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. © 2021 Elsevier Inc.

Anbu S.1, 2 , Paul A.1 , Surendranath K.3 , Sidali A.3 , Pombeiro A.J.L. 1, 4
Elsevier Inc.
  • 1 Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, Lisboa, 1049-001, Portugal
  • 2 Departments of Chemistry and Biomedical Sciences, Cottingham Road, University of Hull, Hull, HU6 7RX, United Kingdom
  • 3 Genome Engineering Laboratory, School of Life Sciences, University of Westminster, London, W1W 6UW, United Kingdom
  • 4 Рeoples' Friendship University of Russia (RUDN University), 6 Miklukho-Maklaya Street, Moscow, 117198, Russian Federation
Cu2+-sensors; Mannich base; Napthalimide; Optical sensors; Phenanthroimidazole; Turn on sensors
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Tuskaev V.A., Gagieva S.C., Kurmaev D.A., Bogdanov V.S., Magomedov K.F., Mikhaylik E.S., Golubev E.K., Buzin M.I., Nikiforova G.G., Vasil'ev V.G., Khrustalev V.N., Dorovatovskii P.V., Bakirov A.V., Shcherbina M., Dzhevakov P.B., Bulychev B.M.
Applied Organometallic Chemistry. John Wiley and Sons Ltd. Vol. 35. 2021.