Monitoring DNA Hybridization with Organic Electrochemical Transistors Functionalized with Polydopamine

Organic electrochemical transistors (OECTs) are finding widespread application in biosensing, thanks to their high sensitivity, broad dynamic range, and low limit of detection. An OECT biosensor requires the immobilization of a biorecognition probe on the gate, or else on the channel, through several, often lengthy, chemical steps. In this work, a fast and straightforward way to functionalize the carbon gate of a fully screen-printed OECT by means of a polydopamine (PDA) film is presented. By chemical immobilization of an amine-terminated single-stranded oligonucleotide, containing the HSP70 promoter CCAAT sequence, on the PDA film, the detection of the complementary DNA strand is demonstrated. Furthermore, the specificity of the developed genosensor is assessed by comparing its response to the fully complementary strand with the one to partially complementary and noncomplementary oligonucleotides. The developed sensor shows a theoretical limit of detection (LOD) of 100 × 10−15 m and a dynamic range over four orders of magnitude.