Luminescent EuIII and TbIII Complexes Containing Dopamine Neurotransmitter: Biological Interactions, Antioxidant Activity and Cellular‐Imaging Studies

• Published in: European journal of inorganic chemistry Vol. 2018; no. 35; pp. 3942 - 3951
• Main Authors: Singh, Khushbu, Goenka, Anshika, Ganesh, Subramaniam, Patra, Ashis K.
• Format: Journal Article
• Language: English; Japanese
• Published: Weinheim Wiley Subscription Services, Inc 23.09.2018
• Subjects: Antioxidants; Biological activity; Catechol; Cellular imaging; Cleavage; Deoxyribonucleic acid; Diethylenetriamine pentaacetic acid; DNA; Dopamine; Dopamines; Energy transfer; Functional groups; Inorganic chemistry; Lanthanides; Luminescence; Medical imaging; Neuroblastoma; Photoexcitation; Plasmids; Serum albumin
• DOI: 10.1002/ejic.201800732
• ISSN: 1434-1948

Two luminescent water‐soluble lanthanide(III) complexes, [Ln(DTPA‐DOPA)(H2O)] (1–2) where Ln = EuIII (1), TbIII (2), formed by reaction with diethylenetriaminepentaacetic acid (DTPA) carrying the neurotransmitter dopamine with catechol functional groups [i.e., DTPA‐bis(3‐hydroxytyramide)], are characterized and their photophysical properties are studied. Strong characteristic red and green luminescence is observed for 1 and 2 upon photoexcitation, followed by efficient energy transfer from dopamine to LnIII, leading to intraconfigurational f–f transitions. They show distinguishable sharp emission bands due to intraconfigurational 5D0→7FJ transitions in EuIII and 5D4→7FJ transitions in TbIII. They exhibit long excited‐state lifetimes [τ = 0.52 ms (1) and 0.33 ms (2)] and calculated quantum yields, Φoverall, of 0.022 (1) and 0.038 (2). The luminescent complexes are studied for their antioxidant activity, ability to interact with calf‐thymus DNA (CT‐DNA) and bovine serum albumin (BSA), hydrolytic cleavage of pUC19 supercoiled plasmid DNA and as cellular‐imaging probes for both cancer cells and neuroblastoma cells. Both the EuIII and TbIII complexes exhibit potent antioxidant activity. These complexes show moderate binding affinity towards CT‐DNA (Kb ≈ 104 m–1) and BSA (KBSA = 103 m–1). The complexes at 200 µm exhibit good hydrolytic cleavage of supercoiled pUC19 DNA. The non‐cytotoxic nature of these complexes makes them efficient candidates for cellular‐imaging probes. Cytosolic localization is observed for both of the complexes in HeLa cells and mouse neuroblastoma (Neuro‐2a) cells. The present systems, with advantageous antioxidant activity, may have potential application in the tracking and delivery of dopamine, which is important for dopamine replacement therapy in various neurodegenerative disorders. Lanthanide(III) complexes of DTPA bisamide dopamine [Ln(DTPA‐DOPA)(H2O)] {Ln = EuIII (1), TbIII (2)} are explored for their interactions with DNA and BSA, DNA hydrolysis, and photophysical, antioxidant, and neuronal‐cell‐imaging properties. The complexes show efficient antioxidant activity and intracellular luminescence in HeLa and neuroblastoma cells, with potential for bioimaging applications.