A label-free G-quadruplex-based luminescent switch-on assay for the selective detection of histidine

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• 作者：Hong-Zhang He ; Modi Wang ; Daniel Shiu-Hin Chan ; Chung-Hang Leung ; Jian-Wen Qiu ; Dik-Lung Ma
• 关键词：ssDNA ; single-stranded DNA ; dsDNA ; double-stranded DNA ; ctDNA ; calf-thymus DNA ; NEM ; N-ethylmaleimide ; CD ; circular dichroism
• 刊名：Methods
• 出版年：15 December, 2013
• 年：2013
• 卷：64
• 期：3
• 页码：205-211
• 全文大小：1072 K

文摘

A label-free G-quadruplex-based luminescent switch-on assay has been developed for the selective detection of micromolar histidine in aqueous solution. In this study, an iridium(III) complex was employed as a G-quadruplex-specific luminescent probe while a guanine-rich oligonucleotide (Pu27, 5鈥?TG₄AG₃TG₄AG₃TG₄A₂G₂-3鈥?/cupric ion (Cu²⁺) ensemble was employed as a recognition unit for histidine. The initial luminescence of the iridium(III) complex in the presence of G-quadruplex DNA is effectively quenched by Cu²⁺ ions due to the Cu²⁺-mediated unfolding of the G-quadruplex motif. The addition of histidine sequesters Cu²⁺ ions from the ensemble, thereby restoring the luminescence of the system. The assay could detect down to 1 渭M of histidine in aqueous media, and also exhibited good selectivity for histidine over other amino acids with the use of the cysteine, masking agent N-ethylmaleimide. Furthermore, the application of the assay for the detection of histidine in diluted urine samples was demonstrated.