title: Block Copolymer-Encapsulated CaWO4 Nanoparticles: Synthesis, Formulation, and Characterization.
abstract: We envision that CaWO4 (CWO) nanocrystals have the potential for use in biomedical imaging and therapy because of the unique ways this material interacts with high-energy radiation. These applications, however, require development of nanoparticle (NP) formulations that are suitable for in vivo applications; primarily, the formulated nanoparticles should be sufficiently small, chemically and biologically inert, and stable against aggregation under physiological conditions. The present study demonstrates one such method of formulation, in which CWO nanoparticles are encapsulated in bioinert block copolymer (BCP) micelles. For this demonstration, we prepared three different CWO nanocrystal samples having different sizes (3, 10, and 70 nm in diameter) and shapes (elongated vs truncated rhombic). Depending on the specific synthesis method used, the as-synthesized CWO NPs contain different surfactant materials (citric acid or cetyltrimethylammonium bromide or a mixture of oleic acid and oleylamine) in the coating layers. Regardless of the type of surfactant, the original surfactant coating can be replaced with a new enclosure formed by BCP materials using a solvent-exchange method. Two types of BCPs have been tested: poly(ethylene glycol-block-n-butyl acrylate) (PEG-PnBA) and poly(ethylene glycol-block-D,L-lactic acid) (PEG-PLA). Both BCPs are able to produce fully PEGylated CWO NPs that are stable against aggregation under physiological salt conditions for very long periods of time (at least three months). The optical and radio luminescence properties of both BCP-encapsulated and surfactant-coated CWO NPs were extensively characterized. The study confirms that the BCP coating structure does not influence the luminescence properties of CWO NPs.
authors.affiliation: School of Chemical Engineering, ‡Department of Veterinary Clinical Sciences, and §Purdue University Center for Cancer Research, Purdue University , West Lafayette, Indiana 47907, United States.
authors.forename: Jaewon
authors.initials: J
authors.lastname: Lee
authors.affiliation: School of Chemical Engineering, ‡Department of Veterinary Clinical Sciences, and §Purdue University Center for Cancer Research, Purdue University , West Lafayette, Indiana 47907, United States.
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Rancilio
authors.affiliation: School of Chemical Engineering, ‡Department of Veterinary Clinical Sciences, and §Purdue University Center for Cancer Research, Purdue University , West Lafayette, Indiana 47907, United States.
authors.forename: Jean M
authors.initials: JM
authors.lastname: Poulson
authors.affiliation: School of Chemical Engineering, ‡Department of Veterinary Clinical Sciences, and §Purdue University Center for Cancer Research, Purdue University , West Lafayette, Indiana 47907, United States.
authors.forename: You-Yeon
authors.initials: YY
authors.lastname: Won
mesh_terms: D017610:Calcium Compounds / Q000138:chemical synthesis / Q000737:chemistry* / Q000627:therapeutic use; D000077286:Cetrimonium; D002593:Cetrimonium Compounds / Q000737:chemistry; D002626:Chemistry, Pharmaceutical; D016503:Drug Delivery Systems; D006801:Humans; D007773:Lactates / Q000138:chemical synthesis / Q000737:chemistry / Q000627:therapeutic use; D008823:Micelles; D053758:Nanoparticles / Q000737:chemistry* / Q000627:therapeutic use; D010316:Particle Size; D011092:Polyethylene Glycols / Q000138:chemical synthesis / Q000737:chemistry / Q000627:therapeutic use; D011827:Radiation; D013501:Surface-Active Agents / Q000138:chemical synthesis / Q000737:chemistry* / Q000627:therapeutic use; D017973:Tungsten Compounds / Q000138:chemical synthesis / Q000737:chemistry* / Q000627:therapeutic use
chemical_list: D017610:Calcium Compounds; D002593:Cetrimonium Compounds; D007773:Lactates; D008823:Micelles; D013501:Surface-Active Agents; D017973:Tungsten Compounds; C088513:poly(lactic acid-ethylene glycol); D011092:Polyethylene Glycols; C018858:calcium tungstate; D000077286:Cetrimonium
keywords: block copolymer; calcium tungstate; encapsulation; fluorescence; nanoparticle; phosphorescence; radioluminescence; stabilization