TABLE 2.

Diffusion coefficients and the corresponding hydrodynamic radii of fluorescently labeled probes in water and in biofilms of S. mutans

Probe	Mwa (g/mole)	Mean Dw ± SD (10−10 m2·s−1)	rHb (nm)	Dw (10−10 m2·s−1) in literature	rH from literatured (nm)	Mean Db ± SD (10−10 m2·s−1)	Db/Dw
Dextran 3K	3,000	1.61 ± 0.22	1.36			1.2 ± 0.3	0.73
Dextran 10K	10,000	1.22 ± 0.04	1.78		1.86	0.8 ± 0.2	0.63
Dextran 40K	40,000	0.47 ± 0.018	4.59	0.45c	4.78	0.25 ± 0.08	0.53
Dextran 70K	70,000	0.37 ± 0.066	5.80	0.38c	6.49	0.20 ± 0.06	0.53
Dextran 2,000K	2000,000	0.062 ± 0.0081	35.7			0.13 ± 0.06	2.10
Rhodamine 6G	479.01	4.0 ± 0.2		4.0 ± 0.3e		2.2 ± 0.7	0.54
Tetramethylrhodamine, methyl ester	500.93	4.12 ± 0.18	0.53			2.3 ± 0.7	0.55
Rhodamine B	479.01	4.2 ± 0.2		4.2 ± 0.3e		1.8 ± 0.7	0.42
Oregon Green 488 carboxylic acid, succinimidyl ester	509.38	3.08 ± 0.10	0.70			0.7 ± 0.2	0.21
Oregon Green 488 carboxylic acid	412.30	3.36 ± 0.11	0.65			0.6 ± 0.2	0.17

^aMolar mass.

^bHydrodyamic radii, r_H, were estimated from the Stokes Einstein equation, r_H = kT/3πηD, where k is the Boltzmann constant, T the temperature, and η the solution's viscosity.

^cReference 13.

^dReference 2.

^eReference 12.