16607
The luminescent and magnetic ( relaxivity ) properties of the Eu : GdF3 nanoparticles have been also evaluated in order to assess their potentiality as " in vitro " optical biolabels and contrast agent for magnetic resonance imaging .
 Eu, GdF3
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 Eu, GdF3