68Ga-Labeled Gold Glyconanoparticles for Exploring Blood–Brain Barrier Permeability: Preparation, Biodistribution Studies, and Improved Brain Uptake via Neuropeptide Conjugation
摘要:
New tools and techniques to improve brain visualization and assess drug permeability across the blood brain barrier (BBB) are critically needed. Positron emission tomography (PET) is a highly sensitive, noninvasive technique that allows the evaluation of the BBB permeability under normal and disease-state conditions. In this work, we have developed the synthesis of novel water-soluble and biocompatible glucose-coated gold nanoparticles (GNPs) carrying BBB-permeable neuropeptides and a chelator of the positron emitter Ga-68 as a PET reporter for in vivo tracking biodistribution. The small GNPs (2 nm) are stabilized and solubilized by a glucose conjugate. A NOTA ligand is the chelating agent for the Ga-68, and two related opioid peptides are used as targeting ligands for improving BBB crossing. The radioactive labeling of the GNPs is completed in 30 min at 70 degrees C followed by purification via centrifugal filtration. As a proof of principle, a biodistribution study in rats is performed for the different Ga-68-GNPs. The accumulation of radioactivity in different organs after intravenous administration is measured by whole body PET imaging and gamma counter measurements of selected organs. The biodistribution of the Ga-68-GNPs varies depending on the ligands, as GNPs with the same gold core size show different distribution profiles. One of the targeted Ga-68-GNPs improves BBB crossing near 3-fold (0.020 +/- 0.0050% ID/g) compared to nontargeted GNPs (0.0073 +/- 0.0024% ID/g) as measured by dissection and tissue counting.