Valorization of Acid Isolated High Yield Lignin Nanoparticles as Innovative Antioxidant/Antimicrobial Organic Materials

Abstract

In this study, dissolution of pristine alkali lignin into ethylene glycol, followed by addition of different acidic conditions (HCl, H2SO4, and H3PO4 at different pH) has been considered as a simple method to prepare high yield lignin nanoparticles (LNP). Field emission scanning electron microscopy (FESEM), Zeta potential, gel permeation chromatography (GPC), and thermogravimetric analysis (TGA) have been utilized to determine the influence of the precipitation procedures on particle size, Zeta potential, molecular weight, and thermal stability of final obtained LNP. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and nuclear magnetic resonance (NMR) were also considered to investigate the influence of lignin chemical structures and composition on its antioxidative and antimicrobial behaviors. Results from DPPH (1,1-diphenyl-2-picryl-hydrazyl) activity revealed the antioxidant response of LNP aqueous solutions, whereas results from antimicrobial tests confirmed LNP as effective antibacterial agents against Gram negative bacteria Pseudomonas syringae pv tomato (CFBP 1323) (Pst), Xanthomonas axonopodis pv vesicatoria (CFBP 3274) (Xav), and Xanthomonas arboricola pv pruni (CFBP 3894) (Xap) plant pathogen strains. The results confirmed how high efficient antioxidant and antimicrobial LNP could be considered as an easy methodology for plant pathogens control. LNPs penetrate the cell wall by its lysis and react with ROS species inducing oxidative stress, ATP depletion, and decrease in intracellular pH of plant bacteria.

Sustainable control strategies for plant protection and food packaging sectors by natural substances and novel nanotechnological approaches

“…In this scenario, bio-based and/or biodegradable molecules and polymers were recently considered to reduce and/or limit the environmental impact with respect to traditional chemicals or plastics. 2,50,97 One strategy concerning active plastic is to increase the safety of horticultural products by restraining the proliferation of micro-organisms among production fields. Develop an active plastic incorporating an antimicrobial agent (e,g, triclosan) can lead to an improvement in the inhibition of phytopathogenic and food pathogenic micro-organisms.…”

“…3) were recently considered as precursors for the extraction and revalorization of lignocellulosic materials subsequently used as nanoreinforcements, such as cellulose nanofibers, cellulose nanocrystals (CNC) and/or nanolignin. 2,97,101 In addition, it should be noted that the use of waste lignocellulosic waste biomass does not compete with the food chain and fodder industry for the synthesis of green, safer and sustainable nanomaterials. 31 Recently, CNC were extracted from both barley straw and husk and then used as reinforcements phases in poly(vinyl alcohol) (PVA) blended with natural chitosan-based films.…”

Plant‐Based Antioxidant Nanoparticles without Biological Toxicity

“…The low‐molecular‐weight nature of lignin enhances infiltration of the cells and mitochondria, which induces inhibition of biological activities (i.e. an antimicrobial effect) . Other synthetic low‐molecular‐weight antioxidants have also been difficult to use in medical studies, owing to their biological toxicity .…”

“…[3,4] Some researchers anticipate the use of lignin as an antioxidant in the pharmaceuticali ndustry,o wing to the stable organic radicals of lignin in its p-conjugated phenolic frame-work. [5,6] However,t he ordinary methodt oe xtract lignin from plants requires treatment with strong/toxic chemicals, such as acids, bases,a nd organic solvents, whichp revents the application of lignin in the food/drink/medical industries, owing to its deterioration and contamination from harmful components during the extraction process. Furthermore, conventional extractiono fl ignin generally yields al ow molecular weight.…”

“…an antimicrobial effect). [6] Other synthetic lowmolecular-weight antioxidantsh ave also been difficult to use in medical studies, owing to their biological toxicity. [7] This has led to the development of antioxidant nanoparticles, which are macromolecules with antioxidant functional groups,such as nitroxylr adicals, as novel antioxidantw ithout biological toxicity, because the infiltration of antioxidants to cells and mitochondria is inhibited.…”