Exogenous near-infrared fluorophores and their applications in cancer diagnosis: biological and clinical perspectives.

INTRODUCTION: Near-infrared fluorescent (NIRF) imaging is a rapidly growing research field which has the potential to be an important imaging modality in cancer diagnosis. Various exogenous NIR fluorophores have been developed for the technique, including small molecule fluorophores and nanoparticles. NIRF imaging has been used in animal models for the detection of cancer overthe last twenty years and has in recent years been used in human clinical trials. AREAS COVERED: This article describes the types and characteristics of exogenous fluorophores available for in vivo fluorescent cancer imaging. The article also discusses the progression of NIRF cancer imaging over recent years and its future challenges, from both a biological and clinical perspective. in The review also looks at its application for lymph node mapping, tumor targeting and characterization, and tumor margin definition for surgical guidance. EXPERT OPINION: NIRF imaging is not in routine clinical cancer practice; yet, the authors predict that techniques using NIR fluorophores for tumor margin definition and lymph node mapping will enter clinical practice in the near future. The authors also anticipate that NIRF imaging research will lead to the development of flurophores with 'high brightness' that will overcome the limited penetration of this modality and be better suited for non invasive tumor targeting.