ABSTRACT
Our laboratory had developed a cell-based bio-bead for protein quantification. However, the selection of antibody in the above immunoassay is limited. This study describes a surface-decorated Saccharomyces cerevisiae for flow cytometric array immunoassay. S. cerevisiae was labeled with fluorescein isothiocyanate (FITC) and oxidized by sodium periodate, in which the saccharide group on the cytoderm outer layer was converted to an aldehyde group. In succession, adipic dihydrazide was bio-conjugated to the aldehyde group and glutaraldehyde bound to the hydrazide group. Phycoerythrin (PE)-labeled goat anti-mouse polyclonal antibody was used to assess the conjugation of mouse anti-human monoclonal antibody to surface-decorated S. cerevisiae. Cytokeratin 19 fragment (Cyfra21-1) and neuron-specific enolase (NSE) antigens were also employed to evaluate the flow cytometric array immunoassay based on surface-decorated S. cerevisiae. Flow cytometry demonstrated that FITC-barcoded S. cerevisiae as two legible populations. PE-labeled polyclonal antibody validated the coating of surface-decorated S. cerevisiae with the monoclonal antibody. The flow cytometric array immunoassays for Cyfra21-1 and NSE documented that the limit of detection (LOD) was at least 0.4 ng/mL. Precision and accuracy assessments appeared that the relative standard deviation (R.S.D.) was <15%, and the relative error (R.E.) ranged from 0.9 to 1.1. The correlation coefficient between this immunoassay and electrochemiluminescence immunoassay was 0.9622 for serum Cyfra21-1 and 0.9918 for serum NSE. In conclusion, the surface-decorated S. cerevisiae may be of use in flow cytometric array immunoassay.
