Evidence of different G-quadruplex DNA binding with biogenic polyamines probed by electrospray ionization-quadrupole time of flight mass spectrometry, circular dichroism and atomic force microscopy

► Binding affinities of polyamines with G-quadruplex DNA were determined by Q-TOF-MS. ► Polyamines can induce conformational changes of the five selected G-quadruplex DNA. ► The structural stability of humtel24 can be improved after combining with polyamines. ► Morphological changes of humtel24 after combining with polyamines were observed by AFM. ► Binding mechanisms of G-quadruplex DNA and polyamines were discussed.