[show abstract][hide abstract] ABSTRACT: We report nanofabrication of protein dot and line patterns using a nanofountain atomic force microscopy probe (NFP). Biomolecules are continuously fed in solution through an integrated microfluidic system, and deposited directly onto a substrate. Deposition is controlled by application of an electric potential of appropriate sign and magnitude between the probe reservoir and substrate. Submicron dot and line molecular patterns were generated with resolution that depended on the magnitude of the applied voltage, dwell time, and writing speed. By using an energetic argument and a Kelvin condensation model, the quasi-equilibrium liquid-air interface at the probe tip was determined. The analysis revealed the origin of the need for electric fields in achieving protein transport to the substrate and confirmed experimental observations suggesting that pattern resolution is controlled by tip sharpness and not overall probe aperture. As such, the NFP combines the high-resolution of dip-pen nanolithography with the efficient continuous liquid feeding of micropipettes while allowing scalability to 1- and 2D probe arrays for high throughput.
Proceedings of the National Academy of Sciences 11/2008; 105(43):16438-43. · 9.74 Impact Factor
[show abstract][hide abstract] ABSTRACT: Scanning probe based patterning techniques have the unique ability to deposit biological material into specific architectures
on substrates and read and analyze the patterns using an atomic force microscope. Such devices are able to make much smaller
biomolecule patterns, on the order of nanometers, than conventional techniques such as microcontact printing and optical lithography.
A reduction in patterned feature size allows for greater sensitivity in biological studies and in life sciences applications
such as drug screening and immunoassays. A variety of tools for the fabrication of nanoarrays are discussed. These include
open- and closed-channel devices and pipette-based devices. Their potential for the integration of active components or augmentation
to large-scale arrays for high-throughput deposition are examined. The mechanisms for deposition and biomolecule transport
are also explained.
[show abstract][hide abstract] ABSTRACT: We report the direct delivery and assembly of negatively charged gold colloidal particles atop positively charged amino-terminated silicon oxide surfaces using a nanofountain atomic force microscopy probe. The experimental results and fluid simulations indicate that the flow of nanoparticles is confined to the core tip region of the probe. This leads to the assembly of high-resolution submicron patterns (200 nm) on the substrate with feature sizes dependent on the tip-substrate contact time. A diffusion mechanism for the patterning is proposed and discussed.