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

Abstract

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.

Nanoneedle Platforms: The Many Ways to Pierce the Cell Membrane

“…More importantly, owing to the advanced micro/nanoprocessing technologies, the geometries (shape, diameter, height, and density) of Si‐based nanoneedle arrays can be elaborately controlled. Other materials, for example, GaP, [ 90 ] InAs, [ 91 ] SiO 2 , [ 92,93 ] Al 2 O 3 , [ 94 ] ZnO, [ 95 ] SnO 2 , [ 96,97 ] carbon, [ 98 ] diamond, [ 99 ] and Pt [ 100,101 ] have been fabricated into nanoneedle arrays for interfacing cells with minimum disruption to cell viability. These nanoneedle arrays can be conductor, semiconductor, or insulator, and have different advantages and disadvantages in terms of the functionality, biocompatibility, and controllability of nanoneedles fabrication.…”

“…Adapted with permission. [ 95 ] Copyright 2019, American Chemical Society. e) Photograph of a self‐powered nanoneedle‐electroporation system for in vivo transdermal delivery.…”

“…In addition, by coupling with nanoelectroporation through the nanostraw structure, intracellular delivery and extraction of the intracellular enzymes could be achieved on the captured CTCs in situ (Figure 8d). [ 95 ] The in situ delivery and detection of intracellular contents would provide powerful tool to transfect or modify CTCs for cancer profiling and investigations, as well as valuable information for comprehensively understanding cancer pathogenesis and progression.…”

Methods for protein delivery into cells: from current approaches to future perspectives

“…This allows the application of lower voltage without reducing the electric field strength. This approach minimizes heating and pH changes [55,56]; as a consequence cell viability after electroporation and transfection efficiency are both increased [57][58][59][60][61][62].…”

Intracellular Labeling with Extrinsic Probes: Delivery Strategies and Applications

“…Based on a similar principle, a multifunctional branched nanostraw (BNS)‐electroporation platform was developed by He et al to perform analysis of circulating tumor cells (CTC) (Figure 5c). [ 83 ] After CTC capture by antibodies on the nanostraws, small fluorescent molecules were delivered, showing safe, efficient, and spatially controlled labeling. Kang et al built a “nanofountain probe electroporation” (NFP‐E) device to precisely deliver molecules into single cells (Figure 5d).…”