Neutral fabrication of UV-blocking and antioxidation lignin-stabilized high internal phase emulsion encapsulates for high efficient antibacterium of natural curcumin

A 3D bioprinted gelatin/quaternized chitosan/decellularized extracellular matrix based hybrid bionic scaffold with multifunctionality for infected full-thickness skin wound healing

Skin wound repair, a highly integrated and overlapping process, is susceptible to infection, hyperoxia and excessive inflammation, which can delay wound healing or even lead to chronic wounds. In this study, a GQL/dGQue bilayered multifunctional scaffold, epidermis composed of gelatin (G), quaternized chitosan (Q) and lignin (L), and dermis composed of skin-derived decellularized extracellular matrix (d), gelatin and quercetin (Que), with bionic skin structure, was constructed by 3D bioprinting technology. The results showed that lignin effectively improved the mechanical properties (Young's modulus above 90 MPa) and regulated the appropriate degradation (about 84 % for 15 d) of the scaffold, as well as endowed it with good UV shielding properties. In addition, GQL/dGQue showed prominent antibacterial activity of 90.76 ± 4.94 % and 90.34 ± 4.14 % against E. coli and S. aureus, respectively, good free radical scavenging (87.22 ± 1.71 %) and significant anti-inflammatory properties. In vivo studies demonstrated that GQL/dGQue scaffold could effectively prevent wound infection and mitigate inflammation, thereby accelerating vascularization and regeneration of hair follicle and sebaceous gland with a remarkable wound closure of 98.29 ± 1.77 % at 21 d. Therefore, the GQL/dGQue bilayered multifunctional scaffold has a considerable potential to apply in skin tissue engineering for clinical wound repair.

A comprehensive review of sustainable hydrogels from lignin for advanced wastewater solutions

Throughout the recent years, water bodies have been significantly contaminated via various industrial and pollution wastes posing threats to the living. To tackle the situation, Lignin-Based Hydrogels have appeared as a material with great potential for wastewater treatment. Biomass-derived polymers for wastewater treatment present a sustainable replacement to plastics based on petroleum owing to its biocompatibility, affordability, eco-friendliness and biodegradability. After cellulose the lignin is the second highest polyaromatic bio-polymer in plants. And serves as the Earth's primary renewable source for aromatic materials. Structurally, it is a cross-linked polymer enriched with hydrophilic functional groups like hydroxyls, methoxyls, carbonyls that makes it a promising precursor towards hydrogel development. This review focuses on hydrogels based on lignin, highlighting their synthesis, traits and potential functions in water treatment. It also examines various methods for extracting lignin from different raw materials. Challenges and limitations associated with real-world applications of LBHs are addressed and along with prospects for future research. Ultimately, this review provides valuable insights into developing sustainable hydrogels based on lignin for efficient elimination of aquatic contaminants.

Construction of curcumin-conjugated pH-responsive lignin-based nanoparticles for alleviating oxidative stress: Stability, antioxidant activity and biocompatibility

Curcumin has a great effect on alleviating oxidative stress, but its poor stability and low biocompatibility limit its application in therapeutic field. In order to overcome these limitations of curcumin, in this study, curcumin was grafted to lignin by esterification, and then prepared into nanoparticles. The results showed that the photothermal stability of curcumin was effectively improved. Moreover, cytotoxicity test showed that Lig-Cur nanoparticles can significantly improve the biocompatibility of curcumin. The ester bonds formed from conjugate also help Lig-Cur nanoparticles have pH-sensitivity in stimulated inflammatory tissue and release curcumin. Finally, by reducing proinflammatory factors, Lig-Cur nanoparticles could effectively scavenge reactive oxygen species (ROS). In addition to alleviating oxidative stress, Lig-Cur nanoparticles were expected to be used as a carrier platform for the treatment of many other inflammatory diseases.

