Physical Membrane-Stress-Mediated Antimicrobial Properties of Cellulose Nanocrystals

Abstract

Cellulose nanocrystals (CNCs) have emerged as a sustainable nanomaterial for several environmental applications, including the development of novel antimicrobial agents. Although previous studies have reported antibacterial activity for CNCs, their toxicity mechanism to bacterial cells is still unknown. Here, we investigate the toxicity of CNCs dispersed in water and coated surfaces against Escherichia coli cells. CNC-coated surfaces were able to inactivate approximately 90% of the attached E. coli cells, confirming potential of CNCs to be applied as a sustainable and cost-effective antibiofouling nanomaterial. The toxicity of CNCs in a suspension was concentration-dependent, and an inhibitory concentration (IC50%) of 200 μg/mL was found. Glutathione and 2′,7′-dichlorodihydrofluorescein diacetate (H2DCFA) assays were conducted to evaluate the role of oxidative stress in the CNC toxicity mechanism. Our findings showed that oxidative stress has no significant effect on the antimicrobial activity of CNC. In contrast, scanning electron microscopy (SEM) images and a leakage assay performed with dye-encapsulated phospholipid vesicles indicated that CNCs inactivate bacteria by physically damaging their cell membrane. CNC interaction with dye-encapsulated vesicles resulted in a dye leakage corresponding to 43% of the maximum value, thus confirming that contact-mediated membrane stress is the mechanism governing the toxicity of CNCs to bacteria cells.

Sustainable Cellulose Nanocrystals for Improved Antimicrobial Properties of Thin Film Composite Membranes

“…However, a previous study performed on E. coli suggests that CNC inactivate bacteria upon contact by inducing membrane damage . This has been further corroborated by a study conducted by Noronha et al, which suggests that contact-mediated stress is the mechanism driving the toxicity of CNC to bacteria cells . Accordingly, the membrane antimicrobial properties could be improved by optimizing the distribution of CNC on the membrane surface.…”

Circular Hazelnut Protection by Lignocellulosic Waste Valorization for Nanopesticides Development

“…Several works have reported the cellulose nanofibrils' ability to disturb bacteria swimming motility in several foodborne pathogens (E. coli, L. monocytogenes, B. aureus and S. typhimurium) or, as shown for E. coli and P. aeruginosa, the CNC capacity to prevent bacterial cell adhesion and biofilm formation [82][83][84]. Noteworthily, Noronha et al (2021) linked bacterial growth inhibition by CNC to the loss of cell membrane integrity in E. coli bacterial cells [85]. This effect was ascribed to the disrupting action of CNC on the membrane phospholipid structure.…”

Preparation and Surface Functionalization of Carboxylated Cellulose Nanocrystals

“…Faria and co-workers produced cCNCs from elephant grass by milling and hydrothermal processing with H 2 SO 4 to remove hemicellulose and other extractives and NaOH to remove lignin [ 32 ]. This pre-treated feedstock was oxidized by TEMPO and mechanically disintegrated by sonication to yield cCNCs.…”