Sequential detection of vitamin B6 cofactors and nitroaromatics by using albumin-stabilized fluorescent copper nanoclusters

The red-emitting bovine serum albumin (BSA) stabilized copper nanoclusters (BSA-CuNCs) was applied for the cascade detection of vitamin B-6 cofactors and nitroaromatics. The fluorescence profile of BSA-CuNCs is perturbed with the addition of cofactors pyridoxal and pyridoxal 5' -phosphate (PLP). The fluorescence intensity at 640 nm of BSA-CuNCs is decreased with the concomitant appearance of a new emission band between 450 and 460 nm. The -CHO group of pyridoxal/PLP is expected to form an imine linkage with the free -NH2 group available with the functionalized BSA, which altered the conformation of BSA and the fluorescence profile of BSA-CuNCs. Importantly, the BSA-CuNCs showed selective fluorescence response towards pyridoxal at lower concentration among the other examined cofactors. Using BSA-CuNCs as a nanoprobe, the concentration of pyridoxal and PLP can be detected down to 66.3 nM and 1.08 mu M, respectively. Subsequently, the pyridoxal and PLP conjugated BSA-CuNCs was applied for the fluorescent detection of nitroaromatics. The fluorescence of pyridoxal and PLP conjugated BSA-CuNCs was selectively quenched with the addition of picric acid and para-nitrophenol due to the energy and electron transfer processes.

Automated summary

The red-emitting BSA-stabilized copper nanoclusters were used for the detection of vitamin B-6 cofactors and nitroaromatics. The fluorescence profile of BSA-CuNCs was changed by the addition of cofactors, and the conjugated BSA-CuNCs showed selective fluorescence response towards pyridoxal at lower concentration. Furthermore, the fluorescence of conjugated BSA-CuNCs was selectively quenched with the addition of nitroaromatics.