Department of Bioproducts and Biosystems, Aalto University, P. O. Box 16300, Espoo, FI-00076, Finland.
Department of Applied Physics, Aalto University, P. O. Box 15100, Espoo, FI-00076, Finland.
Macromol Rapid Commun. 2020 Aug;41(15):e2000201. doi: 10.1002/marc.202000201. Epub 2020 Jul 1.
Despite their sustainable appeal, biomass components are currently undervalued in nanotechnology because means to control the assembly of bio-based nanoparticles are lagging behind the synthetic counterparts. Here, micrometer-sized particles consisting of aligned cellulose nanocrystals (CNCs) are prepared by crosslinking cellulose in cotton linter fibers that are prehydrolyzed with gaseous HCl, resulting in chemical cleavage necessary for CNC formation but retaining the morphology of the native fibers. That way, the intrinsic alignment of cellulose microfibrils within the fiber cell wall can be retained and utilized for top-down CNC alignment. Subsequent crosslinking with citric acid cements the alignment and preserves it, following the dispersion of CNCs trapped end-to-end, connected, and crosslinked within the colloidally stable micrometer-sized particles. Furthermore, thermoporosimetry and cryogenic transmission electron microscopy (Cryo TEM) shows that the particles possess mainly nanoporous (<2 nm) character in water. The approach challenges the current paradigm of predominantly bottom-up methods for nanoparticle assembly.
尽管生物质组件具有可持续性吸引力，但在纳米技术中它们目前被低估了，因为控制基于生物的纳米颗粒组装的方法落后于合成物的对应方法。在这里，通过交联用气态 HCl 进行预水解的棉绒纤维中的纤维素纳米晶体 (CNC) 来制备由微米级颗粒组成的 CNC，这导致了形成 CNC 所必需的化学裂解，但保留了天然纤维的形态。这样，纤维细胞壁内纤维素微纤维的固有取向可以保留，并用于自上而下的 CNC 取向。随后用柠檬酸交联固定取向并保存，同时将被捕获的 CNC 端到端、连接和交联在胶体稳定的微米级颗粒内分散。此外，热孔隙率和低温透射电子显微镜 (Cryo TEM) 表明，这些颗粒在水中主要具有纳米多孔（<2nm）特性。该方法挑战了当前主要用于纳米颗粒组装的自下而上方法的范例。
