Table 1.
Comparison of published tissue clearing methods
| Methods | Main chemicals | Clearing capability | Entire processing time | Tissue morphological change | Molecular integrity | Immunolabeling after tissue clearance | Fluorescence signal preservation | Long-term storage |
|---|---|---|---|---|---|---|---|---|
| BABB | Benzyl alcohol/benzyl benzoate | Strong | 3 Days | Shrinkage | Fluorescent quenching | No | No | Difficult |
| ClearT | Formamide | Medium | 3 Days (embryo) | No tissue expansion | No fluorescent protein quenching | Yes | Yes | Difficult |
| Sca/e | Urea/glycerol TritonX100 | Medium | 3 Weeks to 6 months | Large expansion in tissue volume/tissue becomes fragile | Partial denaturation and protein loss | No | No | Possible |
| 3DISCO | Dibenzyl ether and tetrahydrofuran | Strong | 5–7 Days | No tissue expansion | No fluorescent protein quenching within 1 day | No | No | Difficult |
| CLARITY | SDS, Boric acid/focusclear | Strong | 2 Weeks~ | Tissue expansion during the process | No fluorophore quenching | Yes | Yes (many rounds) | Possible |
| SeeDB | Fructose α-thioglycerol | Weak | 3 Days (brain slice) | No tissue expansion | No fluorescent protein quenching | No | No | Possible |
| CUBIC | Urea/aminoalcohol sucrose/nitrilotriethanol | Strong | 2 Weeks~ | Tissue expansion during the process | No fluorescent protein quenching | Yes | Partially yes | Difficult |
| PACT/PARS | SDS, Boric acid/histodenz | Strong | 2 Weeks~ | Tissue expansion during the process | No fluorescent quenching | Yes | Yes | Possible |
| iDISCO | Benzyl ether | Strong | 14–17 Days (whole brain) | Shrinkage | No fluorescent protein quenching within 2–3 days | No | Partially yes | Difficult |
| Sca/eS | Urea/sorbitol | Medium | 1 Week | No tissue expansion | No fluorescent quenching | Yes | Yes | Possible |
| SWITCH | SDS | Weak | 2 Weeks~ | Large expansion in tissue volume | No fluorescent quenching | Yes | Yes (many rounds) | Possible |
| ACT-PRESTO | SDS, boric acid/sucrose, urea | Strong | 2–3 Days | Tissue expansion during the process | No fluorescent quenching | Yes | Yes | Possible |
| EDC-CLARITY | SDS, boric acid | Strong | ~3 Weeks (brain slice) | Tissue expansion during the process | No fluorescent quenching | Yes | Yes | Possible |
The processing time indicates the time needed for the clearing of the whole brain or hemisphere of adult mouse.
BABB, benzyl alcohol and benzyl benzoate; 3DISCO, 3-dimensional imaging of solvent-cleared organs; CLARITY, clear lipid-exchanged acrylamide-hybridized rigid imaging/immunostaining/in situ hybridization-compatible tissue-hydrogel; SeeDB, see deep brain; CUBIC, clear unobstructed brain imaging cocktails and computational analysis; PACT, passive clear lipidexchanged acrylamide-hybridized rigid imaging/immunostaining/in situ hybridization-compatible tissue-hydrogel; PARS, perfusion-assisted agent release in situ; iDISCO, immunolabeling-enabled 3-dimensional imaging of solvent-cleared organs; SWITCH, system-wide control of interaction time and kinetics of chemicals; ACT, active clarity technique; PRESTO, pressure related efficient and stable transfer of macromolecules into the organs; EDC-CLARITY, 1-ethyl-3-3-dimethyl-aminopropyl carbodiimide-CLARITY; SDS, sodium dodecyl sulfate.