Cell based therapeutics are one of the most promising and exciting breakthroughs in modern medicine. Modification of cell surface with ligands, biologics, drugs and nanoparticles can further enhance the functionality. Indocarbocyanine lipids are used in life sciences for labeling and tracking of cell membranes. Previously we described synthesis of dioctadecyl indocarbocyanine Cy3 analog (aminomethyl-DiI) for efficient and stable painting of mouse erythrocytes with small molecules, enzymes and biologics. Here we synthesized a near infrared aminomethyl dioctadecyl derivative of Cy7 (aminomethyl-DOCy7) and systematically compared it to aminomethyl-DiI as an anchor for modification of human erythrocytes, Jurkat cells and primary T cells with immunoglobulin G. To enable copper-free click chemistry modification of cell membranes, we conjugated methyltetrazine group to the amino indocyanine lipids via PEG linker (3400 Da). DOCy7-PEG3400-MTz showed over 99% painting efficiency of human erythrocytes at 25 μM. Reaction of trans-cyclooctene (TCO) modified IgG with DOCy7-PEG4-MTz-painted RBCs (2-step painting) resulted in ~80,000 IgG molecules per erythrocyte as detected by immuno dot-blot. The number of IgG/RBC was controlled by concentration of IgG. The painting of RBCs with DiI-PEG3400-MTz resulted in a similar number of IgG/RBC. Painting of T-lymphocyte cell line Jurkat with IgG resulted in ~1x106 IgG/cell with either the 1-step or 2-step method, and the painting efficiency was similar for DOCy7 and DiI constructs. Finally, we used DOCy7 and DiI constructs to demonstrate painting of primary CD3+T cells from healthy donors. The painting resulted in over 7x106 IgG/cell, and the efficiency was similar for both dye constructs. In conclusion, click indocarbocyanine conjugates represent a novel multi-color chemical biology toolkit for efficient surface modification of different cells types and can be used for potential imaging and drug delivery applications involving engineered cells.

Clickable methyltetrazine-indocarbocyanine lipids: Novel toolkit for efficient modifications of cell membranes

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.