Sensitive electrochemical detection of hydroxyl radical based on MBs–DNA–AgNPs nanocomposite

A sensitive electrochemical method for the detection of hydroxyl radical (OH) was successfully developed based on magnetic beads (MBs)–DNA–Ag nanoparticles (AgNPs) (MBs–DNA–AgNPs) nanocomposite. MBs were utilized for bioseparation and AgNPs as signal indicator. When OH broke the DNA strands, AgNPs were detached from the surface of the MBs–DNA–AgNPs nanocomposite. Magnetic particles could be easily removed from the solution and the detached AgNPs were collected. Therefore, the anodic stripping voltammetry (ASV) signal of dissolved silver on glassy carbon (GC) electrode depended on the amounts of OH. The results show that the ASV signal linearly increases with the increase of the concentration of OH in the range of 0.05–4 μM, and the detection limit is as low as 10 nM, which is much lower than the detection limit obtained on the recently developed electrochemical and photoelectrochemical methods. In addition, the developed method has potential application in the screening of antioxidants.