[Evaluation of a new, microfluidic chip-based immunoassay for measurement of AFP-L3].

Purpose: AFP-L3 is an isoform of a-fetoprotein which has a fucosylated carbohydrate chain, and the fraction of AFP-L3/total AFP (AFP-L3%) specifically increases in hepatocellular carcinoma (HCC) patients and is widely used for screening and prognosis of HCC. The newly developed microTAS method which combines microchip electrophoresis and lectin affinity electrophoresis can rapidly provide AFP-L3% and total AFP measurements simultaneously at higher sensitivity. Here, we evaluated the system to know its analytical performance and clinical utility.

Method: Fully automated immunoanalyzer, microTASWako i30 which utilizes Liquid-phase Binding Assay-Electrokinetic Analyte Transport Assay (LBA-EATA method) as the assay principle was employed for the measurement of total AFP and AFP-L3%. We evaluated detection sensitivity, precision, accuracy, and correlation of the method.

Results: The detection sensitivity was 0.3 ng/ml for both AFP-L1 and L3. The accuracy of the assay was 91.3-105.0% for total AFP. The precision of the assay was CV 1.9% at 2 ng/ml of total AFP, and CV 1.3% for 10% of AFP-L3% at 20ng/ml of total AFP. The microTAS method showed good correlation with the lectin affinity electrophoresis (AFP-L3 Test Wako) and the LBA methods (LBA Wako AFP-L3 on LiBASys) methods, giving correlation coefficient (r) of 0.988 and 0.988, respectively. The microTAS immunoreaction assay time and the total assay time including chip preparation were 1 and 9 min, respectively.

Conclusion: Since the microchip assay is rapid and highly sensitive, it should have better clinical utility than the current methods.