γ-Valerolactone/water system for lignin fractionation to enhance antibacterial and antioxidant capacities

Xu, Ying-Hong; Zeng, Peng; Li, Mingfei; Bian, Jing; Peng, Feng

doi:10.1016/j.seppur.2021.119780

Cited by 48 publications

(15 citation statements)

References 47 publications

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“…The onset temperatures were in the range of 180 and 250 • C, followed by a rapid decrease in mass (~50%) up to 450 • C. Then, there was a slow decrease in mass until 800 • C. The residual weights of materials extracted with AcOH, AcOH: H 2 O, the standard lignin of AFEX-EH-UHS, and AD-UHS were 40%, 36%, 38%, and 33%, respectively. Similar TGA curves and corresponding residue mass percentages were observed in other work [39], in which the isolated lignin also contained little amounts of carbohydrates. The results confirmed that the presence of recalcitrant carbohydrates with lignin would change the required temperature for decomposition, and thus, affect the amount of produced biochar.…”

Section: Thermogravimetric Analysis (Tga)supporting

confidence: 86%

Isolation of Lignin from Anaerobically Digested Unhydrolyzed Solids Produced in a Biorefinery

et al. 2022

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About 30–40% of lignin-rich unhydrolyzed solids (UHS) are left behind after subjecting lignocellulosic biomass to thermochemical pretreated processes followed by enzymatic hydrolysis (EH) to produce sugars that are fermented to fuels and chemicals in a biorefinery. Ammonia Fiber Expansion (AFEX) is one of the leading alkaline pretreatment processes that use volatile ammonia that can be recovered and reused beneficially for the environment. In this work, we used AFEX-EH-UHS which are produced after subjecting corn stover to AFEX followed by EH and contain carbohydrates, ashes, and other impurities that are detrimental to the conversion of lignin to high-value products. In the study, we discovered that ~80% of the carbohydrates present in AFEX-EH-UHS were hydrolyzed and consumed during the AD process. The resulting solids, hereafter called AD-UHS, were subjected to lignin extraction using different combinations of solvents under reflux conditions. The solvent-extracted lignin was subjected to thermogravimetry, nuclear magnetic resonance (NMR) spectroscopy, and molecular weight analysis. Among the solvents, acetic acid could produce 95% pure lignin with some chemical modification, while aqueous ethanol was able to produce 80% pure lignin without any chemical modification.

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Section: Thermogravimetric Analysis (Tga)supporting

confidence: 86%

Isolation of Lignin from Anaerobically Digested Unhydrolyzed Solids Produced in a Biorefinery

et al. 2022

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“…Mathew's research studies 54 showed that the thermal stability of nanocellulose improved; it also exhibited excellent antioxidant and antibacterial activities, due to the addition of lignin. Li et al 55 proposed that the phenolic hydroxyl groups in lignin result in a low-pH environment around the cell membrane, destroy the proton movement of the cell membrane, and eventually lead to the rupture and dissolution of the cell membrane. In addition, the antibacterial mechanism of lignin may also include leakage of cell contents and enzyme inhibition.…”

Section: Antimicrobial Propertiesmentioning

confidence: 99%

Antimicrobial Lignin-Based Polyurethane/Ag Composite Foams for Improving Wound Healing

Zhang

et al. 2022

Biomacromolecules

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Antimicrobial materials are an urgent need for modern wound care in the clinic. Although traditional polyurethane foams have proven to be clinically valuable for wound treatment, their petroleum-originated preparation and bioinert nature have restricted their efficacy in biomedical applications. Here, we propose a simple one-step foaming method to prepare lignin-based polyurethane foams (LPUFs) in which fully biobased polyether polyols partially replace traditional petroleum-based raw materials. The trace amount of phenolic hydroxyl groups (about 4 mmol) in liquefied lignin acts as a direct reducing agent and capping agent to silver ions (less than 0.3 mmol), in situ forming silver nanoparticles (Ag NPs) within the LPUF skeleton. This newly proposed lignin polyurethane/Ag composite foam (named as Ag NP-LPUF) shows improved mechanical, thermal, and antibacterial properties. It is worth mentioning that the Ag NP-LPUF exhibits more than 99% antibacterial rate against Escherichia coli within 1 h and Staphylococcus aureus within 4 h. Evaluations in mice indicate that the antimicrobial composite foams can effectively promote wound healing of full-thickness skin defects. As a proof of concept, this antibacterial and biodegradable foam exhibits significant potential for clinical translation in wound care dressings.

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“…They found that among the modified lignin samples, epoxy lignin had the most effective antibacterial activity, with minimum inhibitory concentrations (MIC) against Bacillus aryabhattai and Klebsiella of 90 and 200 µg/mL, respectively, demonstrating that lignin has great potential for antibacterial applications. Moreover, the structure and biological activity of lignin are greatly affected by the separation and extraction methods used as well as the molecular weight of the obtained product [ 15 , 16 , 17 ]. Furthermore, Rocca et al [ 18 ] synthesised lignin-doped silver and gold nanoparticles by one-pot thermochemical and photochemical methods, and they found that the nanoparticles had a certain inhibitory effect on E. coli and S. aureus .…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Antibacterial Properties of Oligomeric Dehydrogenation Polymer from Lignin Precursors

2022

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The lignin precursors of coniferin and syringin were synthesised, and guaiacyl-type and guaiacyl-syringyl-type oligomeric lignin dehydrogenation polymers (DHP and DHP-GS) were prepared with the bulk method. The carbon-13 nuclear magnetic resonance spectroscopy showed that both DHP-G and DHP-GS contained β-O-4, β-5, β-β, β-1, and 5-5 substructures. Extraction with petroleum ether, ether, ethanol, and acetone resulted in four fractions for each of DHP-G (C11–C14) and DHP-GS (C21–C24). The antibacterial experiments showed that the fractions with lower molecular weight had relatively strong antibacterial activity. The ether-soluble fractions (C12 of DHP-G and C22 of DHP-GS) had strong antibacterial activities against E. coli and S. aureus. The C12 and C22 fractions were further separated by preparative chromatography, and 10 bioactive compounds (G1–G5 and GS1–GS5) were obtained. The overall antibacterial activities of these 10 compounds was stronger against E. coli than S. aureus. Compounds G1, G2, G3, and GS1, which had the most significant antibacterial activities, contained β-5 substructures. Of these, G1 had the best antibacterial activity. Its inhibition zone diameter was 19.81 ± 0.82 mm, and the minimum inhibition concentration was 56.3 ± 6.20 μg/mL. Atmospheric pressure chemical ionisation mass spectrometry (APCI-MS) showed that the antibacterial activity of G1 was attributable to a phenylcoumarin dimer, while the introduction of syringyl units reduced antibacterial activity.

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γ-Valerolactone/water system for lignin fractionation to enhance antibacterial and antioxidant capacities

Cited by 48 publications

References 47 publications

Isolation of Lignin from Anaerobically Digested Unhydrolyzed Solids Produced in a Biorefinery

Isolation of Lignin from Anaerobically Digested Unhydrolyzed Solids Produced in a Biorefinery

Antimicrobial Lignin-Based Polyurethane/Ag Composite Foams for Improving Wound Healing

Synthesis and Antibacterial Properties of Oligomeric Dehydrogenation Polymer from Lignin Precursors

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