title: A microwave-assisted solution combustion synthesis to produce europium-doped calcium phosphate nanowhiskers for bioimaging applications.
abstract: Biocompatible nanoparticles possessing fluorescent properties offer attractive possibilities for multifunctional bioimaging and/or drug and gene delivery applications. Many of the limitations with current imaging systems center on the properties of the optical probes in relation to equipment technical capabilities. Here we introduce a novel high aspect ratio and highly crystalline europium-doped calcium phosphate nanowhisker produced using a simple microwave-assisted solution combustion synthesis method for use as a multifunctional bioimaging probe. X-ray diffraction confirmed the material phase as europium-doped hydroxyapatite. Fluorescence emission and excitation spectra and their corresponding peaks were identified using spectrofluorimetry and validated with fluorescence, confocal and multiphoton microscopy. The nanowhiskers were found to exhibit red and far red wavelength fluorescence under ultraviolet excitation with an optimal peak emission of 696 nm achieved with a 350 nm excitation. Relatively narrow emission bands were observed, which may permit their use in multicolor imaging applications. Confocal and multiphoton microscopy confirmed that the nanoparticles provide sufficient intensity to be utilized in imaging applications.
authors.affiliation: The University of Toledo, Colleges of Engineering and of Medicine and Life Sciences, Department of Biomedical Engineering, Toledo, OH 43606, USA. darcy.wagner@med.uvm.edu
authors.forename: Darcy E
authors.initials: DE
authors.lastname: Wagner
authors.forename: Kathryn M
authors.initials: KM
authors.lastname: Eisenmann
authors.forename: Andrea L
authors.initials: AL
authors.lastname: Nestor-Kalinoski
authors.forename: Sarit B
authors.initials: SB
authors.lastname: Bhaduri
mesh_terms: D002130:Calcium Phosphates / Q000138:chemical synthesis* / Q000528:radiation effects; D003287:Contrast Media / Q000138:chemical synthesis / Q000528:radiation effects; D003460:Crystallization / Q000379:methods*; D005063:Europium / Q000737:chemistry* / Q000528:radiation effects; D006358:Hot Temperature; D008422:Materials Testing; D036641:Microscopy, Fluorescence, Multiphoton / Q000379:methods*; D008872:Microwaves; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D010316:Particle Size; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D002130:Calcium Phosphates; D003287:Contrast Media; D005063:Europium; C020243:calcium phosphate
keywords: Calcium phosphate; Europium; Fluorescence; Inorganic nanoparticles; Microwave-assisted solution synthesis