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1.
J Agric Food Chem ; 69(37): 10838-10847, 2021 Sep 22.
Artigo em Inglês | MEDLINE | ID: mdl-34515475

RESUMO

The traditional pretreatment leads to the recalcitration of C-C bonds during lignin fractionation, thus hindering their depolymerization into aromatic monomers. It is essential to develop an applicable approach to extract noncondensed lignin for its high-value applications. In this work, noncondensed lignins were extracted from poplar sawdust using recyclable p-toluenesulfonic acid for cleaving lignin-carbohydrate complex bonds effectively and ethanol as a stabilization reagent to inhibit lignin condensation. Lignin yield of 83.74% was recovered by 3 mol/L acid in ethanol at 85 °C for 5 h, and carbohydrates were well preserved (retaining 98.97% cellulose and 50.01% hemicelluloses). During lignin fractionation, the acid concentration and extraction time were the major drivers of condensation. Ethanol reacted with lignin at the α-position to prevent the formation of the condensed structure. The extracted lignin depolymerized over the Pd/C catalysts gave a yield of 50.35% of aromatic monomers, suggesting that the novel extraction process provided a promising way for noncondensed lignin production.


Assuntos
Lignina , Populus , Benzenossulfonatos , Etanol , Madeira
2.
ACS Appl Mater Interfaces ; 13(37): 44243-44253, 2021 Sep 22.
Artigo em Inglês | MEDLINE | ID: mdl-34499461

RESUMO

The photoreforming of lignocellulose is a novel method to produce clean and sustainable H2 energy. However, the catalytic systems usually show low activity under ultraviolet light; thus, this reaction is very limited at present. Visible light-responsive metal-free two-dimensional graphite-phased carbon nitride (g-C3N4) is a good candidate for photocatalytic hydrogen production, but its activity is hindered by a bulky architecture. Although reported layered g-C3N4 modified with active functional groups prepared by the chemical exfoliation enhances the photocatalytic activity, it lost the intrinsic structure and thus is not conducive to understand the structure-activity relationship. Herein, we report an intrinsic monolayer g-C3N4 (∼0.32 nm thickness) prepared by nitrogen-protected ball milling in water, which shows good performance of photoreforming lignocellulose to H2 driven by visible light. The exciton binding energy of g-C3N4 was estimated from the temperature-dependent photoluminescence spectra, which is a key factor for subsequent charge separation and energy transfer. It is found that monolayer g-C3N4 with smaller exciton binding energy increases the free exciton concentrations and promotes the separation efficiency of charge carriers, thereby effectively improving its performance of photocatalytic reforming of lignocellulose, even the virgin lignocellulose and waste lignocellulose. This result could lead to more active catalysts to photoreform the raw biomass, making it possible to provide clean energy directly from locally unused biomass.

3.
Artigo em Inglês | MEDLINE | ID: mdl-34383477

RESUMO

Selective saccharification of cellulose into glucose is a critical step for utilization of lignocellulosic biomass. Molten salt hydrates (MSHs) have shown promising performance in selectively converting cellulose into glucose because of the high solubility of cellulose in the solvent. However, the separation of formed glucose from the MSHs is still a grand challenge. To address this issue, we developed a two-step process, where crystalline cellulose is hydrolyzed into short-chain glucan oligomers in MSHs followed by separation and subsequent hydrolysis of the formed oligomers into glucose under mild conditions. The two-step method provides an easy separation for glucan oligomers from the MSHs without sacrificing the selectivity to glucose. Application of the method for crystalline cellulose is, however, limited to a relatively low concentration, 26.2 mg/mL, because of the formation of byproducts in the MSH that facilitate oligomers degradation. In this work, reactive adsorption was employed to in situ remove the byproducts formed during cellulose hydrolysis in the MSH. It was found that hyper-cross-linked polymer (HCP) made from the polymerization of 4-vinylbenzyl chloride and divinylbenzene can selectively adsorb 5-hydroxymethylfurfural (5-HMF) and levulinic acid (LA) while showing negligible sugar adsorption in both water and the MSH. With the reactive adsorption approach, byproducts including 5-HMF and LA were removed from the reaction media under reaction conditions, and their negative effects on oligomer degradation were inhibited. In the presence of the HCP, the obtained glucan oligomer concentration was enhanced from less than 54.2 to 247.1 mg mL-1 when the weight ratio of cellulose was increased to MSH from 1:60 to 1:4, exhibiting an oligomer yield of 69.5%. The HCP can be effectively separated from the reaction media by filtration and regenerated by oxidation with hydrogen peroxide. Application of reactive adsorption with HCP for cellulose hydrolysis in the MSH provides a promising method to produce glucan oligomers and glucose with an improved yield and efficiency.

