Table 2.
Methods for imaging of NIR probes across spatial scales.
| Method | Probe | Spatial resolution | Temporal resolution | Sensitivity | Spectral multiplexing | Refer ence |
|---|---|---|---|---|---|---|
| Animal whole-body, deep tissues and organs imaging | ||||||
| Planar fluorescence imaging | iRFPs, miRFP. NIR biosensors | >1 mm up to 2 cm deep | >1 ms time resolution* | >105 cells up to 2 cm deep | Two color imaging with m/iRFP670 and m/iRFP720; Combination with blue light optogenetic tools | [1, 15, 17] |
| Fluorescence tomography | >1 mm up to 2 cm deep | <1 s time resolution* | [2, 59] | |||
| Planar NIR bioluminescence imaging | iRFPs-RLuc8s | >1 mm up to 2 cm deep | >1 ms time resolution** | >104 cells up to 2 cm deep | [75] | |
| Fluorescence lifetime tomography | iRFPs, miRFP, NIR biosensors | ˜1 mm up to 1 cm deep | <1 s time resolution* | ˜104 cells up to 1 cm deep | [76] | |
| Photoacoustic tomography | <1 mm up to 1 cm deep | <1 s time resolution* | >104 cells up to 1 cm deep | [57–59,77] | ||
| Reversibly-switchable photoacoustic tomography | BphPl | >100 μm up to 1 cm deep | >1 s time resolution | >102 cells up to 1 cm deep | Combination with blue light optogenetic tools | [60,78] |
| In vivo cellular and subcellular imaging | ||||||
| Two-photon (2P) microscopy | iRFPs, miRFP, NIR biosensors | 10 μm up to 1 mm deep | >1 ms time resolution* | 1 cell up to 1 mm deep | Combination with blue light optogenetic tools | [10,55] |
| 2P microscopy with adaptive optics (AO) |
>1 μm up to 1 mm deep | Subcellular up to 1 mm deep | [56] | |||
| Ex vivo cell analysis | ||||||
| Flow cytometry | miRFPs, iRFPs | Individual cells | – | Individual cells | <4 multispectral m/iRFPs and several dyes/GFP-like FPs | [17,79] |
| Cells and subcellular structures | ||||||
| Fluorescence microscopy (wide-field and confocal) | iRFPs, miRFP, | >350 nm | >1 ms time resolution* | Molecules* | Cross-talk free imaging with green and red GFP-like FPs; |
[18,19,22] |
| Structured illumination | NIR biosensors | >175 nm | >1 ms time | Subcellular | multicolor imaging; Combination with blue | [18, 22 |
| microscopy (SIM) | resolution* | structures | light optogenetic tools | 22] | ||
*
Depends on the power of light source and sensitivity of the detector/camera.
**
Depends on camera sensitivity.