Bioconjugation of a Near-Infrared DNA-Stabilized Silver Nanocluster to Peptides and Human Insulin by Copper-Free Click Chemistry
Vanessa Rück, Narendra Kumar Mishra, Kasper Sørensen, Mikkel Baldtzer Liisberg, Ane Beth Sloth, Cecilia Cerretani, Christian Brinch Mollerup, Andreas Kjær, Chenguang Lou, Knud J. Jensen, Tom Vosch
Abstract
DNA-stabilized silver nanoclusters (DNA-AgNCs) are biocompatible emitters with intriguing properties. However, they have not been extensively used for bioimaging applications due to the lack of structural information and hence predictable conjugation strategies. Here, a copper-free click chemistry method for linking a well-characterized DNA-AgNC to molecules of interest is presented. Three different peptides and a small protein, human insulin, were tested as labeling targets. The conjugation to the target compounds was verified by MS, HPLC, and time-resolved anisotropy measurements. Moreover, the spectroscopic properties of DNA-AgNCs were found to be unaffected by the linking reactions. For DNA-AgNC-conjugated human insulin, fluorescence imaging studies were performed on Chinese hamster ovary (CHO) cells overexpressing human insulin receptor B (hIR-B). The specific staining of the CHO cell membranes demonstrates that DNA-AgNCs are great candidates for bioimaging applications, and the proposed linking strategy is easy to implement when the DNA-AgNC structure is known.