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Advances in Materials Science and Engineering
Volume 2012, Article ID 748098, 15 pages
Research Article

The Role of pH in PEG-b-PAAc Modification of Gadolinium Oxide Nanostructures for Biomedical Applications

1Center for Technologies against Cancer (CTC), Tokyo University of Science, 2669 Yamazaki Noda, Chiba 278-0022, Japan
2Department of Materials Science and Technology, Tokyo University of Science, 2641 Yamazaki Noda, Chiba 278-8510, Japan

Received 6 February 2012; Accepted 26 June 2012

Academic Editor: Dachamir Hotza

Copyright © 2012 Eva Hemmer et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Supplementary Material

FT-IR spectra recorded on the PEG-b-PAAc modified samples (Figure 5, main text) show peaks at 2900 and 1100 cm-1 which are assigned to C-H asymmetric stretching and C-O-C stretching in PEG. Peaks of less intensity observed at 1347 and 950 cm-1 are assigned to CH2 wagging motion as well as CH2 rocking vibrations. The FT-IR spectrum recorded on pure PEG-b-PAAc (Figure S1a) shows peaks in the corresponding wavenumber range indicating the presence of PEG-b-PAAc on the surface of the Gd2O3:Er3+,Yb3+ nanostructures. Further, the spectrum recorded on pure PEG-b-PAAc reveals a sharp and intensive peak at 1730 cm-1 originating from carboxylic acidic groups (–COOH). In modified samples, this peak is replaced by two bands at 1523 and 1406 cm-1. Those are related to carboxylate (—COO-) stretches giving a further confirmation for surface modification.

Figure S1b shows the FT-IR spectrum recorded on gadolinium acetate tetrahydrate. This reference material reveals a broad band at wavenumber range 850 to 550 cm-1. The exhibition of such a band is a potential reason for the broadening observed in the spectra recorded on samples modified with PEG-b-PAAc solutions of pH 5 or lower (Figure 5, main text) and supports the suggested formation of a gadolinium-PEG-b-PAAc-complex.

  1. Supplementary Figure