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Updated: Jun 24, 2026

Tissue-simulating Phantoms for Assessing Potential Near-infrared Fluorescence Imaging Applications in Breast Cancer Surgery
Published on: September 19, 2014
Low molecular weight 4,4'-quinocyanines for in vivo NIR-II fluorescence imaging
Ritesh K Isuri1,2, Michael C Hart3, Serwa Adusei-Poku4
1Department of Radiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA. risuri@sas.upenn.edu.
Abstract:
Fluorescence-guided surgery (FGS) is limited by the shallow penetration and high autofluorescence of currently available NIR-I fluorophores. To address these constraints, we developed a class of low molecular weight organic fluorophores, 4,4'-quinocyanines (QuCy), that extend emission into the NIR-II (950-1700 nm) region. Rational design through substitution of indolenine head groups with N-substituted quinolinium moieties enhanced π-conjugation, reduced HOMO-LUMO gaps, and induced bathochromic shifts of up to 225 nm, confirmed by density functional theory and spectroscopic analyses. Five derivatives (JAM317-319, JAP331, JAP334) were synthesized via a modular route and exhibited emission maxima of 976-1004 nm. Compared with NIR-I dyes, QuCy dyes demonstrated improved depth penetration and contrast due to reduced tissue autofluorescence. In vivo evaluation of JAM317 revealed efficient tumor cell uptake, low cytotoxicity, and high-resolution vascular imaging. These findings establish QuCy dyes as a promising platform for clinically translatable NIR-II contrast agents.
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