Rapid and Reusable Detection of Interferon-Gamma Based on Label-Free Single-Stranded DNA and Thioflavin T

A novel simple and rapid detection method for interferon-gamma (IFN- γ ) was developed based on a label-free single-stranded DNA (ssDNA) and thioflavin T (ThT). The ssDNA is the aptamer of the IFN- γ. The aptamer is a G-rich oligonucleotide, and it can fold into a G-quadruplex structure in the presence of ThT, resulting in a high fluorescence emission. Upon the addition of the target, the aptamer combines with its ligand due to higher affinity and specificity, leading to the disruption of the G-quadruplex and the release of ThT. A remarkable decrease of fluorescence was observed. The proposed strategy shows a limit of detection at 1 nM in both buffer and diluted serum. Moreover, the detection of IFN- γ can be finished in several minutes and it can be used repeatedly.