Interdigitated electrodes based on impedance biosensor for sensing peptide LL-37

An antimicrobial peptide, LL-37, is found in an innate defense system of humans. Patients who suffer urinary tract infection (UTI) will generate LL-37 and which is released into urine. LL-37 can be used as an indicator for the diagnosis of UTI. We have designed a biosensor with an interdigitated electrode on a printed-circuit board (PCB). The surface of the electrode was modified with 3-mercaptopropionic acid and immobilized with anti-LL37 antibody to improve the specificity of the biosensor. By de-embedding jig impedance, the impedance associated with the change of LL-37 concentration was calculated. The sensitivity of this biosensor for LL-37 in a urine sample can reach 50 μg/mL.