There is considerable interest in using engineered colloidal particles to map the distribution of targeted cells in the body, to observe cell migration between and through tissues, and to better understand mechanisms of tissue transport for future nano-based drug delivery vehicles. Imaging specific cellular internalization of a drug or particle could improve our ability to detect disease and evaluate treatment efficacy, yet conventional imaging systems cannot distinguish intracellular particles from those still outside cells. The intracellular distinction can be made using core-etchable nanoprobes combined with a membrane-impermeable, biocompatible etching agent added prior to imaging. I will describe two etchable cores along with their in vivo etching chemistry – one system based on silver plasmonic cores and the other using semiconductor quantum dots. In vitro microscopy indicates efficient removal of extracellular signals (e.g. non-specifically bound particles). We translated the system to a tumor model in mice, and used whole-body longitudinal near-infrared fluorescence imaging to image tumors before and after the final etching step. We found greatly improved contrast in tumor/skin and tumor/liver when etchant was included in the procedure. In vivo etching can thus facilitate live animal tracking of targeting nanoprobes as they distribute and internalize into tissues and cells.

Improved contrast in whole-body imaging with targeted colloids and membrane-impermeable quenchers and etchants

251st National Meeting (2016)

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