Unexpected long-term stability of a cyanine dye bioconjugate

摘要

Biocompatible organic dyes, in general, exhibit poor photostability in aqueous solution. This is especially true at the high concentrations needed for bolus administration in a clinical application. Several years ago, we showed that by using carefully chosen macromolecular additives, the stability of aqueous dye solutions may be enhanced significantly. We now report the observation of an unexpected long-term stability of a near infrared dye-peptide conjugate. The Mallinckrodt developed dye-peptide conjugate known as Cytale is an indocyanine type dye attached to the peptide octreotate. We have previously shown that this compound targets somatostatin receptor rich tumors and provides unambiguous contrast for optical imaging. A freshly prepared aqueous solution of Cytale was mixed with blood (from a rat) in a small glass bollle. An optical image was laken soon after, along with several control samples. The Cytale-blood bottle fluoresced quile nicely. The sample bottles were then left in a lab for three plus years, al room temperalure with ordinary exposure to lab lighls. The sample bottles were imaged after the three year period, and the Cylale-blood bottle fluoresces still.