Surface-bound gradients of protein nanoparticles (pNPs) consisting of the green fluorescence protein (GFP) have been recently shown to influence cell motility (ACS Appl. Mater. Interfaces, 10,25779, 2018). Encouraged by the latter results, which were based only on physical cues (i.e., topography, geometry, and roughness), here we have studied the effects of fibroblast growth factor (FGF) based pNPs that introduce a biochemical activity to the substrate for promoting cell migration.

Eighty areas with different structural and compositional characteristics made of pNPs formed by FGF-pNPs were simultaneously patterned on a glass surface using a recently reported device based on an evaporation-assisted method that relies on the coffee-drop effect. The resulting surface enabled to perform a high-throughput study of the motility of NIH-3T3 fibroblasts under the different conditions including gradient steepness, particle concentrations, and area widths of patterned FGF-pNPs, in a fast way reducing the time and resources needed, as well as the batch to- batch variability that sometimes occurs in the pNP production. With the resulting patterned surface, we studied in the same experiment the influence of the following factors: (A) constant vs gradient concentrations of pNPs, (B) the steepness of pNP gradients, (C) the different absolute concentrations of pNPs, and (D) the impact of broad vs narrow paths (i.e., cell movement constraining on cell motility).

For the data analysis we have used a methodology that includes “heat maps”. From this analysis, we observed that gradients of concentrations of surface-bound FGF-pNPs stimulate the total cell movement but do not affect the total net distances traveled by cells. Moreover, cells tend to move toward an optimal intermediate FGF-pNP concentration. Additionally, a higher motility was obtained when cells were deposited on narrow and highly concentrated areas with pNPs demonstrating that FGF-pNPs can be therefore used to enhance and guide cell migration, confirming that the decoration of surfaces with such pNPs is a promising platform for regenerative medicine and tissue engineering.