Sun Xiaozheng, Xue Yanhua, Li Jianye, Yang Yu, Bai Yu, Chen Yujia
College of Engineering, Northeast Agricultural University No. 600 Changjiang Street HarBin 150030 China
RSC Adv. 2021 Jul 14;11(40):24694-24701. doi: 10.1039/d1ra04812k. eCollection 2021 Jul 13.
High-performance fluorescent composites are key to the development and improvement of fluorescent molecular probe technology. In this study, cellulose nanocrystals (CNC) with high carboxyl concentrations were prepared sequential periodate-chlorite oxidation. Then, fluorescent cellulose nanocrystals (FCNC) were prepared by attaching 7-amino-4-methylcoumarin (AMC) onto CNC under 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMTMM) catalysis. The morphology and fluorescence properties of FCNC were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, elemental analysis, ultraviolet-visible absorbance, fluorescence spectrophotometry, and fluorescence spectroscopy. The results showed that AMC was grafted onto the CNC surface by an amidation reaction, and the absorption and emission maxima for FCNC were blue-shifted from 350 nm and 445 nm of AMC to 335 nm and 440 nm, respectively. FCNC retained the crystallinity and nano-topography size of the CNC. The fluorescence intensity, quantum yield, and fluorescence lifetime of FCNC showed the same change law; it first increased and then decreased with an increase in the graft density of AMC from 0.201 to 0.453 AMC molecules per nm. The FCNC prepared in this study have good optical properties and can be used in the fields of fluorescent molecular probes and biological imaging.
高性能荧光复合材料是荧光分子探针技术发展和改进的关键。在本研究中，通过高碘酸盐-亚氯酸盐顺序氧化制备了具有高羧基浓度的纤维素纳米晶体（CNC）。然后，在4-(4,6-二甲氧基-1,3,5-三嗪-2-基)-4-甲基吗啉鎓氯化物（DMTMM）催化下，将7-氨基-4-甲基香豆素（AMC）连接到CNC上，制备了荧光纤维素纳米晶体（FCNC）。通过傅里叶变换红外光谱、X射线衍射、透射电子显微镜、元素分析、紫外可见吸收光谱、荧光分光光度法和荧光光谱对FCNC的形貌和荧光性能进行了表征。结果表明，AMC通过酰胺化反应接枝到CNC表面，FCNC的吸收和发射最大值分别从AMC的350 nm和445 nm蓝移至335 nm和440 nm。FCNC保留了CNC的结晶度和纳米形貌尺寸。FCNC的荧光强度、量子产率和荧光寿命呈现相同的变化规律；随着AMC接枝密度从每纳米0.201个AMC分子增加到0.453个AMC分子，它先增加后减少。本研究制备的FCNC具有良好的光学性能，可用于荧光分子探针和生物成像领域。
