Bioinspired Lignin-Polydopamine Nanocapsules with Strong Bioadhesion for Long-Acting and High-Performance Natural Sunscreens

Anti-apoptotic, anti-inflammatory, and anti-melanogenic effects of the ethanol extract of Picrasma quassioides (D. Don) Benn

ETHNOPHARMACOLOGICAL RELEVANCE

Picrasma quassioides (D. Don) Benn is a vascular plant belonging to the genus Picrasma of Simaroubaceae family and grows in Korea, China, India, Taiwan, and Japan. Picrasma quassioides extract has been reported to have anti-inflammatory, anti-bacterial, and anti-cancer properties. Moreover, this plant has been also traditionally used to alleviate symptoms of eczema, atopic dermatitis, psoriasis, scabies, and boils in skin.

AIM OF THE STUDY

The Pq-EE has been reported in Chinese pharmacopoeia for its pharmacological effects on skin. However, the detailed mechanism on alleviating skin conditions is not understood. Hence, we investigated the skin improvement potential of Pq-EE against skin damage.

MATERIALS AND METHODS

We used the human keratinocyte cell line (HaCaT) and mouse melanoma cell line (B16F10) to study the effects of Pq-EE on the epidermis. Additionally, in vitro antioxidant assays were performed using a solution that included either metal ions or free radicals.

RESULTS

In colorimetric antioxidant assays, Pq-EE inhibited free radicals in a dose-dependent manner. The Pq-EE did not affect cell viability and promoted cell survival under UVB exposure conditions in the MTT assay. The Pq-EE downregulated the mRNA levels of apoptotic factors. Moreover, MMP1 and inflammatory cytokine iNOS mRNA levels decreased with Pq-EE treatment. With regard to protein levels, caspases and cleaved caspases were more powerfully inhibited by Pq-EE than UVB-irritated conditions. p53 and Bax also decreased with Pq-EE treatment. The melanin contents and secretion were decreased at nontoxic concentrations of Pq-EE. The pigmentation pathway genes also were inhibited by treatment with Pq-EE.

CONCLUSIONS

In summary, we suggest the cell protective potential of Pq-EE against UVB and ROS, indicating its use in UV-protective cosmeceutical materials.

Lignin-Based Antioxidant Hydrogel Patch for the Management of Atopic Dermatitis by Mitigating Oxidative Stress in the Skin

Atopic dermatitis (AD), a chronic skin condition characterized by itching, redness, and inflammation, is closely associated with heightened levels of endogenous reactive oxygen species (ROS) in the skin. ROS can contribute to the onset and progression of AD through oxidative stress, which leads to the release of proinflammatory cytokines, T-cell differentiation, and the exacerbation of skin symptoms. In this study, we aim to develop a therapeutic antioxidant hydrogel patch for the potential treatment of AD using lignin, a biomass waste material. Lignin contains polyphenol groups that enable it to scavenge ROS and exhibit antioxidant properties. The lignin hydrogel patches, possessing optimized mechanical properties through the control of the lignin and cross-linker ratio, demonstrated high ROS-scavenging capabilities. Furthermore, the lignin hydrogel demonstrated excellent biocompatibility with the skin, exhibiting beneficial properties in protecting human keratinocytes under high oxidative conditions. When applied to an AD mouse model, the hydrogel patch effectively reduced epidermal thickness in inflamed regions, decreased mast cell infiltration, and regulated inflammatory cytokine levels. These findings collectively suggest that lignin serves as a therapeutic hydrogel patch for managing AD by modulating oxidative stress through its ROS-scavenging ability.

Unlocking the potential: Evolving role of technical lignin in diverse applications and overcoming challenges

Recent advancements have transformed lignin from a byproduct into a valuable raw material for polymers, dyes, adhesives, and fertilizers. However, its structural heterogeneity, variable reactive group content, impurities, and high extraction costs pose challenges to industrial-scale adoption. Efficient separation technologies and selective bond cleavage are crucial. Advanced pretreatment methods have enhanced lignin purity and reduced contamination, while novel catalytic techniques have improved depolymerization efficiency and selectivity. This review compares catalytic depolymerization methodologies, highlighting their advantages and disadvantages, and noting challenges in comparing yield values due to variations in isolation methods and lignin sources. Recognizing "technical lignin" from pulping processes, the review emphasizes its diverse applications and the necessity of understanding its structural characteristics. Emerging trends focus on bio-based functional additives and nanostructured lignin materials, promising enhanced properties and functionalities. Innovations open possibilities in sustainable agriculture, high-performance foams and composites, and advanced medical applications like drug delivery and wound healing. Leveraging lignin's biocompatibility, abundance, and potential for high-value applications, it can significantly contribute to sustainable material development across various industries. Continuous research in bio-based additives and nanostructured materials underscores lignin's potential to revolutionize material science and promote environmentally friendly industrial applications.

