Melamine-modulated mercaptopropionic acid-capped manganese doped zinc sulfide quantum dots as a room-temperature phosphorescence sensor for detecting clenbuterol in biological fluids

A turn-off room-temperature phosphorescence (RTP) sensor for clenbuterol (CB) based on melamine (MA)-modulated mercaptopropionic acid (MPA)-capped Mn-doped ZnS quantum dots (QDs) was described in this paper. Due to the hydrogen-bonding interaction between CB and MA, introduction of CB into the solution of MPA-capped Mn-doped QDs in the presence of MA could increase the surface defects of the QDs and lead to their reaction aggregation. So that the MA-induced RTP could be enhanced and subsequent CB-induced RTP quenching could be observed. This phenomenon could build a solid base for us to develop a QDs-based turn-off RTP sensor for detecting CB. Under the optimal conditions, the detection limit for CB was 3.2 ng mL−1, the relative standard deviations was 2.9% while the recovery of the method was in the range of 97–104%. The coexisting substances which includes 2000-fold excesses of Na+ and K+, 1500-fold excesses of lysine, cysteine, ascorbic acid, uric acid, Vitamin B1, Vitamin B2, Mn2+, Mg2+, Ca2+, Zn2+ and Al3+, 500-fold excesses Cu2+ and Ag+ did not affect the determination of CB. The proposed method was successfully applied to biological fluids with satisfactory results.