Dual-functional nanoparticles targeting amyloid plaques in the brains of Alzheimer's disease mice.

Alzheimer's disease (AD) is a common neurodegenerative disorder with few treatments. The limitations imposed by the blood-brain barrier (BBB) and the non-selective distribution of drugs in the brain have hindered the effective treatment of AD and may result in severe side effects on the normal brains. We developed a dual-functional nanoparticle drug delivery system based on a PEGylated poly (lactic acid) (PLA) polymer. Two targeting peptides that were screened by phage display, TGN and QSH, were conjugated to the surface of the nanoparticles. TGN specifically targets ligands at the BBB, while QSH has good affinity with Aβ(1-42), which is the main component of amyloid plaque. Tests probing the bEnd.3 cell uptake and in vivo imaging were conducted to determine the best density of TGN on the nanoparticles' surfaces. The optimal amount of QSH was studied using a Thioflavin T (ThT) binding assay and surface plasmon resonance (SPR) experiments. The optimal maleimide/peptide molar ratio was 3 for both TGN and QSH on the surface of the nanoparticles (T3Q3-NP), and these nanoparticles achieved enhanced and precise targeted delivery to amyloid plaque in the brains of AD model mice. A MTT assay also validated the safety of this dual-targeted delivery system; little cytotoxicity was demonstrated with both bEnd.3 and PC 12 cells. In conclusion, the T3Q3-NP might be a valuable targeting system for AD diagnosis and therapy.