TY - JOUR
T1 - Fluorescence lifetime of Rhodamine B in aqueous solutions of polysaccharides and proteins as a function of viscosity and temperature
AU - Mercadé-Prieto, Ruben
AU - Rodriguez-Rivera, Luis
AU - Chen, Xiao Dong
N1 - Funding Information:
This work was supported by the project funding from the Priority Academic Program Development (PAPD) of Jiangsu Higher Education Institution and the “Jiangsu Specially-Appointed Processors Program” of China, the Youth Fund of Natural Science Foundation of Jiangsu Province of China (no. BK20140343), and the National Natural Science Foundation of China, International Cooperation and Exchange Program (21550110192). We thank Prof. Mark Haidekker for helpful discussions.
Publisher Copyright:
© 2017 The Royal Society of Chemistry and Owner Societies.
PY - 2017
Y1 - 2017
N2 - Rhodamine B (RhB) is a well known dye extensively used in thermometric studies, either considering the decrease in the fluorescence intensity or the lifetime (τ) with temperature. Lifetime measurements are preferred over intensity ones as they are more robust. In order to expand microscopy thermometry to complex food fluids, the effect of solutes on the τ of RhB was studied using fluorescence lifetime imaging microscopy (FLIM) in a two-photon microscope. Polysaccharides of different molecular weights (glucose, lactose, dextran, maltodextrin, and sodium alginate), as well as whey proteins, were considered as typical model food ingredients. A linear increase in τ with the concentration is observed in most polysaccharides, highlighting that it is not due to an increase in the macroscopic viscosity, but in maltodextrins a Langmuir-like concentration dependence is observed. There are extensive interactions between RhB and whey proteins at small concentrations that quickly increase τ up to saturation at >10 wt% proteins, with τ modelled well using an adsorption Langmuir model. Therefore, the effect of solutes on RhB τ is not related to changes in the macroscopic viscosity. The temperature sensitivity of τ, quantified using apparent activation energies, decreases at high solute contents.
AB - Rhodamine B (RhB) is a well known dye extensively used in thermometric studies, either considering the decrease in the fluorescence intensity or the lifetime (τ) with temperature. Lifetime measurements are preferred over intensity ones as they are more robust. In order to expand microscopy thermometry to complex food fluids, the effect of solutes on the τ of RhB was studied using fluorescence lifetime imaging microscopy (FLIM) in a two-photon microscope. Polysaccharides of different molecular weights (glucose, lactose, dextran, maltodextrin, and sodium alginate), as well as whey proteins, were considered as typical model food ingredients. A linear increase in τ with the concentration is observed in most polysaccharides, highlighting that it is not due to an increase in the macroscopic viscosity, but in maltodextrins a Langmuir-like concentration dependence is observed. There are extensive interactions between RhB and whey proteins at small concentrations that quickly increase τ up to saturation at >10 wt% proteins, with τ modelled well using an adsorption Langmuir model. Therefore, the effect of solutes on RhB τ is not related to changes in the macroscopic viscosity. The temperature sensitivity of τ, quantified using apparent activation energies, decreases at high solute contents.
UR - http://www.scopus.com/inward/record.url?scp=85033568719&partnerID=8YFLogxK
U2 - 10.1039/c7pp00330g
DO - 10.1039/c7pp00330g
M3 - Article
C2 - 29083002
AN - SCOPUS:85033568719
SN - 1474-905X
VL - 16
SP - 1727
EP - 1734
JO - Photochemical and Photobiological Sciences
JF - Photochemical and Photobiological Sciences
IS - 11
ER -