4.
Food Funct ; 12(16): 7469-7479, 2021 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-34196335

RESUMO

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.

5.
Int J Biol Macromol ; 183: 1450-1458, 2021 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-33974926

RESUMO

In this work, the coordination-based energy sacrificial bonds have been constructed in the interphase between lignin and polyolefin elastomer to prepare high performance lignin-based thermoplastic elastomers (TPEs). The strength and toughness of lignin-based TPEs can be adjusted by choosing different nitrogen heterocyclic compounds as reactive assistants and Fe3+ or Zn2+ as metal coordination centers. It was demonstrated that 3-Amino-1,2,4-triazole with three nitrogen atoms in the heterocyclic ring and one nitrogen branch chain could form the most efficient coordination bond system and generate the best mechanical performance. The system with ferric iron as coordination center exhibited better enhancement effect than divalent zinc. By adjusting the nitrogen-containing reactive additives or metal salts as coordination centers, the mechanical performance of the lignin-based TPE can be regulated, which provides a method for making green bio-composites with good strength and toughness, and also promotes the high value utilization of lignin in polymer materials.


Assuntos
Elastômeros/química , Lignina/química , Nitrogênio/química , Polienos/química
6.
Nat Commun ; 12(1): 2916, 2021 05 18.
Artigo em Inglês | MEDLINE | ID: mdl-34006839

RESUMO

Artificial muscle materials promise incredible applications in actuators, robotics and medical apparatus, yet the ability to mimic the full characteristics of skeletal muscles into synthetic materials remains a huge challenge. Herein, inspired by the dynamic sacrificial bonds in biomaterials and the self-strengthening of skeletal muscles by physical exercise, high performance artificial muscle material is prepared by rearrangement of sacrificial coordination bonds in the polyolefin elastomer via a repetitive mechanical training process. Biomass lignin is incorporated as a green reinforcer for the construction of interfacial coordination bonds. The prepared artificial muscle material exhibits high actuation strain (>40%), high actuation stress (1.5 MPa) which can lift more than 10,000 times its own weight with 30% strain, characteristics of excellent self-strengthening by mechanical training, strain-adaptive stiffening, and heat/electric programmable actuation performance. In this work, we show a facile strategy for the fabrication of intelligent materials using easily available raw materials.


Assuntos
Materiais Biomiméticos/química , Biomimética/métodos , Exercício Físico/fisiologia , Músculo Esquelético/fisiologia , Materiais Inteligentes/química , Órgãos Artificiais , Elastômeros/química , Humanos , Fenômenos Mecânicos , Polienos/química , Robótica/instrumentação , Robótica/métodos
7.
Int J Biol Macromol ; 180: 523-532, 2021 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-33745976

