Potassium sensing by using a newly synthesized squaraine dye in sol-gel matrix

7th Conference on Methods and Applications of Fluorescence (MAF) -- SEP 16-19, 2001 -- AMSTERDAM, NETHERLANDSWOS: 000179175500029Squaraines are a group of fluorescent dyes and pigments derived from squaric acid and dialkylanilines well known in applications such as photoreceptors, organic solar cells, optical recording media, and non-linear optics. Their very promising spectral properties, long wavelength absorption and emission, and high absorptivity and quantum yields have not been exploited so far in relation to optical sensor design. They exhibit excellent solubility in sol-gel matrices, and the ligand is an integral part of the fluorophore pi system, which makes the molecule a fluoroionophore. In this work, potassium-sensing agent, bis[4-N-(1-aza-4,7,10,13,16-pentaox acyclooctadecyl)-3,5-dihydroxyphenyl] squaraine has been used for potassium sensing in a sol-gel matrix. The spectrofluorimetric response of dye-doped tetraethyl ortosilicate (TEOS) film after exposure to certain concentrations of K+ has been investigated, and 62% of relative signal change was achieved. The dynamic working range of the sensor membrane has been found between 10(-9) and 10(-6) M K+, in other terms from nanomolar to micromolar levels, which is an advantage over flame emission spectroscopy, in view of detection limit. The sensor is fully reversible within the dynamic range and the response time (tau(90)) is found to be 2 min under batch conditions. The cross-sensitivity of the molecule to Na+, Ba2+, Ca2+, and NH4+ was also tested in separate solutions.Amersham Pharmac Biotech, ATTO-TEC GmbH, BERTHOLD TECHNOL GmbH & Co KG, Beun Ronde BV, BFi OPTiLAS BV, BIO-RAD Microsci Ltd, BMG Lab GmbH, Byk Nederland BV, Carl Zeiss NV, Carl Zeiss Jena GmbH, City Amsterdam, Coherent BV, Chroma Technol Corp, DSM Food Specialties, Evotec OAI, IBH, ISS, Jobin Yvon SA, Kluwer Acad Publishers, Lambert Instruments, Vision BioTec GmbH, Leica Microsyst, L OREAL Rech Avancee, Molec Devices, Molec Probes Europe BV, Netherlands Soc Biochem & Molec Biol, Organon NV, Netherlands Org Sci Res, Photon Technol Int Inc, PicoQuant GmbH, Sci Vol Imag, Unilever Res, Varian Analyt Instruments, Vrije Univ Amsterdam, Inst Molec Biol Sc