Spatial and Spectral Imaging of Single Micrometer-Sized Solvent Cast Fluorescent Plasticized Poly(vinyl chloride) Sensing Particles

Abstract

Microscale plasticized PVC particles doped with hydrophobic ionophores are prepared by solvent evaporation of aqueous suspensions of sensing cocktails (poly(vinyl chloride), plasticizer, active sensing components, and tetrahydrofuran) and tested as particulate microoptical sensors. The particles contain either only the chromoionophore ETH 2458 as active reagent or the potassium ionophore BME-44, chromoionophore ETH 5294, and lipophilic anionic sites NaTFPB. The former system functions according to an anion-hydrogen ion coextraction mechanism and shows a Hofmeister anion selectivity pattern, while the latter sensor containing additional ionophores represents the more complex, truly selective optical sensors based on ion-exchange equilibria. Single microspheres are simultaneously characterized spatially and spectrally by fluorescence microscopy, coupled to a spectrometer equipped with a CCD detector. The results indicate that these microspheres respond in complete analogy to traditional thin-film-based optodes previously reported in the literature. The introduction of small, spherical ionophore-based sensing particles that operate on the basis of bulk extraction principles holds the promise of significantly expanding the available chemical palette of microsphere-based analytical assays.

Spectral Imaging and Electrochemical Study on the Response Mechanism of Ionophore‐Based Polymeric Membrane Amperometric pH Sensors

“…The Normal Pulse Amperometric data were recorded using LabView 5.0 software (National Instruments, Austin, TX) on a Macintosh computer equipped with a 16-bit data acquisition board (National Instruments, Austin, TX) [23]. The imaging data were collected using a Nikon Eclipse E400 microscope equipped with a Pariss imaging spectrometer (LightForm, Inc., Belle Meade, NJ) and a Model 4920 Peltier cooled CCD camera (Cohu, Inc., San Diego, CA) [26].…”

Micro-miniature Autonomous Optical Sensor Array for Monitoring Ions and Metabolites 1: Design, Fabrication, and Data Analysis

“…[18][19][20] They observed fluorescence intensity change of a single micrometer-sized optode particle in contact with solutions of various analyte concentrations under a fluorescence microscope and concluded that the optode particles respond in complete analogy to traditional thin-film-based optodes previously reported in the literature. 16 More recently, spherical optical nanosensors or PEBBLEs (probes encapsulated by biologically localized embedding) with 20 -200 nm in diameter have been introduced by Kopelman for intracellular measurements of pH, calcium, potassium, chloride and glucose.…”

“…This can be obtained by adopting optode technology that is based on ion exchange between an aqueous sample and a lipophilic membrane loaded with an ionophore molecule that interacts with a suitable chromoionophore to produce color change of the membrane. [11][12][13][14][15][16][17][18][19][20] The microscopic PVC/BEHS based optode beads used in this work contain a hydrogen ion selective chromoionophore, L(beads), a sodium ionophore, I(beads), and a highly lipophilic anion, TFPB -(beads). When the beads are brought in contact with PBS solution, an ion exchange reaction occurs between the beads and the solution phase whose result is a pH-dependent positive charge shift from the ionophore to the chromoionophore: …”

“…11 The capsule contains immobilized glucose oxidase (GOX) that induces pH to gradually decrease inside the capsule as glucose concentration increases outside, due to the enzymatic production of gluconic acid. The color of the coimmobilized pH-sensitive optode [11][12][13][14][15][16][17][18][19][20] type beads responds to the locally induced pH shifts. Thus, capsule color can be linked to sample glucose concentration using prior calibration.…”

Ion-Exchange Reaction of Silver(I) and Copper(II) in Optical Sensors Based on Thiaglutaric Diamide

“…[1][2][3][4] They possess the possibility of improved stability with respect to calibration, particularly in devices where the measured signal is an intensity ratio. Optical sensors can be easily miniaturized for intracellular measurements.…”