Defect-Involved Chemiluminescence of Unary Copper Nanocrystals towards Semi-Automatic Immunoassay

The unary nanocrystals (NCs) of copper are frequently employed as a catalyst, sensitizer, and energy transfer mediator of chemiluminescence (CL). Herein, the direct and defect-involved CL of copper NCs (CuNCs) for the semiautomatic immunoassay is proposed with bovine serum albumin (BSA)-stabilized CuNCs (BSA-CuNCs) as luminophores. The biocompatible BSA-CuNCs are a kind of n-type NC that can directly give off flash CL via charge annihilation between its endogenous electrons and exogenously injected holes by the coexisting oxidative activators. Potassium hexacyanoferrate(III) (K₃[Fe(CN)₆]) can trigger BSA-CuNCs with efficient CL around ∼701 nm, a waveband longer than all commercial-available CL reagent kits. The coexisting citric ion can also directly reduce the hole-injected BSA-CuNCs to further enhance CL emission. The CL of BSA-CuNCs/K₃[Fe(CN)₆] in citrate buffer is consequently utilized to detect myoglobin on the commercialized and semiautomatic IVD device, which exhibits improved determination performance compared to the commercially available CL reagent kits, with a wide linear response range from 0.25 to 1000 pg/mL and a limit of detection of 0.10 pg/mL (S/N = 3). BSA-CuNCs can be safely stored in pure water and label protein without unintended precipitation, which might provide an alternative to the molecule tagged CL reagent kits.