PEGylated Gold Nanoparticles Conjugated to Monoclonal F19 Antibodies as Targeted Labeling Agents for Human Pancreatic Carcinoma Tissue

In this study, we describe optical detection of antibody-conjugated nanoparticles bound to surgically resected human pancreatic cancer tissue. Gold nanoparticles stabilized by heterobifunctional polyethylene glycol (PEG) were prepared using approximately 15 nm spherical gold cores and covalently coupled to F19 monoclonal antibodies. The heterobifunctional PEG ligands contain a dithiol group for stable anchoring onto the gold surface and a terminal carboxy group for coupling of antibodies to the outside of the PEG shell. The nanoparticle-antibody bioconjugates form highly stable dispersions and exhibit long-term resistance to agglomeration. This has been demonstrated by dynamic light scattering, size exclusion chromatography, and transmission electron microscopy. The nanoparticle bioconjugates were used to label tumor stroma in approximately 5 mum thick sections of resected human pancreatic adenocarcinoma. After rinsing away nonbound nanoparticles and fixation, the tissue samples were imaged by darkfield microscopy near the nanoparticle resonance scattering maximum (approximately 560 nm). The images display pronounced tissue features and suggest that this novel labeling method could provide for facile identification of cancer tissue. Tumor samples treated with gold nanoparticles conjugated to nonspecific control antibodies and noncancerous pancreatic tissue treated with mAb-F19-conjugated gold nanoparticles both exhibited correctly negative results and showed no tissue staining.