Neuronal firing modulation by a membrane-targeted photoswitch


Optical technologies allowing modulation of neuronal activity at high spatio-temporal resolution are becoming paramount in neuroscience. In this respect, azobenzene-based photoswitches are promising nanoscale tools for neuronal photostimulation. Here we engineered a light-sensitive azobenzene compound (Ziapin2) that stably partitions into the plasma membrane and causes its thinning through trans-dimerization in the dark, resulting in an increased membrane capacitance at steady state. We demonstrated that in neurons loaded with the compound, millisecond pulses of visible light induce a transient hyperpolarization followed by a delayed depolarization that triggers action potential firing. These effects are persistent and can be evoked in vivo up to 7 days, proving the potential of Ziapin2 for the modulation of membrane capacitance in the millisecond timescale, without directly affecting ion channels or local temperature.

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Fig. 1: Transcis isomerization of Ziapin2 in various environments.
Fig. 2: Ziapin2 distributes to the plasma membrane and lipid rafts in neurons.
Fig. 3: Ziapin2 reversibly modifies membrane thickness in artificial membranes, cell lines and neurons.
Fig. 4: Light-evoked membrane voltage modulation by Ziapin2 in primary neurons.
Fig. 5: Light-evoked firing activity in primary neurons loaded with Ziapin2.
Fig. 6: Light-evoked cortical responses in vivo in mice loaded with Ziapin2 in the somatosensory cortex.

Data availability

The datasets generated and analysed during the current study are available from the corresponding author on reasonable request.


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We thank F. Fruscione and F. Zara (Giannina Gaslini Institute, Genova, Italy) for help in preparing iPSC-derived human neurons; P. Bianchini, M. Oneto and M. Scotto (Center for Nanoscopy and Nikon Imaging Center, Istituto Italiano di Tecnologia, Genova, Italy); L. Cingolani (Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genova, Italy) for providing the ChETA-encoding lentiviral vectors; A. Mehilli and G. Mantero (Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genova, Italy) for precious help in primary cultures and in vivo elelectrophysiology, respectively. This work was supported by the Italian Ministry of Health (project RF-2013-02358313 to G.P., G.L. and F.B.) and Istituto Italiano di Tecnologia (pre-startup project to G.L. and F.B.). The support of the Ra.Mo. Foundation (Milano, Italy), Fondazione 13 Marzo (Parma, Italy), Rare Partners srl (Milano, Italy) and Fondazione Cariplo (project 2018-0505) to G.L. and F.B. is also acknowledged.

Author information

C.B. designed and engineered Ziapin2. S.C., L.C. and F.O. performed the synthesis and characterization of Ziapin2. D.F. calculated the atomic charges and optimized coordinates. G.M.P. performed the spectroscopic characterization. L.M. performed molecular dynamics simulations. M.D.S., L.L. and M.M. performed planar lipid membrane and AFM studies. M.B., G.G. and E.C. studied the in vitro and in vivo distribution of the Ziapin compounds in neurons. M.L.D.F., P.B., E.C. and F.L. performed the in vitro patch-clamp experiments and analysed the data. V.V. elaborated the numerical RC model. J.F.M-V., E.C., D.S. and C.G.E. performed and analysed the in vivo experiments. M.L.D.F., E.C., P.B., G.M.P. and F.L. contributed to paper writing. G.L., C.B. and F.B. conceived the work. G.L. and F.B. planned the experiments, analysed the data and wrote the manuscript.

Correspondence to Guglielmo Lanzani or Fabio Benfenati.

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Peer review information Nature Nanotechnology thanks Or Shemesh, Joao L. Carvalho-de-Souza and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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DiFrancesco, M.L., Lodola, F., Colombo, E. et al. Neuronal firing modulation by a membrane-targeted photoswitch. Nat. Nanotechnol. (2020).

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