Quantum dot-based lab-on-a-bead system for multiplexed detection of free and total prostate-specific antigens in clinical human serum samples.

An immunodiagnostic lab-on-a-bead suspension microarray based on microbeads encoded with quantum dots (QDs) has been developed and preclinically validated for multiplexed quantitative detection of prostate cancer markers in human serum samples. The sensitivity and specificity of the microarray are similar to those of "gold-standard" single-analyte ELISA. Moreover, the array has an improved immunoassay capacity, ensures quantitative detection of multiple cancer biomarkers and may be operational in a considerably wider dynamic range of concentrations. The array is characterized by reduced time and cost of analysis and is compatible with classical flow cytometers. Proof-of-concept preclinical tests ensured simultaneous quantitative determination of free and total prostate-specific antigens in human serum, with clear discrimination between the control and clinical samples. The proposed approach is flexible and paves the way to development of a wide variety of immunodiagnostic assays for multiplexed early diagnosis of various diseases. FROM THE CLINICAL EDITOR: Early diagnosis of cancer can result in better prognosis for patients. Thus, the use of specific tumor markers is widely employed in clinical practice. Traditional screening methods only employ single markers. The authors here developed a microarray system based on microbeads encoded with quantum dots (QDs), which can be used for multiplexed quantitative detection. The validated results on patient samples should lead to the development of a wider variety of assays for other diseases.