We present a generic and flexible method to nanopattern biomolecules on surfaces. Carbon-containing nanofeatures are written at variable diameter and spacing by a focused electron beam on a poly(ethylene glycol) (PEG)-coated glass substrate. Proteins physisorb to the nanofeatures with remarkably high contrast factors of more than 1000 compared to the surrounding PEG surfaces. The biological activity of model proteins can be retained as shown by decorating avidin spots with biotinylated DNA, thereby underscoring the universality of the nano-biofunctionalized platform for the binding of other biotinylated ligands. In addition, biomolecule densities can be tuned over several orders of magnitude within the same array, as demonstrated by painting a microscale image with nanoscale pixels. We expect that these unique advantages open up entirely new ways to design biophysical experiments, for instance, on cells that respond to the nanoscale densities of activating molecules.
[Show abstract][Hide abstract] ABSTRACT: The controlled positioning of nanostructures with active molecular components is of importance throughout nanoscience and nanotechnology. We present a novel three-step method to produce nanostructures that are selectively decorated with functional molecules. We use fluorophores and nanoparticles to functionalize SiO features with defined shapes and with sizes ranging from micrometers to 25 nm. The method is called MACE-ID: molecular assembly controlled by electron-beam-induced deposition. In the first step, SiO nanostructures are written with focused electron-beam-induced deposition, a direct-writing technique. In the second step, the deposits are selectively silanized. In the final step, the silanes are functionalized with fluorescent dyes, polystyrene spheres, or gold nanoparticles. This recipe gives exciting new possibilities for combining the highly accurate control of top-down patterning (e-beam direct writing) with the rich variety of the bottom-up approach (self-assembly), leading to active or responsive surfaces. An important advantage of MACE-ID is that it can be used on substrates that already contain complex features, such as plasmonic structures, nanoantennas, and cavities.
[Show abstract][Hide abstract] ABSTRACT: DNA is a powerful biomaterial for creating rationally designed and functionally enhanced nanostructures. DNA nanoarchitectures positioned at substrate interfaces can offer unique advantages leading to improved surface properties relevant to biosensing, nanotechnology, materials science, and cell biology. This Perspective highlights the benefits and challenges of using assembled DNA as a nanoscale building block for interfacial layers and surveys their applications in three areas: homogeneous dense surface coatings, bottom-up nanopatterning, and 3D nanoparticle lattices. Possible future research developments are discussed at the end of the Perspective.
[Show abstract][Hide abstract] ABSTRACT: This paper presents a versatile way to prepare multiscale and gradient patterns of proteins. The protein patterns are fabricated by conjugating proteins covalently on patterns of polymer brush that are prepared by techniques combining colloidal lithography with photolithography, and two-step colloidal lithography. Taking advantages of this technique, the parameters of protein patterns, such as height, diameters, periods, and distances between two dots, can be arbitrarily tuned. In addition, the protein patterns with varies of architectures, such as microdiscs, microstripes, microrings, microtriangles, microgrids, etc., consisting of protein nanodots, are prepared and the sample size is up to 4 cm2. The as-prepared patterns of fibronectin can promote the cell adhesion and cell location.
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