Abstract
Lignin is the second most abundant biopolymer on the planet. It is a biocompatible, cheap, environmentally friendly and readily accessible material. It has been reported that these biomacromolecules have antimicrobial activities. Consequently, lignin (LIG) has the potential to be used for biomedical applications. In the present work, a simple method to prepare lignin-based hydrogels is described. The hydrogels were prepared by combining LIG with poly(ethylene glycol) and poly(methyl vinyl ether-co-maleic acid) through an esterification reaction. The synthesis took place in the solid state and can be accelerated significantly (24 vs 1 h) by the use of microwave (MW) radiation. The prepared hydrogels were characterized by evaluation of their swelling capacities and with the use of infrared spectroscopy/solid-state nuclear magnetic resonance. The prepared hydrogels showed LIG contents ranging between 40% and 24% and water uptake capabilities up to 500%. Furthermore, the hydrophobic nature of LIG facilitated loading of a model hydrophobic drug (curcumin). The hydrogels were capable of sustaining the delivery of this compound for up to 4 days. Finally, the materials demonstrated logarithmic reductions in adherence of Staphylococcus aureus and Proteus mirabilis of up to 5.0 relative to the commonly employed medical material poly(vinyl chloride) (PVC).
Highlights
The global consumption of fossil fuels is steadily increasing due to industrial development and human population growth
The results obtained for the chemical composition and the Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) analysis of the LIG samples (Figures S1 and S2) suggest that the lignin was isolated from wood using a pulping process containing sulfur delignifying agents and/or was precipitated using sulfuric acid
LIG hydrogels were successfully obtained after combination of the biomolecule with Gantrez S-97 (GAN), a polyacid and Poly(ethylene glycol) (PEG) through an esterification reaction
Summary
The global consumption of fossil fuels is steadily increasing due to industrial development and human population growth. Extensive efforts have been made to find green and sustainable alternatives for material production such as biorenewable polymers.[1] Ligno-cellulose materials have attracted significant attention due to their potential to reduce energy consumption and associated pollution by replacing conventional synthetic materials. This type of material is mainly formed by lignin (LIG), cellulose and hemicellulose.[1−6]. LIG is formed from a network of randomly cross-linked hydroxylated and methoxylated phenylpropane units This molecule is present in the cell walls of cellulosic materials providing mechanical and chemical protection from external stresses. The remainder is used as low grade burning fuel or discarded as waste.[1,13]
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