Circulating tumor cells (CTCs) are
cancer cells that shed from a primary
tumor and circulate in the bloodstream. As a form of "
tumor liquid biopsy", CTCs provide important information for the mechanistic investigation of
cancer metastasis and the measurement of
tumor genotype evolution during treatment and
disease progression. However, the extremely low abundance of CTCs in the peripheral blood and the heterogeneity of CTCs make their isolation and characterization major technological challenges. Recently, nanotechnologies have been developed for sensitive CTC detection; such technologies will enable better cell and molecular characterization and open up a wide range of clinical applications, including early disease detection and evaluation of treatment response and
disease progression. In this review, we summarize the nanotechnology-based strategies for CTC isolation, including representative nanomaterials (such as magnetic nanoparticles,
gold nanoparticles,
silicon nanopillars, nanowires, nanopillars,
carbon nanotubes,
dendrimers,
quantum dots, and
graphene oxide) and microfluidic chip technologies that incorporate nanoroughened surfaces and discuss their key challenges and perspectives in CTC downstream analyses, such as
protein expression and genetic mutations that may reflect
tumor aggressiveness and patient outcome.