Int J Med Sci 2021; 18(7):1541-1553. doi:10.7150/ijms.52816 This issue

Research Paper

Dual Color Imaging from a Single BF2-Azadipyrromethene Fluorophore Demonstrated in vivo for Lymph Node Identification

Niamh Curtin1, Dan Wu1, Ronan Cahill2, Anwesha Sarkar2, Pól Mac Aonghusa3, Sergiy Zhuk3, Manuel Barberio4, Mahdi Al-Taher4, Jacques Marescaux5, Michele Diana4,5,6, Donal F. O'Shea1✉

1. Department of Chemistry, Royal College of Surgeons in Ireland, RCSI, 123 St Stephen's Green, Dublin 2, Ireland.
2. UCD Centre for Precision Surgery, School of Medicine, University College Dublin, Ireland; Department of Surgery, Mater Misericordiae University Hospital, Dublin, Ireland.
3. IBM Research - Ireland, Damastown Industrial Estate, Mulhuddart, Dublin 15, Ireland.
4. IHU-Strasbourg, Institute of Hybrid Image-Guided Surgery, Strasbourg, France.
5. IRCAD, Research Institute against Cancer of the Digestive System, Strasbourg, France.
6. ICube Lab, Photonics Instrumentation for Health, Strasbourg, France.

This is an open access article distributed under the terms of the Creative Commons Attribution License ( See for full terms and conditions.
Curtin N, Wu D, Cahill R, Sarkar A, Aonghusa PM, Zhuk S, Barberio M, Al-Taher M, Marescaux J, Diana M, O'Shea DF. Dual Color Imaging from a Single BF2-Azadipyrromethene Fluorophore Demonstrated in vivo for Lymph Node Identification. Int J Med Sci 2021; 18(7):1541-1553. doi:10.7150/ijms.52816. Available from

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Graphic abstract

Dual emissions at ~700 and 800 nm have been achieved from a single NIR-AZA fluorophore 1 by establishing parameters in which it can exist in either its isolated molecular or aggregated states. Dual near infrared (NIR) fluorescence color lymph node (LN) mapping with 1 was achieved in a large-animal porcine model, with injection site, channels and nodes all detectable at both 700 and 800 nm using a preclinical open camera system. The fluorophore was also compatible with imaging using two clinical instruments for fluorescence guided surgery.

Methods: An NIR-AZA fluorophore with hydrophilic and phobic features was synthesised in a straightforward manner and its aggregation properties characterised spectroscopically and by TEM imaging. Toxicity was assessed in a rodent model and dual color fluorescence imaging evaluated by lymph node mapping in a large animal porcine models and in ex-vivo human tissue specimen.

Results: Dual color fluorescence imaging has been achieved in the highly complex biomedical scenario of lymph node mapping. Emissions at 700 and 800 nm can be achieved from a single fluorophore by establishing molecular and aggregate forms. Fluorophore was compatible with clinical systems for fluorescence guided surgery and no toxicity was observed in high dosage testing.

Conclusion: A new, biomedical compatible form of NIR-dual emission wavelength imaging has been established using a readily accessible fluorophore with significant scope for clinical translation.

Keywords: NIR-AZA fluorophore, dual fluorescence, J aggregate, fluorescence-guided surgery, lymph node mapping.