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Fig. 1 Characterization of biotin- and Cy5-loaded CDs. (A) MALDI mass spectrometry of CD (∼3k Da; blue), CD-Biotin (∼3.5k Da; black), and CD-Cy5 (∼4.2 kDa; red). (B) TEM images of unlabeled, biotin-loaded, and Cy5-loaded CDs. Scale bars are 20 nm. (C) SDS-PAGE chromatograph of CD, Cy5, CD mixed with Cy5, and two different preparations of CD-Cy5 (1 and 2) imaged under 488 nm (CD, pseudocolored cyan) and 647 nm (Cy5, pseudocolored magenta) excitation. CD-Cy5(1) and CD-Cy5(2) were purified using different conventional chromatography methods (1, size exclusion; 2, anion exchange). The far-right gel is a composite of merged images. The arrow indicates new molecular species that appear after EDC/NHS conjugation. The molecular weight (MW) ladder is in kDa.