Monitoring the Kinetics of the Cellular Uptake of a Metal Carbonyl Conjugated with a Lipidic Moiety in Living Cells Using Synchrotron Infrared Spectromicroscopy

Abstract

Presented here is the exploitation of synchrotron infrared spectromicroscopy to evaluate the feasibility of monitoring the cellular uptake of rhenium-tris-carbonyl-tagged (Re(CO)3) lipophilic chains in living cells. To this aim, an in-house thermostated microfluidic device was used to limit water absorption while keeping cells alive. Indeed, cells showed a high survival rate in the microfluidic device over the course of the experiment, proving the short-term biocompatibility of the device. We recorded spectra of single, living, fully hydrated breast cancer MDA-MB231 cells and could follow the penetration of the rhenium complexes for up to 2 h. Despite the strong variations observed in the uptake kinetics between individual cells, the Re(CO)3 complex was traced inside the cells at low concentration and shown to enter them on the hour time scale by active transport.

Cytometry in the Short-Wave Infrared

“…The fitted result gives three parameters, including Hill coefficient n , Michaelis constant k M , and maximum cellular uptake mass m̅ max . The deduced Hill coefficient n at ∼1.66, which is much larger than 1, reveals a positively cooperative uptake nature, or an active internalization process, such as receptor-mediated endocytosis of (6,5) into RAW macrophages. − The Michaelis constant k M at 198.2 μg L –1 estimates the required (6,5) concentration to treat the cells for obtaining half of the maximum cellular (6,5) mass. The (6,5) uptake efficiency gradually decreases when treated (6,5) concentration is higher than the Michaelis constant, indicating a saturation of the RAW macrophages’ active transportation.…”

Cytometry in the short-wave infrared

“…The fitted result gives three parameters, including Hill coefficient 𝑛 , Michaelis constant 𝑘 M , and maximum cellular uptake mass 𝑚 ̅ max . The deduced Hill coefficient 𝑛 at ~1.87, which is much larger than 1, reveals the positively cooperative uptake nature, or the active internalization process, such as receptor-mediated endocytosis of (6,5) into RAW macrophages [39][40][41][42] . The Michaelis constant 𝑘 M at 192.5 µg L −1 estimates the required (6,5) concentration to treat the cells for obtaining half of the maximum cellular (6,5) mass.…”

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

“…407 Quantification of the cellular uptake of the complexes based on their characteristic IR absorption reveals that a longer chain can enhance the cellular permeation and cytotoxic activity of the complexes. The cellular uptake of complex 207c in live MDA-MB-231 cells has been monitored in real time using a microfluidic device to limit water absorption while keeping the cells alive, showing that the intracellular concentration of the complex reaches a plateau within 1 h. 408 This lipophilic complex has also been incorporated into bicosomes to promote its skin penetration for dermatological applications. 409 A related rhenium(I) 1-(2-pyridyl)-1,2,3-triazole complex (208) has also been developed for cellular imaging.…”