Abstract
Nanoparticle uptake and distribution to solid tumors are limited by reticuloendothelial system systemic filtering and transport limitations induced by irregular intra-tumoral vascularization. Although vascular enhanced permeability and retention can aid targeting, high interstitial fluid pressure and dense extracellular matrix may hinder local penetration. Extravascular diffusivity depends upon nanoparticle size, surface modifications, and tissue vascularization. Gold nanoparticles functionalized with biologically-compatible layers may achieve improved uptake and distribution while enabling cytotoxicity through synergistic combination of chemotherapy and thermal ablation. Evaluation of nanoparticle uptake in vivo remains difficult, as detection methods are limited. We employ hyperspectral imaging of histology sections to analyze uptake and distribution of phosphatidylcholine-coated citrate gold nanoparticles (CGN) and silica-gold nanoshells (SGN) after tail-vein injection in mice bearing orthotopic pancreatic adenocarcinoma. For CGN, the liver and tumor showed 26.5 ± 8.2 and 23.3 ± 4.1 particles/100 μm2 within 10 μm from the nearest source and few nanoparticles beyond 50 μm, respectively. The spleen had 35.5 ± 9.3 particles/100 μm2 within 10 μm with penetration also limited to 50 μm. For SGN, the liver showed 31.1 ± 4.1 particles/100 μm2 within 10 μm of the nearest source with penetration hindered beyond 30 μm. The spleen and tumor showed uptake of 22.1 ± 6.2 and 15.8 ± 6.1 particles/100 μm2 within 10 μm, respectively, with penetration similarly hindered. CGH average concentration (nanoparticles/μm2) was 1.09 ± 0.14 in the liver, 0.74 ± 0.12 in the spleen, and 0.43 ± 0.07 in the tumor. SGN average concentration (nanoparticles/μm2) was 0.43 ± 0.07 in the liver, 0.30 ± 0.06 in the spleen, and 0.20 ± 0.04 in the tumor. Hyperspectral imaging of histology sections enables analysis of phosphatidylcholine-coated gold-based nanoparticles in pancreatic tumors with the goal to improve nanotherapeutic efficacy.