title: (99m)Tc-labelled gold nanoparticles capped with HYNIC-peptide/mannose for sentinel lymph node detection.
abstract: The aim of this research was to prepare a multifunctional system of technetium-99m-labelled gold nanoparticles conjugated to HYNIC-GGC/mannose and to evaluate its biological behaviour as a potential radiopharmaceutical for sentinel lymph node detection (SLND).
  
  
  METHODS
  Hydrazinonicotinamide-Gly-Gly-Cys-NH(2) (HYNIC-GGC) peptide and a thiol-triazole-mannose derivative were synthesized, characterized and conjugated to gold nanoparticles (AuNP, 20 nm) to prepare a multifunctional system of HYNIC-GGC-AuNP-mannose by means of spontaneous reaction of the thiol (Cys) present in HYNIC-GGC sequence and in the thiol-mannose derivative. The nanoconjugate was characterized by transmission electron microscopy (TEM), IR, UV-Vis, Raman, fluorescence and X-ray photoelectron spectroscopy (XPS). Technetium-99m labelling was carried out using EDDA/tricine as coligands and SnCl(2) as reducing agent with further size-exclusion chromatography purification. Radiochemical purity was determined by size-exclusion HPLC and ITLC-SG analyses. In vitro binding studies were carried out in rat liver homogenized tissue (mannose-receptor positive tissue). Biodistribution studies were accomplished in Wistar rats and images obtained using a micro-SPECT/CT system.
  
  
  RESULTS
  TEM and spectroscopy techniques demonstrated that AuNPs were functionalized with HYNIC-GGC-NH(2) and thiol-mannose through interactions with thiol groups and the N-terminal amine of cysteine. Radio-chromatograms showed radiochemical purity higher than 95%. (99m)Tc-EDDA/HYNIC-GGC-AuNP-mannose ((99m)Tc-AuNP-mannose) showed specific recognition for mannose receptors in rat liver tissue. After subcutaneous administration of (99m)Tc-AuNP-mannose in rats (footpad), radioactivity levels in the popliteal and inguinal lymph nodes revealed that 99% of the activity was extracted by the first lymph node (popliteal extraction). Biodistribution studies and in vivo micro-SPECT/CT images in Wistar rats showed an evident lymph node uptake (11.58 ± 1.98 %ID at 1 h) which was retained during 24 h with minimal kidney accumulation (0.98 ± 0.10 %ID) and negligible uptake in all other tissues.
  
  
  CONCLUSIONS
  This study demonstrated that (99m)Tc-AuNP-mannose remains within the first lymph node during 24 h and therefore might be useful as a target-specific radionanoconjugate for SLND using "1-day" or "2-day" conventional protocols.
authors.affiliation: Instituto Nacional de Investigaciones Nucleares, Estado de México, Mexico.
authors.forename: Blanca E
authors.initials: BE
authors.lastname: Ocampo-García
authors.forename: Flor de M
authors.initials: Fde M
authors.lastname: Ramírez
authors.forename: Guillermina
authors.initials: G
authors.lastname: Ferro-Flores
authors.forename: Luis M
authors.initials: LM
authors.lastname: De León-Rodríguez
authors.forename: Clara L
authors.initials: CL
authors.lastname: Santos-Cuevas
authors.forename: Enrique
authors.initials: E
authors.lastname: Morales-Avila
authors.forename: Consuelo Arteaga
authors.initials: CA
authors.lastname: de Murphy
authors.forename: Martha
authors.initials: M
authors.lastname: Pedraza-López
authors.forename: Luis A
authors.initials: LA
authors.lastname: Medina
authors.forename: Marco A
authors.initials: MA
authors.lastname: Camacho-López
mesh_terms: D000818:Animals; D006046:Gold / Q000737:chemistry*; D006801:Humans; D037181:Lectins, C-Type / Q000378:metabolism; D008198:Lymph Nodes / Q000378:metabolism*; D008207:Lymphatic Metastasis; D008358:Mannose / Q000378:metabolism*; D000090323:Mannose Receptor; D037241:Mannose-Binding Lectins / Q000378:metabolism; D053768:Metal Nanoparticles / Q000737:chemistry*; D046529:Microscopy, Electron, Transmission; D009842:Oligopeptides / Q000737:chemistry* / Q000378:metabolism* / Q000493:pharmacokinetics; D015609:Organotechnetium Compounds / Q000737:chemistry*; D011854:Radiochemistry; D051381:Rats; D017208:Rats, Wistar; D011956:Receptors, Cell Surface / Q000378:metabolism; D021701:Sentinel Lymph Node Biopsy; D013057:Spectrum Analysis; D013438:Sulfhydryl Compounds / Q000737:chemistry
chemical_list: D037181:Lectins, C-Type; D000090323:Mannose Receptor; D037241:Mannose-Binding Lectins; D009842:Oligopeptides; D015609:Organotechnetium Compounds; D011956:Receptors, Cell Surface; D013438:Sulfhydryl Compounds; D006046:Gold; D008358:Mannose