Molecular Probes pH indicator dextrans, in order of decreasing pKa—Table 20.3 | Thermo Fisher Scientific - US

Table 20.3 Molecular Probes pH indicator dextrans, in order of decreasing pK_a.

Dye	Cat #	pK_a *	Measurement Wavelengths	Application Notes
SNARF	D3303, D3304	~7.5	Emission ratio 580/640 nm excited at 514 or 488 nm	Best conjugate for ratiometric emission measurements
BCECF	D1878, D1880	~7.0	Excitation ratio 490/440 nm detected at 530 nm	Best conjugate for ratiometric excitation measurements
Fluorescein	D1821, D1823, D1844, D3305	~6.4	Excitation ratio 490/450 nm detected at 520 nm	Fluorescence is strongly quenched upon uptake into acidic organelles
Fluorescein and tetramethylrhodamine	D1951	~6.4	Excitation ratio 495/555 nm detected at 580 nm †	Conjugate incorporating both pH-sensitive and pH-insensitive fluorescent dyes
pHrodo	P10361	NA ‡	Emission at 585 nm when excited at 540–560 nm	Best conjugate for measurements requiring broad-range pH sensitivity
Oregon Green 488	D7170, D7172	~4.7	Excitation ratio 490/440 nm detected at 520 nm	Good photostability Optimum pH sensitivity for measurements in lysosomes and late endosomes
Oregon Green 514	D7176	~4.7	Excitation ratio 510/450 nm detected at 530 nm	Excellent photostability Optimum pH sensitivity for measurements in lysosomes and late endosomes
LysoSensor Yellow/Blue	L22460	~4.2	Excitation ratio 340/400 nm detected at 520 nm; emission ratio 450/510 nm excited at 365 nm	Options for dual excitation or dual emission ratio measurements Optimum pH sensitivity for measurements in lysosomes and late endosomes
* pK_a values are those determined for the free dyes. Actual values for dextran conjugates may differ by up to +/– 0.3 pH units and may vary with production lots. † Ratiometric emission measurements at 520/580 nm (with excitation at 495 nm) are also possible in principle; however, the response may be complicated by fluorescence resonance energy transfer. ‡ NA = Not applicable. pHrodo pH indicator exhibits a complex pH titration profile. Decreasing pH (from pH 9 to pH 2) produces a continuous (but nonlinear) fluorescence increase.

For Research Use Only. Not for use in diagnostic procedures.