Evaluation of poly(dimethylsiloxane) microreactors for pattern size miniaturization of microintaglio-printing-based protein microarray

Abstract

We developed a soft lithography-based microintaglio printing method for fabricating robot-free high-density protein microarrays using a poly(dimethylsiloxane) (PDMS) microchamber array. This method provides a simple approach to simultaneously synthesize and capture functional protein microarrays (with 25–100 µm resolution in this study) directly from DNA microarrays in situ on a chip without a spotter and therefore can be an extremely effective tool for the miniaturization of arrays. However, minimizing the scale, which increases the PDMS surface area to sample volume ratio, can alter arraying outcomes because of interfacial phenomena. In this study, we evaluated the suitability of PDMS for miniaturizing cell-free synthesis-based protein microarrays and showed that the amount of a green fluorescent protein synthesized in situ inside PDMS microchambers monotonically decreased with decreasing microchamber (pattern) size and that the protein could not be detected in microchambers with a diameter smaller than 25 µm. The impact of absorption and/or adsorption on the PDMS surface on protein synthesis inside the microchamber was observed, which was reduced by coating techniques. The results obtained here clearly suggest that PDMS interfacial phenomena can be suppressed while obtaining the benefits of cell-free protein synthesis and microintaglio printing, as a step toward developing ultrahigh-density protein microarrays.