Lignin nanoparticle-stabilized pickering emulsion: Mechanism, influencing parameter, and emerging application

Pickering emulsions using solid particles as stabilizers have attracted considerable interest due to their unique properties, environmental protection, high stability, and cost-effectiveness. However, the current solid particles used as stabilizers have been unable to meet the demands for sustainable development. Lignin nanoparticles (LNPs) are nanoscale particles derived from lignin, a complex biopolymer found in the cell walls of woods and plants. In recent years, LNPs have been widely used to stabilize Pickering emulsions due to its abundance, nanometer size, large specific surface area, good wettability, non-toxicity, and biodegradability. In this review, we overview the recent advances in the LNP-stabilized Pickering emulsion and their applications in a wide spectrum of emerging fields. The structure, preparation, and safety of LNPs are briefly overviewed. Then, the stabilization mechanism of LNP-stabilized Pickering emulsion is introduced. Next, two types of LNP-stabilized Pickering emulsion (i.e., unmodified and modified LNPs), their influencing factors, and physiochemical properties are comprehensively discussed. The recent advances in the application of LNP-stabilized Pickering emulsions in five areas are subsequently outlined, i.e., i) nanocomposites, ii) two-phase catalysis, iii) biomedicine, iv) daily skincare products, and v) enhanced oil recovery. Finally, the prospects of LNP-stabilized Pickering emulsion in the aforementioned fields are proposed.

Construction of Iron-Modified Lignin-Based Nanomicrocapsules for Enhancing the Functionality of Natural Product-Based Pesticides

To address the issue of low pesticide utilization owing to poor dispersibility, low leaf surface adhesion, and poor transport within plants, this study exploits electrostatic interactions between sodium lignosulfonate (SL) and dodecyltrimethylammonium chloride (DTAC) to induce self-assembly, followed by iron ion (Fe3+) chelation and loading with a natural product-based pesticide, rosin-based triazole derivative (RTD), yielding RTD@SL-DTAC-Fe nanomicrocapsules (NMs). It is worth noting that the presence of Fe3+ enhances the dispersibility of the NMs. The water dispersibility and photostability of RTD are significantly improved after encapsulation, and a stimulus response to laccase is achieved. Leaf-washing experiments confirm the enhanced adhesion of RTD@SL-DTAC-Fe NMs to the surface of rice plant leaves compared to that of free RTD. Fluorescently labeled NMs exhibit bidirectional transport within rice plants, and RTD@SL-DTAC-Fe NMs demonstrates better transport performance than RTD. In vitro and in vivo antifungal tests indicate that encapsulation by NMs significantly enhanced pesticide activity. Field trials demonstrate that NMs exhibited prolonged efficacy compared to RTD. Finally, the safety evaluation confirms the environmental friendliness of the NMs. This study provides valuable insight for optimizing and improving the utilization efficiency and biosafety of natural product-based pesticides.

Degradable poly(β-amino ester) microparticles for cleansing products and food fortification

Microplastic pollution is a pressing global crisis caused by the extensive use of nondegradable microplastic materials in daily activities. One effective approach to mitigate this issue is to replace nondegradable plastics with degradable materials that have properties amendable for targeted applications. Here we present the development of a degradable microparticle (MP) platform based on a poly(β-amino ester) (PAE) that degrades into sugar and amino acid derivatives. This PAE MP platform showed functional replacement of nondegradable microplastics used in cleansing products and food fortification. In cleansing products, PAE MPs effectively enhanced the cleansing efficiency of a representative rinse-off product and showed effective removal of potentially toxic elements, as an alternative of traditional nondegradable microbeads. In food fortification, PAE MPs provided robust protection for multiple essential vitamins and minerals against extensive cooking and storage conditions with rapid nutrient release in a simulated human digestion system. Collectively, these PAE MPs present a potential platform to replace microplastic usage on a global scale in many applications.

