A folate receptor electrochemical sensor based on terminal protection and supersandwich DNAzyme amplification.

Based on the protecting effect of folate receptor (FR) toward folic acid (FA) modified DNA and the signal amplification of supersandwich DNA structure, we designed an interesting electrochemical biosensor for FR. In the present system, with the increase of FR, protecting more FA bound DNA from hydrolysis by exonuclease I (Exo I), FA bound DNA will hybridize to form more supersandwich DNA structure resulting in an increased electrochemical signal. A relationship between the concentration of the target protein, FR, and the obtained electrochemical signal can be established. The signal was obtained by the catalysis on H₂O₂ in the system containing Fc and hemin/DNAzyme. The detection concentration range of FR was from 1.0 to 20.0 ng/mL with an achieved detection limit of 0.3 ng/mL which approached clinically relevant concentrations of FR.