Fluorogen-free aggregation induced NIR emission from gold nanoparticles

Controlled diluted aqua regia addition leads to NIR (near infrared) luminescence from aggregated gold nanoparticles at 916 nm. This turn-on luminescence has been observed for gold nanoparticles, regardless of reductants used in their preparation. These aggregated nanoparticles are nontoxic and have been used for bioimaging in human liver carcinoma cells.