Uranyl-specific binding at a functionalised interface: a chemophotonic fibre optic sensor platform

Abstract

Detection of radiological materials in the solution phase is restricted by conventional radiation-counting techniques owing to extreme attenuation. Chemical sensing of the resultant radiological species such as uranyl UO₂²⁺ is possible on the surface of a plastic or glass fibre optic. A dihydroxy isoamethryin complex is tethered to the fibre surface which has a large extinction coefficient (119 000 M⁻¹ cm⁻¹ at λ = 439 nm) and changes colour upon binding UO₂²⁺. The spectral changes are greater on the surface than in solution and binding is specific to UO₂²⁺ with small interferences from Gd³⁺. Monitoring the spectral response in three detector bands in the red, green and blue enable the optical power change to be measured with sensitivities of 1 mdB, allowing UO₂²⁺ to be detected confidently at 50–100 ppb levels. Real-time kinetic analysis enables discrimination between the target species and possible interferents.