Toward 4D Nanoprinting with Tip-Induced Organic Surface Reactions

Abstract

Future nanomanufacturing tools will prepare organic materials with complex four-dimensional (4D) structure, where the position (x, y, z) and chemical composition within a volume is controlled with sub-1 μm spatial resolution. Such tools could produce substrates that mimic biological interfaces, like the cell surface or the extracellular matrix, whose topology and chemical complexity combine to direct some of the most sophisticated biological events. The control of organic materials at the nanoscale-level of spatial resolution could revolutionize the assembly of next generation optical and electronic devices or substrates for tissue engineering or enable fundamental biological or material science investigations. Organic chemistry provides the requisite control over the orientation and position of matter within a nanoscale reference frame through the formation of new covalent bonds. Several challenges however preclude the integration of organic chemistry with conventional nanomanufacturing approaches, namely most nanolithography platforms would denature or destroy delicate organic and biologically active matter, confirming covalent bond formation at interfaces remains difficult, and finally, only a small handful of the reactions used to transform molecules in solution have been validated on surfaces. Thus, entirely new approaches, where organic transformations and spatial control are considered equally important contributors, are needed to create 4D organic nanoprinting platforms. This Account describes efforts from our group to reconcile nanolithography, and specifically massively parallel scanning probe lithography (SPL), with organic chemistry to further the goal of 4D organic nanoprinting. Massively parallel SPL involves arrays of elastomeric pyramids mounted onto piezoelectric actuators, and creates patterns with feature diameters below 50 nm by using the pyramidal tips for either the direct deposition of ink or the localized delivery of energy to a surface. While other groups have focused on tip and array architetctures, our efforts have been on exploring their use for localizing organic chemistry on surfaces with nanoscale spatial resolution in 3D. Herein we describe the use of massively parallel SPL to create covalently immobilized patterns of organic materials using thermal, catalytic, photochemical, and force-accelerated reactions. In doing so, we have developed a high-throughput protocol for confirming interfacial bond formation. These efforts have resulted in new opportunities for the preparation of glycan arrays, novel approaches for covalently patterning graphene, and a 3D nanoprinter by combining photochemical brush polymerizations with SPL. Achieving true 4D nanoprinting involves advances in surface chemistry and instrumentation development, and to this end 4D micropatterns were produced in a microfluidic photoreactor that can position polymers composed of different monomers within micrometer proximity. A substantial gap remains, however, between these current technologies and the future's 4D nanoma...

Development of Dip‐Pen Nanolithography (DPN) and Its Derivatives

“…When exposed to light, a total internal reflection was achieved by matching of the high‐refractive‐index SU‐8 pyramidal tips with suitable solvents. Combined with conventional photolithography, BPL has evolved to a simple, flexible, high‐yield and low‐cost tool to generate various surface patterns relevant to optics, electronics and biology, opening up diverse strategies for photochemical patterning …”

“…Combined with conventional photolithography, BPL has evolved to a simple, flexible, high-yield and low-cost tool to generate various surface patterns relevant to optics, electronics and biology, [128][129][130] opening up diverse strategies for photochemical patterning. [39,131]…”

Large‐Area Patterning of Metal Nanostructures by Dip‐Pen Nanodisplacement Lithography for Optical Applications

“…However, because fabrication relies on a scanning electron beam that operates in vacuum, EBL is very expensive and time‐consuming, even when making millimeter‐size samples. In recent years, tip‐based lithography with scanning probes, namely, scanning probe lithography (SPL), has emerged as an alternative maskless strategy to EBL for nanofabrication . SPL makes use of a scanning probe to deliver or subtract materials on a surface with sub‐100 nm resolution.…”

“…In recent years, tip-based lithography with scanning probes, namely, scanning probe lithography (SPL), has emerged as an alternative maskless strategy to EBL for nanofabrication. [12][13][14][15][16][17][18][19][20][21][22][23] SPL makes use of a scanning probe to deliver or subtract materials on a surface with sub-100 nm resolution. When performed under ambient conditions, certain SPL techniques are lower in cost than EBL, and they can be used to fabricate a wider variety of structures.…”

Close-packed silane nanodot arrays by capillary nanostamping coupled with heterocyclic silane ring opening

“…Spatially controlled surface biofunctionalization at the microand nanoscale is a prerequisite for multiplexed bioanalytics, diagnostics and drug screening 1,2 as well as for systematic exploration of the role of spatial protein organization in cell biology. [3][4][5] Microcontact printing 6,7 and polymer pen lithography 8,9 combined with surface-initiated polymerization [10][11][12][13] are oen employed for chemical surface patterning, enabling, for example, reversible modulation of biointerfacial interactions 14,15 and immobilization of biorecognition elements on protein-repellent polymer brushes. 16 Simple patterns such as lines and squares are typically obtained by classical microcontact printing, 17 whereas more complex patterns such as brush-polymer microarrays were obtained by polymer pen lithography.…”