Finance

Physics

Nanotechnology

Organic chemistry

Covalent bond

Silanol

Reagent

Optics

Surface modification

Engineering

Catalysis

Composite material

Economics

Chemistry

Materials science

Silane

Ethylene glycol

Layer (electronics)

Molecule

Passivation

Chemical engineering

PEG ratio

Fluorescence

ACS Applied Materials & Interfaces

Surface passivation to inhibit nonspecific interactions is a key requirement for in vitro single-molecule fluorescent studies. Although the standard passivation methods involve the covalent attachment of poly(ethylene glycol) (PEG) in two steps preferably over quartz surfaces, this protocol and improvements thereon require extensive labor and chemicals. Herein, we report an efficient one-step surface grafting of PEG-silane that yields enhanced passivation, as evidenced by reduced nonspecific interactions, over the conventional method at a minimal time and reagent cost and on glass surfaces. Our method is rooted in a mechanistic understanding of the silane reaction with the silanol groups on the glass surface. Single-molecule fluorescence studies with fluorescently tagged proteins and DNA on PEG-silane-functionalized glass surfaces validate the enhanced performance of the method. Combined with atomic force microscopy surface characterization, our study further illustrates that few remaining pinhole defects, plausibly from defects on the glass, on PEG-silane glass-coated surfaces account for the minimal background, where typically no more than one molecule is nonspecifically attached in a given diffraction-limited spot on the surface.

Efficient One-Step PEG-Silane Passivation of Glass Surfaces for Single-Molecule Fluorescence Studies