Imaging mitochondrial palladium species in living cells with a NIR iridium(III) complex

Shining New Light on Biological Systems: Luminescent Transition Metal Complexes for Bioimaging and Biosensing Applications

Luminescence imaging is a powerful and versatile technique for investigating cell physiology and pathology in living systems, making significant contributions to life science research and clinical diagnosis. In recent years, luminescent transition metal complexes have gained significant attention for diagnostic and therapeutic applications due to their unique photophysical and photochemical properties. In this Review, we provide a comprehensive overview of the recent development of luminescent transition metal complexes for bioimaging and biosensing applications, with a focus on transition metal centers with a d6, d8, and d10 electronic configuration. We elucidate the structure-property relationships of luminescent transition metal complexes, exploring how their structural characteristics can be manipulated to control their biological behavior such as cellular uptake, localization, biocompatibility, pharmacokinetics, and biodistribution. Furthermore, we introduce the various design strategies that leverage the interesting photophysical properties of luminescent transition metal complexes for a wide variety of biological applications, including autofluorescence-free imaging, multimodal imaging, organelle imaging, biological sensing, microenvironment monitoring, bioorthogonal labeling, bacterial imaging, and cell viability assessment. Finally, we provide insights into the challenges and perspectives of luminescent transition metal complexes for bioimaging and biosensing applications, as well as their use in disease diagnosis and treatment evaluation.

Development of a NIR Iridium(III) Complex-Based Probe for the Selective Detection of Iron(II) Ions

As a commonly used metal ion, iron(II) (Fe2+) ions pose a potential threat to ecosystems and human health. Therefore, it is particularly important to develop analytical techniques for the rapid and accurate detection of Fe2+ ions. However, the development of near-infrared (NIR) luminescence probes with good photostability for Fe2+ ions remain challenging. In this work, we report a novel iridium(III) complex-based luminescence probe for the sensitive and rapid detection of Fe2+ ions in a solution based on an Fe2+-mediated reduction reaction. This probe is capable of sensitively detecting Fe2+ ions with a limit of detection (LOD) of 0.26 μM. Furthermore, this probe shows high photostability, and its luminescence remains stable under 365 nm irradiation over a time period of 30 min. To our knowledge, this is first iridium(III) complex-based NIR probe for the detection of Fe2+ ions. We believe that this work provides a new method for the detection of Fe2+ ions and has great potential for future applications in water quality testing and human monitoring.

Recent Advances in Organometallic NIR Iridium(III) Complexes for Detection and Therapy

Iridium(III) complexes are emerging as a promising tool in the area of detection and therapy due to their prominent photophysical properties, including higher photostability, tunable phosphorescence emission, long-lasting phosphorescence, and high quantum yields. In recent years, much effort has been devoted to develop novel near-infrared (NIR) iridium(III) complexes to improve signal-to-noise ratio and enhance tissue penetration. In this review, we summarize different classes of organometallic NIR iridium(III) complexes for detection and therapy, including cyclometalated ligand-enabled NIR iridium(III) complexes and NIR-dye-conjugated iridium(III) complexes. Moreover, the prospects and challenges for organometallic NIR iridium(III) complexes for targeted detection and therapy are discussed.