Study on the stability and magnetically induced demulsification performance of Pickering emulsions based on arginine-modified lignin/Fe3O4 nanoparticles

In this study, four different arginine-modified lignin composites (Lig-Arg-x) were synthesized via the Mannich reaction, followed by the preparation of Lig-Arg-x/Fe3O4 magnetic nanoparticles (NPs) using hydrothermal reduction. The magnetic particles were characterized, and their emulsification properties were investigated. The highest grafting degree was achieved at a 1:1 M ratio of arginine to lignin. Pickering emulsions were formulated and Lig-Arg-x/Fe3O4 NPs as the emulsifier. The study examined the impact of arginine grafting degree, oil-to-water volume ratio, and nanoparticle concentration on emulsion stability and demulsification performance. Optimal emulsion stability, characterized by the smallest droplet size of 20.57 μm, was achieved with a 1:1 M ratio of lignin to arginine, a 7:3 oil-to-water volume ratio, and a nanoparticle concentration of 1.0 w/v%. Magnetic induction experiments demonstrated significant phase separation in the stable emulsion under a magnetic field, confirming the magnetic-induced demulsification capability of the composite particles. Oil displacement experiments demonstrated that Lig-Arg-x/Fe3O4 NPs modulate oil droplet diffusion via the Marangoni effect, indicating their potential for oil recovery applications. After three cycles, Lig-Arg-1/Fe3O4 NPs retained 80 % of their saturation magnetization, demonstrating strong reusability. This study showcases lignin-magnetite nanocomposites' versatility in stabilizing emulsions and exhibiting magnetic responsiveness, advancing demulsification and oil spill recovery technologies.

Thermal stability, antioxidant activity and bioavailability of pea protein-naringin Pickering emulsion for enhanced delivery applications

After successfully addressing to mitigate bitterness of naringin through construction Pickering emulsion using pea protein (PP) and naringin (NG) in our previous study, we now probed thermal stability, antioxidant efficacy, and bioavailability. FTIR analysis and UV-vis spectroscopy indicated predominant interactions between PP and NG were hydrogen and hydrophobic bonds. TGA and DSC analyses demonstrated that PP-NG complexes exhibited superior heat-resistance compared to pure PP and NG. Thermal stability assessments indicated a significant retention of NG in the PP-NG Pickering emulsion than the control NG across varied temperatures (4 °C, 25 °C, 37 °C, and 65 °C). Moreover, the antioxidant activity of PP-NG emulsion was dependent on the concentration of NG, as evidenced by DPPH and ABTS free radicals scavenging abilities, ferric reducing power, and lipid peroxidation resistance. Additionally, PP-NG Pickering emulsion exhibited substantially high bioavailability (92.01 ± 3.91%). These results suggest a promising avenue for the application of NG with improved characteristics.

Multi-Stimuli-Responsive, Topology-Regulated, and Lignin-Based Nano/Microcapsules from Pickering Emulsion Templates for Bidirectional Delivery of Pesticides

The increasing demand for improving pesticide utilization efficiency has prompted the development of sustainable, targeted, and stimuli-responsive delivery systems. Herein, a multi-stimuli-responsive nano/microcapsule bidirectional delivery system loaded with pyraclostrobin (Pyr) is prepared through interfacial cross-linking from a lignin-based Pickering emulsion template. During this process, methacrylated alkali lignin nanoparticles (LNPs) are utilized as stabilizers for the tunable oil-water (O/W) Pickering emulsion. Subsequently, a thiol-ene radical reaction occurs with the acid-labile cross-linkers at the oil-water interface, leading to the formation of lignin nano/microcapsules (LNCs) with various topological shapes. Through the investigation of the polymerization process and the structure of LNC, it was found that the amphiphilicity-driven diffusion and distribution of cyclohexanone impact the topology of LNC. The obtained Pyr@LNC exhibits high encapsulation efficiency, tunable size, and excellent UV shielding to Pyr. Additionally, the flexible topology of the Pyr@LNC shell enhances the retention and adhesion of the foliar surface. Furthermore, Pyr@LNC exhibits pH/laccase-responsive targeting against Botrytis disease, enabling the intelligent release of Pyr. The in vivo fungicidal activity shows that efficacy of Pyr@LNC is 53% ± 2% at 14 days postspraying, whereas the effectiveness of Pyr suspension concentrate is only 29% ± 4%, and the acute toxicity of Pyr@LNC to zebrafish is reduced by more than 9-fold compared with that of Pyr technical. Moreover, confocal laser scanning microscopy shows that the LNCs can be bidirectionally translocated in plants. Therefore, the topology-regulated bidirectional delivery system LNC has great practical potential for sustainable agriculture.

