High‐Aspect‐Ratio Plasmonic Heterostructures for In Vivo Enhanced Optical Coherence Tomography Imaging in the Second Near‐Infrared Biological Window

Abstract

Optical coherence tomography (OCT) is a noninvasive bio‐imaging modality that is widely used in both fundamental research and clinical practice. Contrast agents with strong light‐scattering properties are a prerequisite for OCT imaging. Bio‐imaging in the second near‐infrared window (NIR‐II, 1000–1700 nm) has recently attracted significant attention based on reduced light absorption, suppressed photon scattering, and negligible autofluorescence. OCT contrast agents with both strong light‐scattering cross‐sections in the NIR‐II window and excellent biocompatibility are highly desirable. In this article, Ag‐based rod‐shaped plasmonic nanostructures are presented as NIR‐II OCT contrast agents. As a high‐aspect‐ratio heterostructure, the Ag nanorods coated with mesoporous silica shells (AgNR@mSiO2) are developed to achieve plasmon resonance at 1330 nm and excellent biocompatibility. By taking advantage of their huge light‐scattering cross‐sections, which provide the strongest scattering reported to date among various nanoscale OCT contrast agents, the heterostructures are used to perform efficient in vivo OCT imaging of crucian carp eyes and chicken blood vessels in the NIR‐II window. The captured images exhibit enhanced contrast with large imaging depth. These results demonstrate that the developed AgNR@mSiO2 heterostructures are promising OCT contrast agents, that can provide guidance and reference for the development of highly efficient NIR‐II imaging probes.

Optical Imaging in the Second Near Infrared Window for Vascular Bioimaging

“…[50] Deng and co-workers modified Ag nanorods with mesoporous silica shells (AgNR@mSiO 2 ) to develop a strong OCT probe with plasmon resonance at 1330 nm, providing a high-contrast in vivo OCT imaging. [51] De la Zerda and co-workers reported a new OCT probe gold nanobipyramids (GNBPs) with narrow plasmon resonance spectrum and high sensitivity. Successful multiplexed in vivo imaging was performed with GNBP-I and GNBP-II, which have different plasmon resonance peaks in the NIR-II optical window (1225 and 1415 nm).…”

Chemical Tuning on Resonance Coupling in Gold Nanorod−Monolayer WS2 Heterostructures

“…Gold nanorods were grown using a seed-mediated method with binary surfactant mixture (Ye et al, 2013;Zhuang et al, 2018;Xu et al, 2020). The seed solution was prepared by mixing 2.5 ml HAuCl 4 (0.5 mM) and 2.5 ml CTAB (0.2 M) solution in a 30-ml glass vial.…”

Au/Si Bilayer Nanodisks with Tunable Localized Surface Plasmon Resonance for Optical Coherence Tomography in the Second Near‐Infrared Window

“…[ 17 ] It is required to encapsulate the NRs with biocompatible layers such as polyethylene glycol and silica. [ 4,18 ] Similar to NRs, [ 16,19 ] the resonance wavelengths for Au nanoparticles with nanoring, [ 20,21 ] nanoshell, [ 22 ] hollow NR, [ 23,24 ] nanostar, [ 25,26 ] nanobipyramid, [ 27 ] or nanoprism [ 28 ] shapes can be adjusted to fit within NIR‐II. However, the biocompatibility of surfactant used during synthesis is reduced, the size and shape of synthesized nanoparticles are inconsistent, and reproducibility is poor.…”