CytoCy5S™, a compound of many structures. in vitro and in vivo evaluation of four near-infrared fluorescent substrates of nitroreductase (NTR)

CytoCy5S™, a quenched, red-shifted fluorescent probe, has been used to exploit the imaging potential of nitroreductase (NTR) reporter gene platform. Its use reported in number publications, however there are discrepancies both structure and its physicochemical properties. Herein, we aim highlight these define best candidate four substrates under study for preclinical work NTR reporting by optical applications. We report synthesis, purification characterisation substrates, including alternately described structures currently referred name CytoCy5S. A comparative enzymatic assay was performed assess spectroscopic characteristics different reductively activated probes. The expressing triple-negative breast carcinoma cell line, MDA-MB-231 + , employed compare, vitro vivo suitability probes as reporters activity. Comparison properties achieved flow cytometry, fluorescence microscopy imaging, ex . This evaluated biological concluded that substrate 1 presents features oncological imaging. • Four CytoCy5S analogues synthesised analysed cellulo 4 poorly 3 showed /NTR − ratio but highly dependent on concentration. 2 is quenched compound did not outperform more sensitive than at small tumour volumes with faster biodistribution.