Lin Ai-Hua, Liu Yi-Ming, Ping Qi-Neng
Guangdong Provincial Hospital of Traditional Chinese Medicine, Guangzhou University of Traditional Chinese Medicine, Guangzhou 510120, China.
Yao Xue Xue Bao. 2007 Mar;42(3):323-8.
The relationship of free amino groups on the surface and the characteristics of chitosan nanoparticles (CS-NPs) prepared by ionic gelation method was investigated. Free amino groups on the surface of CS-NPs were determined by colloidal titration, and the effects of the amount of free amino groups and its ionizable level on the particle size, zeta potential, appearance, drug entrapment efficiency and drug release profile in vitro of CS-NPs were investigated. The result showed that the surface free amino groups reduced, the average size, zeta potential, stability of nanoparticles, and the drug release rate and degree all decreased while the drug entrapment efficiency was not affected with the increase of tripolyphosphate (TPP) concentration. With the increase of pH, the free amino groups could be deprotonated and the ionizable level was stepped down, correspondingly the particle size and zeta potential of CS-NPs decreased. Additionally, the drug release rate and degree were elevated in acid medium while descended in neutral or base medium. The amount and ionizable level of free amino groups on the surface are affected by the gelation degree and pH, which further affected the volume phase transitions (swelling/shrinking processes) of CS-NPs. The properties of CS-NPs have correlation with the surface free amino groups.
研究了离子凝胶法制备的壳聚糖纳米粒（CS-NPs）表面游离氨基与特性之间的关系。通过胶体滴定法测定CS-NPs表面的游离氨基，并研究游离氨基的量及其可电离程度对CS-NPs粒径、zeta电位、外观、药物包封率和体外药物释放曲线的影响。结果表明，随着三聚磷酸钠（TPP）浓度的增加，表面游离氨基减少，纳米粒的平均粒径、zeta电位、稳定性以及药物释放速率和程度均降低，而药物包封率不受影响。随着pH值的升高，游离氨基会发生去质子化，可电离程度降低，相应地CS-NPs的粒径和zeta电位减小。此外，药物在酸性介质中的释放速率和程度升高，而在中性或碱性介质中则降低。表面游离氨基的量和可电离程度受凝胶化程度和pH值的影响，进而影响CS-NPs的体积相转变（溶胀/收缩过程）。CS-NPs的性质与表面游离氨基相关。
