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The DLS measurements of the biotinylated vesicle suspensions with avidin showed a trend of
increasing aggregate size for increasing molar ratios of biotin (Figure 3). The 2.0% biotinylated
vesicles had a relative size of 600 nm, 0.5% biotinylated vesicles a relative size of 300 nm and
0.05% biotinylated vesicles a relative size of 220 nm, 96 hours after the addition of avidin.
Furthermore, within the first 24 hours after the addition of avidin, there was a noticeable
difference between the sizes. The extent of aggregation was time dependent, the aggregates
grew larger as time elapsed.
700
600
Size (nm)
500
400
300
2.0% molar ratio of Biotin
0.5% molar ratio of Biotin
0.05% molar ratio of Biotin
200
100
0
0 20 40 60 80 100
Time after the addition of Avidin (hours)
120
Figure 3: Dynamic light scattering results for biotinylated vesicles after the addition of avidin in PBS solution,
pH 7.4.
The freeze-fracture TEM images supported the DLS measurements. Freeze-fracture TEM
provides a replica of the morphology of the vesicles and aggregates. As seen in Figure 4 (a), the
relative size of the aggregates for the vesicles of 0.05% molar ratio biotin was ~100 nm, and (b)
the aggregate size for the vesicles of 2.0% molar ratio biotin was >1000 nm. As a result of the
low concentration of the vesicle solution (1 mg/ml), the vesicle aggregates and unbound vesicles
were found to be sparse on the replica’s surface. Additionally, the replicas for all three samples
showed a large variation of vesicle and aggregate sizes.
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