Novel Water-Soluble Near-Infrared Cyanine Dyes:  Synthesis, Spectral Properties, and Use in the Preparation of Internally Quenched Fluorescent Probes

Abstract

In this paper, we describe the synthesis and the photophysical properties of two novel near-infrared (NIR) cyanine dyes (NIR5.5-2 and NIR7.0-2) which are water soluble potential substitutes of the commercially available Cy 5.5 and Cy 7.0 fluorescent labels respectively. For each one of these cyanine dyes, the synthetic strategy relies on the postsynthetic derivatization of a cyanine precursor in order to introduce the key functionalities required for bioconjugation of these NIR fluorophores. For NIR5.5-2, a reactive amino group was acylated with an original trisulfonated linker for water solubility. For NIR7.0-2, a vinylic chlorine atom was derivatized through a SRN1 reaction for the introduction of a monoreactive carboxyl group for labeling purposes. Unexpectedly, when these two fluorophores were closely associated within a peptidic architecture, mutual fluorescence quenching between NIR5.5-2 and NIR7.0-2 was observed both at 705 (NIR5.5-2) and 798 nm (NIR7.0-2). On the basis of this property, a novel internally quenched caspase-3-sensitive NIR fluorescent probe was prepared.

Easy on-demand self-assembly of lateral nanodimensional hybrid graphene oxide flakes for near-infrared-induced chemothermal therapy

“…The PEGylated surface prevents opsonization; 25 thus, it prolongs the blood circulation time to maintain enhanced fluorescence by nGO@Cy5.5-cPEG. Free Cy5.5 is known to be easily degraded and cleared from the body, 41 resulting in lower fluorescence. The duration for biodistribution analysis was 24 h, and the circulation of flakes could reach a higher extent in tumors at an extended time course (that is, 424 h).…”

“…A potential suitable approach for such conditions is the use of minimally invasive surgical tools. 41 A combination of advanced electronics and fluorescencelabeled nanosystems can enable fluorescence-based mapping, pH sensing and localized photo/chemotherapy for efficient cancer treatments. 44 On the basis of the in vitro assessments, we attempted to verify the anticancer activity of the assembled nGO@DOX-cPEG flakes using an in vivo mouse xenograft model.…”

Synthesis and application of water-soluble, photoswitchable cyanine dyes for bioorthogonal labeling of cell-surface carbohydrates

“…A major difficulty in the development of cyanine dyes is the realization of water solubility and stability at the same time [23]. Increasing length of the polymethine chain correlates with instability [23].…”

“…Increasing length of the polymethine chain correlates with instability [23]. It is known that incorporation of a cyclohexenyl or cyclopentenyl ring in the polymethine chain increases the stability of heptamethine cyanine dyes [23][24][25].…”

“…Increasing length of the polymethine chain correlates with instability [23]. It is known that incorporation of a cyclohexenyl or cyclopentenyl ring in the polymethine chain increases the stability of heptamethine cyanine dyes [23][24][25]. Unfortunately, these groups lead to aggregation in aqueous solution which is indicated by a loss of sharp absorption bands equivalent to loss of fluorescence [26].…”