Exploring chemical reactions to enhance thermal and dispersion stability of kraft and organosolv lignin

Lignin has been overlooked and used as a waste for long due to its complex and partially hydrophobic structure. Many efforts have been carried out to overcome these deficiencies and apply it as a high-value product, which are insufficient to reach the full potential of lignin in various advanced applications, since they require with procedures for the obtaining of more specific and fine-tuned chemical structures. This work focuses on the obtaining of differently structured hydrophilic lignins derived both from Kraft and organosolv isolation processes. The chemical structures of the different lignin types were studied, and the effect of the structural differences in the modification processes and their subsequent properties analyzed, valorizing their potential application for diverse purposes. The carboxymethylation and sulfomethylation reactions were carried out with the aim of enhancing the polarity of the lignin samples, while the methylation reaction aimed to obtain lignins with higher stability. The physicochemical analyses of the samples, carried out by FTIR, GPC, 31P NMR, 13C NMR, and HSQC NMR, verified the effectiveness of the chemical reactions and conditions selected, obtaining lignins with lower hydroxyl content, due to their substitution and insertion of carboxymetyl, sulfomethyl and methyl groups, therefore obtaining more condensed, aromatic and oxygenated aromatic carbon structures. While the methylation reaction was the most efficient in substituting the OH groups, due to its non-selectivity, OL showed higher modification yields than KL. In terms of the thermal and morphological properties, analyzed by DLS and TGA respectively, it was observed that the modified samples showed lower Z potential values, along with higher conductivity, being the sulfomethylated organosolv lignin the one showing the best results, which was also the one with the smallest particle size and polydispersity index. Finally, all the modified samples showed higher T50% values, suggesting a better stability towards degradation.

A double-network porous hydrogel based on high internal phase emulsions as a vehicle for potassium sucrose octasulfate delivery accelerates diabetic wound healing

Diabetic wounds are a difficult medical challenge. Excessive secretion of matrix metalloproteinase-9 (MMP-9) in diabetic wounds further degrades the extracellular matrix and growth factors and causes severe vascular damage, which seriously hinders diabetic wound healing. To solve these issues, a double-network porous hydrogel composed of poly (methyl methacrylate-co-acrylamide) (p(MMA-co-AM)) and polyvinyl alcohol (PVA) was constructed by the high internal phase emulsion (HIPE) technique for the delivery of potassium sucrose octasulfate (PSO), a drug that can inhibit MMPs, increase angiogenesis and improve microcirculation. The hydrogel possessed a typical polyHIPE hierarchical microstructure with interconnected porous morphologies, high porosity, high specific surface area, excellent mechanical properties and suitable swelling properties. Meanwhile, the p(MMA-co-AM)/PVA@PSO hydrogel showed high drug-loading performance and effective PSO release. In addition, both in vitro and in vivo studies showed that the p(MMA-co-AM)/PVA@PSO hydrogel had good biocompatibility and significantly accelerated diabetic wound healing by inhibiting excessive MMP-9 in diabetic wounds, increasing growth factor secretion, improving vascularization, increasing collagen deposition and promoting re-epithelialization. Therefore, this study provided a reliable therapeutic strategy for diabetic wound healing, some theoretical basis and new insights for the rational design and preparation of wound hydrogel dressings with high porosity, high drug-loading performance and excellent mechanical properties.