RESUMO

Nano silica (SiO2) is usually used as a common reinforcing agent in polymer materials, in which the interfacial interaction greatly affects the mechanical properties of the composites. The reinforcement effect of silica on non-polar polymer is restricted due to their poor compatibility. In this work, amphipathic lignin modified by quaternization and alkylation was used as a modifier for silica to prepare hydrophobic lignin/SiO2 nanoparticles by in-situ one-pot co-precipitation method. In alkaline solution, hydrophobic lignin and SiO2 (from Na2SiO3) were self-assembled to form nanospheres through electrostatic and hydrophobic interactions. The results showed that the lignin/SiO2 nanoparticles were highly hydrophobic nanospheres with macropores in the surface. When the lignin/SiO2 nanoparticles (10 wt%) were added to reinforce high-density polyethylene (HDPE), the mechanical properties of HDPE were improved with the strength of 24.5 MPa and the elongation of 1096%, which were increased by 10.4% and 14.3% compared with the control HDPE, because of the good compatibility and large bonding area. This work puts forward a new solution for the application of lignin in reinforcement of non-polar polymers.


Assuntos
Lignina/química , Nanocompostos/química , Nanopartículas/química , Polietileno/química , Dióxido de Silício/química , Álcalis/química , Interações Hidrofóbicas e Hidrofílicas , Fenômenos Mecânicos , Microscopia Eletrônica de Varredura , Modelos Químicos , Estrutura Molecular , Nanocompostos/ultraestrutura , Nanopartículas/ultraestrutura , Polímeros/química , Espectroscopia de Infravermelho com Transformada de Fourier , Eletricidade Estática , Propriedades de Superfície , Difração de Raios X
8.
J Colloid Interface Sci ; 594: 316-325, 2021 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-33773384

RESUMO

Lignin has been demonstrated to be green and effective for the modification of ZnO-based materials. In this work, quaternized lignin/zinc oxide nanostructured hybrid composites (QLS/ZnO NCs) were synthesized with good dispersion and uniform particle size via a facile hydrothermal method. Sodium lignosulfonate (LS) was modified by quaternization to endow the positive charges, which effectively captured bacteria due to the electrostatic interactions. Interestingly, QLS/ZnO NCs show a litchi-like morphology consisting of nanorods with diameters of 5-10 nm, which further resulted in damage to the bacterial cell membrane. Owing to the surface charge and rough surface topology for bacterial capture, QLS/ZnO NCs exhibited greatly enhanced antibacterial activity compared with bare ZnO. After being treated with QLS/ZnO NCs for 90 min, the sterilization rates of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) reached 97.54% and 99.55%, respectively. Due to the reactive oxygen species (ROS) produced by ZnO under light irradiation, the antibacterial activity of QLS/ZnO NCs could be further enhanced. In addition, the minimal inhibition concentrations (MICs) of QLS/ZnO NCs towards E. coli and S. aureus were both 100 µg/mL, and the minimum bactericidal concentrations (MBCs) were 100 µg/mL and 200 µg/mL, respectively. Moreover, with the incorporation of QLS/ZnO NCs into polyurethane films, the composite films showed excellent antibacterial activity, strong tensile strength and enhanced ultraviolet light blocking performance.


Assuntos
Litchi , Nanocompostos , Óxido de Zinco , Antibacterianos/farmacologia , Escherichia coli , Lignina , Poliuretanos , Staphylococcus aureus , Óxido de Zinco/farmacologia
9.
Carbohydr Polym ; 259: 117759, 2021 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-33674013

RESUMO

The simultaneous attainment of high strength and high toughness of transparent cellulose nanofibril (CNF) film can expedite its uses in advanced applications. In this work, a wood-inspired strategy is proposed to address the conflict between strength and toughness by using natural derived lignosulfonic acid (LA) as a reinforcing additive. Only 1 wt% LA addition can double the toughness (11.0±1.3 MJ/m3) of pure CNF film. Consequently, the as-prepared CNF/LA-1 nanocomposite film not only exhibits superior mechanical properties (23.6±1.3 MJ/m3 toughness, 249±6 MPa strength, and 15.4±1.4 % strain), but also maintains an excellent optical transparency of 91.2 % (550 nm). Furthermore, the mechanism for simultaneously enhancing strength and toughness is essentially attributed to the improved hydrogen bonding between CNF-OH and LA-SO3H and effective energy dissipation system. This work provides a green and effective approach to prepare strong yet tough and transparent biodegradable CNF film for high-end applications.

