Gold-nanoparticle/bis-bipyridinium cyclophane-functionalized ion-sensitive field-effect transistors: Novel assemblies for the sensing of neurotransmitters

A film consisting of polyethyleneimine (PEI), Au-nanoparticles (12 ± 1 nm) and coadsorbed cyclobis(paraquat-p-phenylene) (1) was assembled as a sensing interface on the Al₂O₃-gate of an ISFET. Adrenaline (2) and serotonin (3) were sensed by the ISFET with lower detection limits of 1x10^-6 M and 6x10^-3 M, respectively. The sensing ability of the nanostructured device for the analysis of (2) and (3) originates from the pre-concentration of the analytes by the cyclophane via π-π donor-acceptor interactions. Analysis of the neurotransmitters is accomplished by the measurement of the source-drain current (I_ds) or by the gate-source voltage (V_gs). The sensing device is reusable (at least 100 cycles) and exhibits high stability.