Spin-Coating-Based Fabrication of Nanostraw Arrays for Cellular Nano-electroporation

Nano-electroporation technology allows external biomolecules to cross the cell membrane and enter cells. Nanostraws (NSs) with hollow channels are promising nanostructures to provide nano-electroporation for intracellular delivery, yet the preparation processes of NSs usually require intricated nanofabrication instruments and possess high requirements for operations. Here, a straightforward spin-coating processing technique was developed to prepare oxide NS arrays without relying on delicate instruments, which could be further integrated with microfluidic devices for effective cell nano-electroporation. The fabrication procedures of these NSs were simpler than the reported method relying on atomic layer deposition and Cl2 reactive ion etching. By this spin-coating method, SiO2 and TiO2 NSs were successfully prepared with controllable NS diameters and spacing. SiO2 and TiO2 NSs were further integrated with a microfluidic system to build a nano-electroporation system, which realized efficient intracellular drug delivery of cell membrane-impermeable molecules into both HeLa cells and MCF-7 cells. This strategy provides a unique solution for batch fabrication of NSs with a low-cost process, which could serve as the essential module of a nano-electroporation platform for various biomedical studies.