A green synthesis of carbon nanoparticles from honey and their use in real-time photoacoustic imaging

Imaging sentinel lymph nodes (SLN) could provide us with critical information about the progression of a cancerous disease. Real-time high-resolution intraoperative photoacoustic imaging (PAI) in conjunction with a near-infrared (NIR) probe may offer opportunities for the immediate imaging for direct identification and resection of SLN or collecting tissue samples. In this work a commercially amenable synthetic methodology is revealed for fabricating luminescent carbon nanoparticles with rapid clearance properties. A one-pot "green" technique is pursued, which involved rapid surface passivation of carbon nanoparticles with organic macromolecules (e.g., polysorbate, polyethyleneglycol) in solvent-free conditions. Interestingly, the naked carbon nanoparticles are derived for the first time, from commercial food grade honey. Surface coated particles are markedly smaller (∼7 nm) than previously explored particles (gold, single-walled carbon nanotubes, copper) for SLN imaging. The results indicate an exceptionally rapid signal enhancement (∼2 min) of the SLN. Owing to their strong optical absorption in the NIR region, tiny size and rapid lymphatic transport, this platform offers great potential for faster resection of SLN and may lower complications caused in axillary investigation by mismarking with dyes or low-resolution imaging techniques.