As humanity ventures beyond Earth, developing radiation-stable coatings from non-fossil sources becomes essential. Beta radiation can significantly harm materials, making it essential to seek resilient, biobased alternatives to work in corrosive environments and high temperatures. Herein, a novel lignin-based coating demonstrating exceptional beta-radiation resistance and anticorrosion properties is presented. The coatings are applied to copper substrates and exposed to 500 kGy electron beam irradiation in air to evaluate their structural and functional stability under extreme conditions. Spectroscopic, microscopic, and thermogravimetric analyses confirm the structural integrity of the coatings post-irradiation. Anticorrosion efficiencies after irradiation are maintained at 99.6% (H2SO4) and 99.8% (NaCl) for 61 μm thick films, while thinner 9.5 μm films show 86.4% and 85.7% protection in the respective media, with a ≈4% performance drop post-irradiation. Adhesion strength improves from 0.28 to 0.49 MPa after irradiation, and the water contact angle decreases from 74° to 66°, indicating an increase in hydrophilicity. The superior performance is attributed to the aromatic structure of lignin and its thermally triggered cyclization, which renders it stable against chemical chain scission by oxygen radicals formed in atmospheric conditions under radiation exposure. The performance of thicker films in anticorrosion tests is attributed to a reduced penetration of corrosive agents, due to better morphological integrity. These findings demonstrate the viability of lignin-based coatings as radiation-stable and environmentally sustainable solutions for protecting metal surfaces in harsh environments.

There is a growing demand for biobased functional materials that can ensure targeted pesticide delivery and minimize active ingredient loss in the agricultural sector. In this work, we demonstrated the use of esterified lignin nanoparticles (ELNPs) as carriers and controlled-release agents of hydrophobic compounds. Curcumin was selected as a hydrophobic model compound and was incorporated during ELNP fabrication with entrapment efficiencies exceeding 95%. ELNPs presented a sustained release of curcumin over 60 days in an oil medium, with a tunable release rate dependent on the lignin-to-curcumin mass ratio. The ELNPs showed a strong adhesion interaction with the hydrophobic wax surface. Quartz crystal microbalance with dissipation monitoring (QCM-D) and atomic force microscopy (AFM) analysis suggested that the ELNPs permeated into the wax layer, potentially preventing pesticide loss due to runoff or rainwater leaching. Rapidly decreasing contact angles between a droplet containing an aqueous dispersion of the ELNPs and a fresh leaf surface provided further evidence of a favorable interaction between the two. Overall, our results portray ELNPs as promising biobased nanoparticulate systems for pesticide delivery to hydrophobic plant surfaces.

Hair care products have complex surfactant and stabilizer compositions arising from oleochemicals, raising concerns over sustainability. Here, we show a fully biobased hair conditioner based on micellar lignin gels that stabilize emulsions with triglyceride oils. We demonstrate competitive emulsion stability, rheological properties, and performance relative to an off-the-shelf commercial product. Lignin gel emulsion with a 6% weight fraction of coconut oil effectively lubricates damaged hair, confirmed by a 13% reduction in wet combing force and validated through multiscale microscopy analysis. Notably, organic solvent-free production simplifies the ingredient list and offers an environmentally benign route for lignin utilization in hair care.

Surface protection is essential when using wood as a construction material. However, the industry lacks sustainable alternatives to replace the presently dominant fossil-based synthetic water-resistant coatings. Here, we show a fully bio-based wood surface protection system using components sourced from birch bark and spruce bark, inspired by the natural barrier function of bark in trees. The coating formulation contains suberinic acids and spruce bark polyphenols, resulting in a waterborne suspension that is safe and easy to apply to wood. The polyphenols play a dual role in the formulation as they stabilize the water-insoluble suberinic acids and serve as nanofillers in the thermally cured coating, enabling the adjustment of the mechanical properties of the resulting coating. When applied to spruce wood, the coating formulation with 10% polyphenol and 90% suberinic acids achieved a water absorption value of 100 g m−2 after 72 hours of water exposure, demonstrating superior performance compared to an alkyd emulsion coating. We conclude that instead of combusting tree bark, it can serve as a valuable resource for wood protection, closing the circle in the wood processing industry.