Polyphosphazene Microparticles with High Free Radical Scavenging Activity for Skin Photoprotection

Ultraviolet (UV) filters are the core ingredients in sunscreens and protect against UV-induced skin damage. Nevertheless, their safety and effectiveness have been questioned in terms of their poor photostability, skin penetration, and UV-induced generation of deleterious reactive oxygen species (ROS). Herein, an organic UV filter self-framed microparticle sunblock was exploited, in which quercetin (QC) and hexachlorocyclotriphosphazene (HCCP) were self-constructed into microparticles (HCCP-QC MPs) by facile precipitation polymerization without any carriers. HCCP-QC MPs could not only significantly extend the UV shielding range to the whole UV region but also remarkably reduce UV-induced ROS while avoiding direct skin contact and the resulting epidermal penetration of small-molecule QC. Meanwhile, HCCP-QC MPs possess a high QC-loading ability (697 mg g-1) by QC itself as the microparticles' building blocks. In addition, there is no leakage issue with small molecules due to its covalently cross-linked structure. In vitro and vivo experiments also demonstrated that the HCCP-QC MPs have excellent UV protection properties and effective ROS scavenging ability without toxicity. In summary, effective UV-shielding and ROS scavenging ability coupled with excellent biocompatibility and nonpenetration of small molecules make it a broad prospect in skin protection.

Acid-catalyzed phenolation of lignin with tea polyphenol: Enhancing uv resistance and oxidation resistance for potential applications

The rapid development of the industry has led to the destruction of the earth's ozone layer, resulting in an increasingly serious problem of excessive ultraviolet radiation. Exploring effective measures to address these problems has become a hot topic. Lignin shows promise in the design and preparation of anti-ultraviolet products due to its inherent properties. However, it is important to investigate way to enhance the reactivity of lignin and determine its application form in related products. In this study, phenolic reactions with tea polyphenols were conducted through acid-catalyzed conversion, utilizing organic solvent lignin as the primary material. The phenolic hydroxyl content of the original lignin increased significantly by 218.8 %, resulting in notable improvements in UV resistance and oxidation resistance for phenolic lignin. Additionally, micro-nanocapsule emulsions were formed using phenolic lignin particles as surfactants through ultrasonic cavitation with small-molecule sunscreens. A bio-based sunscreen was prepared with phenolated lignin micro-nanocapsules as the active ingredient, achieving an SPF 100.2 and demonstrating excellent stability. The sunscreen also exhibited strong antioxidant properties and impermeability, ensuring user safety. This research offers a current solution for improving the application of lignin in sunscreens while also broadening the potential uses of plant-based materials in advanced functional products.

Preparation and Application of Degradable Lignin/Poly (Vinyl Alcohol) Polymers as Urea Slow-Release Coating Materials

The massive amount of water-soluble urea used leads to nutrient loss and environmental pollution in both water and soil. The aim of this study was to develop a novel lignin-based slow-release envelope material that has essential nitrogen and sulfur elements for plants. After the amination reaction with a hydrolysate of yak hair keratin, the coating formulation was obtained by adding different loadings (2, 5, 8, 14 wt%) of aminated lignin (AL) to 5% polyvinyl alcohol (PVA) solution. These formulations were cast into films and characterized for their structure, thermal stability, and mechanical and physicochemical properties. The results showed that the PVA-AL (8%) formulation had good physical and chemical properties in terms of water absorption and mechanical properties, and it showed good degradation in soil with 51% weight loss after 45 days. It is suitable for use as a coating material for fertilizers. Through high-pressure spraying technology, enveloped urea particles with a PVA-AL (8%) solution were obtained, which showed good morphology and slow-release performance. Compared with urea, the highest urea release was only 96.4% after 30 days, conforming to Higuchi model, Ritger-Peppas model, and second-order dynamic model. The continuous nitrogen supply of PVA-AL coated urea to Brassica napus was verified by potting experiments. Therefore, the lignin-based composite can be used as a coating material to produce a new slow-release nitrogen fertilizer for sustainable crop production.

Lignin-xylan nanospheres prepared by green and quick method from lignocellulose and used as additive in PVA films

Lignin, as an amorphous three-dimensional aromatic polymer, was able to self-assemble into lignin nanoparticles (LNPs) to realize valorization of lignin. Here, lignin-xylan extractives were extracted from grape seed (GS) and poplar by acidic THF at room temperature, and effectively produced lignin-xylan nanospheres via spin evaporation. The morphology and chemical properties of nanospheres were determined by its natural origins, consequently influencing its application. For the lignin-xylan extractive from grape seed, the lignin was composed of guaiacyl (G) and p-hydroxylphenyl (H) units and the hollowed nanospheres (GS-LNPs) with 362.72 nm diameter was produced. The extractive from poplar was composed of G-syringyl (S) typed lignin (80.30 %) and xylan (12.33 %), that can assemble into LNPs with smaller size (229.87 nm), better PDI (0.1), and light color. The hybrid particles showed the qualities of lignin and xylan, that properties led to the LNPs@PVA composite films with UV-blocking capability, strong mechanical strength and hydrophobicity, and transparency ability of visible light. P-LNPs showed better performance as the film additives, due to its lower particles size and high content of unconjugated -OH from xylan. Xylan was significant in the composite films, and lowering the xylan content resulted in the decrease of the composite film's mechanical properties and hydrophobicity.

