Sunscreen Performance of Lignin from Different Technical Resources and Their General Synergistic Effect with Synthetic Sunscreens

Five types of industrial lignin are blended with a pure cream and a commercial sunscreen lotion. Lignin is found to significantly boost their sunscreen performance. Photostability of the lignin-modified lotions is analyzed. The results show that hydrophobic lignin has better sunscreen performance than hydrophilic counterpart. Sun protection factor (SPF) of the pure cream containing 10% organosolv lignin (OL) reaches 8.66. Small amount of hydrophobic lignin dramatically increases SPF value of the sunscreen lotions. Adding 1% lignin almost doubles the sun lotion’s SPF. Addition of 10% OL to the lotion boosts its SPF from 15 to 91.61. However, it is also found that hydrophilic lignin tends to demulsify the lotions due to an electrostatic disequilibrium. After 2 h of UV radiation, UV absorbance of all the five lignin-modified sunscreen lotions increases up to the limit of measuring instrument. All the lignin types studied in this work are found to have a general synergistic effect with sunscreen actives in the commercial lotion. An effort is also made to elucidate radical mechanisms of the synergy

A Degradable Mulch Film with Fertilizer Slow-Release Function Enhanced by Lignin

Mulch film and slow-release fertilizers are widely used in agriculture and horticulture, and it has become a trend to use degradable materials for the preparation of mulch films using slow-release materials. However, most degradable materials have poor performance or relatively high cost. In this study, three types of degradable materials, namely, poly(vinyl alcohol) (PVA), corn starch (CS), and alkali lignin (AL), were used as degradable materials to obtain a mulch film with a slow-release fertilizer function (MSRF). MSRF had excellent performance when 10% AL was added. The properties consisted of elongation at break (180.14%), water vapor permeability (203.8 g m–2 day–1), water resistance (its morphology remained good for 50 days), water absorption (300%), and urea release efficiency (cumulative release of 70.63% in 30 days). Rapid plant growth trials demonstrated that the MSRF had excellent functionality and that the MSRF could reduce the amount of fertilizer applied by about 70%. These excellent performances were due to the combination of chemical cross-linking (chemical bonding) between AL and PVA/CS molecular chains, the hydrogen bonding between the AL, PVA, and CS molecules, and the aggregation properties of AL. This provided a green and efficient strategy for the preparation and application of dual functions of mulching and the slow release of fertilizer

Preparation of Photoresponsive Azo Polymers Based on Lignin, a Renewable Biomass Resource

Lignin-based azo polymers are prepared from alkali lignin, a byproduct in spent liquor from the pulping and papermaking industry, and their structures and photochromic effects are characterized by elemental analysis, Fourier transform infrared, ¹H nuclear magnetic resonance, and ultraviolet–visible spectroscopy. Results show that only the 2-(4-nitrophenyl azo) phenol lignin-modified polymer (AL-azo-NO₂) shows a significant photochromic effect, and its photoresponsive behavior is evidently slower than that of the synthetic polymer with a similar azo chromophore. For the 2-(4-methoxyphenyl azo) phenol lignin-modified polymer, its photoisomerization behavior was expected to be similar to that of azobenzene-type molecules, but its photoresponse is not obvious. The abnormal photochromic effect of AL-azo polymers is related to strong steric hindrance of lignin backbones. With addition of water (poor solvent), AL-azo-NO₂ shrinks gradually, which prevents azobenzene groups from isomerizing and results in a lower isomerization efficiency at higher water contents. Preparation of lignin-based azo polymers offers a novel source of azo polymers and provides a green and sustainable pathway for value-added utilization of lignin biomass recovered from the pulping industry

Conductivity Enhancement of Poly(3,4-ethylenedioxythiophene)/Lignosulfonate Acid Complexes via Pickering Emulsion Polymerization

Poly­(3,4-ethylenedioxythiophene)/lignosulfonate acid (PEDOT/LS) submicron particles are doped into a 3,4-ethylenedioxythiophene (EDOT)/water mixture as a solid stabilizer to form a Pickering emulsion. The conductivity of the new PEDOT/LS complexes prepared by Pickering emulsion polymerization (PEDOT/LS-PEP) is improved by 2 orders of magnitude. The structure and properties of PEDOT/LS-PEP are investigated by UV, FTIR, XRD, XPS, DLS, optical microscope, four point probe meter, and surface resistance tester. The results show that the average particle size increases from 550 nm to 2.4 μm, and the PEDOT content in PEDOT/LS-PEP is 3.5 times that in the original PEDOT/LS submicron particles, while the structure of PEDOT/LS-PEP remains amorphous. Due to the enhancement in conductivity, the coating film made by PEDOT/LS-PEP decreases the surface resistance of glass from 10¹² to 10⁶ Ω sq^–1. These new PEDOT/LS-PEP complexes meet the requirement of industrial antistatic materials well

Synergistic Antioxidant Performance of Lignin and Quercetin Mixtures

A natural, effective, and inexpensive hindered phenolic antioxidant mixture was prepared by blending lignin into quercetin. The antioxidant performance of lignin and quercetin mixture was analyzed by determining the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity and a low-cost and high-efficiency ratio was found to be 4:1 (w/w). After UV radiation for 4 h, the DPPH scavenging ratio of the quercetin/lignin mixture decreased only 13.8%, while that of quercetin and lignin decreased 42.9% and 28.6%, respectively. The UV and fluorescence analysis indicated that quercetin molecules inserted into the lignin to weaken its aggregation and form new conjugated structures. Adding lignin may provide a green alternative to the expensive quercetin or synthetic antioxidants used in food, cosmetics, and pharmaceuticals

