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. Author manuscript; available in PMC: 2013 Jan 24.
Published in final edited form as: ACS Nano. 2011 Dec 19;6(1):512–522. doi: 10.1021/nn2038516

Figure 5.

Figure 5

(A) Calibration curves for HS-PEG-NH2 and ninhydrin-based assay, showing a linear relationship between the absorbance at 565 nm and the concentration of HS-PEG-NH2. (B) UV-vis spectra of the chromophore derived from a reaction between ninhydrin and HS-PEG3000-NH2 (black curves), HS-PEG5000-NH2 (red curves), and HS-PEG20000-NH2 (green curves), respectively. The dotted and solid curves correspond to spectra taken from the original solution and from the supernatant after incubation with 50-nm AuNCs for 12 h, respectively.