Highly selective electrochemical biosensor for the determination of folic acid based on DNA modified-pencil graphite electrode using response surface methodology

► A DNA biosensor was prepared based on pencil graphite electrode. ► The biosensor used as a screening device for the rapid analysis of folic acid. ► Response surface methodology used for the optimization of the experimental variables. ► The electrochemical signal of adenine was used as a probe for the evaluation. ► The biosensor was successfully used to measure folic acid in different real samples.