Surface-Bound Gradient Deposition of Protein Nanoparticles for Cell Motility Studies

A versatile evaporation-assisted methodology based on the coffee-drop effect is described to deposit nanoparticles on surfaces, obtaining for the first time patterned gradients of protein nanoparticles (pNPs) by using a simple custom-made device. Fully controllable patterns with specific periodicities consisting of stripes with different widths and distinct nanoparticle concentration as well as gradients can be produced over large areas (similar to 10 cm(2)) in a fast (up to 10 mm(2)/min), reproducible, and cost-effective manner using an operational protocol optimized by an evolutionary algorithm. The developed method opens the possibility to decorate surfaces a-la-carte with pNPs enabling different categories of high-throughput studies on cell motility.