Polyelectrolyte complexes (PECs) are polymeric structures formed by the self-assembly of oppositely charged polymers. Novel biomaterials based on PECs are currently under investigation as drug delivery systems, among other applications. This strategy leverages the ability of PECs to entrap drugs under mild conditions and control their release. In this study, we combined a novel and sustainably produced hemicellulose-rich lignosulphonate polymer (EH, negatively charged) with polyethyleneimine (PEI) or chitosan (CH, positively charged) and agar for the development of drug-releasing PECs. A preliminary screening demonstrated the effect of several parameters (polyelectrolyte ratio, temperature, and type of polycation) on PECs formation. From this, selected formulations were further characterized in terms of thermal properties, surface morphology at the microscale, stability, and ability to load and release methylene blue (MB) as a model drug. EH/PEI complexes had a more pronounced gel-like behaviour compared to the EH/CH complexes. Differential scanning calorimetry (DSC) results supported the establishment of polymeric interactions during complexation. Overall, PECs' stability was positively affected by low pH, ratios close to 1:1, and the addition of agar. PECs with higher EH content showed a higher MB loading, likely promoted by stronger electrostatic interactions. The EH/CH formulation enriched with agar showed the best sustained release profile of MB during the first 30 h in a pH-dependent environment simulating the gastrointestinal tract. Overall, we defined the conditions to formulate novel PECs based on a sustainable hemicellulose-rich lignosulphonate for potential applications in drug delivery, which promotes the valuable synergy between sustainability and the biomedical field.

The inferior thermoplastic properties have limited production of melt-spun fibers from lignin. Here we report on the controlled esterification of softwood kraft lignin (SKL) to enable scalable, solvent-free melt spinning of microfibers using a cotton candy machine. We found that it is crucial to control the esterification process as melt-spun fibers could be produced from lignin oleate and lignin stearate precursors with degrees of esterification (DE) ranging from 20-50%, but not outside this range. To fabricate a functional hybrid material, we incorporated magnetite nanoparticles (MNPs) into the lignin oleate fibers by melt blending and subsequent melt spinning. Thermogravimetric analysis and X-ray diffraction studies revealed that increasing the weight fraction of MNPs led to improved thermal stability of the fibers. Finally, we demonstrated adsorption of organic dyes, magnetic recovery, and recycling via melt spinning of the regular and magnetic fibers with 95% and 83% retention of the respective adsorption capacities over three adsorption cycles. The mechanical recyclability of the microfibers represents a new paradigm in lignin-based circular materials.

Studies have shown that the size of LNP depends on the molecular weight (M_w) of lignin. There is however need for deeper understanding on the role of molecular structure on LNP formation and its properties, in order to build a solid foundation on structure–property relationships. In this study, we show, for similar M_w lignins, that the size and morphology of LNPs depends on the molecular structure of the lignin macromolecule. More specifically, the molecular structure determined the molecular conformations, which in turn affects the inter-molecular assembly to yield size- and morphological-differences between LNPs. This was supported by density functional theory (DFT) modelling of representative structural motifs of three lignins sourced from Kraft and Organosolv processes. The obtained conformational differences are clearly explained by intra-molecular sandwich and/or T-shaped π–π stacking, the stacking type determined by the precise lignin structure. Moreover, the experimentally identified structures were detected in the superficial layer of LNPs in aqueous solution, confirming the theoretically predicted self-assembly patterns. The present work demonstrates that LNP properties can be molecularly tailored, consequently creating an avenue for tailored applications.

