文摘
A competitive fluorescence method toward tadalafil detection has been developed based on host鈥揼uest recognition by selecting rhodamine B (RhB) and p-sulfonated calix[6]arene functionalized graphene (CX6鈥揋ra) as the 鈥渞eporter pair鈥? Upon the presence of tadalafil to the performed CX6鈥揋ra鈥揜hB complex, the RhB molecules are displaced by tadalafil, leading to a 鈥渟witch鈥搊n鈥?fluorescence signal. The observed fluorescence signal can be used for quantitative detection of tadalafil ranging from 1.00 to 50.00 渭M with a detection limit of 0.32 渭M (S/N = 3). The inclusion complex of tadalafil and CX6 was studied by molecular docking and the results indicated that a 1:1 host鈥揼uest stoichiometry had the lowest 螖G value of 鈭?.18 kcal/mol. The docking studies demonstrated that the main forces including 蟺鈥撓€ interactions, electrostatic interactions, and hydrophobic interactions should be responsible for the formation of this inclusion compound. The mechanism of the competitive host鈥揼uest interaction was clarified. The binding constant (K) of the tadalafil/CX6 complex was more than 5 times greater than that of RhB/CX6.