Fukui Yuuka, Baba Eriko, Fujimoto Keiji
The Center for Chemical Biology, School of Fundamental Science and Technology, Graduate School of Science and Technology, Keio University 3-14-1 Hiyoshi, Kohoku-ku Yokohama 223-8522 Japan
RSC Adv. 2025 Jan 13;15(2):1115-1124. doi: 10.1039/d4ra07142e. eCollection 2025 Jan 9.
We prepared a cellulose nanofiber (CNF)-based porous membrane with three dimensional cellular structures. CNF was concentrated a surfactant-induced assembly by mixing CNF with a cationic surfactant, domiphen bromide (DB). Furthermore, they were accumulated by centrifugation to obtain a CNF-DB sol. Next, when the CNF-DB sol was naturally dried, a membrane composed of densely packed CNF was obtained. On the other hand, when the CNF-DB sol was freeze-dried, a porous membrane with the anisotropic cellular structure could be obtained. The interspace between layered CNF sheets was tunable by the DB concentration in the assembly process and the centrifugal force in the accumulation process. FT-IR analysis of the porous membrane showed the formation of hydrogen bonds between the CNF, resulting in facilitation of crosslinking of the CNF and formation of the cellular structures. The obtained CNF-DB membrane exhibited high water resistance. They showed a high ability to absorb hydrophobic dyes such as Nile red and rhodamine B (RhB) due to the presence of the hydrophobic core of DB micelles. Then, the release of RhB could be controlled by the ionic strength in the medium. In addition, they possessed a high ability to adsorb cationic metals such as Ag ions due to the presence of carboxyl moieties of CNF. Next, synthesis of silver nanoparticles (AgNPs) was carried out by employing the CNF-DB membrane as a template for Ag ion adsorption and reduction. Deposition of AgNPs could be observed on the CNF-DB membrane, which suppressed aggregation of AgNPs. Almost all AgNPs were arrayed apart from each other to generate the hotspots, which could enhance surface-enhanced Raman scattering (SERS) of AgNPs. Such an AgNPs-CNF composite membrane could be applied for a label-free analysis of adsorbed RhB.
我们制备了一种具有三维细胞结构的基于纤维素纳米纤维（CNF）的多孔膜。通过将CNF与阳离子表面活性剂度米芬溴铵（DB）混合，利用表面活性剂诱导组装使CNF浓缩。此外，通过离心使其聚集以获得CNF-DB溶胶。接下来，当CNF-DB溶胶自然干燥时，可得到由紧密堆积的CNF组成的膜。另一方面，当CNF-DB溶胶冷冻干燥时，可获得具有各向异性细胞结构的多孔膜。在组装过程中，层状CNF片层之间的间隙可通过DB浓度调节，在聚集过程中可通过离心力调节。对多孔膜的傅里叶变换红外光谱（FT-IR）分析表明，CNF之间形成了氢键，从而促进了CNF的交联和细胞结构的形成。所制备的CNF-DB膜表现出高耐水性。由于DB胶束疏水核心的存在，它们对尼罗红和罗丹明B（RhB）等疏水性染料具有高吸附能力。然后，RhB的释放可通过介质中的离子强度来控制。此外，由于CNF羧基部分的存在，它们对Ag离子等阳离子金属具有高吸附能力。接下来，以CNF-DB膜为模板进行Ag离子吸附和还原，合成了银纳米颗粒（AgNPs）。在CNF-DB膜上可观察到AgNPs的沉积，这抑制了AgNPs的聚集。几乎所有的AgNPs相互间隔排列形成热点，可增强AgNPs的表面增强拉曼散射（SERS）。这种AgNPs-CNF复合膜可用于对吸附的RhB进行无标记分析。
