Concentration and ionic strength effects on the formation of tetramethyl rosamine aggregates in aqueous solutions.
Mentor 1
Guilherme Indig
Location
Union Wisconsin Room
Start Date
5-4-2019 1:30 PM
End Date
5-4-2019 3:30 PM
Description
The formation of non-fluorescent H-type dye aggregates in subcellular compartments can negatively affect the overall quality of fluorescence microscopy data. These aggregates can also decrease the limits of detection of desirable targets in a variety of biological imaging procedures, including the case of fluorescence-guided delineation of tumor margins in surgical oncology. This study focuses on the analysis of how, and to which extent, concentration and ionic strength affect the aggregation tendencies of the mitochondrial fluorescent dye tetramethyl rosamine (TMR) in aqueous media. TMR was found to show significant tendencies to form H-type dimers in aqueous media. The equilibrium constant for the formation of TMR dimers in pure water was found to be of the order of 2.3 x 103 M-1 at 25 oC. In addition, ionic strength was also found to have a quite large effect on this monomer-dimer equilibrium, with the respective equilibrium constant increasing by up to three orders of magnitude upon going from pure water to aqueous NaCl solutions with increasing ionic strength (up to 4 M). Last but not least, initial studies dealing with the effect of temperature on the respective equilibrium constant, as characterized in pure water and also in NaCl solutions of different ionic strengths, have indicated that upon increasing temperature from 25 oC to 55 oC the equilibrium is always shifted to the side of the dye monomer. Further analysis of our experimental data will provide for the evaluation of standard values or reaction free energy (DGo), reaction enthalpy (DHo) and reaction entropy (DSo), both in pure water and also in aqueous sodium chloride solutions, and permit a more detailed analysis on how and to which extent the hydrophobic effect and changes in entropy may affect dimer formation.
Concentration and ionic strength effects on the formation of tetramethyl rosamine aggregates in aqueous solutions.
Union Wisconsin Room
The formation of non-fluorescent H-type dye aggregates in subcellular compartments can negatively affect the overall quality of fluorescence microscopy data. These aggregates can also decrease the limits of detection of desirable targets in a variety of biological imaging procedures, including the case of fluorescence-guided delineation of tumor margins in surgical oncology. This study focuses on the analysis of how, and to which extent, concentration and ionic strength affect the aggregation tendencies of the mitochondrial fluorescent dye tetramethyl rosamine (TMR) in aqueous media. TMR was found to show significant tendencies to form H-type dimers in aqueous media. The equilibrium constant for the formation of TMR dimers in pure water was found to be of the order of 2.3 x 103 M-1 at 25 oC. In addition, ionic strength was also found to have a quite large effect on this monomer-dimer equilibrium, with the respective equilibrium constant increasing by up to three orders of magnitude upon going from pure water to aqueous NaCl solutions with increasing ionic strength (up to 4 M). Last but not least, initial studies dealing with the effect of temperature on the respective equilibrium constant, as characterized in pure water and also in NaCl solutions of different ionic strengths, have indicated that upon increasing temperature from 25 oC to 55 oC the equilibrium is always shifted to the side of the dye monomer. Further analysis of our experimental data will provide for the evaluation of standard values or reaction free energy (DGo), reaction enthalpy (DHo) and reaction entropy (DSo), both in pure water and also in aqueous sodium chloride solutions, and permit a more detailed analysis on how and to which extent the hydrophobic effect and changes in entropy may affect dimer formation.
