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

Hong Zhang He, Modi Wang, Daniel Shiu Hin Chan, Chung Hang Leung, Jianwen QIU, Edmond Dik Lung MA*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

22 Citations (Scopus)

Abstract

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'-TG4AG3TG4AG3TG4A2G2-3')/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 1μM 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.

Original languageEnglish
Pages (from-to)205-211
Number of pages7
JournalMethods
Volume64
Issue number3
DOIs
Publication statusPublished - 15 Dec 2013

Scopus Subject Areas

  • Molecular Biology
  • Biochemistry, Genetics and Molecular Biology(all)

User-Defined Keywords

  • G-quadruplex
  • Histidine
  • Iridium(III) complex
  • Label-free
  • Luminescence

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