(II) and Pb(II) adsorption capacities of the oyster shell biocomposite were 97.54 and 78.99 mg/g respectively and was obtained at pH 5.56 and 28.48°C. This investigation has provided the possibility of the utilization of alternative biocomposite as a sustainable approach for the biosorption of heavy metal ions from the wastewater stream.

Preparation of nano disperse dyes using sulfomethylated lignin: Effects of sulfonic group contents

The molecular simulation software was firstly applied to analyze the adsorption of sulfomethylated lignin (SAL) on dye surfaces. Then, SALs with different sulfonic group contents were prepared and characterized by FTIR, NMR, EA and GPC measurements using alkali lignin (AL) as raw materials and sodium sulfite as sulfonating agents. Next, SAL_1.53 was determined to the optimum dispersant by TSI, particle size and thermal storage stability measurements, which had the smallest particle size of 173 nm and highest stability, comparable to the commercial Reax 85A lignin dispersant and basically satisfying the requirement of nano disperse dyes used in the digital printing technology. QCM, AFM and zeta potential results indicated that as the sulfonic group content of SAL increased, the adsorption mass, rigidity of the adsorbed layer, adsorption force and absolute zeta potential value all showed a gradually increasing tendency due to an enhanced hydrophilicity, and thus a decreased intermolecular agglomeration and an increased molecular chain stretching degree. A maximum was observed for SAL_1.53. This research not only provided a novel approach to the preparation of high-performance lignin dispersants for nano disperse dyes, but also would broaden the high value-added industrial applications of biomass lignin into the digital printing and dyeing field.

Catalytic hydrogenation of levulinic acid to γ-valerolactone over lignin-metal coordinated carbon nanospheres in water

The hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL) has attracted much attention, as GVL can be used as biofuel, green solvent, and platform chemical. Inspired by Stöber method, various lignin-metal coordinated colloidal nanospheres (LCS) from lignin and cetyltrimethylammonium bromide (CTAB) were synthesized in which the metal ions (Co²⁺) replace formaldehyde as the crosslinker. The characterization of the catalyst revealed that alkali lignin was first self-assembled with CTAB through electrostatic attraction to form a lignin polymer, the subsequent addition of metal ions (Co²⁺) promoted the aggregation of lignin polymers and generated the LCS. Increasing calcination temperature for LCS resulted in the Co²⁺ being reduced to metallic Co. The lignin-metal coordinated colloidal nanospheres calcined at 500 °C possess both CoO and metallic Co active sites, which effectively accelerated the hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL) than simplex metallic Co active sites. A 99.8 % yield of GVL with 100 % LA conversion was obtained after 60 min reaction time at 200 °C and 2 MPa H₂.

Novel lignin-supported copper complex as a highly efficient and recyclable nanocatalyst for Ullmann reaction

In this work, we prepared polyhydroxylated lignin by demethylation and hydroxylation of lignin, and grafted phosphorus-containing groups by nucleophilic substitution reaction, the resulting material could be used as a carrier for the preparation of heterogeneous Cu-based catalysts (PHL-CuI-OPR₂). The optimal PHL-CuI-OP^tBu₂ catalyst was characterized by FT-IR, TGA, BET, XRD, SEM-EDS, ICP-OES, XPS. The catalytic performance of PHL-CuI-OP^tBu₂ in the Ullmann CN coupling reaction was evaluated using iodobenzene and nitroindole as model substrates under nitrogen atmosphere with DME and H₂O as cosolvent at 95 °C for 24 h. The applicability of modified lignin-supported copper catalyst was investigated of various aryl/heteroaryl halides with indoles under optimal conditions, the corresponding products were obtained with high yield. Additionally, it could be easily recovered from the reaction medium by an easy centrifugation and washing.

