Dip-pen nanolithography with lipids (L-DPN) has become a great tool for patterning structured supported lipid membranes with a height range from a single lipid layer (~2 nm) up to layers of 200 nm thickness.
Lipids are delivered through the condensed water meniscus to become ‘physisorbed’ on the substrate, where they self-assemble into a lipid membrane. Humidity controls the phase behavior of the ink at the tip as well as the water meniscus itself; eventually it also controls the lipids diffusion within the assembled membrane and its spreading over the substrate. Depending on the surface properties (hydrophilic or hydrophobic and substrate surface energy) the phospholipids self-assembles either into three dimensional stacks of membranes or are rather spreading to form a single, thin and homogeneous membrane. Generally, the time the tip is in contact with the substrate (dwell time) controls the amount of ink delivered.
We analyse quantitatively the influence of these experimental variables on the feature size, which gives an insight into the membrane growth process, thus allowing us to propose models that describe the processes from the writing to the self-organization of the lipids into membranes.
A robust and braodly applicable model of L-DPN will help to improve the quality of control over the prepared samples, by enabling a systematic informed choice of ideal materials and/or combination of materials for a given need.
Model scheme for the lipids transfer through the water meniscus from an AFM tip to a substrate.
Example of an area spread dependence versus dwell time for writing of a DOPC lipid membrane. Inset: AFM image corresponding to the 10 s feature; contour lines are layers of 1.3 nm thickness.
A diffusive ink transport model for lipid dip-pen nanolithography
A. Urtizberea, M. Hirtz
Nanoscale 7 (2015) 15618-15634, DOI:10.1039/C5NR04352B
Functional Lipid Assemblies by Dip-Pen Nanolithography and Polymer Pen Lithography
M. Hirtz, S. Sekula-Neuner, A. Urtizberea, H. Fuchs
in Soft Matter Nanotechnology: From Structure to Function, first edition. X. Chen, H. Fuchs (eds.) Wiley-VCH, Weinheim (2015) 161-177, DOI:10.1002/9783527682157.ch06
Ink transport modelling in Dip-Pen Nanolithography and Polymer Pen Lithography
A. Urtizberea, M. Hirtz, H. Fuchs
Nanofabrication 2 (2016) 43-53, DOI:10.1515/nanofab-2015-0005
Biomimetic Phospholipid Membrane Organization on Graphene and Graphene Oxide Surfaces: a Molecular Dynamics Simulation Study
N. Willems, A. Urtizberea, A. F. Verre, M. Iliut, M. Lelimousin, M. Hirtz, A. Vijayaraghavan, M. S. P. Sansom
ACS Nano 11 (2017) 1613-1625, DOI:10.1021/acsnano.6b07352
The research leading to these results has received funding from the People Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme FP7/2007-2013/ under REA grant agreement n° 328163