Design and synthesis of a squaraine dye for long wavelength fluorescence-based biosensors

J. Bruce Pitner; K. Joseph Thomas; Douglas B. Sherman; Javier Alarcon; Ghulam Mohiuddin; Keith S. Kyler; Bhaskar R. Venepalli

doi:10.1117/12.588386

4 April 2005 Design and synthesis of a squaraine dye for long wavelength fluorescence-based biosensors

J. Bruce Pitner, K. Joseph Thomas, Douglas B. Sherman, Javier Alarcon, Ghulam Mohiuddin, Keith S. Kyler, Bhaskar R. Venepalli

Author Affiliations +

Proceedings Volume 5704, Genetically Engineered and Optical Probes for Biomedical Applications III; (2005) https://doi.org/10.1117/12.588386
Event: SPIE BiOS, 2005, San Jose, CA, United States

Abstract

The design and synthesis of an environmentally sensitive long wavelength fluorescing squaraine dye for conjugation to proteins is dsecribed. Environmentally sensitive dyes are valuable for probing environmental changes that occur when labeled proteins bind their corresponding ligands and can be used to construct flyorescent sensors. Long wavelength (>650 nm) dyes would enable through-skin wireless sensing with minimum interference from the background. While several environmentally sensitive dyes are known in the visible spectrum, only a few are available in the long wavelength region, and none of them are available with reactive groups suitable for protein conjugation. Several derivatives of squarain dyes are known to be environmentally sensitive and fluorescent in the long wavelength region, but none of them are available with linkers for protein conjugation. In order to achieve this goal, we developed a synthetic scheme to introduce a reactive linker onto an anilinic squaraine that is highly sensitive to its environment. The synthesis involves the preparation of the dye with an iodoacetyl ester linker that readily reacts with a thiol on a cysteine residue of the binding protein. The squaraine dye was conjugated to known binding proteins that were evaluated as optical sensors. Ultimately, we expect these systems to measure analytes in the body and transmit information through the skin to an external monitor.

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J. Bruce Pitner, K. Joseph Thomas, Douglas B. Sherman, Javier Alarcon, Ghulam Mohiuddin, Keith S. Kyler, and Bhaskar R. Venepalli "Design and synthesis of a squaraine dye for long wavelength fluorescence-based biosensors", Proc. SPIE 5704, Genetically Engineered and Optical Probes for Biomedical Applications III, (4 April 2005); https://doi.org/10.1117/12.588386

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