Interventional NIR Fluorescence Imaging of Cancer: Review on Next Generation of Dye-Loaded Protein-Based Nanoparticles for Real-Time Feedback During Cancer Surgery

Abstract

The use of fluorescence imaging technique for visualization, resection and treatment of cancerous tissue, attained plenty of interest once the promise of whole body and deep tissue near-infrared (NIR) imaging emerged. Why is NIR so desired? Contrast agents with optical properties in the NIR spectral range offer an upgrade for the diagnosis and treatment of cancer, by dint of the deep tissue penetration of light in the NIR region of the electromagnetic spectrum, also known as the optical window in biological tissue. Thus, the development of a new generation of NIR emitting and absorbing contrast agents able to overcome the shortcomings of the basic free dye administration is absolutely essential. Several examples of nanoparticles (NPs) have been successfully implemented as carriers for NIR dye molecules to the tumour site owing to their prolonged blood circulation time and enhanced accumulation within the tumour, as well as their increased fluorescence signal relative to free fluorophore emission and active targeting of cancerous cells. Due to their versatile structure, good biocompatibility and capability to efficiently load dyes and bioconjugate with diverse cancer-targeting ligands, the research area of developing protein-based NPs encapsulated or conjugated with NIR dyes is highly promising but still in its infancy. The current review aims to provide an up-to-date overview on the biocompatibility, specific targeting and versatility offered by protein-based NPs loaded with different classes of NIR dyes as next-generation fluorescent agents. Moreover, this study brings to light the newest and most relevant advances involving the state-of-the-art NIR fluorescent agents for the real-time interventional NIR fluorescence imaging of cancer in clinical trials.

Keywords: clinical translation; fluorescent contrast agents; near-infrared dyes; organic nanoparticles.

Figure 1

Schematic representation of the surgical field and NIR fluorescence imaging system able to capture in real-time two imaging channels simultaneously.

Figure 2

Schematic representation of conjugated versus (vs) encapsulated protein-based NPs with NIR emitting fluorophores.

Figure 3

Proteins used for the synthesis of NPs loaded with NIR fluorophores for medical imaging (top line) or other biomedical applications (bottom line) and their molecular weights.

Figure 4

In vivo fluorescence imaging of nude mice bearing KB tumors at 1.5 and 4 h after injection of squaraine and BSA adducts and squaraine, BSA and folic acid adducts. Subcutaneous tumours locations are indicated by arrows. Reprinted from Biomaterials, 35, Gao FP, Lin YX, Li LL, et al. Supramolecular adducts of squaraine and protein for noninvasive tumor imaging and photothermal therapy in vivo. 1004–1014, copyright (2014), with permission from Elsevier.

Figure 5

In vitro fluorescence imaging of HeLa cells treated for 4 h with folic acid decorate and free BSA-based zinc phthalocyanine loaded NPs. Scale bars represent 50 µm. Reprinted with permission from Dong C, Liu Z, Wang S, et al. A protein–polymer bioconjugate-coated upconversion nanosystem for simultaneous tumor cell imaging, photodynamic therapy, and chemotherapy. ACS Appl Mater Interfaces. 2016;8(48):32688–32698. Copyright (2016) American Chemical Society.

Figure 6

In vitro fluorescence imaging of U87 cells treated for 4 h with free ICG (top) vs transferrin-based ICG loaded NPs (bottom). Reprinted with permission from Zhu M, Sheng Z, Jia Y, et al. Indocyanine green-holo-transferrin nanoassemblies for tumor-targeted dual-modal imaging and photothermal therapy of glioma. ACS Appl Mater Interfaces. 2017;9:39249–39258. Copyright year (2017) American Chemical Society.

Figure 7

Real-time in situ NIR fluorescence imaging with bevacizumab-IRDye 800CW drug and high-definition endoscopy of oesophageal adenocarcinoma lesions. Dysplastic area missed during high-definition narrowband-imaging and white-light endoscopy inspection. Reproduced from Near-infrared fluorescence molecular endoscopy detects dysplastic oesophageal lesions using topical and systemic tracer of vascular endothelial growth factor A. Nagengast WB, Hartmans E, Garcia-Allende PB, et al. Gut. 68(1):7–10. Copyright 2019, with permission from BMJ Publishing Group Ltd.

Figure 8

Real-time in situ NIR fluorescence imaging with ICG as the contrast agent of sentinel lymph nodes in vulvar cancer patients. Reproduced from Sentinel lymph node biopsy in vulvar cancer using combined radioactive and fluorescence guidance. Verbeek FPR, Tummers QRJG, Rietbergen DDD, et al. Int J Gynecol Cancer. 25:1086–1093. Copyright (2015), with permission from BMJ Publishing Gorup Ltd.