Afinjuomo Franklin, Fouladian Paris, Barclay Thomas G, Song Yunmei, Petrovsky Nikolai, Garg Sanjay
Pharmaceutical Innovation and Development Group, University of South Australia, Adelaide 5000, Australia.
Vaxine Pty. Ltd., Adelaide 5042, Australia.
Polymers (Basel). 2020 May 1;12(5):1025. doi: 10.3390/polym12051025.
This paper reports the oxidation of inulin using varying ratios of sodium periodate and the characterization of the inulin polyaldehyde. The physicochemical properties of the inulin polyaldehyde (oxidized inulin) were characterized using different techniques including 1D NMR spectroscopy, C Nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), differential scanning calorimetric (DSC), ultraviolet-visible spectroscopy (UV), and scanning electron microscopy (SEM). The aldehyde peak was not very visible in the FTIR, because the aldehyde functional group exists in a masked form (hemiacetal). The thermal stability of the oxidized inulin decreased with the increasing oxidation degree. The smooth spherical shape of raw inulin was destructed due to the oxidation, as confirmed by the SEM result. The HNMR results show some new peaks from 4.8 to 5.0 as well as around 5.63 ppm. However, no aldehyde peak was found around 9.7 ppm. This can be attributed to the hemiacetal. The reaction of oxidized inulin with tert-butyl carbazate produced a carbazone conjugate. There was clear evidence of decreased peak intensity for the proton belonging to the hemiacetal group. This clearly shows that not all of the hemiacetal group can be reverted by carbazate. In conclusion, this work provides vital information as regards changes in the physicochemical properties of the oxidized inulin, which has direct implications when considering the further utilization of this biomaterial.
本文报道了使用不同比例的高碘酸钠对菊粉进行氧化以及菊粉聚醛的表征。采用包括一维核磁共振光谱、碳核磁共振（NMR）、傅里叶变换红外光谱（FTIR）、热重分析（TGA）、差示扫描量热法（DSC）、紫外可见光谱（UV）和扫描电子显微镜（SEM）等不同技术对菊粉聚醛（氧化菊粉）的物理化学性质进行了表征。醛峰在FTIR中不是很明显，因为醛官能团以半缩醛的形式存在。氧化菊粉的热稳定性随着氧化程度的增加而降低。扫描电子显微镜结果证实，由于氧化作用，未氧化菊粉的光滑球形结构被破坏。核磁共振氢谱结果显示在4.8至5.0以及约5.63 ppm处出现了一些新峰。然而，在9.7 ppm附近未发现醛峰。这可归因于半缩醛。氧化菊粉与叔丁基肼反应生成了腙共轭物。属于半缩醛基团的质子的峰强度明显降低，这清楚地表明并非所有半缩醛基团都能被肼逆转。总之，这项工作提供了有关氧化菊粉物理化学性质变化的重要信息，这在考虑这种生物材料的进一步利用时具有直接影响。
