The spectroscopic properties of different infrared-emitting neodymium-doped nanoparticles (LaF3:Nd 3+, SrF2:Nd3+, NaGdF4:Nd3+, NaYF4:Nd3+, KYF4:Nd3+, GdVO4:Nd3+, and Nd:YAG) have been systematically analyzed. A comparison of the spectral shapes of both emission and absorption spectra is presented, from which the relevant role played by the host matrix is evidenced. The lack of a "universal" optimum system for infrared bioimaging is discussed, as the specific bioimaging application and the experimental setup for infrared imaging determine the neodymiumdoped nanoparticle to be preferentially used in each case. (C) 2015 AIP Publishing LLC.