Nano Research & Applications

Near-infrared optogenetic activation of channel rhodopsin expressed in living cells via upconverting nanoparticles with target specificity

International Meeting on Advanced Nanomaterials and Nanotechnology
November 07-08, 2017 Singapore

Kanchan Yadav

National Taiwan University, Taiwan

Posters & Accepted Abstracts: Nano Res Appl

DOI: 10.21767/2471-9838-C1-006

Abstract

Optogenetics is an innovative technology now widely adopted by researchers in different fields of the biological sciences. However, most proteins adopted in optogenetics are excited by ultra-violet or visible light that has a weak tissue penetration capability. Upconverting nanoparticles (UCNPs), which transform near-infrared (NIR) light to short-wavelength emission, can help address this issue. To improve optogenetic performance, we enhance the target selectivity for optogenetic controls by specifically conjugating the UCNPs with light-sensitive proteins at a molecular level, which shortens the distance as well as enhances the efficiency of energy transfer. We tagged V5 epitope to the extracellular N-terminal of channelrhodopsin-2 with a mCherry conjugated at the intracellular C-terminal (V5-ChR2m) and then bound NeutrAvidin-functionalized UCNPs (NAv-UCNPs) to the V5-ChR2m via a biotinylated antibody against V5. The results showed NAv-UCNPs bound to the plasma membranes of cells expressing V5-ChR2m, but not ChR2m without the V5 epitope. Under NIR illumination, the NIR-upconverted blue illumination from UCNP induced an inward cation current and elevated the intracellular Ca2+ concentration in the live cells expressing V5-ChR2m bound with NAv-UCNPs. The fluorescence resonance energy transfer (FRET) from the excited UCNP to the V5-ChR2m was confirmed by fluorescence lifetime imaging measurements. Our results demonstrate that when membrane channelrhodopsin is specifically anchored by UCNPs in the molecular level, the energy transfer via irradiance and FRET can greatly enhance the optogenetic performance.