Highly chemiluminescent TiO2/tetra(4-carboxyphenyl)porphyrin/N-(4-aminobutyl)-N-ethylisoluminol nanoluminophores for detection of heart disease biomarker copeptin based on chemiluminescence resonance energy transfer.

In this work, the chemiluminescence (CL) property of 5,10,15,20-tetrakis(4-carboxyphenyl)-porphyrin- and N-(4-aminobutyl)-N-ethylisoluminol-functionalized TiO2 nanoparticles (TiO2-TCPP-ABEI nanoluminophores) was studied for the first time. It was found that TiO2-TCPP-ABEI nanoluminophores exhibited excellent CL activity in the presence of H2O2. The CL mechanism has been proposed due to the reaction of ABEI with H2O2 and catalytic effect of TiO2 and TCPP. Furthermore, trisodium citrate-stabilized gold nanoparticles were observed to effectively quench the CL of TiO2-TCPP-ABEI due to CL resonance energy transfer (CRET). On this basis, a sensitive and selective CRET-based immunoassay was developed for the determination of copeptin by using TiO2-TCPP-ABEI nanoluminophores as both CL nanointerface and energy donor, and using cit-AuNPs as an effective energy receptor. The immunoassay exhibited a wide dynamic range from 5 × 10-12 to 1 × 10-9 g mL-1 with a low detection limit of 1.54 × 10-12 g mL-1, which was superior to previously reported CL-based immunoassays. It was successfully applied for the determination of copeptin in serum samples, which would provide a good practical perspective on the clinical diagnosis. This strategy may also be used for the detection of other antigens if corresponding antibodies are available. Graphical abstract.