BDNF and neuroblastoma: The data presented in Fig. 3A further shows that 7 h incubation of neuroblastoma cells with PAMAM-BDNF nanoparticles with negatively charged core increases cell viability from 103% (initial value obtained for PAMAM 5.5 without BDNF) to 134% in the case of PAMAM 5.5-based nanoparticles with initial protein concentration equal to 0.1 mgL−1.