10.
Int J Biol Macromol ; 175: 516-525, 2021 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-33571593

RESUMO

This study demonstrated a facile method to synthesize lignin-based carbon dots (L-CDs) first. Results indicated that the L-CDs had a diameter of 2-5 nm and a graphene-like crystalline structure. It was found that under the optimal synthesis conditions, the fluorescence lifetime of L-CDs was about 12 ns. Within the range of pH 1-10, the fluorescence intensity of the L-CDs and pH value followed a linear relationship. With the contribution of L-CDs, pH/temperature dual responsive hydrogel was synthesized. The elastic modulus G' of hydrogel was much higher than viscous modulus G″. When the PVA content was larger than 10 wt%, the temperature sensitivity and water retention rate gradually decreased. The skeleton of hydrogels had a typical porous honeycomb structure, which made it possible to control its internal pore size by adjusting the content of PVA. There was a linear relationship between the fluorescence intensity of hydrogels and pH value in the range of pH 1-7. Therefore, the pH/temperature dual responsive hydrogel presented a new route for designing tissue engineering scaffolds and drug carriers.


Assuntos
Hidrogéis/síntese química , Lignina/química , Pontos Quânticos/química , Carbono/química , Portadores de Fármacos/química , Fluorescência , Corantes Fluorescentes/química , Concentração de Íons de Hidrogênio , Lignina/síntese química , Microscopia de Força Atômica/métodos , Porosidade , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Análise Espectral Raman/métodos , Temperatura , Engenharia Tecidual/métodos , Tecidos Suporte , Viscosidade
11.
J Colloid Interface Sci ; 591: 352-362, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33618293

RESUMO

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.


Assuntos
Quitosana , Nanopartículas , Neoplasias , Emulsões , Lignina , Oligossacarídeos , Tamanho da Partícula , Microambiente Tumoral
12.
J Colloid Interface Sci ; 583: 80-88, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-32977194

RESUMO

Lignin has been considered as a green carrier with excellent biocompatibility for the biomedical applications in drug release, tissue engineering, etc. In this study, silver nanoparticles (AgNPs) incorporated quaternized lignin (QAL) composites (Ag@QAL) were synthesized in-situ with the assistance of the microwave radiation. The positive charged QAL, not only serves as reductive and stabilizing carriers, but also endows with electrostatic effect toward negatively charged Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), resulting in greatly enhanced antibacterial activity. It is worth mentioning that Ag@QAL exhibits the highest antibacterial activity, which causes 3.72 log10 (>99.9%) and 5.29 log10 (>99.999%) CFU/ml reduction against E. coli and S. aureus respectively after contacting for only 5 min. Furthermore, due to the strong interaction between Ag@QAL and Ag+/AgNPs, bacteria can be captured and co-precipitated by Ag@QAL fastly in 30 min with almost none silver ions detected in the supernatant, which prevents Ag+ leaking with extremely low toxicity to the biological environment. This concept of electrostatic capture effect induced antibacterial activity enhancement and environmentally benign features may provide new insights into the design of highly effective antibacterial agents in a sustainable manner.


