Size-Controlled Biocompatible Silver Nanoplates for Contrast-Enhanced Intravital Photoacoustic Mapping of Tumor Vasculature.

Triangular Ag nanoplates with a thickness of 5 nm and tunable edge lengths were fabricated using a seed-mediated protocol, featuring enhanced near-infrared absorption as the edge length of nanoplates increased. The photoacoustic (PA) efficiency of these Ag nanoplates were assessed. Nanoplates with an edge length of 100 nm (r1) performed best among others in the in vitro assessment. In the following in vivo test, r1 nanoplates were also found to boost the PA signal of tumor vessels, while a detailed PA imaging of tumor vasculature was obtained. The in vivo safety assessment of Ag nanoplates demonstrated that no apparent acute toxicity was observed to the heart, liver, spleen, lung and kidneys in mice with a single intravenous PA imaging dose of r1 nanoplates. Therefore, Ag nanoplates with the selected size have great potential as a new alternative PA contrast agent for quantitative imaging-based evaluation of tumor angiogenic vasculature and heterogeneity in tumor microenvironment. More importantly, controllable synthesis of nanoparticles would be an ideal route to optimize Ag nanoplates for biomedical application.