Biotin-Conjugated Poly(Acrylic Acid)-Grafted Ultrasmall Gadolinium Oxide Nanoparticles for Enhanced Tumor Imaging

초록

Herein, biotin (Bio)-conjugated poly(acrylic acid) (PAA)-grafted ultrasmall gadolinium oxide nanoparticles (Bio-PAA-Gd2O3 NPs) were synthesized for enhanced tumor imaging using Bio as a tumor-targeting ligand. The average particle diameter of Gd2O3 NPs was 2.1 nm. The Bio-PAA-Gd2O3 NPs exhibited excellent colloidal stability (i. e., no precipitation) and a high longitudinal water proton spin relaxivity (r(1)) of 23.8 s(-1) mM(-1) (r(2)/r(1)=1.6 and r(2)=transverse water proton spin relaxivity), which was & SIM;6 times higher than those of commercial Gd-chelated magnetic resonance imaging (MRI) contrast agents. Cytotoxicity tests using two cell lines showed that the Bio-PAA-Gd2O3 NPs were almost non-toxic up to the measured concentration of 500 & mu;M Gd. The enhanced tumor imaging of the Bio-PAA-Gd2O3 NPs was demonstrated through their higher positive contrasts and longer contrast retention at the tumor after intravenous injection in T-1 MR images, compared with those of the control PAA-Gd2O3 NPs.

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