Table 1.

Comparison of Tools for Measuring Intracellular pH.

Tool	In Vivo Compatibility	Cytotoxicity	Long-Term Measurements	Spatial Resolution	Brightness	Quantitative	Requires Standardization
Patch Clamp [96]	Incompatible	high	minutes	Single Cell	NA	Yes	No
BCECF [97]	cell-based	mild	minutes-hours	Subcellular	mid	Yes	Yes
SNARF [98]	cell-based	mild	minutes-hours	Subcellular	mid	Yes	Yes
Indole Heptamethine Cyanine Dyes [99]	cell-based	mild	minutes	Subcellular	low	Yes	Yes
Ionic Liquids [100]	cell-based	low	hours	Subcellular	low	Yes	Yes
pHluorin [101]	cell-based, some tissue	low	hours	Subcellular, targetable	low	Yes	Yes
SuperEclipticpHluorin [101,102]	cell-based, some tissue	low	hours	Subcellular, targetable	high	No	Yes
pHluorin-mCherry [103]	cell-based, some tissue	low	hours	Subcellular, targetable	high	Yes	Yes
pHluorin 2 [104]	cell-based, some tissue	low	hours	Subcellular, targetable	mid	Yes	Yes
pHred [105,106]	cell-based, deeper tissue	low-mild	hours	Subcellular, targetable	low	Yes	Yes
pHuji [107]	cell-based, deeper tissue	low-mild	hours	Subcellular, targetable	low	No	Yes
mCherry EA-mutant [108]	cell-based, deeper tissue	low-mild	hours	Subcellular, targetable	low	Yes	Yes