Fabrication of a hydrophobic/hydrophilic hybrid-patterned microarray chip and its application to a cancer marker immunoassay

In this work, we report on a simple process for fabricating a hydrophobic/hydrophilic hybrid-patterned microarray chip for a fast and sensitive immunoassay. Two different types of self-assembled monolayers (SAMs) were used in the fabrication of hydrophilic well patterns and hydrophobic substrates. The hydrophilic/hydrophobic hybrid SAM pattern generates a clear-cut boundary between the sample and the background. A change in the precursor molecules allows for many different types of SAMs to be employed in the fabrication process. Fluorescence image-based detection has previously been used for the quantitative immune-analysis of a specific cancer marker. Here, a titanium-coated glass substrate was utilized to suppress auto-fluorescence signals from substrate backgrounds. Angiogenin (ANG), a small polypeptide implicated in both angiogenesis and tumor growth, was used as a target cancer marker for its validation. Assay results demonstrate that the hybrid-patterned array chip yields a narrower error deviation and a lower coefficient variation than in a conventional 96-well plate ELISA. Furthermore, the sample requirement (1 μL) for the hybrid-patterned chip is about 50 times less than that required in an ELISA (at least 50 μL). The proposed hydrophobic/hydrophilic hybrid-patterned microarray chip is expected to be a highly efficient tool that can be applied to a high throughput immunoassay of a specific cancer marker.