<title>Micellar bio-optode membranes</title>

Abstract

Ion-selective bulk optode membranes have been combined with enzymatic reactions for the determination of neutral analytes in clinical applications. A new development in membrane technology has been introduced, using reverse micelles to entrap the biocatalyst in bulk polymeric membranes. The use of such reverse micellar systems allows the design of a single layer biosensor where the recognition process as well as the chemical transduction into an optical signal take place in the same sensing layer. Urea-sensitive micellar biooptode membranes have been realized; dynamic range, response behaviour, long-term stability as well as the operational lifetime are discussed. Figure 1: Schematic representation of a reverse micellar system. The recognition biomolecule in the water pool is surrounded by the surfactant interfacial film, that protects the biocatalyst against denaturation.

Design and Synthesis of a More Highly Selective Ammonium Ionophore Than Nonactin and Its Application as an Ion-Sensing Component for an Ion-Selective Electrode

“…The availability of a highly selective ammonium ionophore is crucial for the preparation of ammonium ion chemical sensors and biosensors used for the direct measurement of the ammonium ion − as well as ammonium-derived urea, − amines, , or ammonia. , Until recently, the only available practically used ammonium ionophore was nonactin, a natural product, which was first employed as the ion-sensing component for an ammonium ion-selective electrode in 1970 . For many other ions, following the use of natural products as ionophores, many researchers designed and synthesized highly selective synthetic ionophores for an objective ion, but there are no practically successful ionophores for NH 4 + except nonactin. , Previously, we reported the synthesis of novel ammonium ionophores based on glycol benzyl ether derivatives, , which showed a relatively high ammonium ion selectivity toward K + , but their NH 4 + -to-Na + ratios were not sufficient for practical use when utilized as the ion-sensing component for an ammonium ion-selective electrode.…”

Fiber‐Optic Chemical Sensors: A General Review

“…The most suc cessful fi ber-optic sen sors for de tec tion of this spe cies was based on ion-exchange ex trac tion pro cess. [76][77][78][79] The coextraction mech a nism used a lipophilic ion car rier and a flu o res cent anion and both con tained in a solid oil-in-water emul sion. The emul sion is com posed of lipophilic plasticizer (PVC) droplets (typ i cally con tain ing valiomycin) and a hydrogel contain ing the highly solvatochromic an ion dyes (i.e.…”

pH-Insensitive Ion Selective Optode: A Coextraction-Based Sensor for Potassium Ions

“…Small lipophilic plasticizer droplets containing valinomycin are entrapped in a hydrogel. Solid-state emulsions were also described for enzymatic sensors and ion-exchange-based sensors. , By proper choice of the hydrophilic lipophilic balance (HLB) of the anionic dye, no additional blocking layer is required to prevent leaching of the dye. The HLB of the dye determines two partitioning equilibria: where D S is the dye in the sample (means leaching), D H is the dye in the hydrogel, and D L is the dye in the lipophilic droplets.…”