Toward well-defined colloidal particles: Efficient fractionation of lignin by a multi-solvent strategy

Colloidal lignin particles (CLPs) have sparked various intriguing insights toward bio-polymeric materials and triggered many lignin-featured innovative applications. Here, we report a multi-solvent sequential fractionation methodology integrating green solvents of acetone, 1-butanol, and ethanol to fractionate industrial lignin for CLPs fabrication. Through a rationally designed fractionation strategy, multigrade lignin fractions with variable hydroxyl group contents, molecular weights, and high purity were obtained without altering their original chemical structures. CLPs with well-defined morphology, narrow size distribution, excellent thermal stability, and long-term colloidal stability can be obtained by rational selection of lignin fractions. We further elucidated that trace elements (S, N) were reorganized onto the near-surface area of CLPs from lignin fractions during the formation process in the form of -SO42- and -NH2. This work provides a sustainable and efficient strategy for refining industrial lignin into high-quality fractions and an in-depth insight into the CLPs formation process, holding great promise for enriching the existing libraries of colloidal materials.

Preparation of lignin-based hydrogels, their properties and applications

Polymers obtained from biomass are a concerning alternative to petro-based polymers because of their low cost of manufacturing, biocompatibility, ecofriendly and biodegradability. Lignin as the second richest and the only polyaromatics bio-polymer in plant which has been most studied for the numerous applications in different fields. But, in the past decade, the exploitation of lignin for the preparation of new smart materials with improved properties has been broadly sought, because lignin valorization plays one of the primary challenging issues of the pulp and paper industry and lignocellulosic biorefinery. Although, well suited chemical structure of lignin comprises of many functional hydrophilic and active groups, such as phenolic hydroxyls, carboxyls and methoxyls, which provides a great potential to be applied in the preparation of biodegradable hydrogels. In this review, lignin hydrogel is covered with preparation strategies, properties and applications. This review reports some important properties, such as mechanical, adhesive, self-healing, conductive, antibacterial and antifreezing properties were then discussed. Furthermore, herein also reviewed the current applications of lignin hydrogel, including dye adsorption, smart materials for stimuli sensitive, wearable electronics for biomedical applications and flexible supercapacitors. Overall, this review covers recent progresses regarding lignin-based hydrogel and constitutes a timely review of this promising material.

Oleogels and reverse emulsions stabilized by acetylated Kraft lignins

Acetylated Kraft lignins were evaluated for their ability of structuring vegetable oils into oleogels. Microwave-assisted acetylation was used to adjust lignin's degree of substitution according to reaction temperature (130 to 160 °C), and its effect in improving the viscoelasticity of the oleogels, which was related to the hydroxyl group content. The results were compared with those obtained by Kraft lignins acetylated using conventional methods at room temperature. A higher microwave temperature resulted in gel-like oil dispersions with improved viscoelastic properties, and stronger shear-thinning character, along with enhanced long-term stability. Lignin nanoparticles structured castor oil by enhancing hydrogen bonding between the hydroxyl groups of the oil and the nanoparticles. The oil structuring capacity of the modified lignins enhanced the stability of water-in-oil Pickering emulsions that resulted from low-energy mixing.

Nano-Sized Antioxidative Trimetallic Complex Based on Maillard Reaction Improves the Mineral Nutrients of Apple (Malus domestica Borkh.)