Lignin derivatives-based hydrogels for biomedical applications

Recently, numerous studies have been conducted on renewable polymers derived from different natural sources, exploring their suitability for diverse biomedical applications. Lignin as one of the main components of lignocellulosic has garnered significant attention as a promising alternative to petroleum-based polymers. This interest is primarily due to its cost-effectiveness, biocompatibility, eco-friendly nature, as well as its antioxidant and antimicrobial properties. These characteristics could be more beneficial when incorporating lignin into the formulation of value-added products. Although lignin has a chemical structure that is suitable for various applications, these characteristics require modifications to guarantee that the resultant materials display the desired biological, chemical, and physical properties when applied in the creation of biodegradable hydrogels, particularly for biomedical purposes. This study delineates the recent modification approaches that have been employed in the creation of lignin-based hydrogels. These strategies encompass both chemical and physical interactions with other polymers. Additionally, this review encompasses an examination of the current applications of lignin hydrogels, spanning their use as scaffolds for tissue engineering, carriers for pharmaceuticals, materials for wound dressings and biosensors, and elements in flexible and wearable electronics. Finally, we delve into the challenges and constraints associated with these materials, discuss the necessary steps required to attain the appropriate properties for the development of innovative lignin-based hydrogels, and derive conclusions based on the presented findings.

Sensory signature of lignins, new generation of bio-based ingredients in cosmetics

Lignins represent a high interest in cosmetics as promising multifunctional ingredients. Despite this, uncovering the sensory profile of lignin-based emulsions has remained an unexplored frontier. This study aims to bridge this gap by employing expert sensory evaluation and instrumental characterization to assess the sensory attributes of lignin-based emulsions. A comparative analysis with commercial tinted products and discrimination among lignin derivatives were integral components of the research. Results underscored the distinctive sensory properties of lignin emulsions, exhibiting significantly higher "Integrity of shape" (7.0 ± 0.1) compared to commercial products (4.8 ± 0.1). Additionally, lignin emulsions displayed longer play-time until skin absorption (4.3 ± 0.1), contrasting with the quicker absorption of commercial products (2.7 ± 0.4) and their shorter play-time. Depending on application requirements, lignin derivatives offer formulators a versatile sensory toolbox. Discrimination of lignin emulsions on certain texture properties was achieved using various instrumental tools. Despite the complex formulation of commercial products compared to lignin emulsions, similar texture properties were observed, showcasing lignins' potential to replace multiple ingredients in tinted cosmetics. Beyond their established antioxidant, anti-UV, anti-bacterial, and emulsifying properties, this study reveals additional advantageous sensory properties of lignins, positioning them as promising plant-based sensory ingredients in sustainable cosmetic applications.

Long-lasting UV-blocking Mechanism of Lignin: Origin and Stabilization of Semiquinone Radicals

Semiquinone (SQ) radicals play a critical role in the long-lasting UV-blocking application of lignin, while their origin and stable structure are unclear. Here, the organosolv lignin extracted from poplar (OL-P) is self-assembled into normal micelles (LNM) with more phenolic hydroxyl groups on the surface, and reverse micelles (LRM) with more methoxyl groups on the surface. After 12 h UV irradiation, the SQ radical contents in LNM and LRM increase 33% and 78% respectively. The performance of LNM based sunscreen keeps upswinging due to radical stabilization of phenolic hydroxyl groups. LRM based sunscreen experiences a gradual decrease after reaching maximum UV absorbance due to the quick generation and over oxidation of SQ radicals. Density functional theory (DFT) simulations reveal that methoxyl groups in OL-P has bigger bond length and smaller bond dissociation enthalpy than phenolic hydroxyl groups, and are easy to form SQ radicals. The Gibbs free energy (ΔG) needed for SQ-quinone transformation is above 26.10 kcal mol.-1 , while that for SQ-hydroquinone transformation is below -66.78 kcal mol.-1 . Hydroquinone is the stable structure of SQ radicals. This work discloses the origin and stable structure of SQ radicals in lignin under UV irradiation, and provides an important guidance for its long-lasting UV-blocking application.

Recent advances in fabricating injectable hydrogels via tunable molecular interactions for bio-applications

Hydrogels with three-dimensional structures have been widely applied in various applications because of their tunable structures, which can be easily tailored with desired functionalities. However, the application of hydrogel materials in bioengineering is still constrained by their limited dosage flexibility and the requirement of invasive surgical procedures. Compared to traditional hydrogels, injectable hydrogels, with shear-thinning and/or in situ formation properties, simplify the implantation process and reduce tissue invasion, which can be directly delivered to target sites using a syringe injection, offering distinct advantages over traditional hydrogels. These injectable hydrogels incorporate physically non-covalent and/or dynamic covalent bonds, granting them self-healing abilities to recover their structural integrity after injection. This review summarizes our recent progress in preparing injectable hydrogels and discusses their performance in various bioengineering applications. Moreover, the underlying molecular interaction mechanisms that govern the injectable and functional properties of hydrogels were characterized by using nanomechanical techniques such as surface forces apparatus (SFA) and atomic force microscopy (AFM). The remaining challenges and future perspectives on the design and application of injectable hydrogels are also discussed. This work provides useful insights and guides future research directions in the field of injectable hydrogels for bioengineering.

