Application Note
Ion Channels:
ChR2

SyncroPatch 384 optogenetic stimulationand light-gated ion channels

Tools:
SyncroPatch 384
Optogenetic Stimulation
Tool

Nanion Technologies GmbH, Munich.

Summary
Channelrhodopsins (ChRs) are proteins that guide phototaxis
in protists and exhibit light-gated channel conductance when
their genes are heterologously expressed in cell lines such as
HEK293 cells. ChRs are widely used optogenetic tools (e.g.
Nagel et al. 2003), and are the prerequisite to a biological
technique to control the activity of neurons or other celltypes with light. For example, cation- and anion-selective
ChRs enable stimulation and inhibition of neuronal action
potential firing by depolarization and hyperpolarization of themembrane, respectively. More than 400 natural ChR variants
have been identified so far, and sequencing projects add
more each year (e.g. Govorunova et al., 2022).
Light typeUV

Dominant or Peak wavelength (nm)Minimum

Maximum

380

390

Visible--Royal Blue

440

460

The picture above shows one LED module mounted on the SyncroPatch

Blue

460

480

384 electrode board.

Cyan490

510

Green520

540

Amber

588

592

Red-Orange610620

Red620645

Deep Red650670

530 nmThe SyncroPatch 384 enables the control of membrane
voltage by both voltage-clamp and optogenetics using theFigure 1: A series of photocurrent traces generated
by the ChR „HcKCR1“ at 20 mV in response to200 ms light pulses of incremental intensity(SyncroPatch 384 Optogenetic Stimulation Tool).
The bar on top shows the duration of illumination.
Modified from Govorunova et al., 2022.

0.5 nA

modules, each equipped with 96 LEDs.

light intensity

unique Optogenetic Stimulation Tool. The tool includes 6 LED-0.1 s

Figure 2: Modes of operation. Stimulation Gated:
Starts a previously defined light pulse protocol
for the length of the 3rd, 6th, 9th... step of thevoltage/current clamp protocol (except for thelast step). Stimulation Feed Through: LEDs switch
on at every 3rd, 6th, 9th... step (except for the laststep). LEDs switch off at every other step and by
the end of the protocol. Light intensity can also
be defined.

The LED control settings allow different modes of operation.

References

Besides „On“ (Switches the LEDs permanently on), „Off“(Switches the LEDs off) and „Stimulation“ (starts a defined light

1. Nagel, G., Szellas, T., Huhn, W., Kateriya, S., Adeishvili, N.,pulse protocol) there are further more sophisticated modes

Berthold, P., Ollig, D., Hegemann, P., Bamberg, E. (2003).

available:

Channelrhodopsin-2, a directly light-gated cation-selective

Stimulation Gated: Starts a previously defined light pulse
protocol for the length of the 3rd, 6th, 9th... step of the voltage/current clamp protocol (except for the last step).
Stimulation Feed Through: The length of light pulses are definedby the voltage pulse protocol step. LEDs switch on at every 3rd,6th, 9th... step (except for the last step). LEDs switch off at every

membrane channel. PNAS. 100 (24): 13940 - 13945.
2. Govorunova, E.G., Sineshchekov, O.A., Brown, L.S., Spudich,J.L. 2022. Biophysical characterization of light-gated ionchannels using planar automated patch clamp. Front.
Mol. Neurosci., 15: :976910. https://doi.org/10.3389/
fnmol.2022.976910

other step and by the end of the protocol. Light intensity isdefined by the command LED Current Settings.

Key findings
1. The SyncroPatch 384 Optogenetic Stimulation
Tool enables optical modulation of cells andcompounds using diverse wavelengths, in up to 96
wells in parallel.
2. Optical Stimulation Tool enables high temporal
resolution: fast and reversible On/Off switching ofe.g. ChR2.
3. Multiple modes of operation ensure sophisticatedcombination with electrophysiological stimuli andthe use of diverse experimental protocols.

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