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. Author manuscript; available in PMC: 2016 Mar 1.
Published in final edited form as: Pharm Res. 2014 Sep 16;32(3):1028–1044. doi: 10.1007/s11095-014-1515-z

Fig.3.

Fig.3

Relationship between the molar ratio of ethylenediamine (ED) to NHS-activated F127 polymer micelles and the extent that F127 polyethylene oxide blocks (PEO) are cross-linked with ED. Polymer micelles of NHS-activated F127 were incubated with the indicated molar ratio of ED/NHS-F127 at room temperature (pH 6) for 2 h, dialyzed against 100% ethanol, and lyophilized. The percent of total F127 PEO blocks cross-linked with ED was determined by 1H-NMR (Fig.S1) by subtracting the peak area of protons at 3.12 ppm that represent the monovalent conjugation of ED to PEO blocks (Fig.S1B, peak 4) from the peak area of protons at 4.22 ppm (Table S1) that represent both the monovalent and divalent conjugation of ED to PEO blocks (Fig.S1B & C, peak 1A), dividing the difference by 4 (the area of the peak at 4.22 ppm [Fig.S1, peak 1A] expected at 100% ED cross-linking), and multiplying by 100. The peak representing monovalent ED conjugation (3.12 ppm) was not observed over this range of molar ratios. Average percent of total F127 PEO blocks cross-linked with ED ± SD (n=2 samples from the same batch) vs. molar ratio of ED/NHS-F127 was fit by a second order polynomial (dashed line) where Y=B0 + B1X + B2X2