Figure 4

NGF exerts its biological activity upon nanoformulation. (a) Representative images of PC12 cells incubated for 4 days with 100 ng/mL of free NGF or with the same concentration of NGF bound to PNA-conjugated polyacrylamide nanoparticles (ANP:PNA:NGF). As control, PC12 cells were incubated with PNA-conjugated nanoparticles (ANP:PNA) or DPBS. Red and blue asterisks indicate the presence of neurites in cells exposed to NGF and ANP:PNA:NGF, respectively. Scale bar: 300 µm. (b) Quantitative evaluation of neurite length in PC12 cells incubated with NGF or ANP:PNA:NGF. n = 180 neurites from 3 biological replicates, t-test for unpaired data followed by Kolmogorov–Smirnov test. (c) Protective effect of NGF-conjugated polyacrylamide nanoparticles against oxidative stress. ARPE-19 cells were cotreated with 100 ng/mL of free NGF (NGF) or nanoformulated NGF (ANP:PNA:NGF) and 300 µM of H₂O₂ for 24 h. MTT assay was performed to evaluate cell viability. Absorbance values of all the groups were normalised to those of the untreated control sample (CTRL), which was set at 100%. n = 3 biological replicates, one-way ANOVA applying Tukey’s multiple comparisons test. (b,c) ns, p > 0.05 and ****, p < 0.0001.