On/off-switchable electrochemical folic acid sensor based on molecularly imprinted polymer electrode

• Folic acid sensor based on temperature sensitive polymer is reported.
• The folic acid-imprinted electrode was obtained by electropolymerisation of functional monomers.
• The analytical performance of the sensor was evaluated by electrochemical methods.
• A highly specific electrochemical molecular recognition was established on electrode with switching ability.

The combination of smart polymers with molecular imprinting offers a powerful tool to design more effective sensors and medical devices. In this study, a temperature sensitive amine-terminated poly(N-isopropylacrylamide) block with (N,N'-methylenebisacrylamide) cross-linker along with o-phenylenediamine was electropolymerised on a gold electrode in the presence of folic acid (FA) as template to produce an on/off-switchable molecularly imprinted polymer (MIP) affinity sensor for folic acid. Differential pulse voltammetry and cyclic voltammetry were used to characterise the FA-imprinted layer. Incubation of the MIP-modified electrode with FA resulted in a suppression of the ferro/ferricyanide redox process. The highest sensitivity of this temperature gated on/off-switchable folic acid sensor was achieved at 22 °C. Such switchable affinity materials offer considerable potential for the design of highly selective and controllable biosensors and immunoassays.