Construction of photo-responsive lignin as a broad-spectrum sunscreen agent

Lignin has potential to serve as promising sunscreen agents as it has good ultraviolet (UV) absorption and antioxidant properties. However, the weak absorption capacity of lignin in the long-wave UV region (UVA, 320-400 nm) limits its further development. In this work, a spiropyran-modified lignin (DLSP) with photo-responsive property was prepared by in-situ construction of spiropyran (SP) structure in the demethylated lignin (DL). Due to the presence of SP moiety, the absorption of DLSP in the UVA region was significantly improved. Under UV irradiation, its absorption peak was redshifted as unconjugated SP form isomerized to conjugated merocyanine (MC) form, and the UVA/UVB ratio increased from 0.62 to 0.74. The free-radical scavenging ability of lignin could protect SP from photodegradation, which provided DLSP excellent fatigue resistance. DLSP were blended into creams to investigate its sunscreen performance. Results indicated that DLSP exhibited radiation-enhanced sunscreen performance, the sun protection factor (SPF) of cream containing 10 wt% of DLSP improved from 20 to 67 after 8 h of UV irradiation. Moreover, DLSP showed low skin penetration and good biocompatibility. These results provide a useful guideline for the rational design of sunscreens with special functionalities.

Bioinspired polydopamine nanoparticles as efficient antioxidative and anti-inflammatory enhancers against UV-induced skin damage

Excessive and prolonged ultraviolet radiation (UVR) exposure causes photodamage, photoaging, and photocarcinogenesis in human skin. Therefore, safe and effective sun protection is one of the most fundamental requirements. Living organisms tend to evolve various natural photoprotective mechanisms to avoid photodamage. Among them, melanin is the main functional component of the photoprotective system of human skin. Polydopamine (PDA) is synthesized as a mimic of natural melanin, however, its photoprotective efficiency and mechanism in protecting against skin damage and photoaging remain unclear. In this study, the novel sunscreen products based on melanin-inspired PDA nanoparticles (NPs) are rationally designed and prepared. We validate that PDA NPs sunscreen exhibits superior effects on photoprotection, which is achieved by the obstruction of epidermal hyperplasia, protection of the skin barrier, and resolution of inflammation. In addition, we find that PDA NPs are efficiently intake by keratinocytes, exhibiting robust ROS scavenging and DNA protection ability with minimal cytotoxicity. Intriguingly, PDA sunscreen has an influence on maintaining homeostasis of the dermis, displaying an anti-photoaging property. Taken together, the biocompatibility and full photoprotective properties of PDA sunscreen display superior performance to those of commercial sunscreen. This work provides new insights into the development of a melanin-mimicking material for sunscreens.

Human-Hair-Derived Natural Particles as Multifunctional Sunscreen for Effective UV Protection

Excessive ultraviolet (UV) radiation can lead to a series of skin problems. Although commercial sunscreens can protect skin from UV-induced damage to an extent, the side effects caused by such products are still worrisome. Here, inspired by the natural photoprotection effect of human hair, we extracted the multifunctional particles from human hair as sunscreens for UV protection. Both in vitro and in vivo results indicate that hair-derived particles (HDPs) could effectively protect skin from UV radiation. Besides, HDPs retain the antioxidant capability of melanin in hair, which avoids UV-induced oxidative damage. In addition, the unique shape of HDPs can prevent them from penetrating into the skin, thus avoiding potential toxicity. Moreover, owing to their mesoporous structure, the particles can also be used as drug carriers. With the loading of octocrylene, the particles are more effective in blocking UV radiation. This study provides an ingenious tactic for the design and development of sunscreens from a natural substance.

Different Types of Naturally based Drug Delivery Carriers: An Explanation and Expression of Some Anti-cancer Effects

Cancer remains one of the leading causes of death worldwide and a major impediment to increasing life expectancy. However, survival rates with average standard cancer treatment strategies have not significantly improved in recent decades, with tumor metastasis, adverse drug reactions, and drug resistance still posing major challenges. Replacement therapies are essential for treating this terrible disease. Recently, there has been a dramatic increase in the use of phytochemical-derived conjugated chemotherapeutic agents due to their biocompatibility, low cytotoxicity, low resistance, and dynamic physiochemical properties that distinguish normal cells in treating various types of cancer. The use of plant-based carriers has many advantages, such as the availability of raw materials, lower cost, lower toxicity in most cases, and greater compatibility with the body's structure compared to chemical and mineral types of carriers. Unfortunately, several challenges complicate the efficient administration of herbal medicines, including physicochemical disadvantages such as poor solubility and instability, and pharmacokinetic challenges such as poor absorption and low bioavailability that can cause problems in clinical trials. Novel delivery systems such as liposomes, phytosomes, nanoparticles, and nanocapsules are more suitable as delivery systems for phytomedicinal components compared to conventional systems. The use of these delivery systems can improve bioavailability, pharmacological activity, prolonged delivery, and provide physical and chemical stability that increases half-life. This article discusses different types of phytocompounds used in cancer treatment.

The Impact of Flavonoid-Loaded Nanoparticles in the UV Protection and Safety Profile of Topical Sunscreens

Excessive UV radiation exposure is harmful to skin cells since sunburn is accompanied by oxidative burst, leading to a rapid increase in skin cancer. However, the insufficient UV photoprotection of approved sunscreens and the negative impact of their compositions on ecosystems and human health makes the utility of sunscreen a questionable recommendation. Therefore, discovering UV filters with significant antioxidant activity and improved topical performance and photostability is an urgent need. Recently, the use of nanosized natural molecules incorporated in sunscreens has been a scientific hot topic, as it has been suggested that they provide a synergistic effect with synthetic UV filters, improving overall SPF and antioxidant activity, higher retention on the epidermis, and less toxicity. The aim of this review was to verify the usefulness of sunscreens incorporating flavonoid-loaded nanoparticles. A literature review was performed, where original and review articles published in the last 6 years were analyzed. Formulations containing nanosized flavonoids with improved UVA photoprotection and safer toxicological profiles, associated or not with synthetic filters, are promising sunscreens and more clinical investigation must be performed to validate these findings.

