Design of optical chemical nanosensors for Determination of some selected cations and anions in Aqueous samples and evaluation of interference effects

In this thesis, we designed original optical chemical nanosensors exploiting electrospun nanofibrous materials for optical sensing of silver (I), mercury (II), iron (III), hydroxyl, calcium (II) and copper (II) ions at sub-nanomolar levels in aqueous samples.Poly(methyl methacrylate) and ethyl cellulose were used as polymeric materials together with appropriate fluoroionophores and other additives. Cation and /or anion sensing nanomaterials were fabricated by electrospinning that the most convenient way to make a nano-scale continuous polymer uses a high static voltage to draw the fiber from a liquid polymer.Sensors were based on the change in the fluorescence signal intensity of all employed ionophore. The offered nanosensors allow determination of ions in a large linear working range. The preliminary results of Stern?Volmer analysis show that the sensitivities of electrospun nanofibrous membranes to detect ions are 10-100-fold higher than those of the thin film based sensors. The extraordinary sensitivities can be attributed to the high surface area of the nanofibrous membrane structures that provided faster sensor dynamics in applications. In all of the sensor designs, sensor performance characteristics such as the response time, long-short term stabilities, reversibility, limit of detection, linear concentration range, repeatability and interference effects also have been studied.Last of all, we have successfully combined the nanoscale electrospun fiber materials with optical sensing technology exploiting apropriate fluoroionophores for subnanomolar sensing of ions without interference effects.