Ordered Labeling-Facilitated Electrochemical Assay of Alpha-Fetoprotein-L3 Ratio for Diagnosing Hepatocellular Carcinoma

Abstract

Serum alpha fetoprotein (AFP) is a “gold-standard” biomarker for the diagnosis of hepatocellular carcinoma (HCC). Available pieces of evidence suggest that the ratio of AFP-L3 isoform in the total AFP may provide more accurate prediction for the incidence of HCC. In this work, we design an electrochemical aptasensor for high-accuracy assay of AFP-L3 ratio based on differentiated labeling of AFP isoforms in an orderly fashion. Specifically, total AFP is first captured by an AFP aptamer-functionalized electrode and labeled with quantum dots-functionalized DNA probes via mild reduction. Then, AFP-L3 isoform that strongly binds to Lens culinaris agglutinin is labeled with silver nanoparticles after the exonuclease-catalyzed removal of DNA probes. By tracing the electrochemical responses of quantum dots and silver nanoparticles, respectively, the amounts of total AFP and AFP-L3 isoforms are determined and the AFP-L3 ratio is accordingly calculated to favor the accurate HCC diagnosis. Experimental results prove the high-accuracy assay of AFP-L3 ratio based on the AFP quantitation in a linear range of 0.0008–40 ng mL–1 and AFP-L3 quantitation in a linear range of 0.004–40 ng mL–1. The aptasensor also displays satisfactory specificity and good recoveries even in the complex serum samples. Therefore, the aptasensor may provide a valuable tool for the assay of the AFP-L3 ratio and have a great potential use in early warning of HCC for clinical application.

Utility of Alpha-Fetoprotein and Ultrasound in the Diagnosis and Prognosis of Patients with Hepatocellular Liver Cancer

“…While AFP has a specificity of 90.0%, not all patients with HCC have increased AFP levels, and elevations are also observed in those with chronic liver disease. 21 In addition to AFP, several other tumour markers have been identified as being significantly elevated in patients with HCC, including AFP-L3 fragments (which could be used to enhance the diagnostic specificity of AFP) 22 and des-gamma-carboxy prothrombin…”

Alpha-fetoprotein: Past, present, and future

“… 11 12 The ratio of these isoforms has been found to be a predictor for malignancy, thereby adding another layer of clinical utility to AFP as a diagnostic biomarker in HCC. 13 14 …”

Unique Electron-Transfer-Mediated Electrochemiluminescence of AuPt Bimetallic Nanoclusters and the Application in Cancer Immunoassay

“…AFP is not produced in mature and healthy hepatocytes, and serum AFP levels in healthy adults are below 20 ng•mL −1 [36]. However, when people suffer from certain malignant tumors, AFP concentrations in serum are usually higher than 25 ng•mL −1 [37][38][39]. Therefore, it is very important to develop new methods to detect AFP in human serum accurately, which is of great significance for the early diagnosis of diseases.…”