title: Nanocolloidal albumin-IRDye 800CW: a near-infrared fluorescent tracer with optimal retention in the sentinel lymph node.
abstract: OBJECTIVE
  At present, the only approved fluorescent tracer for clinical near-infrared fluorescence-guided sentinel node (SN) detection is indocyanine green (ICG), but the use of this tracer is limited due to its poor retention in the SN resulting in the detection of higher tier nodes. We describe the development and characterization of a next-generation fluorescent tracer, nanocolloidal albumin-IRDye 800CW that has optimal properties for clinical SN detection.
  
  
  METHODS
  The fluorescent dye IRDye 800CW was covalently coupled to colloidal human serum albumin (HSA) particles present in the labelling kit Nanocoll in a manner compliant with current Good Manufacturing Practice. Characterization of nanocolloidal albumin-IRDye 800CW included determination of conjugation efficiency, purity, stability and particle size. Quantum yield was determined in serum and compared to that of ICG. For in vivo evaluation a lymphogenic metastatic tumour model in rabbits was used. Fluorescence imaging was performed directly after peritumoral injection of nanocolloidal albumin-IRDye 800CW or the reference ICG/HSA (i.e. ICG mixed with HSA), and was repeated after 24 h, after which fluorescent lymph nodes were excised.
  
  
  RESULTS
  Conjugation of IRDye 800CW to nanocolloidal albumin was always about 50% efficient and resulted in a stable and pure product without affecting the particle size of the nanocolloidal albumin. The quantum yield of nanocolloidal albumin-IRDye 800CW was similar to that of ICG. In vivo evaluation revealed noninvasive detection of the SN within 5 min of injection of either nanocolloidal albumin-IRDye 800CW or ICG/HSA. No decrease in the fluorescence signal from SN was observed 24 h after injection of the nanocolloidal albumin-IRDye 800CW, while a strong decrease or complete disappearance of the fluorescence signal was seen 24 h after injection of ICG/HSA. Fluorescence-guided SN biopsy was very easy.
  
  
  CONCLUSIONS
  Nanocolloidal albumin-IRDye 800CW is a promising fluorescent tracer with optimal kinetic features for SN detection.
authors.affiliation: Department of Otolaryngology/Head and Neck Surgery, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Derrek A
authors.initials: DA
authors.lastname: Heuveling
authors.forename: Gerard W M
authors.initials: GW
authors.lastname: Visser
authors.forename: Mattijs
authors.initials: M
authors.lastname: de Groot
authors.forename: Johannes F
authors.initials: JF
authors.lastname: de Boer
authors.forename: Marian
authors.initials: M
authors.lastname: Baclayon
authors.forename: Wouter H
authors.initials: WH
authors.lastname: Roos
authors.forename: Gijs J L
authors.initials: GJ
authors.lastname: Wuite
authors.forename: C René
authors.initials: CR
authors.lastname: Leemans
authors.forename: Remco
authors.initials: R
authors.lastname: de Bree
authors.forename: Guus A M S
authors.initials: GA
authors.lastname: van Dongen
mesh_terms: D000818:Animals; D001557:Benzenesulfonates / Q000737:chemistry / Q000493:pharmacokinetics*; D004195:Disease Models, Animal; D005260:Female; D005456:Fluorescent Dyes / Q000737:chemistry / Q000493:pharmacokinetics; D007211:Indoles / Q000737:chemistry / Q000493:pharmacokinetics*; D008197:Lymph Node Excision; D008198:Lymph Nodes / Q000000981:diagnostic imaging* / Q000378:metabolism* / Q000601:surgery; D008207:Lymphatic Metastasis; D011817:Rabbits; D011859:Radiography; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000737:chemistry / Q000378:metabolism; D021701:Sentinel Lymph Node Biopsy / Q000379:methods; D012878:Skin Neoplasms / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology; D019265:Spectroscopy, Near-Infrared; D013668:Technetium Tc 99m Aggregated Albumin / Q000737:chemistry / Q000493:pharmacokinetics*
chemical_list: D001557:Benzenesulfonates; D005456:Fluorescent Dyes; C562366:IRDye 800CW; D007211:Indoles; D019275:Radiopharmaceuticals; D013668:Technetium Tc 99m Aggregated Albumin