Stabilized potentiometric solid-state polyion sensors using silver-calixarene complexes as additives within ion-exchanger-based polymeric films

Abstract

Novel solid-state sensors for biomedically important polyions (i.e., heparin and protamine) that exhibit significantly enhanced initial EMF stability are prepared by incorporation of lipophilic silver-calixarene complexes along with the required ion-exchangers within polymeric films. A dithioether of tertiary butyl calix[4]arene together with its silver complex are added to the polyion sensing membranes which are deposited on a silver-epoxy conductor of a solid-state transducer. The silver-complex serves as a reversible electron transfer agent between the organic polymer film and the underlying solid-state conductor, resulting in highly reproducible starting EMF values and improved initial signal stability. This approach is further employed to devise a heparin sensing cartridge for blood measurements based on a novel differential measurement mode. One sensor responds to heparin, while the second identical solid-state sensor serves as a pseudo reference electrode with all heparin present in the sample within this half-cell complexed by the addition of excess protamine. The cartridges are evaluated by monitoring heparin response in spiked dog blood using poly(vinyl chloride) (PVC) blends and fluorinated silicone rubber (Dow Corning RTV 730) films containing appropriate levels of ionexchanger and Ag +-calixarene/free calixarene additives.

An all-solid-state polymeric membrane Pb2+-selective electrode with bimodal pore C60 as solid contact

“…C 60 powders (99.5% pure) were purchased from JC nano Materials Tech Co., Ltd. (Nanjing, China), lead ionophore IV, [tert-butylcalix [4] …”

“…The BP-C 60 materials with macro-and meso-pore architectures, including BP-C 60 (I) and BP-C 60 (II), were synthesized respectively in the mixture solvents of CCl 4 and benzene with the weight ratios of 2:8 and 1:9 by the liquid-liquid interfacial precipitation method [16]. A BP-C 60 suspension was prepared by adding 1 mL toluene containing 0.15 mg mL À1 BP-C 60 into acetonitrile of 3 mL with stirring.…”

“…Unfortunately, coated wire electrodes show long-term potential instability, which is attributed to the lack of a well-defined interface between the ionically conductive sensing membrane and the electronically conductive conductor and the formation of a thin water layer between them [2,3]. By incorporation of appropriate redox-active compounds to the ISE membranes [4,5] or using conducting polymers (CPs) such as polypyrrole, poly(3-octylthiophene), polyaniline and poly (3,4-ethlyenedioxythiophene) as solid contacts [6], the potential stabilities of all-solid-state ISEs can be largely improved. However, these methods may still suffer from problems of the presence of the water layers, undesired side reactions with redox interferences and sensitivity to light, dissolved oxygen and CO 2 [6,7].…”

Calixarene-Based Molecules for Cation Recognition

“…The Ag + -complex of 28 acts as reversible electron-transfer agent and by this way stabilizes the phase boundary potential in solid-state sensors for polyanions [164]. Thioether-substituted calixarenes self-assemble on surfaces of Au or Ag, allowing mono-or multilayered structures with recognition sites such as the molecular cavity.…”

Novel all-solid-state copper(II) microelectrode based on a dithiomacrocycle as a neutral carrier

“…In recent years, there has been an increasing interest in the field of ISEs based on all solid-state contact free of inner reference solution using different materials as an intermediary layer [13][14][15][16][17][18][19][20][21][22][23][24].…”