Determining folic acid content of food using a double strand nucleic acid biosensor

Folate is essential to cell division and growth. Folic acid is commonly measured using HPLC-MS، spectroscopy، ELISA، and microbial methods that are cost-intensive and time-consuming because they require long extraction and purification times. It is known that electrochemical methods are simple and inexpensive and that analytical techniques require a small sample size. Biosensors also have higher selectivity than other sensors. The present study proposes an electrochemical DNA biosensor as a screening device for rapid analysis of folic acid using a pencil graphite electrode modified with salmon sperm ds-DNA. Solution pH، DNA concentration، time of DNA deposition، and potential deposition were optimized using RSM. The binding of folic acid to DNA immobilized on a pencil graphite electrode was then measured using variations in the electrochemical signal of adenine. This biosensor was successfully used to measure folic acid in real samples، such as flour and spinach. The optimum values for the reaction were pH of 4. 8، DNA concentration of 24 μg mL−1، deposition time of 304 s، and deposition potential of 0. 60 V، which produced an adenine signal of 3. 04 μA. The folic acid concentration showed a linear correlation with the adenine signal current at 0. 1–10. 0 μM L−1 with a detection limit of 1. 06×10−8 μM L−1. The results showed that the DNA-based biosensor showed high sensitivity، selectivity، and speed of folic acid determination.