A photoelectrochemical biosensor for determination of DNA based on flower rod-like zinc oxide heterostructures

The work describes a photoelectrochemical (PEC) biosensor for the detection of DNA. It employs oriented hierarchical ZnO flower-rod architectures (ZnO FRs) and DNA dendrimers. ZnO FRs act as photoactive material that yields a photocurrent of up to 23 μA. The photogenerated electron transfer is inhibited once the probe DNA and the target DNA oligonucleotides hybridize, and this results in a reduced photocurrent. The use of DNA dendrimers with scores of DNA branches further amplifies the signal of the PEC biosensor. The PEC sensor displays a response that is linear in the DNA concentration range from 10 fM to 0.1 μM with a detection limit of 3.7 fM (at S/N = 3). The sensor was applied to the determination of DNA in human serum samples and was found to work with acceptable accuracy. Due to the use of ZnO FRs and DNA dendrimers, the assay is highly sensitive, rapid, and repeatability.