DNA-Templated Silver Nanoclusters Used as a Label-Free Fluorescent Probe for the Detection of O6-Methyltransferase Activity

O-6-methylguanine DNA methyltransferase (MGMT) is one of the most premutagenic, precarcinogenic and precytotoxic DNA lesions formed by alkylating agents. Repairing DNA damage is achieved by the protein MGMT which transfers the alkyl groups from the O-6-position of guanine to a cysteine residue in the active center of MGMT. The most common assays of MGMT activity are time-consuming and have to employ radioactivity. In order to avoid these shortcomings, in this study we have developed a novel biosensing strategy for measuring the activity of MGMT based on fluorescence of DNA-silver nanoclusters. The results showed that a wide range from 0.01 to 1.0 mu g/mL was achieved for MGMT assay and limit of detection of 8 ng/mL. The method has high sensitivity, good reproducibility, simplicity, also it is label free, rapid and cheap. Therefore, we can conclude that the developed strategy holds a great potential for quantitative measurement of MGMT activity with desirable sensitivity and reproducibility.