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. Author manuscript; available in PMC: 2012 Feb 18.
Published in final edited form as: J Am Chem Soc. 2010 Oct 13;132(40):14024–14026. doi: 10.1021/ja106619w

Figure 3. Erosion and content-release by TPR smart-gels.

Figure 3

(A) A piece of gel was placed into a solution of 0.01M sodium phosphate pH 7.4, at different ionic strengths, 25 °C and removed and weighed at various times following immersion. The percent gel mass remaining is plotted versus time for the different ionic strength solutions. (B) An aliquot of fluorescent protein (mVFP) or (C) the small molecule rhodamine (MW 422 Da) was entrapped during gelation. The release of entrapped molecule was monitored as a function of time, following the increase in fluorescence of the solution in which the gel was immersed. These measurements were made in DMEM (Dulbecco/Vogt modified Eagle's minimal essential medium), a commonly used tissue culture medium, which has an ionic strength of 166 mM, pH 7.4, at 37°C. Release of the 26 kDa mVFP protein from the gel clearly mirrors gel erosion. Note that there is virtually no release in the 30 mM ionic strength solution (grey circles). (C) Data are shown for 0.01M sodium phosphate pH 7.4, plus 0.01M NaCl (light red) or plus 0.5M NaCl (dark red) at 25oC. Release of rhodamine is far more rapid than the erosion of the gel. The lines through the points in all plots are included as a guide for the eye.