Lignin nanoparticles (LNPs) are considered as intriguing green, renewable alternatives to fossil-based nanomaterials. However, the predisposition of LNPs to dissolve under alkaline conditions makes covalent surface functionalisation in the dispersion state difficult and limits applications demanding morphological stability under challenging pH conditions. Mechanistic studies suggest that during the formation of LNPs by nanoprecipitation the higher molecular weight fractions of lignin likely start precipitating first, while the low molecular weight fractions tend to deposit later and thus locate on the outer shell. Capitalising this aggregation pattern, the present work presents a strategy to prepare surface-functionalised LNPs that can find applications as adhesives and alkaline stable LNPs. The entire process is based on a single-step solvent fractionation of lignin using either ethanol or ethyl acetate, subsequent functionalisation of selected fractions with epichlorohydrin, and recombination according to the original mass proportions in line with the so-called zero waste principle. Aqueous colloidal dispersions of lignins were synthesised by nanoprecipitation of epoxidised low molecular weight (M_W) fractions combined with the corresponding unmodified high M_W ones, and vice versa. Upon thermal treatment, LNPs containing the epoxidised insoluble fraction underwent intraparticle crosslinking, proving dimensional stability at pH 12. Conversely, LNPs including epoxidised solvent-soluble fractions resulted in interparticle crosslinking upon heating, which confirmed the surface localisation of such low M_W fractions. The latter system was exploited to develop green LNP-based adhesives for aminated glass with lap shear strength outperforming prior adhesive systems based on lignin particles.

Colloidal lignin nanoparticles are promising buildingblocks forsustainable functional materials. However, their instability in organicsolvents and aqueous alkali limits their applicability. Current stabilizationmethods require nonrenewable and toxic reagents or tedious workupprocedures. Here we show a method to prepare hybrid nanoparticlesusing only natural components. Urushi, a form of black oriental lacquer,and lignin are coaggregated to form hybrid particles, with Urushiacting as a sustainable component that stabilizes the particles viahydration barrier effect and thermally triggered internal cross-linking.The weight fractions of the two components can be adjusted to achievethe desired level of stabilization. Hybrid particles with Urushi content>25 wt % undergo interparticle cross-linking that produces multifunctionalhydrophobic protective coatings that improve the water resistanceof wood. This approach provides a sustainable and efficient methodfor stabilizing lignin nanoparticles and opens up neoteric possibilitiesfor the development of lignin-based advanced functional materials.

The natural polymer, lignin, possesses unique biodegradable and biocompatible properties, making it highly attractive for the generation of nanoparticles for targeted cancer therapy. In this study, we investigated spruce and eucalyptus lignin nanoparticles (designated as S-and E-LNPs, respectively). Both LNP types were generated from high-molecular-weight (M_w) kraft lignin obtained as insoluble residues after a five-step solvent fractionation approach, which included ethyl acetate, ethanol, methanol, and acetone. The resulting S-and E-LNPs ranged in size from 16 to 60 nm with uniform spherical shape regardless of the type of lignin. The preparation of LNPs from an acetone-insoluble lignin fraction is attractive because of the use of high-M_w lignin that is otherwise not suitable for most polymeric applications, its potential scalability, and the consistent size of the LNPs, which was independent of increased lignin concentrations. Due to the potential of LNPs to serve as delivery platforms in liver cancer treatment, we tested, for the first time, the efficacy of newly generated E-LNPs and S-LNPs in two types of primary liver cancer, hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA), in vitro. Both S-LNPs and E-LNPs inhibited the proliferation of HCC cells in a dose-dependent manner and did not affect CCA cell line growth. The inhibitory effect toward HCC was more pronounced in the E-LNP-treated group and was comparable to the standard therapy, sorafenib. Also, E-LNPs induced late apoptosis and necroptosis while inhibiting the HCC cell line. This study demonstrated that an elevated number of carbohydrates on the surface of the LNPs, as shown by NMR, seem to play an important role in mediating the interaction between LNPs and eukaryotic cells. The latter effect was most pronounced in E-LNPs. The novel S- and E-LNPs generated in this work are promising materials for biomedicine with advantageous properties such as small particle size and tailored surface functionality, making them an attractive and potentially biodegradable delivery tool for combination therapy in liver cancer, which still has to be verified in vivo using HCC and CCA models.