National University of Singapore,
Keywords: stimulated Raman scattering microscopy, real-time monitoring, living cells drug delivery
Summary:Dynamics of mitochondria play a pivotal role in biological events such as cell metabolism, early stage apoptosis and cell differentiation. Mitochondrial dysfunctions can be one of the major causes resulting in cancer and neurodegenerative diseases in biological and biomedical system. Triphenylphosphonium (TPP) is a popular mitochondria targeting agent used in design of imaging probes and drugs. However, its pharmacokinetic behaviors in living systems have not yet been well understood due to a lack of suitable imaging tools. This technology is the utility of stimulated Raman Scattering (SRS) microscopy associated with an aryl-diyne-based Raman tag to monitor the pharmacokinetics of the Raman-tagged triphenylphosphonium (TPP- BDDBPDM) in living cells with subcellular resolution. With the merits of the excellent photostability and linear dependence of SRS signal with the TPP- BDDBPDM concentrations, our method enables real-time measurements of the cellular uptake rate as well as the intracellular distribution of TPP under various mitochondrial conditions. The time-lapsed SRS imaging of mitochondria using TPP-BDDBPDM uncovers a sequence of mitochondrial fission and fusion processes in response to carbonyl cyanide m-chlorophenylhydrazone (CCCP), providing new avenue of observing unprecedented events under conventional fluorescence imaging techniques. SRS microscopy associated with Raman tag is a promising tool for pharmacokinetic characterization of TPP in live cells at subcellular level, promoting the development of mitochondria-targeted imaging probes and therapies in future.