Nile Red Loaded PLGA Nanoparticles Surface Modified with Gd-DTPA for Potential Dual-Modal Imaging

Here, a novel poly(lactic-co-glycolic acid) (PLGA)-based nanoparticles (NPs) for magnetic resonance (MR) and fluorescence imaging was developed for cell imaging. PLGA NPs loaded with fluorescent dye Nile red (NR) and surface-coated with poly(ethyleneimine) (PEI) were produced in a single step nanoprecipitation process. Diethylenetriamine pentaacetic dianhydride (DTPA) was conjugated to PLGA/NR@PEI NPs through amidation reaction between –COOH of DTPA and –NH2 of PEI, which can chelate gadolinium (Gd3+) as an MR imaging contrast agent. The PLGA/NR@PEI-DTPA-Gd NPs exhibited a uniform particle size of ∼200 nm and were stable in culture medium. These NPs had a high T 1 relaxivity (R 1) of 28.36 mM−1S−1. They did not introduce serious cytotoxicity against A549 lung cancer cells. Furthermore, fluorescence and MR imaging studies on A549 lung cancer cells in vitro revealed that PLGA/NR@PEI-DTPA-Gd NPs can serve as an efficient fluorescence/MR dual-modality imaging nanoprobe.