An interesting phenomenon is described that the fluorescence signal of poly(adenine) (A) DNA-templated gold nanoclusters (AuNCs) is greatly improved in the presence of l-histidine by means of l-histidine-DNA interaction. The modified nanoclusters display strong fluorescence emission with excitation/emission maxima at 290/475 nm. The fluorescence quantum yield (QY) is improved from 1.9 to 6.5%. Fluorescence enhancement is mainly ascribed to the l-histidine-DNA interaction leading to conformational changes of the poly(A) DNA template, which offer a better microenvironment to protect AuNCs. The assay enables l-histidine to be determined with good sensitivity and a linear response that covers the 1 to 50 nM l-histidine concentration range with a 0.3 nM limit of detection. The proposed method has been applied to the determination of imidazole-containing drugs in pharmaceutical samples.

Graphical abstract

中文翻译：

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l-组氨酸-DNA相互作用：改善聚（腺嘌呤）DNA模板金纳米簇荧光信号的策略

描述了一个有趣的现象，即聚（腺嘌呤）（A）DNA 模板金纳米簇（AuNCs）的荧光信号在l-组氨酸存在下通过l-组氨酸-DNA 相互作用大大改善。修饰的纳米团簇显示出强烈的荧光发射，激发/发射最大值在 290/475 nm。荧光量子产率 (QY) 从 1.9% 提高到 6.5%。荧光增强主要归因于l-组氨酸-DNA 相互作用导致 poly(A) DNA 模板的构象变化，这为保护 AuNCs 提供了更好的微环境。该测定法能够以良好的灵敏度和涵盖 1 至 50 nM l的线性响应来测定l-组氨酸 -组氨酸浓度范围，检测限为 0.3 nM。该方法已应用于药物样品中含咪唑类药物的测定。

图形概要