Abstract
3D nanostructures are widely exploited in cell cultures for many purposes such as controlled drug delivery, transfection, intracellular sampling, and electrical recording. However, little is known about the interaction of the cells with these substrates, and even less about the effects of electroporation on the cellular membrane and the nuclear envelope. This work exploits 3D plasmonic nanoelectrodes to study, by surface‐enhanced Raman scattering (SERS), the cell membrane dynamics on the nanostructured substrate before, during, and after electroporation. In vitro cultured cells tightly adhere on 3D plasmonic nanoelectrodes precisely in the plasmonic hot spots, making this kind of investigation possible. After electroporation, the cell membrane dynamics are studied by recording the Raman time traces of biomolecules in contact or next to the 3D plasmonic nanoelectrode. During this process, the 3D plasmonic nanoelectrodes are intracellularly coupled, thus enabling the monitoring of different molecular species, including lipids, proteins, and nucleic acids. Scanning electron microscopy cross‐section analysis evidences the possibility of nuclear membrane poration compatible with the reported Raman spectra. These findings may open a new route toward controlled intracellular sampling and intranuclear delivery of genic materials. They also show the possibility of nuclear envelope disruption which may lead to negative side effects.
Highlights
Membrane processes and cells with these substrates, and even less about the effects of electroporation on the cellular membrane and the nuclear envelope
The typical surface-enhanced Raman scattering (SERS) spectrum of a cell lying on the 3D plasmonic nanoelectrode before the electrical pulse train application is shown as a black line in Figure 3a, while the red line represents the typical SERS spectrum acquired from the same Raman electrode just after electroporation, and the blue spectrum is the recorded signal after 20 min from the permeabilization
This is in agreement with the fact that when the plasma membrane undergoes a process of permeabilization, a period of rearrangement of the lipid bilayer follows with the aid of several membrane proteins and protein complexes at the interface with the membrane.[10,27,37]
Summary
The fabrication process of our device is based on milling by focused ionic beam (FIB) of an optical resist and its consequent inversion.[23]. We relied only on the optical images (see Figure S4c,f, Supporting Information), and the data presented in this study were acquired from 3D plasmonic nanoelectrodes close to the center of the cells In this configuration, the probability of being in proximity to the nucleus is high, making accessible, in theory, the nuclear envelope and its content. The Raman excitation was obtained with a monochromatic laser (λ = 785 nm) focused on the 3D plasmonic nanostructure creating intense hot spots in correspondence of its tip From the literature, it is well-known that the electromagnetic field of localized plasmonic modes decays very fast (after few tens of nm) in space.[32,33,34] By characterizing the radial profile of our 3D plasmonic nanoelectrodes, we showed that the optical distribution vanishes within 20 nm from the tip surface, allowing us to detect the Raman signal coming only from a small volume around the 3D nanoelectrode, as shown in Figure S2 (Supporting Information) (more details about the optical distribution can be found, Supporting Information). Lower applied voltages could be less effective for local permeabilization of the cell membrane
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
