Photoacoustic detection of breast cancer cells in human blood

Abstract

Detection of breast cancer cells in human blood may provide early determination of metastasis, enabling aggressive treatment prior to detection by conventional radiographic methods. We developed a photoacoustic flowmetry system in which we irradiated breast cancer cells in suspension to simulate metastatic breast cancer cells derived from human blood. In order to provide optical discrimination between the breast cancer cells and lymphocytes, we attached antibody labeled latex microspheres and gold nanoparticles to breast cancer cells. The breast cancer cells were derived from an estrogen receptor (ER) positive cell line, MCF-7. The particles were conjugated to ER antibodies. We irradiated the cell suspension using the photoacoustic flowmeter consisting of a glass flow chamber with a piezoelectric sensor. We irradiated the suspension at 422 and 530nm and solved a linear system of equations in two variables to separate the contribution of the photoacoustic wave from the breast cancer cells and possible erythrocytes that may be present in a patient blood draw. We found a detection threshold of 10 breast cancer cells using this flowmeter. Future optimization of the system may decrease the detection threshold to single breast cancer cells.