Nanomolar Synthesis in Droplet Microarrays with UV‐Triggered On‐Chip Cell Screening

Abstract

Miniaturization and parallelization of combinatorial organic synthesis is important to accelerate the process of drug discovery while reducing the consumption of reagents and solvents. This work presents a miniaturized platform for on‐chip solid‐phase combinatorial library synthesis with UV‐triggered on‐chip cell screening. The platform is based on a nanoporous polymer coating on a glass slide, which is modified via photolithography to yield arrays of hydrophilic (HL) spots surrounded by superhydrophobic (SH) surface. The combination of HL spots and SH background enables confinement of nanoliter droplets, functioning as miniaturized reactors for the solid‐phase synthesis. The polymer serves as support for nanomolar solid‐phase synthesis, while a photocleavable linker enables the release of the synthesized compounds into the droplets containing live cells. A 588 compound library of bisamides is synthesized via a four‐component Ugi reaction on the chip and products are detected via stamping of the droplet array onto a conductive substrate and subsequent matrix‐assisted laser desorption ionization mass spectrometry. The light‐induced cleavage shows high flexibility in screening conditions by spatial, temporal, and quantitative control.

High-Throughput Methods in the Discovery and Study of Biomaterials and Materiobiology

“… 576 Matrix degradation and remodeling are also an intrinsic part of tissue homeostasis, thus spatiotemporal cues have been recognized as useful parameters in biomaterial engineering, managing to evoke specific biological responses over time. Recently, Brehm et al 530 have described the miniaturization and parallelization of combinatorial organic synthesis, through the development of an on-chip solid-phase combinatorial library synthesis method. The microarray platform used was the Droplet-Microarray developed by Levkin and co-workers, 528 , 533 and a hydroxyethyl linker was used for the solid-phase synthesis, as it can be cleaved using a UV light of 365 nm (shown to be nontoxic to cells 577 ).…”

“… 473 Moreover, biomaterials that enable reversible biophysical and biochemical properties will also be great additions to high throughput assays. 530 For example, the use of photoresponsive and photocleavable reactions on hydrogels, which permits user-defined quantities of proteins to be anchored within distinct subvolumes of a 3D matrix, and tailored subsequent removal using ortho -nitrobenzyl ester photoscission. 583 In this manner, hydrogels can be designed with spatially defined ligand availability, and modified over time of cell culture to induce a certain cellular response.…”

Tailoring Materials with Specific Wettability in Biomedical Engineering

“…[147] In the next research conducted by the same group, Brehm et al also employed the miniaturized droplet microarrays formed on the superhydrophobic background with hydrophilic spots to perform a simultaneously combinatorial synthesis of over 500 compounds and cellbased screening, as shown in Figure 4e,f. [148] The solid-phase synthesis was based on the four-component Ugi reaction and a photocleavable linker as anchor point, thus imparting the compounds with photo-controlled release capacity. After irradiation by UV light, the synthesized compounds could be released to the droplets with cell adhesion for biological screening.…”

Membrane Fusion Models for Bioapplications

“…The need for studying cellular processes/responses and performing confined high throughput reactions has led to the development of ultrasmall volume analytical systems. These include platforms such as microfluidic devices, microarrays and nanovial arrays [146,147] . Some of the limitations with these systems include evaporation and the inability to control individual reaction conditions such as temperature and incubation time independently.…”

“…These include platforms such as microfluidic devices, microarrays and nanovial arrays. [146,147] Some of the limitations with these systems include evaporation and the inability to control individual reaction conditions such as temperature and incubation time independently. Liposomes have been shown to perform as self-enclosed nanovials [148][149][150] by encapsulating molecules when placed in an aqueous solution, allowing for control over the internal environment and reducing concerns associated with evaporation.…”