Assuntos
Nanopartículas Metálicas , Prata , Antibacterianos/farmacologia , Escherichia coli , Lignina , Testes de Sensibilidade Microbiana , Micro-Ondas , Prata/farmacologia , Staphylococcus aureus , Eletricidade Estática
13.
J Colloid Interface Sci ; 587: 334-346, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33370659

RESUMO

Green synthesis of silver nanoparticles (AgNPs) has received increasing attention. In this study, AgNPs were prepared through in-situ reduction by aminated alkaline lignin (AAL). Compared with alkaline lignin (AL), AAL exhibited stronger reduction capacity (increased by 36%) due to the introduced amine groups and better water solubility. Moreover, the coordination effect of amine groups on AAL improved the binding force between lignin and AgNPs. The content of AgNPs in AgNPs/AAL composite were 2.4 times higher than that in AgNPs/AL, such content could be further increased through increasing the reduction pH or prolonging the heating time. The results of XPS, XRD and TEM showed that the AgNPs were spherical and monodisperse with an average particle size about 17 nm. Additionally, the size of AgNPs was affected by the amination degree of lignin. AgNPs/AAL exhibited good catalytic performance for the reduction of 4-nitrophenol to 4-aminophenol, and this compound could be easily recovered and reused for at least eight cycles.

14.
Polymers (Basel) ; 12(11)2020 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-33113775

RESUMO

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.

15.
J Agric Food Chem ; 68(35): 9451-9460, 2020 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-32786822

RESUMO

The effects of cetyltrimethylammonium bromide (CTAB) on the aggregation behavior of sodium lignosulfonate (NaLS) in concentrated solutions were investigated by rheology, conductivity, ζ-potential, surface tension, contact angle, and elemental analysis measurements. Results showed that the presence of CTAB led to increased aggregate effects and enhanced association networks due to intermolecular bridging caused by the formation of mixed aggregates containing NaLS hydrophobes and CTAB molecules at CTAB/NaLS mixing ratios (w/w) below stoichiometric mass ratio (SMR). However, further addition of CTAB resulted in the progressive disruption of network structures due to electrostatic repulsions between aggregates. There were electrostatic and hydrophobic interactions between NaLS and CTAB. The NaLS/CTAB mixing system could form regular colloidal spheres via electrostatic and hydrophobic self-assembly in an EtOH/water mixture. As the addition of CTAB increased, the ζ-potential of NaLS/CTAB colloidal spheres was decreased, and the particle size was increased. This work provides a novel approach to the value-added utilization of lignosulfonate biomass resources.


Assuntos
Cetrimônio/química , Lignina/análogos & derivados , Sódio/química , Coloides/química , Interações Hidrofóbicas e Hidrofílicas , Lignina/química , Tamanho da Partícula , Reologia , Eletricidade Estática
16.
ChemSusChem ; 13(17): 4691-4701, 2020 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-32666648

RESUMO

Reusable, self-healable, removable, and strong bio-based polyurea adhesives were successfully synthesized via partially substituting polyetheramine with polyetheramine-grafted lignin and introducing a chain extender containing dynamic disulfide bonds. The polyetheramine-grafted lignin endowed the polyurea adhesives with significantly enhanced adhesion strength on either metal or wood substrates by introducing intensive hydrogen bonding interactions; the dynamic disulfide bonds played a key role in the excellent self-healing and reusable performance. The thermostability of polyurea adhesives was also improved by introducing lignin. This work provides a novel approach for the high-value utilization of low-cost lignin in recyclable adhesives with excellent comprehensive performance.

17.
ChemSusChem ; 13(18): 4974-4984, 2020 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-32666708

RESUMO

In this work, inspired by the dynamic sacrificial hydrogen bonds in biological materials, a very strong, super-tough, antibacterial, and cost-effective biodegradable poly(vinyl alcohol) (PVA) nanocomposite material was developed by incorporating the nanoscale antibacterial agent TA@LS-Ag. TA@LS-Ag was prepared from the green biomass tannic acid (TA) and sodium lignosulfonate (LS), and was facilely incorporated into the PVA matrix with a homogeneously interspersed nanoparticle size of about 20 nm. The PVA nanocomposite film with 2 wt % addition of TA@LS-Ag achieved the highest specific toughness of 262 J g-1 among the PVA-based films to date, which is far higher than that of natural spider silk (150-190 J g-1 ), as well as a very high tensile strength of 131.6 MPa. The excellent tensile strength and superior toughness were attributed to synergy of the nanophase separation structure and the intense hydrogen-bonding interactions between the nanoparticles and PVA matrix. The PVA/TA@LS-Ag nanocomposite films exhibited good antibacterial properties, despite the extremely low silver content (0.032-0.32 wt ‰). TA@LS-Ag also endowed the PVA films with excellent antioxidant and UV-shielding performance. As the biomass-derived LS and TA and the PVA matrix are all biodegradable, this work offers a facile strategy for preparing high-performance antibacterial and biodegradable polymeric materials.


