Multifunctional Branched Nanostraw-Electroporation Platform for Intracellular Regulation and Monitoring of Circulating Tumor Cells.

Downstream analysis of circulating tumor cells (CTCs) has provided new insights into cancer research. In particular, the detection of CTCs, followed by the regulation and monitoring of their intracellular activities, can provide valuable information for comprehensively understanding cancer pathogenesis and progression. However, current CTC detection techniques are rarely capable of in situ regulation and monitoring of the intracellular microenvironments of cancer cells over time. Here, we developed a multifunctional branched nanostraw (BNS)-electroporation platform that could effectively capture CTCs and allow for downstream regulation and monitoring of their intracellular activities in a real-time and in situ manner. The BNSs possessed numerous nanobranches on the outer sidewall of hollow nanotubes, which could be conjugated with specific antibodies to facilitate the effective capture of CTCs. Nanoelectroporation could be applied through the BNSs to nondestructively porate the membranes of the captured cells at a low voltage, allowing the delivery of exogenous biomolecules into the cytosol and the extraction of cytosolic contents through the BNSs without affecting cell viability. The efficient delivery of biomolecules (e.g., small molecule dyes and DNA plasmids) into cancer cells with spatial and temporal control and, conversely, the repeated extraction of intracellular enzymes (e.g., caspase-3) for real-time monitoring were both demonstrated. This technology can provide new opportunities for the comprehensive understanding of cancer cell functions that will facilitate cancer diagnosis and treatment.