Probing ND7/23 neuronal cells before and after differentiation with SERS using Sharp-tipped Au nanopyramid arrays

The development of local plasmonic nano sensors which are sensitive, whilst remaining non-invasive with high cell viability is challenging but of great interest for the investigation of cellular processes. With this aim, we developed an effective SERS active biointerface to monitor cell activity and discriminate between undifferentiated and differentiated neurons through principal component analysis. We propose a plasmonic tipped Au nanopyramids (Au NPs) array, which benefits from high aspect ratios and sharp tips that are excellent SERS sensors. To realise the structure, we developed a large-scale inexpensive fabrication route based on the assembly of charged nanospheres used as a mask by means of a colloidal lithography technique, to better space and shape the NPs. Here we show that Au NPs with tip curvatures of 10 nm and localized plasmon resonance at 785 nm can non-destructively probe ND7/23 neurons. We prove that these tips allow us to track ND7/23 neurons on the SERS substrate, detecting both the membrane constituents, proteins and lipids, and even intracellular DNA/RNA fragments.