Tailored chemosensors for chloroaromatic acids using molecular imprinted TiO2 thin films on ion-sensitive field-effect transistors

The SiO2 gate of an ion-sensitive held-effect transistor, (ISFET), is functionalized with a TiO2 film that includes imprinted molecular sites for 4-chlorophenoxy acetic acid, (1), or 2,4-dichlorophenoxy acetic acid, (2). The functionalized devices that include the imprinted interfaces reveal an impressive selectivity in the sensing of the imprinted substrates Na+-1 or Na+-2. The detection limit for Na+-1 is (5 +/- 2) x 10(-4) M, which corresponds to 38 mv dec-l in the concentration range of 0.5 to 6 mM. The detection limit for the analysis of Na+-2 is (1.0 +/- 0.2) x 10(-5) M, which corresponds to 28 mV.dec(-1) in the concentration range 0.1-9.0 mM. The equilibration time of the devices is ca. 5 min.