[ early detection of amyloid plaques in Alzheimer's disease by Pittsburgh compound B-modified magnetic nanoparticles].

To construct magnetic nanoparticles targeting β-amyloid (Aβ) plaques, the pathological biomarker of Alzheimer's disease (AD) and to study their binding capability . Superparamagnetic nanoparticles Mn(0.6)Zn(0.4)Fe(2)O(4) (MZF) were coated with amphiphilic star-block copolymeric micelles and modified with Aβ-specific probe Pittsburgh compound B (PiB) to construct a novel magnetic nanoparticle MZF-PiB, which specifically targeted amyloid plaques. Transmission electron microscope was used to study the morphological features of MZF-PiB. Superparamagnetism of MZF-PiB was assessed by its r(2) relaxation rate by using 3.0 T MRI scanner. Cytotoxic test was applied to determine biosafety of MZF-PiB nanoparticles in differentiated human neuroblastoma cells (SH-SY5Y) and Madin-Darby canine kidney (MDCK). binding tests were conducted via immunohistochemistry on 6-month old AD mice brain sections. Differences of cell viability between groups were compared with one-way analysis of variance. MZF-PiB nanoparticles were successfully constructed. Transmission electron microscope images showed that the nanoparticles were about 100 nm in size. The r(2) relaxation rate was 163.11 mMS(-1). No differences were found in cell viability of SH-SY5Y and MDCK incubated with MZF-PiB suspension for 24 h or 48 h when compared with those of untreated cells (=2.336, 2.539, 0.293, 1.493, all >0.05). binding tests indicated that the MZF-PiB were specifically bound to amyloid plaques. The smallest size of detected plaques was 27 μm. PiB-modified nanoparticles targeting Aβ are biologically safe and highly superparamagnetic, possessing the capability to detect amyloid plaques early and the potential for early diagnosis of AD.