Sodium-Selective Fluoroionophore-Based Optodes for Seawater Salinity Measurement

Abstract

A new fluorescent sensor for Na is presented. The sensor relies on a Na selective fluoroionophore based on a bright red-emitting BODIPY chromophore. The fluorescence of the fluoroionophore is enhanced upon binding of Na-ions to the highly selective aza-crown ether receptor due to reduction of the photoinduced electron transfer (PET) quenching. Solid state sensing materials were prepared by physically embedding the fluoroionophore into water-swellable biocompatible polymer matrices (polyurethane hydrogels), thus enabling continuous measurements of aqueous samples. Despite the simple design, the sensor showed no leaching of the indicator and featured fast and reversible response. Among different polyurethane hydrogels investigated, the hydrogel D1 featuring the highest water uptake was found to be the most suitable due to the highest dynamics between "off" and "on" states. Due to little or no cross sensitivity to other ions (e.g., Mg, Ca, K) and its insensitivity to potential changes in pH, this sensor is promising for use in clinical diagnostics and for biological and marine applications. Fiber-optic sensors based on referenced read-out with a compact phase fluorimeter were prepared. To demonstrate their practical applicability, the sensors were used to determine the salinity in the seawater and brackish water of the Baltic Sea.

In Situ Detection of Macronutrients and Chloride in Seawater by Submersible Electrochemical Sensors

“…25–42 with acceptable accuracy, its use in low salinity waters is however limited , and consequently the desalination unit may provide an alternative for in situ salinity measurements in most types of natural water. Optical sensors − are currently emerging for this same purpose, but they have not yet been implemented for in situ measurements and field data continue to be extracted from EC measurements using CTD multiparameter probes.…”

Nanoparticle‐Based Fluoroionophore for Analysis of Potassium Ion Dynamics in 3D Tissue Models and In Vivo

“…We wondered if the K + -sensitive crown ether sensor groups exposed at the surface of nanoparticles could participate in observed improvement of cellular uptake. To test this, we stained neural cells with Na + -sensitive FI3 analog (Na-FI3) [28] under the same conditions and analyzed them by microscopy (Figures 4E, S3B). We found that both K + and Na + -sensitive nanoparticles displayed comparable ability to stain live cells suggesting the potential role of crown ether in improving the cell staining efficiency of RL100-based nanoparticles.…”

“…[8g] Na-FI3 was synthesized as described before. [28] Cholera toxin, subunit B, Alexa Fluor 488 conjugate, CoroNa Green-AM and B-27 serum-free media supplement were from ThermoFisher (BioSciences, Dublin, Ireland). Fibroblast growth factor (FGF), Epidermal growth factor (EGF), R-spondin and MilliCell membranes were from Millipore (Cork, Ireland).…”

A versatile optode system for oxygen, carbon dioxide, and pH measurements in seawater with integrated battery and logger

“…This cross‐talk is marginal in ocean water but in other environments (brackish water) has to be compensated with help of external salinity data. Salinity data can be obtained via conventional conductivity measurement or using a recently reported sodium optode (Müller et al ).…”