Fluorescein Derivatives as Fluorescent Probes for pH Monitoring along Recent Biological Applications

Guern, Florent Le; Mussard, Vanessa; Gaucher, Anne; Rottman, Martin; Prim, Damien

doi:10.3390/ijms21239217

Cited by 113 publications

(75 citation statements)

References 104 publications

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“…The plot of the ratio of the integrated FI of FITC and NR as function of pH (Fig. 2g, inset) yields a pKa value of 7.47 ± 0.02 that is slightly shifted to basic pH values compared to unbound FITC (pKa value of 6.5) 39 . This shift is attributed to the coupling of FITC to a negatively charged particle 40 .…”

Section: Resultsmentioning

confidence: 97%

Monitoring And Imaging Ph In Biofilms Utilizing A Fluorescent Polymeric Nanosensor

Kromer

Schwibbert

Gadicherla

et al. 2022

Preprint

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Biofilms are ubiquitous in nature and in the man-made environment. Given their harmful effects on human health, an in-depth understanding of biofilms and the monitoring of their formation and growth are important. Particularly relevant for many metabolic processes and survival strategies of biofilms is their extracellular pH. However, most conventional techniques are not suited for minimally invasive pH measurements of living biofilms. Here, a fluorescent nanosensor is presented for ratiometric measurements of pH in biofilms in the range of pH 4.5-9.5 using confocal laser scanning microscopy. The nanosensor consists of biocompatible polystyrene nanoparticles loaded with pH-inert dye Nile Red and is surface functionalized with a pH-responsive fluorescein dye. Its performance was validated by fluorometrically monitoring the time-dependent changes in pH in E. coli biofilms after glucose inoculation at 37°C and 4°C. This revealed a temperature-dependent decrease in pH over a 4-hour period caused by the acidifying glucose metabolism of E. coli. These studies demonstrate the applicability of this nanosensor to characterize the chemical microenvironment in biofilms with fluorescence methods.

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Section: Resultsmentioning

confidence: 97%

Monitoring And Imaging Ph In Biofilms Utilizing A Fluorescent Polymeric Nanosensor

Kromer

Schwibbert

Gadicherla

et al. 2022

Preprint

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“…Both tartrazine and fluorescein are well‐known dyes, the first commonly used as pharmaceutical and food colorant, [13,14] while the second is a broadly used fluorescent probe in biological and biochemical applications [15,16] . Unlike tartrazine, fluorescein and its derivatives can exist in aqueous solution in a number of prototropic forms: cationic, neutral, monoanionic and di‐anionic (Figure 2A).…”

Section: Resultsmentioning

confidence: 99%

The Exception That Proves the Rule: How Sodium Chelation Can Alter the Charge‐Cell Binding Correlation of Fluorescein‐Based Multimodal Imaging Agents

et al. 2022

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In the present study we describe and explain an aberrant behavior in terms of receptor binding profile of a fluoresceinbased multimodal imaging agent for gastrin releasing peptide receptor (GRPR) visualization by elucidating a chelating mechanism on sodium ions of its fluorescent dye moiety. This hypothesis is supported by both biological results and spectroscopic analyses of different fluorescein-carrying conjugates and an equally charged set of analogous tartrazine-based GRPRbinding imaging agents. Fluorescein interacts with sodium which reduces the overall negative charge of the dye molecule by one. This reduction in apparent total net charge explains the exceptional behavior found for the fluorescein-based multimodal bioconjugate in the context of the charge-cell binding correlation hypothesis.

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“…Additionally, ELISA revealed that with speci c parameters, EA stimulation increased the amount of exogenous NGF in the brain under physiological and pathological conditions but did not affect the physical structure of the BBB, which is important for preserving cellular integrity and the health of the brain and the CNS (42). To visually observe the passage of NGF across the BBB, we labeled the primary amine group of NGF with FITC, establishing a stable urea bond covalently to form FITC-NGF (43). In general, FITC-NGF emits yellow-green uorescence that permits tracing of the bonded NGF.…”

Section: Discussionmentioning

confidence: 99%

The Influence of Electronic Acupuncture At A Specific Frequency In Facilitating The Passage of NGF Through The Blood-Brain Barrier And Its Effect On Learning And Memory In MCAO/R Rats

Zhao

Mao

Wang

et al. 2021

Preprint

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The blood-brain barrier (BBB) maintains the balance of the internal environment of the brain and strictly controls substance exchange between the brain and blood dynamically but stably. Transient increases in the permeability of the BBB plays an important role in helping macromolecular drugs enter the brain to exert their pharmacological effects. Previous research has revealed that electronic acupuncture (EA) stimulation at a specific frequency can enhance the permeability of the BBB and induce the entry of 20 kDa fluorescein isothiocyanate-dextran (FITC-dextran) into the cerebral cortex, but whether it can also allow drugs to pass the BBB remains unknown. We hypothesized that EA at a specific frequency could open the BBB and induce the entry of nerve growth factor (NGF) into the brain to exert its therapeutic effect. To simulate the clinical apoplexy sequelae observed in patients and determine the basic timing of BBB repair under pathological conditions, we employed the middle cerebral artery occlusion (MCAO) model and assessed changes in the permeability and structure of the BBB by measuring both the intensity of Evans blue (EB) staining and the cerebral infarction volume and evaluating the ultrastructure of the BBB. Then, we used a laser spectrometer and immunofluorescence to observe entry of NGF into the brain. Finally, we assessed the learning and memory ability of rats and used the DeadEnd TM Fluorometric TUNEL System to assess apoptosis in the hippocampus. Our results showed that the BBB was essentially repaired three weeks after MCAO, indicating that EA stimulation at a specific frequency can enhance BBB permeability and induce NGF uptake by prefrontal neurons. In the presence of EA stimulation, entry of NGF into the brain promoted learning and memory in rats and inhibited the apoptosis of neurons in the hippocampus. In this study, the MCAO model was used to determine the timing of BBB repair under pathological conditions and assess the EA stimulation-induced entry of NGF into the brain to exert its therapeutic effect. EA could serve as a new strategy for delivering therapeutics to the central nervous system (CNS), given that EA stimulation at a specific frequency was shown to increase the permeability of the BBB. Further study of the mechanism underlying the opening of the BBB and its timing is needed.

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Fluorescein Derivatives as Fluorescent Probes for pH Monitoring along Recent Biological Applications

Cited by 113 publications

References 104 publications

Monitoring And Imaging Ph In Biofilms Utilizing A Fluorescent Polymeric Nanosensor

Monitoring And Imaging Ph In Biofilms Utilizing A Fluorescent Polymeric Nanosensor

The Exception That Proves the Rule: How Sodium Chelation Can Alter the Charge‐Cell Binding Correlation of Fluorescein‐Based Multimodal Imaging Agents

The Influence of Electronic Acupuncture At A Specific Frequency In Facilitating The Passage of NGF Through The Blood-Brain Barrier And Its Effect On Learning And Memory In MCAO/R Rats

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