On-Chip Flow Cytometry: Where is it Now and Where is it Going?

Abstract

Flow cytometry is a powerful, high-throughput, single-cell characterization and sorting tool, which has a unique capability to provide fast and quantitative analyses of individual cells and physical separation of cells of particular interest from other cells [1]. In flow cytometry, the cell analyses are performed by passing a narrow stream of cells through a focused laser beam at a rate of thousands of cells per second. Information regarding the size, type and content of cells can subsequently be derived through the analyses of the excited fluorescence emission or scattered light arising from each individual cell. In recent years, flow cytometry has rapidly become an indispensable instrument for many clinical diagnostics, ranging from routine blood tests to diagnoses of lethal diseases such as leukemia, respiratory infection and HIV/AIDS. Flow cytometry can screen multiple parameters and can be used for immunophenotyping. This has allowed diagnosis of diseases associated with B lymphocytes [1] and progress in the Human Immunology Project [2]. HIV is also typically monitored using flow cytometry [1]. Additionally, cell-sorting techniques have enabled flow cytometry to become a key tool for studying circulating tumor cells, which have potential in screening for and monitoring cancer [3,4]. With its extraordinary single-cell ana lysis and sorting capabilities, flow cytometry has been used extensively in numerous fields such as molecular biology, pathology, immunology, plant biology and marine biology. Despite their significant impact, current commercial f low cytometry systems have the following drawbacks: high cost, large instrumentation size and the constant requirement of highly trained personnel for maintenance (the latter two resulting from its complex system configuration).