The metallic complex is widely used in agricultural applications. Due to the oxidation of the metal and environmental unfriendliness of ligand, maintaining an efficient mineral supply for plants without causing environmental damage is difficult. Herein, an antioxidative trimetallic complex with high stability was synthesized by interacting Ca²⁺, Fe²⁺, and Zn²⁺ with the biocompatible ligands from the Maillard reaction. The composite structure elucidation was carried out by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR). Thermal stability was measured by thermogravimetric (TG). Antioxidative activities were evaluated by ferric reducing antioxidant power and radical scavenging activity assays. The three metals were successfully fabricated on the Maillard reaction products (MRPs) with contents of Ca (9.01%), Fe (8.25%), and Zn (9.67%). Microscopy images revealed that the three metals were uniformly distributed on the MRPs with partial aggregation of <30 nm. FTIR and XPS results revealed that the metals were interacted with MRPs by metal-O and metal-N bonds. TG and antioxidative activity assays showed that the trimetallic complex meets the requirements of thermodynamics and oxidation resistance of horticultural applications. Additionally, the results of the exogenous spraying experiment showed that the trimetallic complex significantly increased the mineral contents of the "Fuji" apple. By treatment with the complex, the concentrations of Ca, Fe, and Zn were increased by 85.4, 532.5, and 931.1% in the leaf; 16.0, 225.2, and 468.6% in the peel; and 117.6, 217.9, and 19.5% in the flesh, respectively. The MRP-based complexes offered a higher growth rate of the mineral content in apples than ones based on sugars or amino acids. The results of the spraying experiment carried out in 2 years show that the method has high reproducibility. This study thus promotes the development of green metallic complexes and expands the scope of agrochemical strategy.

Pickering Emulsions Stabilized by an Alkyl Chain-Bridged Lignin-Based Polymer without Additives and Organic Solvents

In this article, an alkyl chain-bridged lignin polymer was prepared from our previous study. Then, an ultrafiltration method was used to classify the polymer into three fractions with a narrow molecular weight distribution. These three fractions were used to prepare novel Pickering emulsions without additives and organic solvents. The results show that the Pickering emulsion with fraction-3 of the highest molecular weight shows the best result compared with the other two fractions, and the Pickering emulsion is formed of droplets. The influence of oil-water ratios and fraction-3 dosages on the Pickering emulsions was also investigated in our study. The results show that the diameter of the droplets increases with increasing oil proportion and decreases with increasing lignin-based polymer dose. UV spectroscopy shows that the prepared Pickering emulsions have strong absorption properties from 300 to 800 nm, which will be expected to be applied in cosmetics, especially in sunscreen creams. Finally, the Pickering emulsion was also used to deliver ibuprofen, and the results showed that the embedding rate was as high as 10%. It is suggested that the Pickering emulsion stabilized by lignin-based polymers can be used for drug delivery. This will provide a potential research idea for high-value applications of lignin.

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.

Mechanism and Characteristics of Oil Recovery from Oily Sludge by Sodium Lignosulfonate Treatment

The separation of oil components from oily sludge is an important component of soil remediation and energy recovery. Therefore, establishing a green and efficient separation technology is of great significance. In this study, oily sludge was separated using sodium lignosulfonate (SL) treatment. The effects of temperature, SL concentration, rotate speed, time, and pH on the oil removal rate were studied. The optimal conditions were as follows: temperature, 30 °C; SL concentration, 2.0 g·L-1; rotate speed, 200 rpm; time, 60 min; and pH 11. The maximum oil removal rate was 83.21%. The physicochemical properties of oily sludge were analyzed. The soil was looser, and the contact angle (55°) of the soil surface was reduced. Alkanes, aldehydes, ketones, carbonic acids, benzene rings, and alicyclic ethers were removed. The result shows that the SL treatment removed a wider range of petroleum hydrocarbon and had a stronger oil removal capacity. It provides a new method for the green and efficient separation of oily sludge.

Curcumin-loaded high internal phase emulsions stabilized with lysine modified lignin: a biological agent with high photothermal protection and antibacterial properties

