Peroxidase-mimicking DNAzymes for biosensing applications: a review

DNAzymes are single stranded DNA molecules that exhibit catalytic activity and are exploited in medicine, biology and material sciences. Development in this area is related to the many advantages of DNAzymes over conventional protein enzymes, such as thermal stability and simpler preparation. DNAzymes with peroxidase-like activity have recently attracted great interest. To assure such catalytic activity, oligonucleotides have to adopt a G-quadruplex structure, which can bind the hemin molecule. This system facilitates a redox reaction between the target molecule and hydrogen peroxide, which results in the appearance of an oxidized target molecule (product). DNAzymes with peroxidase-mimicking activity have great potential in bioanalytical chemistry. This review presents fundamentals concerning the design and engineering of DNAzymes with peroxidase-like activity, describes their properties and spectral characteristics and shows how DNAzymes can contribute to bioanalytical research. Examples of bioanalytical applications of DNAzymes with peroxidase-like activity include nucleic acid probes with DNAzyme labels for the detection of specific DNA sequences in colorimetric or chemiluminescent assays. Assays for telomerase or methyltransferase activity, which are potential targets in anticancer therapy, are also described in this review. Other applications include the determination of metal cations such as Ag(+), K(+), Hg(2+), Pb(2+) or Cu(2+) and amplified detection of small molecules such as adenosine, cocaine or AMP and proteins such as lysozyme or thrombin. In the last decade, DNAzymes have become part of numerous applications in many areas of science from chemistry to biology to medicine.