A method of using light to activate or suppress neurons without requiring genetic modification (as in optogenetics) has been developed by scientists from the University of Chicago and the University of Illinois at Chicago.
The new technique, described in the journal Neuron, uses targeted, heated gold nanoparticles. The researchers says it’s a significant technological advance with potential advantages over current optogenetic methods, including possible use in the development of therapeutics for diseases such as macular degeneration.
Ref: Photosensitivity of Neurons Enabled by Cell-Targeted Gold Nanoparticles. Neuron (8 April 2015) | DOI: 10.1016/j.neuron.2015.02.033
Unmodified neurons can be directly stimulated with light to produce action potentials, but such techniques have lacked localization of the delivered light energy. Here we show that gold nanoparticles can be conjugated to high-avidity ligands for a variety of cellular targets. Once bound to a neuron, these particles transduce millisecond pulses of light into heat, which changes membrane capacitance, depolarizing the cell and eliciting action potentials. Compared to non-functionalized nanoparticles, ligand-conjugated nanoparticles highly resist convective washout and enable photothermal stimulation with lower delivered energy and resulting temperature increase. Ligands targeting three different membrane proteins were tested; all showed similar activity and washout resistance. This suggests that many types of ligands can be bound to nanoparticles, preserving ligand and nanoparticle function, and that many different cell phenotypes can be targeted by appropriate choice of ligand. The findings have applications as an alternative to optogenetics and potentially for therapies involving neuronal photostimulation.