Interactions between Rhodamine Dyes and Model Membrane Systems-Insights from Molecular Dynamics Simulations
Nisa Magalhães1,2, Guilherme M Simões1,2, Cristiana Ramos1,2
1Coimbra Chemistry Center-Institute of Molecular Sciences (CQC-IMS), University of Coimbra, 3004-535 Coimbra, Portugal.
Molecules (Basel, Switzerland)
|February 25, 2022
Summary
Rhodamine dyes interact differently with cell membranes. Rhodamine B shows higher membrane affinity than Rhodamine 123, impacting its behavior in biological systems and P-glycoprotein interactions.
Area of Science:
- Biophysics
- Chemical Biology
Background:
- Rhodamine dyes are crucial fluorescent probes for cell imaging and studying membrane potential.
- Understanding rhodamine-biomembrane interactions is vital for their effective application.
Purpose of the Study:
- To elucidate the distinct interactions of Rhodamine 123 (Rh123) and Rhodamine B (RhB) with lipid bilayers.
- To correlate structural differences with membrane affinity and probe behavior.
Main Methods:
- Atomistic molecular dynamics (MD) simulations.
- Fluorescence spectroscopy.
- Umbrella sampling MD for free energy profiling.
Main Results:
- MD simulations revealed differences in the orientation and positioning of Rh123 and RhB within POPC bilayers.
- Rhodamine B exhibited a significantly higher lipid/water partition coefficient (>100x) compared to Rhodamine 123.
- Subtle distinctions were observed among different ionization states of the rhodamine probes.
Conclusions:
- Structural variations between Rh123 and RhB dictate their differential interactions with lipid bilayers.
- Rhodamine B's enhanced membrane affinity leads to higher local concentrations, explaining its increased apparent affinity for P-glycoprotein in model membranes.
