Label-free detection of hepatocellular carcinoma markers based on photoluminescence of antibody-conjugated ZnO arrays

Hepatocellular carcinoma (HCC) is a malignant disease that is prevalent all around the world, especially in Asia. The combined detection of four common HCC markers, alpha-fetoprotein (AFP), carcinoembryonic antigen (CEA), carbohydrate antigen 125 (CA125) and 19-9 (CA19-9), can significantly improve the accuracy of early screening and diagnosis of this disease, which is very important for its effective treatment in a curable stage. In this article, hierarchical ZnO column arrays with core-shell structure were prepared, and specific antibodies of HCC markers were successfully conjugated onto ZnO arrays via the carbodiimide chemistry. The photoluminescence (PL) intensity of antibody-ZnO increased after HCC markers were bound. In the range of 0.5-15 ng/mL for AFP or CEA (or 0.5-15 U/mL for CA125 or CA19-9), the apparent linear relations between the PL enhancements and the concentrations of HCC markers offered simple standard curve for HCC detection in serum samples, indicating that the PL-enhanced antibody-ZnO arrays could be utilized in early clinical screening. A preliminary mechanism of PL intensity enhancement can be established based on this work.