Bacterial infections and multidrug resistance can seriously endanger the health and lives of humans, therefore the development of novel and efficient antibacterial strategies and drugs is urgently needed. Herein, a series of highly biocompatible lysine modified enzymatic hydrolysis lignins (EHL-Lys-x) were synthesized using the Mannich reaction. The sterilizing efficiency of EHL-Lys-2.0 against S. aureus and E. coli at 20 mg mL^-1 is 93% and 50%, respectively, which is 26% higher than pure EHL. Quartz crystal microbalance with dissipation monitoring (QCM-D) and atomic force microscopy (AFM) analysis showed that the adsorption and adhesive force between EHL-Lys-x and bacteria increase with the increased amount of grafting of Lys on EHL owing to the increase of the electrostatic interaction between the EHL-Lys-x and bacteria, which results in an improvement in the antimicrobial activity of EHL-Lys-x. Subsequently, EHL-Lys-x combined with alkyl polyglucoside (APG) was used to stabilize the high internal phase emulsion containing curcumin (HIPEs-cur). The dispersed phase fraction of HIPE-cur is 87 vol%, which is the highest internal phase reported to date in the medical research area. The highest residual levels of curcumin in HIPEs are 60-fold, 3-fold and 5-fold compared to that in bulk oil after treatment with UV radiation, thermal emittance and after storage, respectively. The minimum inhibitory concentrations of HIPEs-cur against S. aureus and E. coli were found to be 1.56 and 6.25 mg mL^-1, respectively, which are far higher than that of pure EHL-Lys-x. This strategy not only increases the chemical stability and bioavailability of curcumin, but also provides a novel method for the application of lignin in biomedical science.

Antimicrobial Activity of Curcumin in Nanoformulations: A Comprehensive Review

Curcumin (CUR) is a natural substance extracted from turmeric that has antimicrobial properties. Due to its ability to absorb light in the blue spectrum, CUR is also used as a photosensitizer (PS) in antimicrobial Photodynamic Therapy (aPDT). However, CUR is hydrophobic, unstable in solutions, and has low bioavailability, which hinders its clinical use. To circumvent these drawbacks, drug delivery systems (DDSs) have been used. In this review, we summarize the DDSs used to carry CUR and their antimicrobial effect against viruses, bacteria, and fungi, including drug-resistant strains and emergent pathogens such as SARS-CoV-2. The reviewed DDSs include colloidal (micelles, liposomes, nanoemulsions, cyclodextrins, chitosan, and other polymeric nanoparticles), metallic, and mesoporous particles, as well as graphene, quantum dots, and hybrid nanosystems such as films and hydrogels. Free (non-encapsulated) CUR and CUR loaded in DDSs have a broad-spectrum antimicrobial action when used alone or as a PS in aPDT. They also show low cytotoxicity, in vivo biocompatibility, and improved wound healing. Although there are several in vitro and some in vivo investigations describing the nanotechnological aspects and the potential antimicrobial application of CUR-loaded DDSs, clinical trials are not reported and further studies should translate this evidence to the clinical scenarios of infections.

Fabrication of pickering high internal phase emulsions stabilized by pecan protein/xanthan gum for enhanced stability and bioaccessibility of quercetin

The stabilizing effect of pecan protein (PP)/xanthan gum (XG) complex on the Pickering high internal phase emulsion (HIPE) has been examined in this study. Shear viscosity of HIPEs increased with respect to XG concentration due to the formation of hydrogen bonds between PP and XG. Confocal laser scanning microscopy (CLSM) imaging showed fairly even distribution and polygonal shapes of oil droplets (30-70 μm). When used to encapsulate quercetin, this Pickering HIPE exhibited high retention rate and improved gel strength. Furthermore, the interface film of PP/XG on oil-water interface contributed to the high retention of quercetin in Pickering HIPEs when exposure to heat, iron ions, and hydrogen peroxide in aqueous phase. The bioaccessibility of quercetin after in vitro simulated digestion were also improved by HIPE encapsulation than that in oil. To conclude, PP/XG complex stabilized HIPEs may be suitable delivery systems for improving colloidal stability and bioaccessibility of hydrophobic bioactives.