A Bioinspired Skin UV Filter with Broadband UV Protection, Photostability, and Resistance to Oxidative Damage

In recent years, sunscreens' adverse impacts on the environment and biology have gained wide attention. The improvement of sunscreen safety has become one of the major priorities in skin photoprotection research. It is an effective strategy to develop bionic photoprotective materials by simulating the photoprotective mechanism existing in nature. Inspired by the photoprotective mechanisms of skin and plant leaves, the bionic photoprotective material CS-SA-PDA nanosheet was developed using the free radical grafting method and Michael addition, with natural melanin analogue polydopamine (PDA) nanoparticles and plant sunscreen molecular sinapic acid (SA) as sun protection factors and natural polymer chitosan (CS) as the connecting arm. The results show that CS-SA-PDA can effectively shield UVB and UVA due to the possible synergistic effect between PDA and SA. The introduction of polymer CS significantly improved the photostability of SA and reduced the skin permeability of PDA nanoparticles. The CS-SA-PDA nanosheet can also effectively scavenge photoinduced free radicals. Furthermore, in vivo toxicity and anti-UV evaluations confirm that CS-SA-PDA has no skin irritation and is excellent against skin photodamage, which makes it an ideal skin photoprotective material.

All-biodegradable soy protein isolate/lignin composite cross-linked by oxidized sucrose as agricultural mulch films for green farming

Microplastics produced from the discarded traditional non-degradable mulch film deteriorate the ecological environment and pose a great threat to human health. Developing eco-friendly and biodegradable materials to substitute traditional plastic mulch film highly contributed to the progress of green agriculture. Herein, a category of eco-friendly and all-biodegradable soy protein isolate (SPI)/oxidized sucrose (OS)/Lignin mulch film was innovatively proposed by employing OS as green cross-linker and lignin as nanofiller under chemical/physical interaction. The cross-linking effect and hydrogen bonds between biopolymers act as sacrificial bonds for energy dissipation and effectively reinforced the intermolecular interactions as well as tensile strength from 6.67 MPa of pristine SPI film to 8.45 MPa of SPI/OS/Lignin film. Moreover, the SPI/OS/Lignin mulch film also presented excellent UV-shielding, moisture retention, heat preservation effect and sustained urea release properties. Benefitting from the above-mentioned merits, higher germination rate of cabbage seed was achieved when the natural soil was covered by such multifunctional mulch film compared to traditional low-density PE film. Our findings paved a solid way in rational designing and fabricating eco-friendly, low-cost and all-biodegradable mulch film to facilitate the crops growth, boosting the development of green farming.

Plant Polysaccharides in Engineered Pharmaceutical Gels

Hydrogels are a great ally in the pharmaceutical and biomedical areas. They have a three-dimensional polymeric structure that allows the swelling of aqueous fluids, acting as an absorbent, or encapsulating bioactive agents for controlled drug release. Interestingly, plants are a source of biogels, specifically polysaccharides, composed of sugar monomers. The crosslinking of these polymeric chains forms an architecture similar to the extracellular matrix, enhancing the biocompatibility of such materials. Moreover, the rich hydroxyl monomers promote a hydrophilic behavior for these plant-derived polysaccharide gels, enabling their biodegradability and antimicrobial effects. From an economic point of view, such biogels help the circular economy, as a green material can be obtained with a low cost of production. As regards the bio aspect, it is astonishingly attractive since the raw materials (polysaccharides from plants-cellulose, hemicelluloses, lignin, inulin, pectin, starch, guar, and cashew gums, etc.) might be produced sustainably. Such properties make viable the applications of these biogels in contact with the human body, especially incorporating drugs for controlled release. In this context, this review describes some sources of plant-derived polysaccharide gels, their biological function, main methods for extraction, remarkable applications, and properties in the health field.

Role of mitochondria on UV-induced skin damage and molecular mechanisms of active chemical compounds targeting mitochondria

Mitochondria are the principal place of energy metabolism and ROS production, leading to mtDNA being especially sensitive to the impacts of oxidative stress. Our review aims to elucidate and update the mechanisms of mitochondria in UV-induced skin damage. The mitochondrial deteriorative response to UV manifests morphological and functional alterations, including mitochondrial fusion and fission, mitochondrial biogenesis, mitochondrial energy metabolism and mitophagy. Additionally, we conclude the effect and molecular mechanisms of active chemical components to protect skin from UV-induced damage via mitochondrial protection which have been described in the last five years, showing prospective prospects in cosmetics as new therapeutic targets.

Bioadhesive Nanoparticles for Local Drug Delivery

Local drug delivery is an effective strategy for achieving direct and instant therapeutic effects. Current clinical treatments have fallen short and are limited by traditional technologies. Bioadhesive nanoparticles (NPs), however, may be a promising carrier for optimized local drug delivery, offering prolonged drug retention time and steadily maintained therapeutic concentrations. In addition, the possibility of clinical applications of this platform are abundant, as most polymers used for bioadhesion are both biodegradable and biocompatible. This review highlights the major advances in the investigations of polymer-based bioadhesive nanoparticles and their innumerable applications in local drug delivery.

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.

