title: Characterization of Calcium Phosphate Nanoparticles Based on a PEGylated Chelator for Gene Delivery.
abstract: Calcium phosphate (CaP) nanoparticles are promising gene delivery carriers due to their bioresorbability, ease of preparation, high gene loading efficacy, and endosomal escape properties. However, the rapid aggregation of the particles needs to be addressed in order to have potential in vivo. In addition, there is a need to better understand the relationship between CaP nanoparticle properties and their interactions with cells. Here, a new synthesis route involving click chemistry was developed to prepare the PEGylated chelator PEG-inositol 1,3,4,5,6-pentakisphosphate (PEG-IP5) that can coat and stabilize CaP nanoparticles. Two methods (1 and 2) differing on the time of addition of the PEGylated chelator were employed to produce stabilized particles. Method 1 yielded amorphous aggregated spheres with a particle size of about 200 nm, whereas method 2 yielded 40 nm amorphous loose aggregates of clusters, which were quickly turned into needle bundle-like crystals of about 80 nm in a few hours. Nanoparticles prepared by method 1 were internalized with significantly higher efficiency in HepG2 cells than those prepared by method 2, and the uptake was dramatically influenced by the reaction time of Ca2+and PO43-and sedimentation of the particles. Interestingly, morphological transformations were observed for both types of particles after different storage times, but this barely influenced their in vitro cellular uptake. The transfection efficiency of the particles prepared by method 1 was significantly higher, and none of the formulations tested showed signs of cytotoxicity. This study provides a better understanding of the properties (e.g., size, morphology, and crystallinity) of PEGylated CaP nanoparticles and how these influence the particles' in vitro uptake and transfection efficiency.
authors.affiliation: Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, ETH Zurich , Vladimir-Prelog-Weg 1-5/10, 8093 Zurich, Switzerland.
authors.forename: Xiangang
authors.identifier: http://orcid.org/0000-0001-8948-7879
authors.initials: X
authors.lastname: Huang
authors.affiliation: Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, ETH Zurich , Vladimir-Prelog-Weg 1-5/10, 8093 Zurich, Switzerland.
authors.forename: Diana
authors.initials: D
authors.lastname: Andina
authors.affiliation: Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, ETH Zurich , Vladimir-Prelog-Weg 1-5/10, 8093 Zurich, Switzerland.
authors.forename: Jingshui
authors.initials: J
authors.lastname: Ge
authors.affiliation: Department of Pharmacology and Therapeutics, McGill University , 3655 Prom. Sir-William-Osler, Montréal, Québec H3G 1Y6, Canada.
authors.forename: Anne
authors.initials: A
authors.lastname: Labarre
authors.affiliation: Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, ETH Zurich , Vladimir-Prelog-Weg 1-5/10, 8093 Zurich, Switzerland.
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Leroux
authors.affiliation: Department of Pharmacology and Therapeutics, McGill University , 3655 Prom. Sir-William-Osler, Montréal, Québec H3G 1Y6, Canada.
authors.forename: Bastien
authors.initials: B
authors.lastname: Castagner
mesh_terms: D002130:Calcium Phosphates; D002614:Chelating Agents; D018014:Gene Transfer Techniques; D053758:Nanoparticles; D010316:Particle Size; D011092:Polyethylene Glycols; D014162:Transfection
chemical_list: D002130:Calcium Phosphates; D002614:Chelating Agents; D011092:Polyethylene Glycols
keywords: PEGylated chelator; calcium phosphate nanoparticles; gene delivery; morphological transformations; particle properties