Naphthalimide-phenanthroimidazole incorporated new fluorescent sensor for “turn-on” Cu2+ detection in living cancer cells

In recent years, fluorescent sensors have emerged as attractive imaging probes due to their distinct responses toward bio-relevant metal ions. However, the bioimaging application main barrier is the ‘turn-off’ response toward paramagnetic metal ions such as Cu2+ under physiological conditions. Herein, we report a new sensor (2-methyl(4-bromo-N-ethylpiperazinyl-1,8-naphthalimido)-4-(1H-phenanthro[9,10-d]imidazole-2-yl) phenol) NPP with multifunctional (Naphthalimide, Piperazine, Phenanthroimidazole) units for fluorescent and colourimetric detection of Cu2+ in an aqueous medium. Both absorption and fluorescence spectral titration strategies were used to monitor the Cu2+-sensing property of NPP. The NPP displays a weak emission at ca. 455 nm, which remarkably enhances (⁓3.2-fold) upon selective binding of Cu2+ over a range of metal ions, including other paramagnetic metal ions (Mn2+, Fe3+, Co2+). The stoichiometry, binding constant (Ka) and the LOD (limit of detection) of NPP toward Cu2+ ions were found to be 1:1, 5.0 (± 0.2) × 104 M−1 and 6.5 (± 0.4) × 10−7 M, respectively. We have also used NPP as a fluorescent probe to detect Cu2+ in live (human cervical HeLa) cancer cells. The emission intensity of NPP was almost recovered in HeLa cells by incubating ‘in situ’ the derived Cu2+ complex (NPP-Cu2+) in the presence of a benchmark chelating agent such as EDTA (ethylenediaminetetraacetate). The fluorescent emission of NPP was reverted significantly in each cycle upon sequencial addition of Cu2+ and EDTA to the NPP solution. Overall, NPP is a novel, simple, economic and portable sensor that can detect Cu2+ in biological and environmental scenarios.

Anbu S.1, 2 , Paul A.1 , Pombeiro A.J.L. 1, 4 , Surendranath K. 3 , Sidali A. 3
Elsevier Inc.
  • 1 Centro de Química Estrutural|Instituto Superior Técnico|Universidade de Lisboa
  • 2 Departments of Chemistry and Biomedical Sciences|Cottingham Road|University of Hull
  • 3 Рeoples' Friendship University of Russia (RUDN University)
  • 4 Genome Engineering Laboratory|School of Life Sciences
Ключевые слова
Cu<sup>2+</sup>-sensors; Mannich base; Napthalimide; optical sensors; Phenanthroimidazole; Turn on sensors
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