Nanowire Arrays for Rare Cell Analysis

Quantitation and comprehensive analysis of cellular biomarkers such as antigen-specific T cell subtypes and circulating tumor cells from peripheral blood is of great clinical value for early detection and stratification of complex human diseases, e.g. cancer and AIDS. But such analysis remains a grand challenge due to the rarity and intrinsic heterogeneity of these cells. Here we present a nanowire array-enabled laser scanning imaging cytometry for rare cell capture and analysis, which represents the first attempt towards quantitative, automated, and functional evaluation of blood-borne cellular biomarkers. Immuno-functionalized nanowire arrays were demonstrated as a superior material to capture rare cells from heterogeneous cell populations. The laser scanning cytometry method enables large-area, automated quantitation of captured cells and rapid evaluation of functional cellular parameters (e.g. size, shape and protein levels) at the single cell level. Using human lung carcinoma cells as a model, our technology quantitatively identified a four-fold enhancement in capture efficiency as compared to the planar substrate-based conventional imaging cytometry. In the settings of complex biospecimens such as lung carcinoma cells mixed with white blood cell lines or even spiked in the whole peripheral blood mononuclear cell pool, the nanowire substrate shows excellent capture efficiency and reasonably good purity. We further demonstrated it is possible to push the limit of detection to a few tumor cells. Using a high content image analysis algorithm, cellular morphometric parameters can be extracted. This platform enables informative functional analysis of captured rare cells in situ for potential subclassification of CTCs, a key step towards the identification of true metastasis-initiating cells. We also extend this platform to quantitation of CD4+ T cells and other rare immune cells. This nano-enabled platform may have important clinical values to analyze rare cellular biomarkers in clinical specimens for differential diagnosis and informative immune monitoring.