Laboratory of Applied Bionanotechnology, Department of Biotechnology, Lorena School of Engineering, University of São Paulo, 12602-810, Lorena, São Paulo, Brazil.
Laboratory of Applied Bionanotechnology, Department of Biotechnology, Lorena School of Engineering, University of São Paulo, 12602-810, Lorena, São Paulo, Brazil.
Carbohydr Res. 2023 Dec;534:108970. doi: 10.1016/j.carres.2023.108970. Epub 2023 Oct 6.
Cellulose nanocrystals (CNCs) are a rapidly growing bionanomaterial with remarkable properties that have been harnessed in various applications, including mechanical reinforcement, biomedical materials, and coatings. However, for non-water-based applications, hydrophobization of CNCs while preserving their integrity is crucial. In this study, we propose a new eco-friendly, one-pot surface esterification method for hydrophobizing enzymatic CNCs in aqueous suspension without solvent exchange. By establishing an appropriate set of reaction conditions, it was possible to create a miscibility gradient that enabled a low-cost, and renewable fatty acid to be utilized as an acyl donor and solvent, allowing direct hydrophobic modification of the as-produced aqueous suspension of enzymatic CNC. FT-IR and AFM-IR analyses confirmed the formation of ester groups, while C NMR confirmed the emergence of carboxyl groups. XPS revealed a high degree of surface substitution (0.39) in the modified CNC, while a substantial increase in contact angle (from 40 to approximately 90°) quantitatively confirmed the high efficiency of the enzymatic CNC's hydrophobic modification. Additionally, important properties such as morphology remained practically unchanged, except for a slight increase in thermal stability and crystallinity of the CNCs. Therefore, hydrophobic enzymatic CNCs were successfully produced via a simple, scalable, and environmentally friendly approach without compromising their properties. These hydrophobic CNCs have the potential to enhance nanocomposite compatibility, improve packaging performance for electronics and foods, optimize adhesion in coatings, and offer advancements in cosmetics and drug delivery. However, comprehensive studies are needed to confirm their applicability across these sectors.
纤维素纳米晶体（CNCs）是一种快速发展的生物纳米材料，具有卓越的性能，已在各种应用中得到利用，包括机械增强、生物医学材料和涂料。然而，对于非水基应用，保持 CNCs 完整性的同时对其进行疏水处理至关重要。在这项研究中，我们提出了一种新的环保、一锅法表面酯化方法，用于在水悬浮液中对酶处理的 CNC 进行疏水处理，无需进行溶剂交换。通过建立适当的反应条件，可以创建一个可混溶性梯度，从而可以使用低成本、可再生的脂肪酸作为酰基供体和溶剂，直接对酶处理的水悬浮液中的 CNC 进行疏水性修饰。FT-IR 和 AFM-IR 分析证实了酯基的形成，而 C NMR 证实了羧基的出现。XPS 显示修饰后的 CNC 表面取代度很高（0.39），接触角的大幅增加（从 40 度左右增加到约 90 度）定量证实了酶处理的 CNC 疏水性修饰的高效率。此外，除了 CNC 的热稳定性和结晶度略有增加外，其形态等重要性质实际上保持不变。因此，通过简单、可扩展和环保的方法成功制备了疏水性酶处理的 CNC，而不会影响其性能。这些疏水性 CNC 具有增强纳米复合材料相容性、改善电子产品和食品包装性能、优化涂料附着力以及在化妆品和药物输送方面取得进展的潜力。然而，需要进行综合研究来确认它们在这些领域的适用性。
