Microcontact printing of quantum dot bioconjugate arrays for localized capture and detection of biomolecules

The nanometer size scale of quantum dots (QDs) along with their unique luminescent properties offers great potential as photostable, color-metrically addressable nanoparticle platforms for high-throughput detection and identification of proteins. Here we apply microcontact printing for assembling quantum dot nanoparticle arrays with retained biomolecular capture functionality onto glass surfaces. This method allows the creation of addressable QD arrays on macroscopic glass surfaces. Using fluorescence and AFM imaging, we find that microcontact-printed QDs self-assemble predominantly as monolayers with highly resolved definition. Microcontact-printed streptavidin-conjugated red QDs exhibit retained adsorption onto silane-treated glass and exhibit functionality as demonstrated by the capture of discrete groups of biotin-conjugated red QDs by printed streptavidin-green QD bioconjugates that is at the detection limit of a few discrete protein binding events. These results indicate that microcontact printing of QD bioconjugate arrays serves as a simple technique that allows localized spatial capture and sensitive detection of proteins. This technique may be useful for development of future fluorescent QD-based systems aimed at the parallel capture and detection of trace concentrations of protein.