Quantitative evaluation of dielectrophoretic separation efficiency of cancer exosomes based on fluorescence imaging

Abstract

Liquid biopsies for cancer diagnosis using exosomes have been studied. Separating cancer cell-derived exosomes from a sample mixture is crucial, especially when they do not dominate the sample at an early stage of cancer. A method based on their electrical properties could provide a simpler separation than immune-affinity methods. We have identified the differences in electrical properties of cancerous exosomes from those of normal ones, suggesting the possibility for their dielectrophoresis (DEP) based separation. This study separated cancerous exosomes from a mixture of normal exosomes. The DEP of fluorescence-labeled exosomes suspended in aqueous media with varying electrical conductivities was investigated. The observed DEP was quantitatively evaluated using the normalization method accounting for the fluorescence fading effect. The results showed that the cancerous exosomes were preferentially concentrated under the appropriate conditions. This suggests that DEP can enable the selective capture of cancer exosomes without chemical labeling.