title: Controlled superficial assembly of DNA-amorphous calcium phosphate nanocomposite spheres for surface-mediated gene delivery.
abstract: Surface-mediated gene delivery systems have many potential applications in tissue engineering. We recently fabricated an assembly consisting of DNA-amorphous calcium phosphate (DNA-ACP) nanocomposite spheres on a polymer substrate via coprecipitation in a labile supersaturated calcium phosphate (CaP) solution and demonstrated the assembly's high gene delivery efficacy. In this study, we conducted a detailed investigation of the coprecipitation process in solution and revealed that the negatively charged DNA molecules were immobilized in the ACP spheres during the initial stage of coprecipitation and functioned as both sphere-dispersing and size-regulating agents. As a result, the DNA-ACP nanocomposites grew into size-regulated submicrospheres in solution and assembled onto the substrate via gravity sedimentation. The assembled nanocomposite spheres were chemically anchored to the substrate surface through an intermediate layer of CaP-based nanoparticles that was formed heterogeneously at the substrate surface. The coprecipitation conditions, i.e., coprecipitation time and Ca and P concentrations in solution, greatly affected the state of assembly of the nanocomposite spheres, thereby influencing the gene expression level of the cells cultured on the substrate. Increasing the number density and decreasing the size of the nanocomposite spheres did not always increase the assembly's gene delivery efficacy (per surface area of the substrate) due to adverse effects on cellular viability. As demonstrated herein, controlling the coprecipitation conditions is important for designing a cell-stimulating and biocompatible scaffold surface consisting of an assembly of DNA-ACP nanocomposite spheres.
authors.affiliation: Nanomaterials Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan. Electronic address: a-oyane@aist.go.jp.
authors.forename: Ayako
authors.initials: A
authors.lastname: Oyane
authors.affiliation: Nanomaterials Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan.
authors.forename: Hiroko
authors.initials: H
authors.lastname: Araki
authors.affiliation: Nanomaterials Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan.
authors.forename: Maki
authors.initials: M
authors.lastname: Nakamura
authors.affiliation: Nanomaterials Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan.
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Shimizu
authors.affiliation: Nanomaterials Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan.
authors.forename: Quazi T H
authors.initials: QTH
authors.lastname: Shubhra
authors.affiliation: Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Central 6, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan.
authors.forename: Atsuo
authors.initials: A
authors.lastname: Ito
authors.affiliation: Nanomaterials Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan; Department of Neurosurgery, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, Ibaraki 305-8575, Japan.
authors.forename: Hideo
authors.initials: H
authors.lastname: Tsurushima
mesh_terms: D000818:Animals; D016466:CHO Cells; D002130:Calcium Phosphates / Q000138:chemical synthesis / Q000737:chemistry*; D006224:Cricetinae; D003412:Cricetulus; D004247:DNA / Q000737:chemistry / Q000235:genetics*; D015870:Gene Expression; D018014:Gene Transfer Techniques; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D008163:Luminescent Measurements / Q000379:methods; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D008863:Microspheres; D053761:Nanocomposites / Q000737:chemistry* / Q000648:ultrastructure; D010316:Particle Size; D013499:Surface Properties; D014162:Transfection / Q000379:methods; D014961:X-Ray Diffraction
chemical_list: D002130:Calcium Phosphates; C519480:amorphous calcium phosphate; D004247:DNA; D008156:Luciferases
keywords: Biomineralization; Calcium phosphate; Coating; Coprecipitation; Nanoparticles; Scaffold; Supersaturated solution; Transfection