Molecularly imprinted polymers can be used as "plastic antibodies" for cell and tissue imaging, as demonstrated using hyaluronan on cell surfaces as a model target. Fluorescent nanoparticles binding a hyaluronan substructure, glucuronic acid, are used to image fixated and living cells and tissues. Plastic antibodies can be tailored to specific targets and easily labeled, and are physically and chemically stable.

Advanced tools for cell imaging are of great interest for the detection, localization, and quantification of molecular biomarkers of cancer or infection. We describe a novel photopolymerization method to coat quantum dots (QDs) with polymer shells, in particular, molecularly imprinted polymers (MIPs), by using the visible light emitted from QDs excited by UV light. Fluorescent core-shell particles specifically recognizing glucuronic acid (GlcA) or N-acetylneuraminic acid (NANA) were prepared. Simultaneous multiplexed labeling of human keratinocytes with green QDs conjugated with MIP-GlcA and red QDs conjugated with MIP-NANA was demonstrated by fluorescence imaging. The specificity of binding was verified with a non-imprinted control polymer and by enzymatic cleavage of the terminal GlcA and NANA moieties. The coating strategy is potentially a generic method for the functionalization of QDs to address a much wider range of biocompatibility and biorecognition issues.

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