Antimicrobial activity enhancement of cationic lignin by phenolation
5 affiliations
- 1Department of Chemical and Biomolecular Engineering, University of Nebraska-Lincoln Lincoln Nebraska 68588 USA [email protected].
- 2Department of Chemistry and Nebraska Center for Integrated Biomolecular Communication, University of Nebraska-Lincoln Lincoln Nebraska 68588-0304 USA.
- 3Department of Biochemistry, University of Nebraska-Lincoln Lincoln Nebraska 68588 USA.
- 4Nebraska Redox Biology Center, University of Nebraska-Lincoln Lincoln Nebraska 68588 USA.
- 5Fred & Pamela Buffett Cancer Center Omaha Nebraska 68198 USA.
Abstract
In this work, we developed a new class of highly cationic antimicrobials (QPALs) from alkali lignin (AL). Unlike conventional cationization of AL, lignin was first phenolated here to increase its phenolic hydroxyl content, followed by quaternization with glycidyltrimethylammonium chloride (GTMAC). By varying phenolation conditions, a library of phenolated lignins (PALs) was synthesized, from which 3 representative samples with low, intermediate, and high phenolic contents were down-selected (PAL1, PAL2, PAL3) and converted to QPAL (QPAL1, QPAL2, QPAL3) with enhanced ion exchange capacities: 2.1-2.7 mmol g⁻¹ vs. 1.2 mmol g⁻¹ for non-phenolated cationic lignin (QAL). QPAL exhibited markedly improved antimicrobial activity against wild-type, ampicillin-resistant, and kanamycin-resistant E. coli. With a short 5 min treatment, 40 μg mL⁻¹QPAL1, QPAL2, and QPAL3 achieved 75%, 90%, and >98% colony forming unit (CFU) reduction, respectively, outperforming PALs (PAL1: <15%, PAL2: <16%, PAL3: <16%), AL (<11%), and QAL (59%). Complete bacterial inactivation (100% CFU reduction) was achieved within 1 h for all QPAL samples (40 μg mL⁻¹), corroborating with predominantly dead cells seen in live/dead assays upon QPAL treatment. In contrast, QAL required 150-300 µg mL⁻¹ to reach comparable % CFU reduction efficacy. Due to higher cationic charge density and more branched architecture (achieved by phenolation before cationization), QPAL was able to cause severe membrane disruption, ROS generation, morphological deformation, and intracellular leakage upon QPAL treatment. Importantly, QPAL maintained low cytotoxicity toward human embryonic kidney cells. These findings demonstrate phenolation-enabled enhanced cationization as an effective strategy for developing high-performance lignin-based antimicrobials.
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BibTeX
@article{cerda2026antimicrobial,
title = {{Antimicrobial activity enhancement of cationic lignin by phenolation}},
author = {Karen Acurio Cerda and Gunjan Purohit and Martha Morton and Oleh Khalimonchuk and Rajib Saha and Shudipto Konika Dishari},
journal = {RSC applied polymers},
year = {2026},
month = oct,
doi = {10.1039/d6lp00215c},
url = {https://europepmc.org/article/PMC/PMC13718744},
note = {CC BY-NC},
}
RIS
TY - JOUR
TI - Antimicrobial activity enhancement of cationic lignin by phenolation
AU - Karen Acurio Cerda
AU - Gunjan Purohit
AU - Martha Morton
AU - Oleh Khalimonchuk
AU - Rajib Saha
AU - Shudipto Konika Dishari
PY - 2026
DA - 2026/10/15
JO - RSC applied polymers
DO - 10.1039/d6lp00215c
UR - https://europepmc.org/article/PMC/PMC13718744
AB - In this work, we developed a new class of highly cationic antimicrobials (QPALs) from alkali lignin (AL). Unlike conventional cationization of AL, lignin was first phenolated here to increase its phenolic hydroxyl content, followed by quaternization with glycidyltrimethylammonium chloride (GTMAC). By varying phenolation conditions, a library of phenolated lignins (PALs) was synthesized, from which 3 representative samples with low, intermediate, and high phenolic contents were down-selected (PAL1, PAL2, PAL3) and converted to QPAL (QPAL1, QPAL2, QPAL3) with enhanced ion exchange capacities: 2.1-2.7 mmol g⁻¹ vs. 1.2 mmol g⁻¹ for non-phenolated cationic lignin (QAL). QPAL exhibited markedly improved antimicrobial activity against wild-type, ampicillin-resistant, and kanamycin-resistant E. coli. With a short 5 min treatment, 40 μg mL⁻¹QPAL1, QPAL2, and QPAL3 achieved 75%, 90%, and >98% colony forming unit (CFU) reduction, respectively, outperforming PALs (PAL1: <15%, PAL2: <16%, PAL3: <16%), AL (<11%), and QAL (59%). Complete bacterial inactivation (100% CFU reduction) was achieved within 1 h for all QPAL samples (40 μg mL⁻¹), corroborating with predominantly dead cells seen in live/dead assays upon QPAL treatment. In contrast, QAL required 150-300 µg mL⁻¹ to reach comparable % CFU reduction efficacy. Due to higher cationic charge density and more branched architecture (achieved by phenolation before cationization), QPAL was able to cause severe membrane disruption, ROS generation, morphological deformation, and intracellular leakage upon QPAL treatment. Importantly, QPAL maintained low cytotoxicity toward human embryonic kidney cells. These findings demonstrate phenolation-enabled enhanced cationization as an effective strategy for developing high-performance lignin-based antimicrobials.
SN - 2755-371X
ER -