Chemosensory Optode Array Based on Pluronic-Stabilized Microspheres for Differential Sensing

Abstract

Differential sensing techniques are becoming nowadays an attractive alternative to classical selective recognition methods due to the “fingerprinting” possibility allowing identifying various analytes without the need to fabricate highly selective binding recognition sites. This work shows for the first time that surfactant-based ion-sensitive microspheres as optodes in the microscale can be designed as cross-sensitive materials; thus, they are perfect candidates as sensing elements for differential sensing. Four types of the newly developed chemosensory microspheres—anion- and cation-selective, sensitive toward amine- and hydroxyl moiety—exhibited a wide range of linear response (two to five orders of magnitude) in absorbance and/or fluorescence mode, great time stability (at least 2 months), as well as good fabrication repeatability. The array of four types of chemosensitive microspheres was capable of perfect pattern-based identification of eight neurotransmitters: dopamine, epinephrine, norepinephrine, γ-aminobutyric acid (GABA), acetylcholine, histamine, taurine, and phenylethylamine. Moreover, it allowed the quantification of neurotransmitters, also in mixtures. Its selectivity toward neurotransmitters was studied using α- and β-amino acids (Ala, Asp, Pro, Tyr, taurine) in simulated blood plasma solution. It was revealed that the chemosensory optode set could recognize subtle differences in the chemical structure based on the differential interaction of microspheres with various moieties present in the molecule. The presented method is simple, versatile, and convenient, and it could be adopted to various quantitative and qualitative analytical tasks due to the simple adjusting of microspheres components and measurement conditions.

Toward an Electronic Tongue Based on Surfactant-Stabilized Chemosensory Microparticles with a Dual Detection Mode

“…The microspheres selective for both anions (A) and cations (C) contained a chromoionophore (CH) as an optical transducer, which can be protonated/deprotonated in the presence of an ion exchanger (R). This change in the protonation degree of the chromoionophore is responsible for the change in the optical properties of the produced microspheres according to eqs and (for AS-MPs and CS-MPs, respectively). ,, The next two types of microspheres were incorporated with the manganese porphyrins, which played the double role of an ionophore and an optical transducer, according to eqs and . CH normalm + normalR normalm + + normalH aq + + normalA aq − ⇆ CHH normalm + + normalR + normalA normalm − CHH normalm + + normalR normalm − + normalC aq + ⇆ CH normalm + normalH aq + + normalC + normalR normalm − MnOEPCl normalm + normalA aq − ⇆ MnOEPA normalm …”

“…In our previous work, we showed that such chemosensory nano-/ microspheres can be fabricated reliably with a high degree of repeatability, and their lifetime exceeds 2 months. 6 The microspheres selective for both anions (A) and cations (C) contained a chromoionophore (CH) as an optical transducer, which can be protonated/deprotonated in the presence of an ion exchanger (R). This change in the protonation degree of the chromoionophore is responsible for the change in the optical properties of the produced microspheres according to eqs 1 and 2 (for AS-MPs and CS-MPs, respectively).…”

“…Recently, monodisperse ion-selective nano-/microspheres were proposed, containing a lipophilic pH indicator, an ion exchanger, a plasticizer, and (optionally) an ionophore . Their composition can be optimized to achieve the desired properties in terms of the selectivity pattern and particle size. ,, Moreover, their pH cross-response and limited selectivity toward specific ions, which would be considered disadvantageous in classical sensing, are in fact advantageous in differential sensing …”

“…31 Their composition can be optimized to achieve the desired properties in terms of the selectivity pattern and particle size. 6,32,33 Moreover, their pH cross-response and limited selectivity toward specific ions, which would be considered disadvantageous in classical sensing, are in fact advantageous in differential sensing. 6 Therefore, in this work, we propose a novel type of electronic tongue based on chemosensory microparticles (MPs) with a lipophilic core stabilized by a nonionic poloxamer surfactant.…”

“…6,32,33 Moreover, their pH cross-response and limited selectivity toward specific ions, which would be considered disadvantageous in classical sensing, are in fact advantageous in differential sensing. 6 Therefore, in this work, we propose a novel type of electronic tongue based on chemosensory microparticles (MPs) with a lipophilic core stabilized by a nonionic poloxamer surfactant. The lipophilic core components reflect the composition of bulk ion-selective optodes with emphasis given to achieve cross-sensitivity.…”