A sensitive atomic absorption spectrometric metalloimmunoassay with copper nanoparticles labeling

A sensitive metalloimmunoassay based on copper nanoparticle labeling was demonstrated with atomic absorption spectrometry. Stable nanosized CuO particles of 5-10 nm diameter were synthesized by an alcothermal method, and conjugated to antibody under moderate conditions. The immunoassay conditions were optimized. After immunoreaction, the copper atoms were released with diluted nitric acid and measured by electro-thermal atomic absorption spectrometry. The atomic absorbance signal had a good linearity with logarithm of the CIgG (concentration of IgG, g/mL). The detection limit was calculated to be 0.19 ng/mL and the assay was linear in the range of 10− 9-10− 5 g/mL human IgG. The relative standard deviation (RSD) for 10 ng/mL human IgG was 3.0%. The human IgG results obtained by the proposed method correlated well with those obtained by inductively coupled plasma-based immunoassay.