Enhanced Stability of Lipid Structures by Dip-Pen Nanolithography on Block-Type MPC Copolymer

Abstract

Biomimetic lipid membranes on solid supports have been used in a plethora of applications, including as biosensors, in research on membrane proteins or as interfaces in cell experiments. For many of these applications, structured lipid membranes, e.g., in the form of arrays with features of different functionality, are highly desired. The stability of these features on a given substrate during storage and in incubation steps is key, while at the same time the substrate ideally should also exhibit antifouling properties. Here, we describe the highly beneficial properties of a 2-methacryloyloxyethyl phosphorylcholine (MPC) copolymer for the stability of supported lipid membrane structures generated by dip-pen nanolithography with phospholipids (L-DPN). The MPC copolymer substrates allow for more stable and higher membrane stack structures in comparison to other hydrophilic substrates, like glass or silicon oxide surfaces. The structures remain highly stable under immersion in liquid and subsequent incubation and washing steps. This allows multiplexed functionalization of lipid arrays with antibodies via microchannel cantilever spotting (µCS), without the need of orthogonal binding tags for each antibody type. The combined properties of the MPC copolymer substrate demonstrate a great potential for lipid-based biomedical sensing and diagnostic platforms.

Rapid Capture of Cancer Extracellular Vesicles by Lipid Patch Microarrays

“…The ABs can also be delivered to individual patches by spotting techniques, in case multiplexed detection arrays are desired. [ 31 ] When the arrays are exposed to liquids containing EVs carrying the targeted surface markers, these will attach to the lipid patches carrying matching ABs (Figure 1d). In addition to the mere attachment, the SLM‐based approach allows for membrane fusion taking place between captured EVs and the lipid patches in the array (Figure 1e).…”

“…The inkwell was loaded with 2 µL of the desired phospholipid mixture (20 mg mL −1 in chloroform) in each reservoir and chloroform evaporated in a vacuum desiccator (15 min) or overnight in a damp‐proof box. Afterward, the coated tips were moved to the desired location on the substrate (either glass cover slips cleaned by sonification subsequently with chloroform, isopropanol and DI water, or 2‐methacryloyloxyethyl phosphorylcholine (MPC) copolymer covered slides [ 31 ] ) and lipid‐patch arrays were written. The patches (30 × 30 µm 2 ) were written at 30–40% RH with hatch lines of 0.5 µm pitch and a writing speed of 0.2–2 µm s −1 .…”

Cell-membrane-inspired polymers for constructing biointerfaces with efficient molecular recognition

“…For example, poly(MPC-co-3-methacryloylpropyltriethoxysilane) and poly(MPCco-3-methacryloylpropyltrimthoxysilane (MPTMSi)) (PMSi) have been synthesized for immobilization on metal oxide and glass surfaces, permitting coupling reactions. [169][170][171][172] The silane coupling group reacts with a substrate under mild conditions, that is, the MPTMSi units covalently bond to the oxide surface to form a stable MPC layer. Even in an extremely thin polymer layer (approximately 10 nm), the surface is completely covered with PC groups.…”

Microcontact Printing of Biomolecules on Various Polymeric Substrates: Limitations and Applicability for Fluorescence Microscopy and Subcellular Micropatterning Assays

“…Chemical methods to increase surface energy and to generate functional groups (such as carboxyl, amine, hydroxyl, or epoxy groups) include modifications such as plasma treatment, UV irradiation, and monolayer self-assembly. 3−5 Topographical modification methods in the micron-and even submicron scale include photolithography, 6 dip-pen lithography, 7 DW), 8 microchannel cantilever spotting, 9 and soft lithography via microcontact printing (μCP). 10 Micropatterned biomolecules on different substrates have numerous biological applications in the fields of biomimetic sensors, 11 microarrays, 12 and lab-on-a-chip systems.…”

“…However, polymer substrates can be modified both chemically and topographically. Chemical methods to increase surface energy and to generate functional groups (such as carboxyl, amine, hydroxyl, or epoxy groups) include modifications such as plasma treatment, UV irradiation, and monolayer self-assembly. − Topographical modification methods in the micron- and even submicron scale include photolithography, dip-pen lithography, laser-based “matrix assisted pulsed laser evaporation direct write” (MAPLE DW), microchannel cantilever spotting, and soft lithography via microcontact printing (μCP) …”