Table 1.

Common cationic probes for detection of anionic polysaccharides in the microbial glycocalyx

	Alcian blue	Safranin O a	Ruthenium red	L-lysine
MW(Daltons)	1299	351	858	182.6
Charge	+4	+2-+3	+6	+2
Shape	Planar	Planar	Spherical	Planar
Size	~4 × 4 nm	~3 × 2 nm	1.1 nm	~1 × 2 nm

^aMW (molecular weight) for safranin O may vary because the dye is a mixture of dimethyl and trimethyl isomers (Luft 1971; Erdos 1986; Fassel and Edmiston 1999; Horobin and Kiernan 2002).