The Fabrication and Applications of Protein Patterns Produced Via Particle Lithography

Abstract

A novel particle lithography technique with the ability to pattern protein in hexagonal dot arrays was developed. The patterning method consists of a simple three-step procedure: (1) formation of a close-packed polystyrene microsphere monolayer, (2) grafting of a protein-resistant layer of poly(ethylene glycol) (PEG), and (3)selective adsorption of protein into the resulting PEG holes. The diameter and center-to-center spacing of the patterned features was varied simultaneously by changing the diameter of the spheres used in the lithographic mask or independently using a simple heating modification. A combination of the original and modified procedures was used to produce patterns of protein dots with diameters of 450 nm - 9 ìm and center-to-center spacings of 2 - 10 ìm. To demonstrate the applicability of the particle lithography technique, a fluorescent-based immunoassay was created using quantum dot bioconjugates (QDBCs). The millions of protein dot features per patterned substrate served as redundant sampling points that produced a subpicomolar detection limit. Finally, the QDBC patterns were also used to investigate the differences between neutrophil spreading on patterned and homogenously coated anti-PSGL-1 (PL1) surfaces.