Photolithographic Patterning of FluorAcryl for Biphilic Microwell-Based Digital Bioassays and Selection of Bacteria

Arianna Toppi, Louise L. Busk, Hongxia Hu, Asli A. Dogan, Alexander Jönsson, Rafael J. Taboryski, Martin Dufva*

*Corresponding author for this work

Research output: Contribution to journalJournal articlepeer-review

Abstract

FluorAcryl 3298 (FA) is a UV-curable fluoroacrylate polymer commonly employed as a chemically resistant, hydrophobic, and oleophobic coating. Here, FA was used in a cleanroom-based microstructuring process to fabricate hydrophilic-in-hydrophobic (HiH) micropatterned surfaces containing femtoliter-sized well arrays. A short protocol involving direct UV photopatterning, an etching step, and final recovery of the hydrophobic properties of the polymer produced patterned substrates with micrometer resolution. Specifically, HiH microwell arrays were obtained with a well diameter of 10 μm and various well depths ranging from 300 nm to 1 μm with high reproducibility. The 300 nm deep microdroplet array (MDA) substrates were used for digital immunoassays, which presented a limit of detection in the attomolar range. This demonstrated the chemical functionality of the hydrophilic and hydrophobic surfaces. Furthermore, the 1 μm deep wells could efficiently capture particles such as bacteria, whereas the 300 nm deep substrates or other types of flat HiH molecular monolayers could not. Capturing a mixture of bacteria expressing red- and green-fluorescent proteins, respectively, served as a model for screening and selection of specific phenotypes using FA-MDAs. Here, green-fluorescent bacteria were specifically selected by overlaying a solution of gelatin methacryloyl (GelMA) mixed with a photoinitiator and using a high-magnification objective, together with custom pinholes, in a common fluorescence microscope to cross-link the hydrogel around the bacteria of interest. In conclusion, due to the straightforward processing, versatility, and low-price, FA is an advantageous alternative to more commonly used fluorinated materials, such as CYTOP or Teflon-AF, for the fabrication of HiH microwell arrays and other biphilic microstructures.

Original languageEnglish
JournalACS Applied Materials and Interfaces
Volume13
Issue number37
Pages (from-to)43914-43924
ISSN1944-8244
DOIs
Publication statusPublished - 2021

Keywords

  • Bacteria trapping
  • Biphilic surface
  • FluorAcryl
  • Microdroplet array
  • Microfabrication
  • Microwell array
  • Single-cell isolation
  • Single-molecule counting

Fingerprint

Dive into the research topics of 'Photolithographic Patterning of FluorAcryl for Biphilic Microwell-Based Digital Bioassays and Selection of Bacteria'. Together they form a unique fingerprint.

Cite this