Study on the co-luminescence effect of terbium–gadolinium–nucleic acids–cetylpyridine bromide system

In this paper, the luminescence mechanism of a new co-luminescence system (Tb–Gd–nucleic acids–cetylpyridine bromide) was studied. The experiment has shown that cetylpyridine bromide (CPB) could combine with nucleic acids through both electrostatic forces and hydrophobic forces, then Gd3+ and Tb3+ were bound to PO43− of nucleic acid and formed Tb–nucleic acid–CPB and Gd–nucleic acid–CPB complexes, respectively. When the system was excited, the DNA–CPB absorbed light energy and then transferred it to Tb3+ through both intramolecular energy transfer in Tb–nucleic acid–CPB complex and intermolecular energy transfer between Gd–nucleic acid–CPB and Tb–nucleic acid–CPB complexes. In addition, it was found that the gadolinium complex acted not only as the energy donor but also the energy-insulating sheath, which improved the fluorescence quantum efficiency.