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. Author manuscript; available in PMC: 2012 Jun 7.
Published in final edited form as: Phys Chem Chem Phys. 2011 Mar 9;13(21):10028–10035. doi: 10.1039/c0cp02434a

Fig. 3.

Fig. 3

Spectral and TEM measurements of the colloidal stabilities of GNRs with various surface chemistries. (a–e) Vis-NIR spectra of GNR@CTAB, GNR@PSS, GNR@SH–PEG, GNR@SiO2, and GNR@SiO2@PE-PEG dispersed in water, PBS buffer, 100 mM NaCl solution, OptiMEM, and RPMI cell culture medium. Agglomeration can be detected based on the spectral shift of GNRs’ longitudinal bands. (f–h) Representative TEM images of GNR@CTAB, GNR@SiO2, and GNR@SiO2@PE-PEG dispersed in 100 mM NaCl. This comparison clearly shows that GNR@CTAB and GNR@SiO2 are clustered but GNR@SiO2@PE-PEG remain single.