A coordination-driven fluorescent platform for selective detection of valine in living cells and food samples based on dopamine-functionalized nitrogen doped graphene quantum dots and its construction of molecular logic gate

The design of a fluorescent system for tracking valine remains a challenge till date. This work demonstrated the first use of the metal complex of dopamine-functionalized nitrogen doped graphene quantum dots (N-GQDs-DA) as coordination-driven fluorescent platform for selective detection of valine in human serum and real food samples. The fluorescence of the N-GQDs-DA was quenched after the addition of Cr 3+ , which acts as both a fluorescence quencher and a receptor for target molecule. The quenched fluorescence of the N-GQDs-DA/Cr 3+ sensing system was linearly restored as the valine concentration increased from 1.33 × 10 −4 M to 62.5 × 10 −4 M. Different coordination states of Cr 3+ opened or blocked a PET course, which constructed “turn-off or turn-on” fluorescence switching. The “INHIBIT” logic gate operation can be carried out using the Cr 3+ and valine as inputs and the emission bands EM 315 nm and EM 440 nm as outputs, indicating that they have promising applications in intelligent dual analyte sensing systems. MALDI-TOF mass spectra elucidated the formation of a low-fluorescent species [C 55 H 32 Cl 3 Cr 2 N 4 O 10 ] + and a high-fluorescent species [C 70 H 58 Cr 2 N 7 O 14 ] + without and with valine, respectively. This methodology provides a new concept for the design and development of highly selective optical system for single amino acid. • The complex of N-GQDs-DA/Cr 3+ was used to detect valine selectively. • Coordination-driven fluorescence spectra constructed a fluorescence switching. • The sensing system can detect valine in living cells and real foods.