Preparation of uniform lignosulfonate-based colloidal spheres for UV-absorbing thermoplastics

Lignosulfonate-based colloidal spheres were prepared from sodium lignosulfonate and cetyltrimethylammonium bromide (NaLS/CTAB) complex through electrostatic and hydrophobic self-assembly. Due to the stronger hydrophobicity and UV-blocking performance, NaLS/CTAB colloids were easier to be blended with HDPE than lignosulfonate, and therefore applied to UV-absorbing thermoplastics. Results showed NaLS/CTAB colloidal spheres had a particle size of 160 nm with a polydispersity index of 0.081. NaLS/CTAB molecules started to form spheres at critical water content of 64 vol% when the initial concentration of NaLS/CTAB in EtOH was 0.5 mg/cm³ and the obtaining of colloids was completed at a water content of 90 vol%. The size and polydispersity of spheres were well controlled by adjusting initial concentrations of NaLS/CTAB in EtOH. Since NaLS/CTAB colloidal spheres retained phenylpropane units and phenolic hydroxyl groups of NaLS, NaLS/CTAB/HDPE composites displayed excellent UV-absorbing properties. Meanwhile, the mechanical property of NaLS/CTAB/HDPE composites was also superior to that of frequently-used CaCO₃/HDPE materials in industry, reaching the requirement of industrial uses. However, too high additions would result in the increased agglomeration of NaLS/CTAB spheres in HDPE, and thus the deteriorated mechanical property. Additionally, the added spheres played a role of "ball", which caused the decreased viscosity, improved flowability and processability of composites.

A Rapid and Reversible pH Control Process for the Formation and Dissociation of Lignin Nanoparticles

As a new and green type of nanomaterials, lignin nanoparticles (LNPs) have been considered as high-value renewable materials for application in many fields. However, the industrialization of LNPs faces many challenges, such as high manufacturing costs and small-scale production. Here, a simple but rapid and reversible approach for the fabrication of LNPs was provided via switching pH environments. The LNPs were regularly shaped in the acetonitrile/water system, and their size appeared to be very homogeneous. The alternation of forming and dissolving of LNPs could be repeated many times simply by alternately adding acid and alkaline solutions. There was little difference in the molecular structures between the original and regenerated LNPs. In addition, the consumption of solvents for LNPs production was only 200 mL g^-1 , reduced by more than 10 times compared with conventional solvent exchange methods. The concentration of LNPs in the solution also improved to 5.0 g L^-1 . This study not only provides a new, simple, and effective strategy for the fabrication of LNPs but also paves the way towards their real green production and application.

Lignin-Mediated Silver Nanoparticle Synthesis for Photocatalytic Degradation of Reactive Yellow 4G and In Vitro Assessment of Antioxidant, Antidiabetic, and Antibacterial Activities

This study explored the potential of abundantly available sodium lignosulfonate (LS) as a reducer and fabricating agent in preparing silver nanoparticles (LS–Ag NPs). The operational conditions were optimized to make the synthesis process simpler, rapid, and eco-friendly. The prepared LS–Ag NPs were analyzed via UV–Vis spectroscopy, X-ray diffraction spectroscopy, Fourier transform infrared spectroscopy, and high-resolution transmission electron microscopy. Results demonstrated that LS–Ag NPs were of crystalline structure, capped with LS constituents, and spherical in shape with a size of approximately 20 nm. Under optimized conditions, LS–Ag NPs exhibited significant photocatalytic activity in Reactive Yellow 4G degradation. The effects of photocatalyst (LS–Ag NPs) dosage, dye concentration, and its reusability for dye degradation were studied to make the process practically applicable in textile wastewater treatment. Additionally, the synthesized LS–Ag NPs displayed significant free radical scavenging against 2-diphenyl-1-picrylhydrazyl (DPPH) with an IC₅₀ value of (50.2 ± 0.70 µg/mL) and also exhibited antidiabetic activity in terms of inhibition in the activity of carbohydrate-degrading marker enzyme α-glucosidase with an IC₅₀ value of (58.1 ± 0.65 µg/mL). LS–Ag NPs showed substantial antibacterial potential against pathogenic strains, namely E. coli and S. aureus. In conclusion, LS–Ag NPs can be a reliable and eco-friendly material for their possible application in the treatment of dye-containing wastewater and have a great perspective in the biomedical and pharmaceutical sectors.