WEB Plasmonic copper sulfide nanoparticles afford negative contrast in optical coherence tomographyWednesday (01.01.2020) 00:45 - 01:00 Part of:
Plasmonic nanoparticles feature large light extinction coefficients (absorption + scattering) at photon frequencies matching those of the natural oscillation of the charge carriers delocalized in the nanoparticle volume. This capability to absorb and/or scatter light with an increased efficiency compared to other nanoparticles can be harnessed in several ways in the biomedical arena.
Although noble-metal-based systems are by far the most investigated plasmonic nanoparticles, in recent years semiconductor nanoparticles with plasmonic properties have appeared on the scene. To that end copper sulfide nanoparticles feature strong light extinction capabilities in the near infrared (approx. 750-1800 nm), where the biological tissues are less opaque to light. This is pivotal in the development of effective therapeutic or imaging contrast agents for light-assisted techniques.
To that end, optical coherence tomography (OCT) is a powerful light-assisted diagnostic technique where near infrared light is often preferred over visible. OCT affords optical biopsies exploiting the diverse interaction with light exhibited by different tissue components and interfaces. Ophthalmology, dermatology, and cardiology are only some of the fields where this technique has proven itself a useful diagnostic and surgical tool. To allow better visualizing structures of interests within the tissues, several contrast agents have been proposed. All of them rely on sizeable scattering of the OCT probing light, thus yielding a bright signal in OCT scans (positive contrast). However, some tissues appear already bright, thus negative (dark) contrast agents would be better suited for visualizing them.
In this talk, the key features of copper sulfide nanoparticles will be presented and compared to the ones of more widely investigated gold nanosystems. The prowess of copper sulfide nanoparticle in biological applications will be showcased in particular in the context of OCT. The strong absorption of the probing light, in hand with the negligible scattering featured by the nanoparticles, was leveraged to achieve for the first time negative contrast in OCT. Among other scenarios, this unprecedented report on the possibility of achieving negative contrast in OCT opens the door to the detection of atheromatous plaques at a nowadays unmatched early stage.