Bioorthogonal chemistry amplifies nanoparticle binding and enhances the sensitivity of cell detection

Nanoparticles have emerged as key materials for biomedical applications because of their unique and tunable physical properties, multivalent targeting capability, and high cargo capacity1,2. Motivated by these properties and by current clinical needs, numerous diagnostic3,4,5,6,7,8,9,10 and therapeutic11,12,13 nanomaterials have recently emerged. Here we describe a novel nanoparticle targeting platform that uses a rapid, catalyst-free cycloaddition as the coupling mechanism. Antibodies against biomarkers of interest were modified with trans-cyclooctene and used as scaffolds to couple tetrazine-modified nanoparticles onto live cells. We show that the technique is fast, chemoselective, adaptable to metal nanomaterials, and scalable for biomedical use. This method also supports amplification of biomarker signals, making it superior to alternative targeting techniques including avidin/biotin. Two-step bioorthogonal chemistry increases nanoparticle binding for more sensitive cell detection compared with standard techniques, including the biotin–avidin system.