Abstract The analysis of residual kanamycin (KANA) has drawn great attentions based on its potential threat to human health and environment caused by its residual in aquatic and soil system. Herein, an ultrasensitive fluorescent aptasensing system was proposed based on the fluorescence change resulting from the conformation switch of kanamycin-aptamer (KANA-aptamer) with or without kanamycin in the sensing system, in which berberine was employed as the fluorescence reporter and KANA-aptamer as the recognition unit. Free berberine emits weak fluorescence at 535 nm in aqueous solution, and its fluorescence enhanced remarkably after it intercalated to KANA-aptamer. Once kanamycin was introduced into the sensing system, the randomly coiling structure of KANA-aptamer switched to a hairpin form, which made the dissociation of berberine from the KANA-aptamer, thus the fluorescence was quenched. Various experimental conditions including the concentration of berberine, KANA-aptamer, pH, ion strength and equilibrium time were studied in detail. Under the optimal experimental condition, a good correlation was obtained between the fluorescence of the sensing system and the concentration of kanamycin ranged from 5.0 nM to 71.0 nM with LOD at 2.3 nM. The presented fluorescent aptasensor also showed a delightful recovery of 96.50%–101.20% in human serum and milk. The excellent analytical performance of kanamycin shows a promising prospect in the practical application.

中文翻译：

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卡那霉素超灵敏分析荧光适配传感系统的研制

摘要 卡那霉素（KANA）残留在水体和土壤系统中，对人类健康和环境存在潜在威胁，因此其分析受到了广泛关注。在此，基于卡那霉素适体（KANA-aptamer）在传感系统中有或没有卡那霉素的构象转换引起的荧光变化，提出了一种超灵敏荧光适体传感系统，其中采用小檗碱作为荧光报告分子和KANA-适体作为识别单位。游离小檗碱在水溶液中在535 nm处发出微弱的荧光，嵌入KANA-aptamer后荧光显着增强。一旦将卡那霉素引入传感系统，KANA-aptamer 的随机卷曲结构就会转变为发夹形式，这使得小檗碱从 KANA 适体上解离，从而使荧光猝灭。详细研究了各种实验条件，包括小檗碱的浓度、KANA-适体、pH、离子强度和平衡时间。在最佳实验条件下，传感系统的荧光与卡那霉素浓度范围为 5.0 nM 至 71.0 nM，LOD 为 2.3 nM 之间获得了良好的相关性。所提出的荧光适体传感器在人血清和牛奶中也显示出令人愉快的 96.50%–101.20% 的回收率。卡那霉素优异的分析性能在实际应用中显示出广阔的前景。离子强度和平衡时间进行了详细研究。在最佳实验条件下，传感系统的荧光与卡那霉素浓度范围为 5.0 nM 至 71.0 nM，LOD 为 2.3 nM 之间获得了良好的相关性。所提出的荧光适体传感器在人血清和牛奶中也显示出令人愉快的 96.50%–101.20% 的回收率。卡那霉素优异的分析性能在实际应用中显示出广阔的前景。离子强度和平衡时间进行了详细研究。在最佳实验条件下，传感系统的荧光与卡那霉素浓度范围为 5.0 nM 至 71.0 nM，LOD 为 2.3 nM 之间获得了良好的相关性。所提出的荧光适体传感器在人血清和牛奶中也显示出令人愉快的 96.50%–101.20% 的回收率。卡那霉素优异的分析性能在实际应用中显示出广阔的前景。