Evaluation of Cytokeratin in Lymph Node Metastasis Using Magnetic Nanoparticles and Protein Aggregates

We aim to apply protein sensors to rapid intraoperative diagnosis of lymph node metastasis. In the present study, cytokeratin, which is a biomarker of lymph node metastasis, was bound to protein G-coated magnetic nanoparticles (FG beads, 180 nm<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\phi $ </tex-math></inline-formula>) via primary antibody [Anti-Cytokeratin AE1/AE3 Antibody (Monoclonal Mouse IgG1)]. The increase of the protein aggregated the magnetic nanoparticles and enhanced the magnetic signal. We have observed magnetic nanoparticles and protein aggregates by cryo-electron microscopy to obtain evidence for this hypothesis. By adding gold nanoparticles to the antibody, we observed the crossbridging of magnetic nanoparticles via the antigen. Lymph nodes were obtained from two esophageal cancer patients and one noncancer patient (corrosive esophagitis). Lymph nodes from cancer patients contain cytokeratin, which promotes the aggregation of magnetic nanoparticles and increases the magnetic signal. Statistically significant differences could be assessed between two cancer and noncancer patients, suggesting the potential of intraoperative rapid diagnosis.