Tumor microenvironment-responsive, high internal phase Pickering emulsions stabilized by lignin/chitosan oligosaccharide particles for synergistic cancer therapy

HYPOTHESIS

The stability of anti-cancer drugs and the adverse drug reactions (ADRs) caused by drug-drug interactions (DDIs) are two major challenges of combination chemotherapy. In this work, hydrophilic drug loaded lignin-based nanoparticles were applied to stabilize high internal phase Pickering emulsions (HIPPEs) containing hydrophobic drug in the oil phase, which not only improved the stability of anti-cancer drugs, but also reduced the risk of DDIs.

EXPERIMENTS

Highly biocompatible enzymatic hydrolysis lignin/chitosan oligosaccharide (EHL/COS-x) nanoparticles were prepared and used to load hydrophilic cytarabine (Ara-C). The morphology, loading capacity, encapsulation efficiency and emulsifying properties of nanoparticles were characterized and predicted. Subsequently, these nanoparticles were applied to stabilize HIPPEs with soybean oil containing hydrophobic curcumin as dispersed phase. The effects of the morphology, amphipathy and concentration of nanoparticles and oil/water ratio on the microstructure and stability of HIPPEs were investigated. Meanwhile, the controlled release, protective performance, cytotoxicity and bio-activity of HIPPEs were also evaluated.

FINDINGS

EHL/COS-x nanoparticles loaded with Ara-C could stabilize HIPEs with 85 vol% soybean oil containing curcumin. The two drugs were separately loaded in same delivery system, which effectively lowered the risk of DDIs. Meanwhile, HIPPEs provided outstanding UV, thermal and oxidation protection for these two environmentally sensitive anti-cancer drugs. In addition, HIPPEs displayed a good pH-responsive release in a tumor environment. In vitro experiments show that the killing efficiency of two drugs co-loaded HIPPEs against the leukemia cell is two times higher than that of single drug loaded systems. This strategy can be extended to the synergistic therapy of two or more drugs with different physicochemical properties.

Lignin as a UV Light Blocker-A Review

Lignin is the by-product of pulp and paper industries and bio-refining operations. It is available as the leading natural phenolic biopolymer in the market. It has chromophore functional groups and can absorb a broad spectrum of UV light in range of 250–400 nm. Using lignin as a natural ingredient in sunscreen cream, transparent film, paints, varnishes and microorganism protection has been actively investigated. Both in non-modified and modified forms, lignin provides enhancing UV protection of commercial products with less than a 10% blend with other material. In mixtures with other synthetic UV blockers, lignin indicated synergic effects and increased final UV blocking potential in compare with using only synthetic UV blocker or lignin. However, using lignin as a UV blocker is also challenging due to its complex structure, polydispersity in molecular weight, brownish color and some impurities that require more research in order to make it an ideal bio-based UV blocker.

High internal phase emulsions stabilized with carboxymethylated lignin for encapsulation and protection of environmental sensitive natural extract

Oil-in-water (O/W) high internal phase emulsions (HIPEs) are widely used in foods, pharmaceuticals and cosmetics due to the high drug loading ratio, specific rheological behaviors and long shelf life. However, protective performance of active components within HIPEs maintains a low level. Herein, a series of carboxymethylated enzymatic hydrolysis lignin (EHL-CM-x) were synthesized by nucleophilic substitution and applied as macromolecular surfactant to stabilize the O/W HIPEs. It was found that EHL-CM-x combined with a small dosage of alkyl polyglycoside (APG) are able to stabilize HIPEs with 87 vol% soybean oil under neutral condition, which could be recognized as the highest internal phase reported in foods and pharmaceuticals. As a bioactive compound carrier, such EHL-CM-x stabilized HIPEs enable to provide outstanding UV, thermal and oxidation protection for sensitive natural extracts. The residual drug level obtained in this work is more than two times other gliadin/chitosan hybrid particles and sulfomethylated lignin stabilized HIPEs after UV irradiation. In vitro experiments showed that the minimum inhibitory concentration of curcumin within HIPEs against S. aureus and E. coli was 3.13 mg/mL and 12.5 mg/mL, respectively. Such lignin stabilized HIPEs could be potentially used in various areas, especially those with high stability and biosafety requirements.