Fabrication of a Nanoplasmonic Chip to Enhance Neuron Membrane Potential Imaging by Metal-Enhanced Fluorescence Effect

Abstract

Optical imaging is a useful tool to acquire neural activities because of its high spatial resolution, and various voltage indicators were developed to image membrane potential of neurons. Voltage sensitive dyes (VSDs) are one of them but their signal-to-noise ratio (SNR) is so low that enhancing SNR of VSD has become important. In this study, we investigated the metal-enhanced fluorescence (MEF) effect on VSD imaging by fabricating nanoplasmonic resonance chip using gold nanorods (GNRs). To amplify the fluorescence signal we used polyelectrolyte layers to control the distance between metal nanoparticles and fluorophore. Cultured rat hippocampal neurons and di-8-ANEPPS, a widely used VSD, were used to test the nanoplasmonic resonance chip, and the maximum level of fluorescence signal was obtained when nine layers of polyelectrolyte spacer were used. The nanoplasmonic resonance chip with GNR showed the possibility of the improvement in voltage imaging of neurons and is expected to enhance the availability of neuronal activity imaging in the future.