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Beilstein J Nanotechnol ; 8: 1484-1493, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28900602


New multifunctional nanoparticles (NPs) that can be used as contrast agents (CA) in different imaging techniques, such as photoluminescence (PL) microscopy and magnetic resonance imaging (MRI), open new possibilities for medical imaging, e.g., in the fields of diagnostics or tissue characterization in regenerative medicine. The focus of this study is on the synthesis and characterization of CaF2:(Tb3+,Gd3+) NPs. Fabricated in a wet-chemical procedure, the spherical NPs with a diameter of 5-10 nm show a crystalline structure. Simultaneous doping of the NPs with different lanthanide ions, leading to paramagnetism and fluorescence, makes them suitable for MR and PL imaging. Owing to the Gd3+ ions on the surface, the NPs reduce the MR T1 relaxation time constant as a function of their concentration. Thus, the NPs can be used as a MRI CA with a mean relaxivity of about r = 0.471 mL·mg-1·s-1. Repeated MRI examinations of four different batches prove the reproducibility of the NP synthesis and determine the long-term stability of the CAs. No cytotoxicity of NP concentrations between 0.5 and 1 mg·mL-1 was observed after exposure to human dermal fibroblasts over 24 h. Overall this study shows, that the CaF2:(Tb3+,Gd3+) NPs are suitable for medical imaging.

Methods Mol Biol ; 1601: 111-122, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28470522


Nanoparticles (NPs) in biotechnology hold great promise for revolutionizing medical treatments and therapies. In order to bring NPs into clinical application there is a number of preclinical in vitro and in vivo tests, which have to be applied before. The initial in vitro evaluation includes a detailed physicochemical characterization as well as biocompatibility tests, among others. For determination of biocompatibility at the cellular level, the correct choice of the in vitro assay as well as NP pretreatment is absolutely essential. There are a variety of assay technologies available that use standard plate readers to measure metabolic markers to estimate the number of viable cells in culture. Each cell viability assay has its own set of advantages and disadvantages. Regardless of the assay method chosen, the major factors critical for reproducibility and success include: (1) choosing the right assay after comparing optical NP properties with the read-out method of the assay, (2) verifying colloidal stability of NPs in cell culture media, (3) preparing a sterile and stable NP dispersion in cell culture media used in the assay, (4) using a tightly controlled and consistent cell model allowing appropriate characterization of NPs. This chapter will briefly summarize these different critical points, which can occur during biocompatibility screening applications of NPs.

Sobrevivência Celular/efeitos dos fármacos , Teste de Materiais/métodos , Nanopartículas/química , Nanopartículas/toxicidade , Células CACO-2 , Coloides/química , Meios de Cultura/química , Espectroscopia Dielétrica , Sistemas de Liberação de Medicamentos , Humanos , Concentração de Íons de Hidrogênio , Tamanho da Partícula
Chemistry ; 15(29): 7150-5, 2009 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-19544503


Herein we report for the first time full details on the synthesis and structural characterization of novel homodinuclear bridging cobalt and nickel borylene complexes containing bridging carbonyl ligands, an unusual coordination motif rarely before observed for homodinuclear borylene complexes. Furthermore, the homodinuclear nickel complex represents the first instance of a nickel borylene complex. Quantum chemical analyses of charge-density topology, electron localization function (ELF) and natural charges indicate the absence of direct metal-metal bonds in both the cobalt and nickel systems, in contradiction with electron counting. The topology of the Laplacian of the electron density and of the ELF around the bridging boron atom is consistent with a bis-metallo-substituted borane situation for the dicobalt system, but with a three-center-bonding borylene for the dinickel complex.