Preparation, Characterization, Antioxidant and Antimicrobial Activities of Lignin and Eco-friendly Lignin Nanoparticles from Egyptian Cotton Stalks

Abstract

Pathogenic microorganisms are a major source of environmental concerns, according to their capability of prolif-eration on all surfaces. Antimicrobial drugs of new types are now has been developed to inhibit bacteria adher-ence and biofilm formation. However, they are generally of synthetic origin and have a lot of disadvantages. Nat-ural biopolymers as cellulose, hemicellulose, and lignin, look interesting as antibacterial agents. Lignin, a com-mon plant biopolymer, is known to have antioxidant activity. Nanoparticles have qualities that are either better or worse than their bulk materials or parent polymers. The objectives of this article are to recycle cotton stalks into environmentally friendly products by extracting lignin from two Egyptian cotton cultivars (by-products): Giza 86 and Giza 90, using the organosolv technique, and transferring them into lignin nanoparticles. Also, to determine whether lignin and lignin nanoparticle bioactivities (i.e., antioxidant and antibacterial) may be used to treat tex-tiles for medical applications against seven harmful bacteria (Staphylococcus aureus, Staphylococcus sciuri, Ba-cillus cereus, Salmonella enterica, Salmonella typhi, Escherichia coli, and Pseudomonas aeruginosa) and five mycotoxigenic fungi (Aspergillus flavus, Aspergillus ochraceus, Aspergillus niger, Fusarium proliferatum, and Penicillium verrucosum). LNPs were studied using Particle Size Analyzer, Fourier Transformer Infrared Spec-troscopy (FTIR), and transmission electron microscope (TEM). The results revealed that organosolv lignin nano-particles 90 (OLNP90) had the strongest antioxidant effectiveness with an IC50 of 9.41 μg/mL whereas the min-imum antioxidant activity for organosolv lignin nanoparticles 86 (OLNP86) was found with an IC50 of 11.66 μg/mL. On the other hand, treatment with lignin and lignin nanoparticles had a greater effect on bacteria than fungi. Penicillium verrucosum exhibited the greatest inhibition zone (15.5 mm) for OLNP86 with no significant differences with Nystatin (15.8 mm), while Salmonella typhi exhibited the greatest inhibition zone (14.7 mm) for OLNP86 in comparison of Tetracycline (25.4 mm). Similarly, the study of textiles treated with lignin and nano-lignin showed a clear effect on bacteria and fungi under study, where Penicillium verrucosum exhibited the great-est inhibition zone (30.7 mm), while Pseudomonas aeruginosa exhibited the greatest inhibition zone (36.3 mm) for OLNP86. As a result, the current study showed that OLNP's antioxidant and antimicrobial characteristics can be further utilized in medical textiles (surgical bandages, clothing, bed sheets, and towels), which can be used for patients with conditions such as diabetes, high blood pressure, and kidney failure who cannot tolerate antibiotics.