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Amyloid β (Aβ) aggregates are considered as possible targets for therapy and/or diagnosis of Alzheimer disease (AD), and nanoparticles functionalized with Aβ-specific ligands are considered promising vehicles for imaging probes and therapeutic agents. Herein, we characterized the binding properties of nanoliposomes decorated with an anti-Aβ monoclonal antibody (Aβ-MAb). The Aβ-MAb was obtained in mice by immunization with Aβ antigen followed by hybridoma fusion. Surface Plasmon Resonance (SPR) studies confirmed the very high affinity of purified Aβ-MAb for both Aβ monomers and fibrils ( K D = 0.08 and 0.13 n m , respectively). The affinity of the biotinylated Aβ-MAb, used thereafter for liposome decoration, was lower although still in the low nanomolar range ( K D = 2.1 and 1.6 n m , respectively). Biotin-streptavidin ligation method was used to decorate nanoliposomes with Aβ-MAb, at different densities. IgG-decorated liposomes were generated by the same methodology, as control. Vesicles were monodisperse with mean diameters 124–134 nm and demonstrated good colloidal stability and integrity when incubated with serum proteins. When studied by SPR, Aβ-MAb-liposomes, but not IgG-liposomes, markedly bound to Aβ monomers and fibrils, immobilized on the chip. K D values (calculated on Aβ-MAb content) were about 0.5 and 2 n m with liposomes at high and low Aβ-MAb density, respectively. Aβ-MAb-liposome binding to Aβ fibrils was additionally confirmed by ultracentrifugation technique, in which interactions occur in solution under physiological conditions. Moreover, Aβ-MAb-liposomes bound amyloid deposits in post-mortem AD brain samples, confirming the potential of these nanoparticles for the diagnosis and therapy of AD.

Amyloid β (Aβ) aggregates are considered as possible targets for therapy and/or diagnosis of Alzheimer disease (AD). It has been previously shown that curcumin targets Aβ plaques and interferes with their formation, suggesting a potential role for prevention or treatment of AD. Herein, a click chemistry method was used to generate nanoliposomes decorated with a curcumin derivative, designed to maintain the planar structure required for interaction with Aβ, as directly confirmed by Surface Plasmon Resonance experiments. Another type of liposomes was formed starting from curcumin-phospholipid conjugate, in which the planar structure of curcumin is disrupted. Both types of generated curcumin-decorated vesicles had mean diameters in the nano range (131-207 nm) and slightly negative ζ-potential values according to their lipid composition, and were stable for periods up to 20 days. They also demonstrated high integrity during incubation in presence of plasma proteins. Surface Plasmon Resonance experiments, measuring the binding of flowing liposomes to immobilized Aβ1-42, indicated that the liposomes exposing the curcumin derivative (maintaining the planarity) have extremely high affinity for Aβ1-42 fibrils (1-5 nM), likely because of the occurrence of multivalent interactions, whereas those exposing non-planar curcumin did not bind to Aβ1-42. In summary, we describe here the preparation and characterization of new nanoparticles with a very high affinity for Aβ1-42 fibrils, to be exploited as vectors for the targeted delivery of new diagnostic and therapeutic molecules for AD. © 2010 Elsevier Ltd.

A novel application of capillary electrophoresis with laser-induced fluorescence detection (CE-LIF) was proposed to efficiently detect and monitor the interaction between polymeric nanoparticles and the β-Amyloid peptide (Aβ(1-42)), a biomarker for Alzheimer's Disease (AD), at concentrations close to physiological conditions. The CE-LIF method allowed the interaction between PEGylated poly(alkyl cyanoacrylate) nanoparticles (NPs) and the soluble Aβ(1-42) peptide monomers to be highlighted. These results were confirmed by surface plasmon resonance (SPR) and confocal laser scanning microscopy (CLSM). Whereas SPR showed an interaction between the NPs and the Aβ(1-42) peptide, CLSM allowed the formation of large aggregates/assemblies at high NP and peptide concentrations to be visualized. All these results suggested that these nanoparticles could bind the Aβ(1-42) peptide and influence its aggregation kinetics. Interestingly, the non-PEGylated poly(alkyl cyanoacrylate) NPs did not alter the aggregation kinetics of the Aβ(1-42) peptide, thus emphasizing the high level of discrimination of the CE-LIF method with respect to NPs.

The neurotoxic beta-amyloid peptide (Abeta), formed in anomalous amounts in Alzheimer's disease (AD), is released as monomer and then undergoes aggregation forming oligomers, fibrils and plaques in diseased brains. Abeta aggregates are considered as possible targets for therapy and/or diagnosis of AD. Since nanoparticles (NPs) are promising vehicles for imaging probes and therapeutic agents, we realized and characterized two types of NPs (liposomes and solid lipid nanoparticles, 145 and 76 nm average size, respectively) functionalized to target Abeta(1-42) with high affinity. Preliminary immunostaining studies identified anionic phospholipids [phosphatidic acid (PA) and cardiolipin (CL)] as suitable Abeta(1-42) ligands. PA/CL-functionalized, but not plain, NPs interacted with Abeta(1-42) aggregates as indicated by ultracentrifugation experiments, in which binding reaction occurred in solution, and by Surface Plasmon Resonance (SPR) experiments, in which NPs flowed onto immobilized Abeta(1-42). All these experiments were carried out in buffered saline. SPR studies indicated that, when exposed on NPs surface, PA/CL display very high affinity for Abeta(1-42) fibrils (22-60 nm), likely because of the occurrence of multivalent interactions which markedly decrease the dissociation of PA/CL NPs from Abeta. Noteworthy, PA/CL NPs did not bind to bovine serum albumin. The PA/CL NPs described in this work are endowed with the highest affinity for Abeta so far reported. These characteristics make our NPs a very promising vector for the targeted delivery of potential new diagnostic and therapeutic molecules to be tested in appropriate animal models.