Figure 2 shows the schematic diagram of an ISFET-based aptamer sensor for adenosine. Following a
primary silanization of Al2O3 gate with 3-aminopropyltriethoxysilane, the surface was subsequently
modified with glutaric dialdehyde. After the covalent immobilization of amine-functionalized aptamer
on the gate surface, the hybridization of the nucleic acid to the aptamer was investigated by ISFET
measurement. Consequently, the tested ISFET-based aptamer sensor exhibited the detection limit of
approximately 5 × 10−5 M, and showed high specificity, as the aptamer-modified ISFET did not
respond to other nucleotides, such as cytidine.