Fig 2. Moisture sorption isotherms.

Moisture content in samples prepared either as an aqueous solution (black symbols) or as a freeze-dried matrix (white and grey symbols) was measured after equilibration in chambers with controlled relative humidity. The BET model (Eq 3) was fit (dotted lines) to observations from freeze-dried samples, except for the trehalose-PBS case, in which aqueous solution data were used for fitting; in the trehalose-water experiment, outlier values at 75% relative humidity (grey symbols) were omitted from the fit. See Table 1 for detailed composition of each mixture.