Fluorescence Imaging of Microdialysis Sampling

Many biomolecules including proteolytic enzymes known as matrix metalloproteinases (MMPs) are released when a material, such as a microdialysis probe, is implanted in a living organism. The MMPs cleave structural protein components of the extracellular matrix and play an important role in biological functions such as wound healing.1-3 Many enzymatic substrates for MMPs have fluorescent product mimics, and the mimics can be used as agents to monitor biochemical processes.1 In this study, microdialysis, a minimally invasive sampling technique, was combined with fluorescence imaging to determine the possibility of monitoring microdialysis in real-time, and thus provide a method that could ultimately lead to the ability to monitor localized MMPs.. In vitro studies were conducted with fluorescent dyes IR-820 and Rhodamine B, producing promising results that illustrate combining microdialysis and fluorescence imaging is quite feasible. The IR-820 was unpredictable during in vitro studies; therefore, it was not used in vivo, and Rhodamine B was selected to develop and optimize the combined method due to its stability. Microdialysis probes embedded in agarose phantoms, perfused with Rhodamine B, and imaged via a fluorescent imaging system clearly revealed a diffusion profile developing with time. Increased intensity surrounding the probe during infusion was also visible