Fig. 4: Assessment of biocompatibility and biosafety of protein contrast agents.

a Histological images of major organs obtained after intravenous injection of LanND-Gd. Experiments were repeated independently in three animal groups, yielding similar results. b Morphology analysis of cortical neurons incubated with either PBS or LanND-Gd. Neurons were transfected with GFP for neurite identification. c Quantification of total dendrite length. d Analysis of neuronal dendrite complexity. Sholl intersection numbers were quantified at different radii from the soma center. e Monitoring of body temperature during sequential injections of LanND-Gd (n = 10) or PBS (n = 9). f Dietary monitoring of animals during sequential injections of LanND-Gd (n = 5) or PBS (n = 5) to evaluate changes in eating behavior. g Body weight monitoring after intravenous injection of LanND-G (n = 4) or PBS (n = 6). h Experimental time points for neurobehavioral tests. i Analysis of open-field moving traces of animals subjected to sequential administrations of PBS or LanND-Gd. j Statistics of the duration of access to the central area during open field testing. k Total distance of exploration during open field testing. l Assessment of brain damage through histological (top) and Nissl’s staining (bottom). Major brain regions, including the hippocampus (green dashed circle), amygdala (pink dashed circle), and hypothalamus (blue dashed circle) are highlighted. Experiments were biologically repeated in three animal groups, yielding similar results. m Representative traces of action potential firing in prefrontal cortex neurons from control or LanND-Gd injected group. n Statistical analysis of neural firing frequency induced by varying injection currents. o Summary of rheobase of the neurons. Data are presented as mean ± SEM in (c–g, j, k, and n–o). Unpaired Student’s t-test (two-tailed with criteria of significance: ^*p  < 0.05) was calculated for (c, j, k, and o). Source data are provided as a Source Data file.