Multilayered mucoadhesive hydrogel films based on Ocimum basilicum seed mucilage/thiolated alginate/dopamine-modified hyaluronic acid and PDA coating for sublingual administration of nystatin

The present study establishes an experimental design for the preparation of new bi and tri-layer mucoadhesive sublingual films based on basil (Ocimum basilicum L.) seed mucilage (OBM) as novel plant-polysaccharide for oromucosal administration of nystatin (Nys). The films formulation consists of a drug reservoir-mucoadhesive layer cross-linked via CaCl₂, with protective mucoadhesive layers based on thiolated alginate (TA) and polydopamine (PDA). OBM served as a new mucoadhesive polysaccharide in second layers, where the dopamine-modified-hyaluronic acid (DHA) improved the mucoadhesive strength and swelling rate properties. The drug-loaded formulations of trilayer film with PDA coating, and bilayer film with DHA/OBM (1:1) in the second layer, showed the desired mucoadhesion properties (about 69 and 75.3% respectively). The obtained results revealed that the bilayer film containing DHA had a superior swelling degree in the range of 15-19 (g/g). While the PDA coating sample showed the highest resistance to water uptake and erosion. The bilayer film (DHA/OBM with 1:1 ratio) provided a maximum drug release of 86% after 4 h. The selected formulations indicated good mechanical properties with no cytotoxicity.

A recent advancement on preparation, characterization and application of nanolignin

Each year, 50 to 70 million tonnes of lignin are produced worldwide as by-products from pulp industries and biorefineries through numerous processes. Nevertheless, about 98% of lignin is directly burnt to produce steam to generate energy for the pulp mills and only a handful of isolated lignin is used as a raw material for the chemical conversion and for the preparation of various substances as well as modification of lignin into nanomaterials. Thus, thanks to its complex structure, the conversion of lignin to nanolignin, attracting growing attention and generating considerable interest in the scientific community. The objective of this review is to provide a complete understanding and knowledge of the synthesis methods and functionalization of various lignin nanoparticles (LNP). The characterization of LNP such as structural, thermal, molecular weight properties together with macromolecule and quantification assessments are also reviewed. In particular, emerging applications in different areas such as UV barriers, antimicrobials, drug administration, agriculture, anticorrosives, the environment, wood protection, enzymatic immobilization and others were highlighted. In addition, future perspectives and challenges related to the development of LNP are discussed.

Depolymerization and Demethylation of Kraft Lignin in Molten Salt Hydrate and Applications as an Antioxidant and Metal Ion Scavenger

To improve the reactivity and enrich the functionality of lignin for valorization, kraft lignin was depolymerized and demethylated via cleaving aryl and alkyl ether bonds in acidic lithium bromide trihydrate (∼60% LiBr aqueous solution). It was found that the cleavage of the ether bonds followed the order of β-O-4 ether > aryl alkyl ether in phenylcoumaran > dialkyl ether in resinol > methoxyl (MeO). The depolymerization via β-O-4 cleavage occurred under mild conditions (e.g., <0.5 M HCl at 110 °C), while sufficient demethylation of the lignin needed harsher conditions (>1.5 M HCl). Both depolymerization and demethylation generated new aromatic hydroxyl (ArOH). With 2.4 M HCl, MeO content dropped from 4.85 to 0.95 mmol/g lignin, and ArOH content increased from 2.78 to 5.09 mmol/g lignin. The depolymerized and demethylated kraft lignin showed excellent antioxidant activity and Cr(VI)-scavenging capacity, compared with original kraft lignin and tannins.

Experimental and Simulation Study of the Solvent Effects on the Intrinsic Properties of Spherical Lignin Nanoparticles

Spherical lignin nanoparticles (LNPs) fabricated via nanoprecipitation of dissolved lignin are among the most attractive biomass-derived nanomaterials. Despite various studies exploring the methods to improve the uniformity of LNPs or seeking more application opportunities for LNPs, little attention has been given to the fundamental aspects of the solvent effects on the intrinsic properties of LNPs. In this study, we employed a variety of experimental techniques and molecular dynamics (MD) simulations to investigate the solvent effects on the intrinsic properties of LNPs. The LNPs were prepared from softwood Kraft lignin (SKL) using the binary solvents of aqueous acetone or aqueous tetrahydrofuran (THF) via nanoprecipitation. The internal morphology, porosity, and mechanical properties of the LNPs were analyzed with electron tomography (ET), small-angle X-ray scattering (SAXS), atomic force microscopy (AFM), and intermodulation AFM (ImAFM). We found that aqueous acetone resulted in smaller LNPs with higher uniformity compared to aqueous THF, mainly ascribing to stronger solvent–lignin interactions as suggested by MD simulation results and confirmed with aqueous 1,4-dioxane (DXN) and aqueous dimethyl sulfoxide (DMSO). More importantly, we report that both LNPs were compact particles with relatively homogeneous density distribution and very low porosity in the internal structure. The stiffness of the particles was independent of the size, and the Young’s modulus was in the range of 0.3–4 GPa. Overall, the fundamental understandings of LNPs gained in this study are essential for the design of LNPs with optimal performance in applications.

