Evaluation of Sialic Acid Expression on Cancer Cells via an Electrochemical Assay Based on Biocompatible Au@BSA Architecture and Lectin‐modified Nanoprobes

The changes of sialic acid (SA) expression on cell surface are closely associated with various malignant diseases. The analysis of SA expression is therefore becoming an important parameter in clinical diagnosis. In this paper, we reported a sensitive electrochemical cytosensor for the analysis of SA expression on cell surface using three-dimensional architecture of Au@BSA and nanoprobes of carbon nanospheres modified with Au nanoparticles (CNS/AuNPs). Au@BSA microspheres provided an effective matrix for binding of Concanavalin A (Con A) which acted as the recognizer and capturer for cells via the specific affinity to mannose and the core trimannoside of N-glycan on the cell surface. On the basis of the specific recognition of Sambucus nigra agglutinin (SNA) to cell surface sialic acid groups, the SNA and HRP modified CNS/AuNPs nanoprobes were introduced onto the electrode surface, and amplified signals were produced by an enzymatic catalytic reaction of HRP toward the oxidation of hydroquinone (HQ) by H2O2. This cytosensor was successfully applied to the analysis of SA expression on cell surface disturbed by sialidase and to detect MCF-7 cells and BGC-823 cells with a low detection limit of 40 cells mL−1 and 120 cells mL−1. Therefore, the proposed strategy offers a new way for insight into the SA function in biological processes and helps improve cancer diagnosis and treatment.