Disk-like hydrogel bead-based immunofluorescence staining toward identification and observation of circulating tumor cells

Assays toward analysis of rare heterogeneous cells among identical specimen raise a significant challenge in many cell biological studies and clinical diagnosis applications. In this work, we report a disk-like hydrogel bead-based stratagem for rare cell researches at single cell level after a facile microfluidic-based particle synthesis approach. Cells of interested can be encapsulated into alginate droplets which are subsequently solidified into disk-like calcium alginate hydrogel beads and the bead size and cell number inside can be precisely controlled. Due to stability, permeability and disk-like shape of calcium alginate beads, cells immobilized in the disk-like beads can be treated with different chemicals with limited mechanical or fluidic operation influences and observed without distortion comparing with conventional methods or droplet microfluidic methods. Identification of circulating tumor cells, related to early-stage cancer diagnosis, is targeted to demonstrate the potential of our technique in rare cell analysis. This hydrogel bead-based stratagem is performed in immunofluorescence staining treatment and observation of cancer cells from normal hematological cells in blood sample. This method would have a great potential in single cell immobilization, manipulations and observation for biochemical cellular assays of rare cells.