Fig. 3

CT images of a Au PENPs-CTX and b Omnipaque at different concentrations of Au or I, and c their X-ray attenuation intensities. In vitro CT images of C6 cells treated with d Au PENPs and e Au PENPs-CTX for 4 h at the Au concentrations of 12.5, 25, 50 and 100 μM, respectively, and f their quantitative CT values. In vitro SPECT images of C6 cells treated with g ¹³¹I-Au PENPs and h ¹³¹I-Au PENPs-CTX for 4 h at the radioactive concentrations of 25, 50, 100, 200 and 400 μCi/mL, respectively, and i their relative SPECT signal intensities