Plasmonic Gold Nanostar-Enhanced Multimodal Photoacoustic Microscopy and Optical Coherence Tomography Molecular Imaging To Evaluate Choroidal Neovascularization

Although
photoacoustic microscopy (PAM) and optical coherence tomography
(OCT) allow visualization of the retinal microvasculature, distinguishing
early neovascularization from adjacent vessels remains challenging.
Herein, gold nanostars (GNSs) functionalized with an RGD peptide were
utilized as multimodality contrast agents for both PAM and OCT. GNSs
have great absorption and scattering characteristics in the near-infrared
region where most vasculature and tissue generates a less intrinsic
photoacoustic signal while having a small size, excellent biocompatibility in vivo, and great photostability under nanosecond pulsed
laser illumination. This enabled visualization and differentiation
of individual microvasculature in vivo using multimodal
PAM and OCT imaging. Detailed three-dimensional imaging of GNSs was
achieved in an important choroidal neovascularization model in living
rabbits. Through the administration of GNSs, PA contrast increased
up to 17-fold and OCT intensities increased 167%. This advanced molecular-imaging
platform with GNSs provides a unique tool for detailed mapping of
the pathogenesis of the microvasculature.