Bitounis Dimitrios, Pyrgiotakis Georgios, Bousfield Douglas, Demokritou Philip
Center for Nanotechnology and Nanotoxicology, HSPH-NIEHS Nanosafety Center, Department of Environmental Health, Harvard T. H. Chan School of Public School, Harvard University, 665 Huntington Boston, MA 02115, USA.
Department of Chemical and Biological Engineering, University of Maine, Orono, ME 04469, USA.
NanoImpact. 2019 Mar;15. doi: 10.1016/j.impact.2019.100171. Epub 2019 May 31.
The characterization of cellulose-based nanomaterial (CNM) suspensions in environmental and biological media is impaired because of their high carbon content and anisotropic shape, thus making it difficult to derive structure activity relationships (SAR) in toxicological studies. Here, a standardized method for the dispersion preparation and characterization of cellulose nanofibrils (CNF) and nanocrystals (CNC) in biological and environmental media was developed. Specifically, electron microscopy was utilized and allowed to specify optimum practices for efficiently suspending CNF and CNC in water and cell culture medium. Furthermore, a technique for measuring the particle kinetics of CNF and CNC suspended in cell culture medium utilizing fluorescently tagged materials was developed to assess the delivery rate of such CNM at the bottom of the well. Interestingly, CNF were shown to settle and create a loosely packed layer at the bottom of cell culture wells within a few hours. On the contrary, CNC settled gradually at a significantly slower rate, highlighting the discordance between administered and delivered mass dose. This work is both novel and urgent in the field of environmental health and safety as it introduces well-defined techniques for the dispersion and characterization of emerging, cellulose-based engineered nanomaterials. It also provides useful insights to the behavior of suspended anisotropic nanomaterials in general, which should enable dosimetry and comparison of toxicological data across laboratories as well as promote the safe and sustainable use of nanotechnology.
由于纤维素基纳米材料（CNM）悬浮液的高碳含量和各向异性形状，其在环境和生物介质中的表征受到影响，因此在毒理学研究中难以得出结构活性关系（SAR）。在此，开发了一种在生物和环境介质中制备和表征纤维素纳米纤维（CNF）和纳米晶体（CNC）分散体的标准化方法。具体而言，利用电子显微镜确定了在水和细胞培养基中有效悬浮CNF和CNC的最佳方法。此外，还开发了一种利用荧光标记材料测量悬浮在细胞培养基中的CNF和CNC颗粒动力学的技术，以评估此类CNM在孔底部的递送速率。有趣的是，研究表明CNF在几小时内在细胞培养孔底部沉降并形成松散堆积层。相反，CNC沉降速度明显较慢，这突出了给药剂量与递送质量剂量之间的不一致。这项工作在环境健康与安全领域既新颖又迫切，因为它引入了用于新兴的纤维素基工程纳米材料分散和表征的明确技术。它还为一般悬浮各向异性纳米材料的行为提供了有用的见解，这应该能够实现跨实验室的剂量测定和毒理学数据比较，并促进纳米技术的安全和可持续使用。
