Synthesis of red photoluminescent nickel doped self-assembled copper nanoclusters and their application in biothiol sensing

Copper nanoribbons (Cu NRs) and Ni-doped copper nanowires (Cu NWs) with red photoluminescent (PL) were prepared and employed for detection of biothiol. Using 4-(trifluoromethyl) thiophenol as both reducing agent and protecting ligand, the copper nanoclusters (Cu NCs) were synthesized and assembled to nanoribbons. And the Cu NCs were assembled to nanowires by adding nickel ion precursor in synthetic process. The Cu NWs with 3% Ni doping showed a 3-fold emission enhancement than Cu NRs, and the absolute quantum yield was obviously increased from 4.53% to 19.76%. The doped Ni induced Ni-Cu metallophilic interaction, which facilitated the radiative relaxation of excited electrons and furtherly resulted in stronger PL emitting. The morphologies, composition, electronic states, geometrical configuration and arrangement of Cu NCs in assembled architecture were studied by experimental and theoretical investigation. Moreover, the PL of Cu NCs assembly was sensitive to cysteine, homocysteine, and glutathione attributed to surface ligands exchange of Cu NCs through interaction between metal and sulfydryl group. Therefore, a rapid, sensitive, and selective sensing strategy for detection of biothiol was proposed. And the PL test strips based on Cu NCs assembly were fabricated for visual detection of biothiol. Finally, the practical application of sensing system and PL test strips were verified in fetal bovine serum samples spiked with cysteine and homocysteine.