Ionophore-based pH independent detection of ions utilizing aggregation-induced effects

Abstract

Here, aggregation-induced emission and quenching were incorporated for the first time in ionophore-based optical nanosensors.

Ion-Induced Phase Transfer of Cationic Dyes for Fluorescence-Based Electrolyte Sensing in Droplet Microfluidics

“…According to the calibration curve, only about 3.5 and 0.6% of K + is depleted from the 10 –4 and 10 –3 M KCl solutions, respectively. As expected, this methodology does not suffer from significant cross-sensitivity toward pH fluctuation of the sample (Figure S6), which is consistent with all other ion-selective optodes using the dye-exchange chemistry. − There are fluorescence spikes preceding most oil segments but not aqueous segments. These spikes enable us to identify which sections in the fluorescence trace are from the oil segments when both phases have fluorescence.…”

“…A wide variety of cationic fluorophores are available including those previously used in ion-selective optodes. − Most rhodamine derivatives have very high quantum yields in water or other highly polar solvents such as methanol . Phenothiazine derivatives such as methylene blue also have appreciable fluorescence in water .…”

“…In recent years, ion sensing has been advanced by the emergence of new ion-selective optodes with improved analytical performance . One example is the optodes based on ion-triggered exchange of cationic dyes from the sensor phase to the sample. − Since no protonation or deprotonation process is involved, this method is intrinsically independent of the sample pH, representing an attractive feature compared to classical pH indicator-based optodes. A prerequisite for this sensing principle to work is that the dye needs to display a significant disparity in the fluorescence of the optode phase and the aqueous phase because fluorescence measurements are performed to a mixture of two phases (e.g., nanoparticle/nanoemulsion suspensions).…”

Ionophore-Based Potassium Selective Fluorescent Organosilica Nano-Optodes Containing Covalently Attached Solvatochromic Dyes

“…The nano-optodes could share a similar sensing mechanism with polymer film-based bulk optodes where an increase of K + concentration ([K + ]) leads to the deprotonation of a pH indicator (H + chromoionophore) in the nanospheres [19][20][21]. For example, the group of Bakker, Michalska, Clark, Cash, and our own have reported such nano-optodes based on different materials including Pluronic F-127, lipid covered plasticizer nanodroplets, conducting polymers, organosilicas, and quantum dots [14,15,[22][23][24][25][26][27][28][29].…”

Ionophore-based ion-selective electrodes: signal transduction and amplification from potentiometry

“…1,3,[38][39][40] However, the measurements depend on the concentration of a reference ion such as H + as well as positively charged dyes. [41][42][43][44][45][46][47][48][49][50][51][52][53][54] Secondly, traditional optical sensors generate signals directly in the samples, which could suffer from the color, autoluminescence, and turbidity of the sample. Although sample pretreatment with paper-based devices and hydrogels have been integrated in ion-selective optical sensors, [54][55][56][57][58][59][60][61][62][63][64] complete separation between the sample and detection compartments could overcome potential background optical interference.…”