Assuntos
Antibacterianos/química , Nanopartículas Metálicas/química , Nanocompostos/química , Álcool de Polivinil/química , Prata/química , Animais , Escherichia coli/efeitos dos fármacos , Ligação de Hidrogênio , Lignina/análogos & derivados , Lignina/química , Testes de Sensibilidade Microbiana , Seda/química , Aranhas , Taninos/química , Resistência à Tração , Raios Ultravioleta
18.
Biomacromolecules ; 21(8): 3231-3241, 2020 08 10.
Artigo em Inglês | MEDLINE | ID: mdl-32662631

RESUMO

UV filters that contain one or two aromatic rings in conventional sunscreens generally have a poor photo- and thermal stability and can easily penetrate through stratum corneum and dermis into the blood vessel, thus causing potential health-threatening issues. Herein, a series of bioinspired photostable and biocompatible polydopamine-grafted lignin (AL-PDA) with strong bioadhesion have been synthesized through free radical addition of dopamine (DA) and alkali lignin (AL). AL-PDA was used to emulsify organic UV filters and further cross-linked to form nanocapsules through ultrasonic cavitation. The retention rate of optimal AL-PDA nanocapsules on the skin surface reached 87% after a thorough rinse with water and negligible penetration was observed, which demonstrates their excellent bioadhesion property. Force measurements using atomic force microscopy (AFM) quantitatively revealed the adhesion between the nanocapsules and skin. An average DA grafting number of 4 would be required to endow the AL-PDA nanocapsules with suitable water-penetration resistance. The nanocapsules were used as the sole active ingredient for formulating sunscreen, whose sun protection factor (SPF) value could reach 195.33 with a dosage ∼10 wt % lasting for over 8 h under UV radiation. The as-prepared nanocapsules possess excellent antioxidant capacity and biocompatibility, ensuring their superior performance and safe use in the sunscreen. This work provides new insights into the development of biomass lignin for advanced function materials and high-end products.


Assuntos
Nanocápsulas , Protetores Solares , Indóis , Lignina , Polímeros , Pele , Raios Ultravioleta
19.
ACS Appl Mater Interfaces ; 12(23): 26399-26404, 2020 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-32427459

RESUMO

Cellulosic materials are attractive candidates for nature piezoelectrics. Vertically aligned cellulose nanocrystal (CNC) films are expected to show strong piezoelectricity as the largest dipole moment in CNCs exists along the cellulose chain. In this work, we adapted the confinement cell technology that was used to fabricate colloidal opal structures to align CNC rods vertically on a large scale. The high interfacial energy between the CNC-poly(tetrafluoroethylene) (PTFE) surface and torque induced by the shear force led to a large degree to the vertical alignment of CNC rods. An external DC electric field was added to further align the dipole moment of each CNC to the same direction. The as-obtained CNC film displayed excellent piezoelectric performance, and the piezoelectric coefficient was found to be 19.3 ± 2.9 pm/V, comparable to the piezoelectric coefficient d33 of poly(vinylidene difluoride) (PVDF) (20-30 pm/V). This work presents a new class of high-performance piezoelectric polymeric materials from renewable and biocompatible natural resources.

20.
Int J Biol Macromol ; 158: 430-442, 2020 Apr 19.
Artigo em Inglês | MEDLINE | ID: mdl-32320804

RESUMO

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.

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