Femtolitre chemistry assisted by microfluidic pen lithography

Abstract

Chemical reactions at ultrasmall volumes are becoming increasingly necessary to study biological processes, to synthesize homogenous nanostructures and to perform high-throughput assays and combinatorial screening. Here we show that a femtolitre reaction can be realized on a surface by handling and mixing femtolitre volumes of reagents using a microfluidic stylus. This method, named microfluidic pen lithography, allows mixing reagents in isolated femtolitre droplets that can be used as reactors to conduct independent reactions and crystallization processes. This strategy overcomes the high-throughput limitations of vesicles and micelles and obviates the usually costly step of fabricating microdevices and wells. We anticipate that this process enables performing distinct reactions (acid-base, enzymatic recognition and metal-organic framework synthesis), creating multiplexed nanoscale metal-organic framework arrays, and screening combinatorial reactions to evaluate the crystallization of novel peptide-based materials.

A Porphyrin Spin Qubit and Its 2D Framework Nanosheets

“…Although challenging, this appears feasible since these techniques have been able to deposit a controlled number of isolated magnetic molecules on the most sensitive areas of other solid‐state devices such as μ‐SQUID or μ‐Hall sensors. An alternative procedure for the formation of the nanosheets locally at the nanoconstriction would be the use of dip‐pen nanolithography with microfluidic pens, allowing femtoliter chemistry on surfaces by handling and mixing femtolitre volumes of reagents . One critical issue could be the ability to reliably control the degree of magnetic dilution at the single nanosheet level, to ensure only one qubit is present at each constriction of the proposed hybrid architecture.…”

Biomimetic Replication of Microscopic Metal–Organic Framework Patterns Using Printed Protein Patterns

“…Herein, we demonstrate that this new concept can offer a rapid route for fabricating MOF thin films and patterns directly from surface bound proteins, to replicate the pattern of the proteins with micrometer‐scale resolution ( Scheme ). Essentially, a pattern of proteins, which can be easily created using various lithographic techniques such as contact printing, tip‐based nanolithography or photolithography, can be used to promote the spatially controlled growth of MOF biocomposites. Furthermore, functional MOF biocomposite patterns can be rapidly formed on a flexible polymer film, allowing for the patterned functionality to be retained even during bending.…”

“…To reduce the size of the MOF patterns, we employed the serial lithographic technique of microfluidic‐pen lithography (MPL) to deposit arrays of BSA dots with various sizes. MPL utilizes a microfluidic‐based patterning tool as a pen to deposit materials at the sub‐micrometer scale upon contact with a surface . Arrays of BSA dots with various diameters from 5 to 30 μm were deposited and dried on a piece of silicon wafer (Figure e and Figure S10, Supporting Information).…”

Chemistry in nanoconfined water

“…5 While chemistry in microfluidic systems is now a very mature field, 6 chemistry in the nanofluidic regime is yet an emerging field. Only in recent years have we seen stunning advances such as fabrication of reaction chambers at the nanoscale 7 including carbon nanotubes, 8 nanofiber junctions 9 or vesicles, 10 as well as the formation and manipulation of liquid nanodroplets.…”