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. Author manuscript; available in PMC: 2013 May 1.
Published in final edited form as: Biomaterials. 2012 Feb 21;33(14):3756–3769. doi: 10.1016/j.biomaterials.2012.01.054

Fig. 6.

Fig. 6

Crystallization on vaccine-coated microneedles. (a) Representative optical micrographs showing (i) a five-needle microneedle array at low magnification and individual microneedles exhibiting (ii) crystallization, (iii) phase separation with small bumps and (iv) phase separation with large bumps. Microneedles measure 750 μm in length and 200 μm in width. The insets in images (iii) and (iv) show small bumps (<15 μm) and large bumps (>15 μm), respectively. (b) Representative optical micrographs of vaccine-coated microneedles showing the evolution of crystallization on the same microneedle as a function of storage time for one month. In this case, the nucleation and growth of crystals initiated close to the needle tip. (c) Time-course of crystallization observed on vaccine-coated microneedles. Average crystallization behavior observed after coating using four different dip-coating cycles is shown (n = 20–30 for each group, mean ± SD). The degree of crystallization was determined as described in Fig. 2.