Facile fabrication of transparent lignin sphere/PVA nanocomposite films with excellent UV-shielding and high strength performance

With the rapid development of human society, more and more concerns are directed to utilization of environment-friendly and biodegradable materials. To meet this demand, we fabricated an environment-friendly poly (vinyl alcohol) (PVA)/lignin nanocomposite films with excellent UV-shielding and visible-transparent performance. The lignin-based nanosphere (LNSs) were prepared via self-assembly and uniformly distributed in the PVA matrix by forming strong hydrogen bonds with PVA matrix. With the introduction of LNSs into PVA matrix, the various performance such as tensile strength, thermal stability, and UV-shielding of PVA/Lignin nanocomposite films were enhanced. Amazingly, the UV-shielding results revealed that UVB (320-275 nm) and UVC (275-200 nm) were completely shielded and UVA (400-320 nm) was mostly shielded with addition of 4 wt% LNSs. Meanwhile, the tensile strength of the nanocomposite film was dramatically enhanced, in which the strength increased from 76 MPa to 112 MPa. Since both lignin and PVA were biodegradable materials, this work provides a simple and valuable method for the preparation of biodegradable and functional films.

The role of lignin and lignin-based materials in sustainable construction - A comprehensive review

The construction industry in the 21st century faces numerous global challenges associated with growing concerns for the environment. Therefore, this review focuses on the role of lignin and its derivatives in sustainable construction. Lignin's properties are defined in terms of their structure/property relationships and how structural differences arising from lignin extraction methods influence its application within the construction sector. Lignin and lignin composites allow the partial replacement of petroleum products, making the final materials and the entire construction sector more sustainable. The latest technological developments associated with cement composites, rigid polyurethane foams, paints and coatings, phenolic or epoxy resins, and bitumen replacements are discussed in terms of key engineering parameters. The application of life cycle assessment in construction, which is important from the point of view of estimating the environmental impact of various solutions and materials, is also discussed.

Direct Construction of Catechol Lignin for Engineering Long-Acting Conductive, Adhesive, and UV-Blocking Hydrogel Bioelectronics

Long-active conductivity, adhesiveness, and environmental stability are essential in the applications of hydrogel electronics. Integrating different functional materials into one system suffers from compatibility and cost problems. Inspired by the unique o-methoxyl structure in polyphenol lignin and its binding role in plants, catechol lignin (DAL) is constructed by one-step demethylation, which endows the lignin with a mussel-like bioadhesion, good reducibility, as well as a high ultraviolet absorption. The DAL is then applied to reduced graphene oxide, and the products-the oxidized DAL and the reduced graphene oxide mixture (DAL/rGO) is added into a sodium alginate/polyacrylamide (SA/PAM) double network hydrogel. Based on the Schiff base reaction between the quinone of the oxidized DAL and the amino of the skin, the DAL/rGO incorporated hydrogels could stably adhere to the skin, and sensitively respond to physiological signals. In addition, the DAL could provide the hydrogels with long-active sunscreen property when applied to real skin. These DAL based hydrogels have potential for on-skin sensing and outdoor sport equipment.

Enzymatic Preparation and Characterization of Spherical Microparticles Composed of Artificial Lignin and TEMPO-Oxidized Cellulose Nanofiber

A one-pot and one-step enzymatic synthesis of submicron-order spherical microparticles composed of dehydrogenative polymers (DHPs) of coniferyl alcohol as a typical lignin precursor and TEMPO-oxidized cellulose nanofibers (TOCNFs) was investigated. Horseradish peroxidase enzymatically catalyzed the radical coupling of coniferyl alcohol in an aqueous suspension of TOCNFs, resulting in the formation of spherical microparticles with a diameter and sphericity index of approximately 0.8 μm and 0.95, respectively. The ζ-potential of TOCNF-functionalized DHP microspheres was about -40 mV, indicating that the colloidal systems had good stability. Nanofibrous components were clearly observed on the microparticle surface by scanning electron microscopy, while some TOCNFs were confirmed to be inside the microparticles by confocal laser scanning microscopy with Calcofluor white staining. As both cellulose and lignin are natural polymers known to biodegrade, even in the sea, these woody TOCNF-DHP microparticle nanocomposites were expected to be promising alternatives to fossil resource-derived microbeads in cosmetic applications.

State-of-the-Art: Applications and Industrialization of Lignin Micro/Nano Particles

As a new product of high-value utilization of lignin, lignin micro/nano particles (LMNPs) have attracted the attention of researchers due to their non-toxicity, corrosion-resistance, UV resistance, and other excellent characteristics and potential application value. This article outlined the main preparation methods of LMNPs at the current stage, summarized and compared them from three perspectives of preparation technology, final product state and product composition. Subsequently, based on the different focuses of the properties of LMNPs, their application research progress as fillers, UV blockers, drug delivery carriers, among others, were introduced. Then a concise analysis of the technical and economic assessment and life cycle assessment of LMNPs in the process of industrialization was made. Finally, the main problems at present and the future development directions were analyzed and prospected to provide references for the deep processing of forest resources and the development of bio-based nanomaterials.

