nirButterfly

Near-infrared VSFP-Butterfly variant using bacterial phytochrome-derived fluorescent proteins.

Category: VSD-FRET GEVI
Published: 2020-11-04 — ACS Chemical Neuroscience 2020
Derived from: VSFP-Butterfly
Response polarity: negative-going (fluorescence decreases on depolarization)
Spectrum: excitation peak 644 nm, emission peak 670 nm (nirButterfly)
Plasmid: Addgene #136590
Tags: Ci-VSP, NIR FP, FRET, Biliverdin

Headline values (as shown in the GEVIBench table)

Metric	Value	Definition
Brightness (B/B_EGFP)	0.04× 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)	2.2 / 2.1 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	-9.8% (median of 2 measurements: −10%)	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	0.1% (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	-6%	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)	—	Full width at half maximum of the optical spike waveform.
Photostability t75% @ 100 mW/mm²	1.0 min	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)	2	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 2.16 ms, τ_off 2.13 ms at 23°C — Monakhov 2020, Fig. 1g

ΔF/F per 100 mV

-9.8%, 1P — Monakhov 2020, Table 1
+10.2%, 1P — Monakhov 2020, Main text

ΔF/F per action potential

-6%, 1P — Monakhov 2020, Table 1

Brightness comparisons

486× the brightness of Arch — Monakhov 2020, Table 1
7× the brightness of Archon1 — Song 2024, Fig. 2b
3.17× the brightness of SomArchon — Monakhov 2020, Fig. S2

Photobleaching

t75% = 139 s at 44 mW/mm², 1P — Monakhov 2020, Fig. S2

Fluorescence–voltage (F–V) curve

ΔF/F (%) at each membrane potential, normalized to 0 at −70 mV: -100 mV: 3%; -80 mV: 1%; -70 mV: 0%; -60 mV: -1%; -40 mV: -4%; -20 mV: -6%; 0 mV: -7%; 20 mV: -9%; 40 mV: -10%; 60 mV: -11% — Monakhov 2020, Fig. 3b (NIR GEVIb)

Research papers using nirButterfly (2)

Screening and Cellular Characterization of Genetically Encoded Voltage Indicators Based on Near-Infrared Fluorescent Proteins — Monakhov MV, Matlashov ME, Colavita M, Song C, Shcherbakova DM, Antic SD, Verkhusha VV, Knöpfel T, ACS Chemical Neuroscience 2020 (HEK293 cells and mouse cortical/hippocampal neurons, in vitro)
Characterization of two near-infrared genetically encoded voltage indicators — Song C, Matlashov ME, Shcherbakova DM, et al., Neurophotonics 2024 (Mouse, hippocampal CA3 slices, in vitro)

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.