An ultra sensitive fluorescent nanosensor for detection of ionic copper

A stable and ultra sensitive nano-scale fluorescent chemo-sensor for trace amounts of Cu²⁺ was proposed. The Cu²⁺ selective fluoroionophore 2-{[(2-aminophenyl)imino]methyl}-4,6-di-tert-butylphenol (DMK-7) was encapsulated in polymeric ethyl cellulose. The sensing membranes were fabricated in form of nanofibers and thin films. When embedded in polymers, the exploited DMK-7 dye exhibited enhanced photophysical characteristics in absorbance, Stoke's shift, fluorescence quantum yield, and short and long-term photostability with respect to the solution phase. Sensing abilities of the nanofibers and thin films were tested by steady state and time resolved fluorescence spectroscopy. To our knowledge, this is the first attempt using the DMK-7-doped electrospun nanofibrous materials for copper sensing. The offered sensor displayed a sensitive response with a detection limit of 3.3 × 10^-13 M for Cu²⁺ ions over a wide concentration range of 5.0 × 10^-12-5.0 × 10^-5. Additionally, exhibited high selectivity over convenient cations; Na⁺, K ⁺, Ca²⁺, Mg²⁺, NH₄⁺ and Ag⁺, Al³⁺, Ba²⁺, Co²⁺, Cr ³⁺, Fe³⁺, Fe²⁺, Hg²⁺, Li ⁺, Mn²⁺, Ni²⁺, Pb²⁺, Sn²⁺ and Zn²⁺.