NADH-depletion triggered energy shutting with cyclometalated iridium (III) complex enabled bimodal Luminescence-SERS sensing and photodynamic therapy

• Published in: Biosensors & bioelectronics Vol. 204; p. 114087
• Main Authors: Shamjith, Shanmughan, Joseph, Manu M., Murali, Vishnu Priya, Remya, Geetha S., Nair, Jyothi B., Suresh, Cherumuttathu H., Maiti, Kaustabh Kumar
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 15-05-2022
• Subjects: Biosensing Techniques; Computational modelling; Enhanced therapeutic; Iridium - chemistry; Iridium complex; Luminescence; Multiphase-PDT; NAD - chemistry; NAD radical; NADH-Sensing; Photochemotherapy; Iridium complex; Enhanced therapeutic; NAD radical; Multiphase-PDT; Computational modelling; NADH-Sensing
• ISSN: 0956-5663; 1873-4235
• DOI: 10.1016/j.bios.2022.114087

The nicotinamide adenine dinucleotide-reduced (NADH) function as a hydride (H) carrier to maintain cellular homeostasis. Herein, we report a quinoline appended iridium complex (QAIC) as a molecular probe in fluorescence and surface-enhanced Raman spectroscopy (SERS) modalities to evaluate the endogenous NADH status. NADH-triggered activation of QAIC enabled luminescence (turn-ON) and SERS (turn-OFF) switching phenomenon with a detection limit of 25.6 nM and 15 pM for NADH in luminescence and SERS respectively. Transition state modelling using density functional theory calculations proved that a facile migration of H from NADH to QAIC transformed the activated QAIC (N-QAIC) with an energy span of 19.7 kcal/mol. Furthermore, N-QAIC is probed as a photosensitizer to source singlet oxygen by blocking the photo induced electron transfer (PeT) and generate NAD radicals. Therefore, an efficient light triggered cyclometalated iridium-based molecular probe has been divulged to promote bimodal NADH sensing and multiphase photodynamic therapy.
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•A theranostic molecular probe based on quinoline appended cyclometalated iridium complex QAIC was synthesized.•The molecular probe exhibited bimodal detection properties in fluorescence and surface-enhanced Raman spectroscopy.•DFT calculations proved a facile migration of H ̶ from NADH to QAIC with an energy span of 19.7 kcal/mol.•PeT switching process transformed into an activated motif N-QAIC to exert targeted PDT in hepatocellular carcinoma cells.•QAIC generate NAD radical upon laser trigger to facilitate oxygen independent photodynamic therapy in hypoxic tumor.