DNA-directed capture of primary cells from a complex mixture and controlled orthogonal release monitored by SPR imaging.

Many biological samples are composed of several cell types. Qualitative and quantitative analysis of these complex mixtures is of major interest for both diagnostic and biomedical applications. Because large amounts of biological material are often challenging to collect, tremendous efforts have been made for a decade to design miniaturized platforms-such as lab-on-a-chip or microarrays-to run sensitive and reliable analysis from tiny quantities of starting material. Although barely explored so far, the release of resolved cellular samples constitutes an exciting strategy for further cell analysis. Herein, we propose a DNA-based biochip suitable for cell-type analysis in a label-free manner. The DNA-array is firstly converted into antibody-array using antibody-DNA conjugates. These protein-DNA hybrid molecules are chemically synthesized by covalent coupling of short oligonucleotides to antibodies directed against cell-type specific markers. We show not only specific capture of primary spleen cells on protein-DNA microarray spots but also their fast and specific orthogonal release according to the antibody-DNA combinations by incorporating restriction sites in DNA. Both molecular and cellular interactions occurring on the biochip are monitored by surface plasmon resonance (SPR) imaging. This optical technique turns out to be a powerful way to monitor, in real-time, biological interactions occurring on the microarrayed features.