Abstract
Colloidal gold nanoparticles (GNPs) serve as promising contrast agents in photoacoustic (PA) imaging, yet their utility is limited due to their absorption peak in the visible window overlapping with that of hemoglobin. To overcome such limitation, this report describes an ultrapure chain-like gold nanoparticle (CGNP) clusters with a redshift peak wavelength at 650 nm. The synthesized CGNP show an excellent biocompatibility and photostability. These nanoparticles are conjugated with arginine-glycine-aspartic acid (RGD) peptides (CGNP clusters-RGD) and validated in 12 living rabbits to perform multimodal photoacoustic microscopy (PAM) and optical coherence tomography (OCT) for visualization of newly developed blood vessels in the sub-retinal pigment epithelium (RPE) space of the retina, named choroidal neovascularization (CNV). The PAM system can achieve a 3D PAM image via a raster scan of 256 × 256 pixels within a time duration of 65 s. Intravenous injection of CGNP clusters-RGD bound to CNV and resulted in up to a 17-fold increase in PAM signal and 176% increase in OCT signal. Histology indicates that CGNP clusters could disassemble, which may facilitate its clearance from the body.
Highlights
Colloidal gold nanoparticles (GNPs) serve as promising contrast agents in photoacoustic (PA) imaging, yet their utility is limited due to their absorption peak in the visible window overlapping with that of hemoglobin
The transmission electron microscopy (TEM) images (Fig. 1b, c) revealed that the synthesized chain-like gold nanoparticle (CGNP) clusters-RGD had an average length of 64 nm and an average width of 20 nm determined by the diameter of the GNP
This study described ultra-pure CGNP clusters that can be used as multimodal photoacoustic microscopy (PAM) and optical coherence tomography (OCT) contrast agents
Summary
Colloidal gold nanoparticles (GNPs) serve as promising contrast agents in photoacoustic (PA) imaging, yet their utility is limited due to their absorption peak in the visible window overlapping with that of hemoglobin. To validate our CGNP clustersRGD as PA molecular imaging agents and to demonstrate its safety and biocompatibility, we performed in vivo PA imaging using two rabbit models of choroidal neovascularization (CNV): (1) retinal vein occlusion (RVO) induced via photocoagulation, and (2) subretinal injection of vascular endothelial growth factor (VEGF-165). In all these in vivo studies, CGNP clusters-RGD were intravenously injected via the rabbits’ marginal ear veins
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