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

Abstract

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.

The Golden Age: Shining the Light on Theragnostics

“…The earlier research group recently demonstrated that gold nanoprisms with strong scattering in the NIR‐II window could be used as the contrast agents for deep‐tissue OCT. After intravenous injection of PEGylated gold nanoprisms, significant improvement of the contrast in OCT angiograms was achieved, allowing for in vivo melanoma tumor detection based on the tumor microvasculature characterization. [ 39 ] In another recent study from Nguyen et al, gold nanostars functionalized with an RGD peptide were utilized as the contrast agents to evaluate choroidal neovascularization in living rabbits by multimodal PA microscopy and OCT. [ 40 ] As shown in Figure 4b, the peak PA amplitudes were obtained at wavelength matching with the absorption of gold nanostars, where PA contrast increased by up to 17‐folds and OCT intensities increased 167%.…”

Enhanced medical diagnosis for dOCTors: a perspective of optical coherence tomography

“…Among these piezoelectric transducers, needle transducers are most commonly used. So far, OC-PAM using needle transducers has been applied in choroidal and retinal imaging [119][120][121][122][123][124][125][126][127] extensively. Some technical advancements of needle-transducer-based OC-PAM systems have also been reported such as for dynamic focusing 128,129 and for incorporating additional imaging modalities.…”

Ultra-widefield photoacoustic microscopy with a dual-channel slider-crank laser-scanning apparatus for in vivo biomedical study

“…Particularly, based on the much stronger and tighter optical beam than the acoustic beam, OR-PAM takes extreme advantage of the high resolution over AR-PAM. In addition, with the rich optical absorption contrast, OR-PAM becomes a promising imaging tool in many research fields including biology, dermatology, neurology, oncology, ophthalmology, and pathology [ [3] , [4] , [5] , [6] , [7] , [8] , [9] , [10] , [11] , [12] , [13] , [14] , [15] , [16] ]. Typical OR-PAM systems implement a confocal and coaxial structure of the excitation light beam and the PA emission beam to maximize the signal-to-noise ratio (SNR) and optimize the spatial resolutions [ 6 , 8 , 12 , 17 ].…”