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Fluorescence lifetime of Rhodamine B in aqueous solutions of polysaccharides and proteins as a function of viscosity and temperature
Photochemical & Photobiological Sciences ( IF 3.1 ) Pub Date : 2017-10-13 00:00:00 , DOI: 10.1039/c7pp00330g
Ruben Mercadé-Prieto 1, 2, 3, 4, 5 , Luis Rodriguez-Rivera 6, 7, 8, 9 , Xiao Dong Chen 1, 2, 3, 4, 5
Affiliation  

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.

中文翻译:

罗丹明B在多糖和蛋白质水溶液中的荧光寿命与粘度和温度的关系。

罗丹明B(RhB)是一种广泛用于测温研究的众所周知的染料,考虑到荧光强度的降低或寿命(τ)随温度的降低。寿命测量比强度测量更可取,因为它们更可靠。为了扩大显微镜测温到复杂的食品流体,溶质对效果τ在双光子显微镜使用荧光寿命成像显微术(FLIM)进行了研究罗丹明B。不同分子量的多糖(葡萄糖,乳糖,右旋糖酐,麦芽糊精和藻酸钠)以及乳清蛋白被认为是典型的模型食品成分。τ线性增加在大多数多糖中都观察到浓度的变化,这表明这不是由于宏观粘度的增加,而是在麦芽糖糊精中观察到了朗缪尔样的浓度依赖性。在低浓度的RhB和乳清蛋白之间存在广泛的相互作用,可迅速将τ增加到> 10 wt%的蛋白饱和度,并且使用吸附Langmuir模型很好地模拟了τ。因此,溶质的罗丹明B上的效果τ是不相关的宏观粘度变化。用表观活化能量化的温度敏感性τ在高溶质含量下会降低。
更新日期:2017-11-08
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