Varian unity

mPEG-block-poly(L-alanine) (PEA) copolymer was prepared by the ring-opening polymerization (ROP) of L-Ala-NCAs using mPEG-NH₂ as the initiator according to the previously reported method 51 , 52 . Briefly, mPEG-NH₂ and Ala-NCAs were dissolved in anhydrous dimethyl formamide. The solution was heated at 40°C for 24 h and the obtained crude products were added dropwise into cold anhydrous diethyl ether. The precipitate was filtrated and washed by diethyl ether for three times. Finally, the PEA copolymer was dried in vacuum. The chemical composition of PEA was determined by ¹H NMR (Varian Unity, 500 MHz, Varian Medical Systems, Inc., Palo Alto, CA, USA). The secondary structure was also examined by circular dichroism (CD, Jassco J-815) spectroscopy within the temperature range of 10-60°C.

Optical imaging was performed 48 hours after the injection of NIR-830 dye labeled targeted IONPs using the Kodak FX In Vivo imaging system. Regions of Interests (ROIs) were selected for measuring the mean intensities of tumors and ex vivo images of tumors and organs.
MRI was performed on mice before, 24, and 48 hours following the i.p. injection of different IONPs using a 4.7T animal scanner (Varian Unity, Agilent, CA). T₂-weighted fast spin echo imaging sequence was used to acquire images. MRI contrast in the tumor was analyzed using the ROI method and Image J software (National Institutes of Health, Bethesda, MD). Averaged signal intensities of the ROI were obtained from all tumor areas traced from MR images and the signal intensity of the muscle was used as a baseline to normalize the signal intensity in the tumor. The percentage of the mean signal change as the result of the targeted accumulation of IONPs was calculated from comparing the mean signal intensity of the tumors in the mice before and 24 and 48 hours after received i.p. delivery.