Whitening Sulfonated Alkali Lignin via H₂O₂/UV Radiation and Its Application As Dye Dispersant

Sulfonated alkali lignin (SAL) can be used as dye dispersants, but its dark color may lead to a severe staining problem, thus hindering its application. Here, a UV/H₂O₂ whitening process was applied to decolorize SAL and the color was faded by 50%. The structural changes of SAL before and after whitening were characterized by GPC, UV–vis, FTIR, fluorescence, and potentiometric titration, and the mechanism of decolorization was deduced. The results show that the contents of aromatic ring, methoxyl, and phenolic hydroxyl groups in SAL decreased by 37%, 64%, and 78%, respectively, while the content of carboxylic groups increased by 187% after being radiated in H₂O₂ for 20 h. The changes in chromophoric group and the contribution of each chromophoric group to the overall color before and after whitening were also investigated. Due to the removal of chromophores, the staining phenomenon of light-colored SAL (LSAL) was reduced effectively when it was used as a dye dispersant

Fabrication of Lignosulfonate Vesicular Reverse Micelles to Immobilize Horseradish Peroxidase

Sodium lignosulfonate reverse micelles (SLRMs) with vesicular structure were prepared by self-assembling in ethanol–water media and applied to encapsulate horseradish peroxidase (HRP). Results showed that sodium lignosulfonate (SL) could not form SLRMs until the ethanol content reached 63% when its initial concentration was 7.5 g L^–1. Owing to strong electrostatic repulsion, solid spherical SLRMs gradually swelled to stable vesicular structures with an average size of 240 nm. The shell of the SLRM thickened when NaCl was added to screen the electrostatic interaction. HRP can be effectively encapsulated while retaining its activity in the hydrophilic core of a SLRM. When hydrogen peroxide was added to initiate the catalytic activity of HRP, SL molecules would be polymerized and the structure of SLRMs would be fixed. Furthermore, HRP immobilized in polymerized SLRMs showed high activity at a more acidic pH of 4 and at a lower optimal temperature decrease of 35 °C compared to free HRP. SLRM allows enzymes such as HRP to work at more acidic and lower temperature conditions

Novel 1,8-Naphthalimide Derivatives As Antitumor Agents and Potent Demethylase Inhibitors

Functional 1,8-naphthalimide derivatives are rapidly developing in the field of anticancer research. Herein, we designed and synthesized a series of naphthalimide derivatives with different substituents. Interestingly, 1,8-naphthalimide derivatives 1 and 7 inhibited a human demethylase FTO (the fat mass and obesity-associated protein). Computer simulation studies further indicated that 1 and 7 entered the FTO’s structural domain II binding pocket through hydrophobic and hydrogen bonding interactions. Anticancer mechanism studies showed that 1 and 7 induced DNA damage and autophagic cell death in A549 cells. The high antiproliferative activity of 1 and 7 was further confirmed by 3D multicellular A549 tumor spheroid assays. This study focuses on the cytotoxicity and mode of action of naphthalimide derivatives, which not only have potential anticancer activity but also are potent demethylase inhibitors

Activation of C–H Bonds in Nitrones Leads to Iridium Hydrides with Antitumor Activity

We report the design and synthesis of a series of new cyclometalated iridium hydrides derived from the C–H bond activation of aromatic nitrones and the biological evaluation of these iridium hydrides as antitumor agents. The nitrone ligands are based on the structure of a popular antioxidant, α-phenyl-<i>N</i>-<i>tert</i>-butylnitrone (PBN). Compared to cisplatin, the iridium hydrides exhibit excellent antitumor activity on HepG2 cells. The metal-coordinated compound with the most potent anticancer activity, <b>2f</b>, was selected for further analysis because of its ability to induce apoptosis and interact with DNA. During in vitro studies and in vivo efficacy analysis with tumor xenograft models in Institute of Cancer Research (ICR) mice, complex <b>2f</b> exhibited antitumor activity that was markedly superior to that of cisplatin. Our results suggest, for the first time, that metal hydrides could be a new type of metal-based antitumor agent

Indazolin‑<i>s</i>‑ylidene–N-Heterocyclic Carbene Complexes of Rhodium, Palladium, and Gold: Synthesis, Characterization, and Catalytic Hydration of Alkynes

A novel series of Indy-N-heterocyclic carbene ligands (Indy = indazolin-<i>s</i>-ylidene) have been developed and investigated. Via a mild Ag carbene transfer route, these new carbene ligands reacted with rhodium, palladium, and gold salts to yield the corresponding air-stable metal complexes. The product complexes were characterized by NMR spectroscopic methods and X-ray diffraction analysis. The electronic properties of these complexes were modified by the introduction of different substituents at the coordinated NHC ligands. Catalytic properties of the gold complex were evaluated in the hydration of alkynes to give the corresponding ketone products. This new type of gold N-heterocyclic carbene complex showed a high catalytic activity in the hydration of alkyne at room temperature