Construction of Surface-Modified Polydopamine Nanoparticles for Sequential Drug Release and Combined Chemo-Photothermal Cancer Therapy

Single chemotherapy often causes severe adverse effects and drug resistance to limit therapeutic efficacy. As a noninvasive approach, photothermal therapy (PTT) represents an attractive option for cancer therapy due to the benefits of remote control and precise treatment methods. Nanomedicines constructed with combined chemo-photothermal properties may exert synergistic effects and improved antitumor efficacy. In this study, we developed polydopamine (PDA)-coated nanoparticles grafted with folic acid (FA) and polyethylene glycol to transport doxorubicin (DOX) for targeted cancer therapy. The results showed that this delivery vehicle has a nanoscale particle size and narrow size distribution. No particle aggregation or significant drug leakage was observed during the stability test. This system presented excellent photothermal conversion capability under near-infrared light (NIR) laser irradiation due to the PDA layer covering. In vitro dissolution profiles demonstrated that sequential and triggered DOX release from nanoparticles was pH-, NIR irradiation-, and redox level-dependent and could be best fitted with the Ritger-Peppas equation. FA modification effectively promoted the intracellular uptake of nanoparticles by HepG2 cells and therefore significantly inhibited cell recovery and induced tumor cell apoptosis. Compared to the free DOX group, nanoparticles reduced the DOX concentration in the heart to avoid drug-related cardiotoxicity. More importantly, the in vivo antitumor efficacy results showed that compared with the single chemotherapy strategy, the nanoparticle group exerted combined and satisfactory tumor growth inhibition effects with good biocompatibility. In summary, this nanocarrier delivery system can organically combine chemotherapy and PTT to achieve effective and precise cancer treatment.

Lignin-Incorporated Nanogel Serving As an Antioxidant Biomaterial for Wound Healing

Oxidative phosphorylation is an important biological process in the body to produce energy, during which oxygen free radicals are generated as byproduct. Excessive oxygen free radicals cause cell death and reduce the rate of tissue regeneration and healing in a wound. Lignin is a natural antioxidant derived from plants, but its biomedical application is restricted because of the uncertain biocompatibility. In this work, we developed a lignin-incorporated nanogel and explored its application for wound healing. Lignin was extracted from coconut husks and determined to have strong antioxidant activity (IC₅₀ = 25.7 ppm). Various amounts of lignin were incorporated into thermoresponsive nanogels, which were produced from polyurethane copolymers of polyethylene glycol (PEG), polypropylene glycol (PPG), and polydimethylsiloxane (PDMS). It was shown that the addition of lignin had minimal effects on the gelation and rheological properties of the nanogel but slightly increased the critical micelle concentration (CMC) of poly(PEG/PPG/PDMS urethane) copolymer from 3.38 × 10^-4 g mL^-1 to 4.61 × 10^-4 g mL^-1. The lignin-incorporated nanogels did not display detectable cytotoxicity. The lignin-incorporated nanogel possessed antioxidant activity, as it reduced the active oxygen level, protecting the LO2 cells from apoptosis caused by oxidative stress. More importantly, in vivo studies demonstrated that the lignin-incorporated nanogels accelerated the healing of burn wounds in mice as proved by the increased expression of Ki67, one marker of cell proliferation. The present work demonstrates that lignin-incorporated nanogel could serve as an antioxidant wound-dressing material and facilitate the wound healing.

Natural components in sunscreens: Topical formulations with sun protection factor (SPF)

Artificial sunscreens are already gaining traction in order to protect the skin from sunburns, photoaging and photocarcinogenesis. However, the efficacy and safety of most artificial sunscreen constituents are hindered by their photostability, toxicity and damage to marine ecosystems. Natural selection and evolution have ensured that plants and animals have developed effective protective mechanisms against the deleterious side effects of oxidative stress and ultraviolet radiation (UV). Hence, natural antioxidants such as sun blockers are drawing considerable attention. The exact mechanism by which natural components act as sunscreen molecules has not been clearly established. However, conjugated π system is reported to play an important role in protecting the vital genetic material within the organism. Compared to artificial sunscreens, natural sunscreens with strong UV absorptive capacities are largely limited by low specific extinction value and by their inability to spread in large-scale sunscreen cosmetic applications. Previous studies have documented that natural components exert their photoprotective effects (such as improved skin elasticity and hydration, skin texture, and wrinkles) through their antioxidant effects, and through the regulation of UV-induced skin inflammation, barrier impairment and aging. This review focuses on natural antioxidant topical formulations with sun protection factor (SPF). Lignin, melanin, silymarin and other ingredients have been added to high sun protection nature sunscreens without any physical or chemical UV filters. This paper also provides a reference for adopting novel technical measures (extracting high content components, changing the type of solution, optimizing formulation, applying Nano technology, et al) to design and prepare nature sunscreen formulations equated with commercial sunscreen formulations. Another strategy is to add natural antioxidants from plants, animals, microorganisms and marine organisms as special enhancer or modifier ingredients to reinforce SPF values. Although the photoprotective effects of natural components have been established, their deleterious side effects have not been elucidated.

Lignin-Based Nanoparticles: A Review on Their Preparations and Applications

Lignin is the most abundant by-product from the pulp and paper industry as well as the second most abundant natural renewable biopolymer after cellulose on earth. In recent years, transforming unordered and complicated lignin into ordered and uniform nanoparticles has attracted wide attention due to their excellent properties such as controlled structures and sizes, better miscibility with polymers, and improved antioxidant activity. In this review, we first introduce five important technical lignin from different sources and then provide a comprehensive overview of the recent progress of preparation techniques which are involved in the fabrication of various lignin-based nanoparticles and their industrial applications in different fields such as drug delivery carriers, UV absorbents, hybrid nanocomposites, antioxidant agents, antibacterial agents, adsorbents for heavy metal ions and dyes, and anticorrosion nanofillers.