title: Silica nanoparticles: preparation, characterization and in vitro/in vivo biodistribution studies.
abstract: BACKGROUND
  The current progress in pharmaceutical nanotechnology field has been exploited in the design of functionalized radiolabelled nanoparticles that are able to deliver radionuclides in a selective manner to improve the outcome of diagnosis and treatment. Silica nanoparticles (SNPs) have been widely developed for biomedical applications due to their high versatility, excellent functional properties and low cost production, with the possibility to control different topological parameters relevant for multidisciplinary applications.
  
  
  OBJECTIVE
  The aim of the present study was to characterize and evaluate both in vitro, by microscopy techniques, and in vivo, by scintigraphic imaging, the biodistribution of silica nanostructures derivatives (Cy5.5 conjugated SNPs and (99m)Tc radiolabelled SNPs) to be applied as radiotracers in biomedicine.
  
  
  METHODS
  SNPs were synthesized by hydrolysis and condensation of silicon alkoxides, followed by surface functionalization with amino groups available for fluorescent dye and radiolabelling possibility.
  
  
  RESULTS
  Our data showed the particles size distribution (200-350 nm), the surface charge (negative for bare and fluorescent SNPs and positive for amino SNPs), polydispersity index (broad distribution), the qualitative composition and the toxicity assessments (safe material) that made the obtained SNPs candidates for in vitro/in vivo studies. A high uptake of fluorescent SNPs in all the investigated organs was evidenced by confocal microscopy. The (99m)Tc radiolabelled SNPs biodistribution was quantified in the range of 12-100% counts/g organ using the scintigraphic images.
  
  
  CONCLUSIONS
  The obtained results reveal improved properties, namely, reduced toxicity with a low level of side effects, an improved biodistribution, high labelling efficiency and stability of the radiolabelled SNPs with potential to be applied in biomedical science, particularly in nuclear medicine as a radiotracer.
authors: Centre for the Study and Therapy of Pain, "Gr. T. Popa" University of Medicine and Pharmacy, Iasi, Romania.
authors: B I
authors: BI
authors: Tamba
authors: Centre for the Study and Therapy of Pain, "Gr. T. Popa" University of Medicine and Pharmacy, Iasi, Romania.
authors: A
authors: A
authors: Dondas
authors: Centre for the Study and Therapy of Pain, "Gr. T. Popa" University of Medicine and Pharmacy, Iasi, Romania.
authors: M
authors: M
authors: Leon
authors: Laboratory of Animal Histology, Faculty of Biology, "Alexandru Ioan Cuza" University of Iasi, Romania.
authors: A N
authors: AN
authors: Neagu
authors: Faculty of Chemical Engineering and Environmental Protection, "Gheorghe Asachi" Technical University of Iasi, Romania; SCIENT - Research Centre for Instrumental Analysis, Bucharest, Romania.
authors: G
authors: G
authors: Dodi
authors: Department of Biophysics and Medical Physics, "Gr. T. Popa" University of Medicine and Pharmacy, 700115 Iasi, Romania. Electronic address: cipriana.stefanescu@yahoo.com.
authors: C
authors: C
authors: Stefanescu
authors: FHNW, School of Life Sciences, Switzerland.
authors: A
authors: A
authors: Tijani
mesh_terms: D000818:Animals; D002232:Carbocyanines / Q000493:pharmacokinetics; D004339:Drug Compounding; D005456:Fluorescent Dyes / Q000493:pharmacokinetics; D006168:Guinea Pigs; D008297:Male; D051379:Mice; D053758:Nanoparticles / Q000633:toxicity; D010316:Particle Size; D012822:Silicon Dioxide / Q000493:pharmacokinetics* / Q000633:toxicity; D013499:Surface Properties; D014018:Tissue Distribution
chemical_list: C098793:CY5.5 cyanine dye; D002232:Carbocyanines; D005456:Fluorescent Dyes; D012822:Silicon Dioxide
keywords: Biodistribution; Fluorescent; Microscopy; Scintigraphy; Silica nanoparticles