Fabrication of Biotinylated Gradient Surface Based on the Micropatterned Polymer Brushes

The biotin-avidin reaction system has shown remarkable advantages in immunoassays and biomedical fields due to its high specificity, excellent sensitivity and stability. The ability to generate biotinylated surface with gradient features would further promote the potential application of the biotin-avidin system in various fields ranging from high-throughput analysis to multifunctional biological surface. Here, based on the micropatterned polymer brushes functionalized with azido groups, a promising method was presented for fabricating the biotinylated gradient surfaces. Micropatterned poly(2-(2-azido-2-methyl-1-oxopropoxy) ethyl methacrylate) (PAMEMA) brushes bearing azido groups were fabricated through employing a digital mirror device (DMD) based light modulation technique to regulate a surface-initiated photoinduced atom transfer radical polymerization (Photo-ATRP) process. X-ray photoelectron spectroscopy (XPS) and time of flight-secondary ion mass spectrometry (TOF-SIMS) measurements were performed to characterize the surface elemental composition of silicon substrates micropatterned with PAMEMA brushes, whose results indicate the spatially selective distribution of azido groups. The terminal azido groups of PAMEMA brushes could provide reactive sites for covalent immobilization of DBCO-PEG4-biotin through the highly specific orthogonal "click" reaction, leading to the biotinylation of PAMEMA brushes micropatterned surface. The streptavidin-fluorophore conjugate binding experiment was performed to characterize the distribution of biotins on the patterned surface. The fluorescence characterizations demonstrated the functionality of the micropatterned PAMEMA brushes with various thicknesses to regulate the spatial density of immobilized biotins, which resulted in the successful creation of biotinylated gradient surfaces with various complicated structures. The research extends the application of polymer brush micropattern in functional gradient surfaces preparation, and provides fundamental technical support for expanding biotinylated gradient surfaces applications in high-throughput detection chips and combinatorial chemistry. [GRAPHICS]