Ace2N-mNeon2

Improved Ace2N-mNeon variant optimized for lower illumination power.

Category: eFRET GEVI
Published: 2022-11-04 — Science 2022
Derived from: Ace2N-mNeon
Response polarity: negative-going (fluorescence decreases on depolarization)
Spectrum: excitation peak 506 nm, emission peak 517 nm (Ace2N-mNeon2)
Plasmid: Addgene #195518
Tags: Ace opsin

Headline values (as shown in the GEVIBench table)

Metric	Value	Definition
Brightness (B/B_EGFP)	3.04× EGFP	Molecular brightness relative to EGFP (extinction coefficient × quantum yield, or a measured ratio). Sensors not measured against EGFP directly are placed through a chain of pairwise brightness comparisons, combined by geometric mean.
Kinetics τ_on / τ_off (ms)	1.5 / 1.5 ms	Activation / decay time constants in ms (amplitude-weighted mean τ for multi-exponential fits). The value shown averages the measurements made at physiological temperature (≥33 °C); if there are none, it is the measurement closest to 33 °C.
ΔF/F per 100 mV	-26.1% (median of 3 measurements: −26.7%)	Steady-state fluorescence change for a 100 mV depolarization step (−70 → +30 mV); the sign gives the polarity. The table shows the first listed measurement; the median across measurements (one-photon preferred) is used for sorting.
ΔF/F per mV	0.2% (estimated from the F–V curve)	Subthreshold sensitivity: fluorescence change per mV near rest (−90 to −50 mV). Where no value is reported directly, it is estimated from the F–V curve.
ΔF/F per AP	16.5% (median of 3 measurements: 13.2%)	Fluorescence change per single action potential in neurons. The table shows the first listed measurement; the median across measurements (one-photon preferred) is used for sorting.
AP width (FWHM, ms)	5 ms	Full width at half maximum of the optical spike waveform.
Photostability t75% @ 100 mW/mm²	17 s	Time for fluorescence to fall to 75% of its initial value under one-photon illumination, linearly dose-scaled to 100 mW/mm² (t50% is used where the 75% crossing falls inside a fast initial transient). Two-photon curves are not dose-scaled and are excluded.
Papers using it (N_used)	5	Number of published research papers, tracked by GEVIBench, that used the sensor for an experiment (a popularity / track-record measure).

Measurements and sources

Kinetics

τ_on 1.54 ms, τ_off 1.51 ms at 22°C — Kannan 2022, Table S1

ΔF/F per 100 mV

-26.1%, 1P — Kannan 2022, Table S1
-26.7%, 1P — Cao 2025, Table S2
-29.5%, 1P — Hasseman 2022, Fig. 1

ΔF/F per action potential

16.5%, 1P — Kannan 2022, Fig. 1I
11%, 1P — Hasseman 2022, Fig. 2
13.2%, 1P — Cao 2025, Table S2

AP width (FWHM)

2.1 ms at 400 Hz sampling, Mouse, V1 VIP+ interneurons, awake, in vivo, 1P, 37°C — Kannan 2022, Fig. 1I
8 ms at 1000 Hz sampling, Mouse, primary hippocampal neurons, in vitro (culture), 1P, 22°C — Zhang 2025, Fig. 1j

Brightness comparisons

1.1× the brightness of Ace2N-mNeon — Kannan 2022, Fig. S11A
0.5× the brightness of Vega — Cao 2025, Fig. 1B
0.625× the brightness of ElectraOFF — Zhang 2025, Fig. 1e

Photobleaching

t75% = 277 s at 5 mW/mm², 1P — Zhang 2025, Fig. S4h
t75% = 35 s at 30 mW/mm², 1P — Cao 2025, Fig. 1D
t75% = 79 s, 1P — Kannan 2022, Fig. S11B
t75% = 332 s at 10 mW/mm², 1P — Zhang 2025, Fig. 1h

Fluorescence–voltage (F–V) curve

ΔF/F (%) at each membrane potential, normalized to 0 at −70 mV: -150 mV: 15%; -130 mV: 12%; -110 mV: 8%; -90 mV: 4%; -70 mV: 0%; -50 mV: -4%; -30 mV: -10%; -10 mV: -15%; 10 mV: -21%; 30 mV: -25%; 50 mV: -31% — Kannan 2022, Fig. 1D

Research papers using Ace2N-mNeon2 (5)

Dual-polarity voltage imaging of the concurrent dynamics of multiple neuron types — Kannan M, Vasan G, Haziza S, Huang C, Chrapkiewicz R, Luo J, Cardin JA, Schnitzer MJ, Pieribone VA, Science 2022 (Mouse, visual cortex and hippocampus, in vivo; Drosophila, dopamine neurons, in vivo; HEK cells, in vitro)
Imaging high-frequency voltage dynamics in multiple neuron classes of behaving mammals — Haziza S, et al., Cell 2025 (Mouse, visual cortex and hippocampus, in vivo)
Prefrontal gamma oscillations engage dynamic cell type-specific configurations to support flexible behavior — Phensy AJ, et al., bioRxiv 2025 (Mouse, medial prefrontal cortex, in vivo)
Bright and Photostable Voltage Sensors Derived from mBaoJin — Zhang H, Zhou S, Kuzmicheva TP, Subach OM, Grimm C, Eom M, Baror-Sebban S, Adam Y, Yoon YG, Emilliani V, Subach FV, Piatkevich KD, bioRxiv 2025 (HeLa cells; Mouse, primary hippocampal neurons, in vitro; Mouse, hippocampus CA1, in vivo (benchmark comparison against ElectraON/ElectraOFF))
A photostable genetically encoded voltage indicator for imaging neural activities in tissue and live animals — Cao C, Zhu R, Zhou S, Zhao Z, Lin C, Liu S, Peng L, Subach FV, Piatkevich KD, Zou P, bioRxiv 2025 (HEK293T cells, in vitro; Rat, hippocampal neurons, in vitro; Mouse, acute brain slices, ex vivo)

Data and citation

llms.txt — summary for language models
llms-full.txt — every sensor in full (Markdown)
gevis.json — all values and measurements with sources (JSON)
gevis.csv — one row per sensor (CSV)

Cite GEVIBench as: Adam E. Cohen and Daozheng Gong (2026). Voltage imaging: A practical guide. Neuron. https://doi.org/10.1016/j.neuron.2026.08.002

Generated from the GEVIBench database on 2026-10-12.