Tip-based Nanolithography

New methods for fabricating supramolecular nanostructures on surfaces are essential to scientific and technological progress in many areas of biology, physics, chemistry, and materials science. With the advent of high-resolution lithographic techniques (e.g. Dip-Pen nanolithography (DPN), Fountain Pen Nanolithography (FPN), Local Oxidation Lithography (LON), etc.), NANOUP Group is deeply involved on developing novel methodologies for controlling the positioning, nucleation, growth and orientation of supramolecular nanostructures on surfaces. This level of control is crucial to start to conceive the integration of supramolecular architectures on supports for studying their fundamental properties and fabricating complex surface sensors, separation membranes, drug-delivery platforms and catalysts.

Supramolecular Nanostructures on Surfaces

For this purpose, NANOUP Group is currently working with a variety of techniques, including DPN, μ-contact printing and FPN. Among them, DPN is one of our most important techniques because of its high resolution and registration, versatility and parallelization capabilities. This technique, which was introduced by Mirkin’s group in 1999, is a direct-write scanning probe-based lithography in which an AFM tip is used to deliver chemical reagents directly to nanoscopic regions of a target substrate.
It is then especially useful for chemists because it allows performing Nanochemistry on surfaces. For example, it can be used to pattern alkanethiol self-assembled monolayers (SAMs) onto gold surfaces with sub-100 nm resolution and registration. And these nanostructures can be further used as molecular templates for creating metal and semiconductor nanostructures, biological nanoarrays (e.g. proteins, DNA, and viruses), and arrays of different nanoscale building blocks (e.g. carbon nanotubes, nanoparticles, etc.). DPN also allows the direct deposition and location of a great variety of species, such as proteins, DNA, polymers and nanoparticles, on different surfaces.

In addition to its high resolution and versatility, DPN has also experienced exciting technological innovations. Taking the single-tip as the starting point, DPN has been transformed from a serial to a parallel process through the use of 1- and 2-D cantilever arrays. In principle, the use of these arrays retains the direct write, high resolution, ambient deposition, chemical and material flexible attributes of DPN, while multiplying the desired pattern as many times as number of pens used across larger regions of the substrates. In such a context, NANOUP Group is currently able to use a 55000 tip array to simultaneously fabricate functional arrays composed of molecular nanostructures with dimensions down to 100 nm, covering an overall area of 1 cm².

Supramolecular Nanostructures on Surfaces

NANOUP Group is then dedicated to explore novel methodologies that allow the controlled fabrication of complex supramolecular architectures on surfaces. An illustrative example of our current achievements is the controlled deposition of a certain number of proteins on surfaces by direct-write DPN. From this control, we can now control the deposition of a single protein, such as ferritin, on a specific location of a surface and the growth of single MOF crystals on surfaces. We are currently interested in establishing protocols and developing novel technologies for making combinatorial reactions at the nanoscale (nanochemistry) directly on surfaces, to study the fundamental properties (e.g. adsorption) of nanoscale materials deposited on specific surface locations, and to create complex supramolecular nanomaterials. In addition, and thanks to a recent collaboration contract with the company NanoInk, Inc. (Chicago, USA) though which the ICN becomes its European Reference Center in such type of techniques and to the recent acquisition of the new NLP2000 system, we are in a privilege position to collaborate with scientists around the world, helping them to nanopatterning on surfaces.