Potential issues specific to cytotoxicity tests of cellulose nanofibrils

Abstract

Cellulose nanofibrils (also called cellulose nanofibers or nanofibrillated cellulose [CNFs]) are novel polymers derived from biomass with excellent physicochemical properties and various potential applications. However, the introduction of such new materials into the market requires thorough safety studies to be conducted. Recently, toxicity testing using cultured cells has attracted attention as a safety assessment that does not rely on experimental animals. This article reviews recent information regarding the cytotoxicity testing of CNFs and highlights the issues relevant to evaluating tests. In the literature, we found that a variety of cell lines and CNF exposure concentrations was evaluated. Furthermore, the results of cytotoxicity results tests differed and were not necessarily consistent. Numerous reports that we examined had not evaluated endotoxin/microbial contamination or the interaction of CNFs with the culture medium used in the tests. The following potential specific issues involved in CNF in vitro testing, were discussed: (1) endotoxin contamination, (2) microbial contamination, (3) adsorption of culture medium components to CNFs, and (4) changes in aggregation/agglomeration and dispersion states of CNFs resulting from culture medium components. In this review, the available measurement methods and solutions for these issues are also discussed. Addressing these points will lead to a better understanding of the cellular effects of CNFs and the development of safer CNFs.

Cytotoxicity and Inflammatory Effects of Chitin Nanofibrils Isolated from Fungi

“…It should be noted that the cytotoxicity of novel materials at the nanoscale based on natural biopolymers strongly depends on the source, isolation protocol, functionalization, dimensions and studied cell line. , Thus, a direct comparison between different nanomaterials is difficult due to the lack of well-established protocols. Some review papers have tried to summarize those recent studies dealing with the cytotoxicity of cellulose-based nanomaterials, which share structural and chemical similarities to the ChNFs presented herein. , Hanif et al prepared cellulose nanocrystals of controlled shape and size and studied their potential cytotoxicity with murine fibroblasts (NIH3T3) . The prepared CNCs did not have any detrimental effect on cell viability at concentrations of up to 250 μg·mL –1 .…”

“…Some review papers have tried to summarize those recent studies dealing with the cytotoxicity of cellulose-based nanomaterials, which share structural and chemical similarities to the ChNFs presented herein. 54 , 55 Hanif et al prepared cellulose nanocrystals of controlled shape and size and studied their potential cytotoxicity with murine fibroblasts (NIH3T3). 28 The prepared CNCs did not have any detrimental effect on cell viability at concentrations of up to 250 μg·mL –1 .…”

A 28-Day Repeated Oral Administration Study of Mechanically Fibrillated Cellulose Nanofibers According to OECD TG407

“…In discussing the safety of CNFs, Nadia et al [19] reported that endotoxin (lipopolysaccharide, LPS) is a component of the cell wall of Gram-negative bacteria and is responsible for various pathological conditions in bacterial infections. Moriyama et al [20] described the presence of endotoxin in CNFs. Menas et al [21] used the Pierce LAL Chromogenic Endotoxin Quantitation Kit (Thermo Fisher Scientific, Waltham, MA, USA) to measure endotoxin contamination in five different nanocellulose materials, including lyophilized CNF powder.…”

Material matters: exploring the interplay between natural biomaterials and host immune system

“…The results revealed an elevation in the levels of these cytokines in response to the presence of unmodified CNFs. Notably, the proinflammatory impact was not found in the cells when they were subjected to treatment with modified CNFs (214). The utilization of a crosslinking agent, namely polyethyleneimine, along with a surfactant called cetyltrimethylammonium bromide, for the purpose of modifying CNFs, led to a noteworthy diminution in both the viability and proliferation of fibroblast cells as compared to the unmodified CNFs in their pure form (215).…”