Nanopatterning of Mobile Lipid Monolayers on Electron-Beam-Sculpted Teflon AF Surfaces

Abstract

Direct electron-beam lithography is used to fabricate nanostructured Teflon AF surfaces, which are utilized to pattern surface-supported monolayer phospholipid films with 50 nm lateral feature size. In comparison with unexposed Teflon AF coatings, e-beam-irradiated areas show reduced surface tension and surface potential. For phospholipid monolayer spreading experiments, these areas can be designed to function as barriers that enclose unexposed areas of nanometer dimensions and confine the lipid film within. We show that the effectiveness of the barrier is defined by pattern geometry and radiation dose. This surface preparation technique represents an efficient, yet simple, nanopatterning strategy supporting studies of lipid monolayer behavior in ultraconfined spaces. The generated structures are useful for imaging studies of biomimetic membranes and other specialized surface applications requiring spatially controlled formation of self-assembled, molecularly thin films on optically transparent patterned polymer surfaces with very low autofluorescence.

Multifunctional Structured Platforms: From Patterning of Polymer-Based Films to Their Subsequent Filling with Various Nanomaterials

“…Vinje et al have carefully established control over the spatial resolution and fabrication process within films of SU-8 polymer-based resist and have obtained arrays of high-aspect ratio lines and pillars with a horizontal periodicity of~100 nm [2]. Other more complex polymeric patterns for biological purposes can be sculptured by EBL [17]. For example, spherical patterns of few hundreds of micrometers in diameter containing many branches of a lateral size down to 50 nm were demonstrated in Teflon AF coatings (Figure 4c) and employed in experiments related to phospholipid monolayer spreading and behavior in ultraconfined spaces [17].…”

“…Other more complex polymeric patterns for biological purposes can be sculptured by EBL [17]. For example, spherical patterns of few hundreds of micrometers in diameter containing many branches of a lateral size down to 50 nm were demonstrated in Teflon AF coatings (Figure 4c) and employed in experiments related to phospholipid monolayer spreading and behavior in ultraconfined spaces [17].…”

“…Sometimes, active macromolecules [8], lipids [17], or structures such as live microorganisms [22] can also be assembled within specific surface relief patterns in order to fabricate eccentric platforms that can target novel applications. For instance, structured arrays of living yeasts and fungal spores trapped within square-like patterns of PDMS show huge potential in shaping future bio-experiments on living cells [22].…”

“…For instance, structured arrays of living yeasts and fungal spores trapped within square-like patterns of PDMS show huge potential in shaping future bio-experiments on living cells [22]. Meanwhile, solutions of lipids [17] and of active materials [8] can be used to fill the EBL-and NILsculptured surface relief patterns in order to fabricate platforms that can be used for the phospholipid monolayer spreading experiments [17] or for the fabrication of efficient photovoltaic devices [8].…”

“…Nowadays, the number and diversity of such devices significantly increased inclusively due to the fact that the periodic surface relief patterns can be routinely fabricated on (polymer-covered) solid or flexible substrates and can be further filled with other (functional) materials by employing a variety of available deposition methodologies [11][12][13][14]. The resulting structured platforms (SPs), i.e., periodic surface relief patterns of certain shape and dimension that are filled in a disordered or (hierarchically) ordered manner with various materials of different size, shape, and function [15][16][17][18], are being currently used in a variety of optoelectronic [9,16,19], photonic [20], biological [17,21,22], sensing [13], or storage media [18] applications. Therefore, it is obvious that in order to further exploit such applications, we have to design and develop novel SPs with puzzling properties.…”