Optomicrofluidic device for detection and isolation of drop encapsulated target cells in single-cell format
Single-cell analysis has emerged as a powerful method for the characterisation of genomics, transcriptomics, proteomics, and metabolomics at the individual cell level. Here, we demonstrate a technique for detection and selective isolation of target cells encapsulated in microdroplets in single-cell format. Sample containing a mixed population of cells with target cells fluorescently labelled is focused using a sheath fluid to direct cells in single-file toward a droplet junction wherein the cells are encapsulated inside droplets. The droplets containing the cells migrate toward the centre of the channel owing to the non-inertial lift force. The cells present in the droplets are interrogated and characterised based on forward scatter (FSC), side scatter (SSC) and fluorescence (FL) signals. The FL signals from the target cells activate a selective isolation module based on electro-coalescence, using a suitable electronics and program to sort droplets containing the target cells in single-cell format from the droplets containing the background cells. We demonstrated detection and isolation of target cells (cancer cells – HeLa and DU145) from a mixed population of cells, peripheral blood mononuclear cells (PBMC) + cervical cancer cell (HeLa) and PBMC + human prostate cancer cell (DU145) at a concentration range 〖10〗^4-〖10〗^6/ml at 300 cells/s. The performance of the device is characterised in terms of sorting efficiency (>97%), enrichment (>1800X), purity (>98%), and recovery (>95%)). The sorted target cells were found to be viable (>95% viability) and showed good proliferation when cultured, which showed the potential of the proposed sorting technique for downstream analysis.