Scanning Probe-Directed Assembly and Rapid Chemical Writing Using Nanoscopic Flow of Phospholipids

Abstract

Nanofluidic systems offer a huge potential for discovery of new molecular transport and chemical phenomena that can be employed for future technologies. Herein, we report on the transport behavior of surface-reactive compounds in a nanometer-scale flow of phospholipids from a scanning probe. We have investigated microscopic deposit formation on polycrystalline gold by lithographic printing and writing of 1,2-dioleoyl-sn-glycero-3-phosphocholine and eicosanethiol mixtures, with the latter compound being a model case for self-assembled monolayers (SAMs). By analyzing the ink transport rates, we found that the transfer of thiols was fully controlled by the fluid lipid matrix allowing to achieve a certain jetting regime, i.e., transport rates previously not reported in dip-pen nanolithography (DPN) studies on surface-reactive, SAM-forming molecules. Such a transport behavior deviated significantly from the so-called molecular diffusion models, and it was most obvious at the high writing speeds, close to 100 μm s–1. Moreover, the combined data from imaging ellipsometry, scanning electron microscopy, atomic force microscopy (AFM), and spectroscopy revealed a rapid and efficient ink phase separation occurring in the AFM tip-gold contact zone. The force curve analysis indicated formation of a mixed ink meniscus behaving as a self-organizing liquid. Based on our data, it has to be considered as one of the co-acting mechanisms driving the surface reactions and self-assembly under such highly nonequilibrium, crowded environment conditions. The results of the present study significantly extend the capabilities of DPN using standard AFM instrumentation: in the writing regime, the patterning speed was already comparable to that achievable by using electron beam systems. We demonstrate that lipid flow-controlled chemical patterning process is directly applicable for rapid prototyping of solid-state devices having mesoscopic features as well as for biomolecular architectures.

Influence of Substrate Hydrophilicity on Structural Properties of Supported Lipid Systems on Graphene, Graphene Oxides, and Silica

“…Bicelles are certainly well adapted for studying parts of ruptured vesicles close to the edges, and infinite bilayers could model well parts far from the edges. Other techniques have been developed, and some overcome the limitations of the VR techniques, permitting to obtain a better coverage of the substrate and less defects, such as Langmuir–Blodgett (LB)/Langmuir–Schaefer (LS) techniques, or their combination, ,, techniques involving the direct manipulation of the lipids on the surface using high-precision tools, e.g., an ink-jet nozzle, a microstamp, or a microfluidic device, ,− lipid self-spreading, ,,,, or spin-coating . Interestingly, deposition of bicelles is also used straightforwardly to form SLBs, ,, allowing for more direct comparison with our model systems.…”

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

“…On hydrophilic substrates, strict control in membrane stack height is needed, to ensure that the transformation into a SLB upon transfer into liquid preserves pattern fidelity and avoids deterioration of patterns by excessive spreading of material from upper layers in the membrane stack [ 33 ]. The use of thin membrane stacks and SLBs is fine for the presentation of proteins or similar cell-interface applications [ 34 , 35 , 36 ]; applications where the lipid patches act as specific binding points on surfaces, e.g., for protein crystallization [ 37 ]; or when the lipid acts as carrier matrix for other small molecules that should be delivered to the surface [ 38 , 39 ].…”

“Writing biochips”: high-resolution droplet-to-droplet manufacturing of analytical platforms

“…The topic of femtoliter scale reactors was already investigated by Guardingo and coworkers 95 in 2016 by a model reaction involving the ligand 4-[2-(pyridine-4-yl)ethyl]benzene-1,2-diol with a cobalt salt to produce coordination polymer nanoparticles in spotted droplets, with good monodispersity and tunable dimensions (in the range 600–200 nm) by selecting the experimental conditions. Another DPN-based femtoliter chemistry study is the one from Navikas and coworkers 96 who instead engineered an ink formulation that combined eicosanethiol with the phospholipid 1,2-dioleoyl- sn-glycero -3-phosphocholine. Different from the expected diffusive ink transport from the thiol ink onto gold surfaces, the addition of phospholipids triggered an almost two times faster deposition process in comparison with the pure thiol ink.…”