Fast detection of mycoplasma pneumoniae by interaction of tetramolecular G-quadruplex with graphene oxide

Fast and sensitive detection of mycoplasma pneumoniae (MP) is quite momentous in early diagnosis of respiratory infections. Herein, we present a new biosensing platform for MP based on the interaction of a designed parallel-stranded tetrapod G-quadruplex (TP-G4) with graphene oxide. The G-quadruplex is formed with four fluorescent dye labeled ssDNA molecules, which is demonstrated with gel electrophoresis, CD spectra and fluorescence spectra. The interaction induces the adsorption of TP-G4 on graphene oxide, which leads to the fluorescence quenching of the dye. Upon the recognition of the adsorbed ends to target MP, the TP-G4 can be released from graphene oxide surface, producing a "signal-on" fluorescence biosensor for MP. The designed biosensing strategy shows a detection limit of 3.96 nM and an analytical time of 10 min. The facile and fast operation process and acceptable sensitivity meet the demands of early point-of-care testing of mycoplasma pneumoniae, showing its promising application in clinic diagnosis.