title: Degradation of magnetic nanoparticles mimicking lysosomal conditions followed by AC susceptibility.
abstract: BACKGROUND
  A deeper knowledge on the effects of the degradation of magnetic nanoparticles on their magnetic properties is required to develop tools for the identification and quantification of magnetic nanoparticles in biological media by magnetic means.
  
  
  METHODS
  Citric acid and phosphonoacetic acid-coated magnetic nanoparticles have been degraded in a medium that mimics lysosomal conditions. Magnetic measurements and transmission electron microscopy have been used to follow up the degradation process.
  
  
  RESULTS
  Particle size is reduced significantly in 24 h at pH 4.5 and body temperature. These transformations affect the magnetic properties of the compounds. A reduction of the interparticle interactions is observed just 4 h after the beginning of the degradation process. A strong paramagnetic contribution coming from the degradation products appears with time.
  
  
  CONCLUSIONS
  A model for the in vivo degradation of magnetic nanoparticles has been followed to gain insight on the changes of the magnetic properties of iron oxides during their degradation. The degradation kinetics is affected by the particle coating, in our case being the phosphonoacetic acid-coated particles degraded faster than the citric acid-coated ones.
authors.forename: Lucía
authors.identifier: http://orcid.org/0000-0003-2366-3598
authors.initials: L
authors.lastname: Gutiérrez
authors.forename: Sonia
authors.initials: S
authors.lastname: Romero
authors.forename: Gustavo B
authors.initials: GB
authors.lastname: da Silva
authors.forename: Rocío
authors.initials: R
authors.lastname: Costo
authors.forename: Maria D
authors.initials: MD
authors.lastname: Vargas
authors.forename: Célia M
authors.initials: CM
authors.lastname: Ronconi
authors.forename: Carlos J
authors.initials: CJ
authors.lastname: Serna
authors.forename: Sabino
authors.initials: S
authors.lastname: Veintemillas-Verdaguer
authors.forename: María
authors.initials: M
authors.lastname: Del Puerto Morales
mesh_terms: D040761:Biomimetic Materials / Q000737:chemistry / Q000528:radiation effects; D001826:Body Fluids / Q000737:chemistry; D019343:Citric Acid / Q000737:chemistry*; D020099:Coated Materials, Biocompatible / Q000737:chemistry / Q000528:radiation effects; D017097:Electric Impedance; D007700:Kinetics; D008247:Lysosomes / Q000737:chemistry* / Q000648:ultrastructure*; D058185:Magnetite Nanoparticles / Q000737:chemistry* / Q000528:radiation effects / Q000648:ultrastructure*; D008422:Materials Testing; D010316:Particle Size; D010746:Phosphonoacetic Acid / Q000737:chemistry*; D013696:Temperature
chemical_list: D020099:Coated Materials, Biocompatible; D058185:Magnetite Nanoparticles; D019343:Citric Acid; D010746:Phosphonoacetic Acid