低场核磁共振技术在鱼用冻干疫苗保护剂筛选中的应用

Applicationof low field NMR technology to screening of protective agents of freeze-dried fish vaccines

为筛选适合鱼类冻干疫苗中使用的保护剂,采用低场核磁共振技术(LF-NMR)对冻干后不同保护剂中的水分分布和迁移规律进行了分析。根据水中氢质子的弛豫时间,可将保护剂中的残留水分为结合水、不易移动水和自由水3种形态。结果显示:冷冻干燥过程中二次干燥温度对甘露醇和蔗糖中残留水的分布有较大影响,随着温度从4℃升高到37℃,大部分自由水解吸而小部分转化为结合水。当冻干后的样品暴露在相对湿度43%和温度25℃的环境中时,大部分保护剂吸收水分,并将其固定为结合水,而甘露醇中的部分结合水则转变为自由水,并解吸到环境中。不同冻干保护剂中的水分分布和迁移并不相同,代表其具有不同的水分结合能力。该研究结果有助于鱼用冻干疫苗中保护剂的筛选和冻干工艺的优化,以便获得更加稳定的疫苗产品。

To screen protective agents suitable for freeze-dried fish vaccines,low-field nuclear magnetic resonance(LF-NMR)was applied to analyze the water distribution and mobility in different protective agents after freeze drying.According to the relaxation time of hydrogen protons,resident water can be divided into three states:bound water,immobilized water and free water.Results showed that secondary drying temperature had a great impact on the water distribution in mannitol and sucrose,and with the increase of temperature from 4℃to 37℃,most free water desorbed and some shifted to bound water.When placed in environment with relative humidity of 43%and temperature of 25℃,most protective agents absorbed water and immobilized it to bound water,except that some bound water in mannitol shifted to free water which desorbed to the environment.Water distribution and mobility in different freeze-drying protective agents were not the same,which indicated their different ability in water binding.This research would be helpful for screening of protective agents of freeze-dried fish vaccines and optimization of freeze-drying process,to form a more stable vaccine product.