The NIR-II part of the spectrum corresponds to wavelengths between 900 nm and 1700 nm. Compared to visible imaging, that takes place between 400 nm and 800 nm, NIR-II has a great advantage for in vivo fluorescence imaging: scattering, absorption and auto-fluorescence from tissue are significantly lower. It becomes therefore possible to image at greater depths with much better sensitivity and resolution. For these reasons, the LIOPA decided to invest in the acquisition of both the instrumentation and the expertise needed to perform NIR-II fluorescence imaging.
They first selected a SWIR camera popular for biomedical applications, and then asked us at Kaer Labs to build a complete imaging system, with electronics, optics, mechanics and software around the camera. The system is now installed and running, and they perform their imaging protocols with the fully integrated system.
Johanne Seguin preparing the injection of the NIR-II nanoparticles
Among others, NIR-II imaging at the LIOPA will be used for the development of a thermal bioimaging technology featuring sub-microscale resolution. First experiments with NIR-II nanoparticles developed in this project and functionalized for IV injection, were performed last week.
Liver accumulation of NIR-II nanoparticles (left) and control mouse (right). Images were acquired with a Kaer Imaging Platform controlling a Princeton camera (excitation 808 nm, collection from 1064 nm, exposure time 500 ms). Acquisition was performed 4 days after the injection of the particles. Unlike protocols for visible or near infrared fluorescence, animals did not need to be shaved here in order to detect the fluorescence signal.
Question to Cyrille Richard and Johanne Seguin from the LIOPA: What does NIR-II imaging brings to your imaging platform?
Cyrille: reducing the effect of signal diffusion and autofluorescence, as well as improving the resolution of images is key for in vivo optical imaging. Fluorescence in the NIR-II helps us really move one step forward to improve such parameters, resulting in better images and thus, a higher precision in the biological answers. This is a project we have envisioned since we saw the publication from the group of Hongjie Dai, featuring the use of carbon nanotubes in order to visualize tumoral vessels.
Johanne: resolution is really a critical parameter. We have routine procedures to develop and test new imaging probes. Having the capability to visualize precisely where they distribute when we inject them in animal models is key to our work.
Beyond the question of technical performances, as a platform it is also essential for us to be able to cover a large spectrum of modalities for optical in vivo imaging. Academic, biotech and pharma laboratories may have very different agents to develop and test, and the ability to cover this large spectrum is part of our mission to the scientific community.
About the LIOPA
The Small Animal Optical Imaging Laboratory (LIOPA), from the Paris Descartes In Vivo Imaging Platforms network, provides its expertise and tools to the scientific community for R&D projects in the field of in vivo optical imaging. The LIOPA has a park of instruments for several imaging modalities: bioluminescence (BLI), fluorescence (box) and open fluorescence (FLI), as well as the possibility to perform bimodal applications with magnetic resonance imaging (MRI) and optical (BLI of FLI) imaging.
The LIOPA is managed by researchers from the Unité des Technologies Chimiques et Biologiques pour la Santé (director Dr. Nathalie Mignet). The mission of the UTCBS is to develop innovative technologies for health, like siRNA, DNA, antibodies and cytokines, but also new chemical probes and biomarkers for the diagnosis and characterization of cancer and hepatic fibrosis.
The Kaer Imaging Platform and Kaer Imaging System
At the request of several laboratories, Kaer Labs has adapted, from its Kaer Imaging System (KIS) the optical, electronic and software architecture. This made it possible to control other existing equipment already present in laboratories, as the NIRvana Princeton camera for the case of the LIOPA presented here.
Kaer Labs now also proposes its fully integrated, open fluorescence system for NIR-II, combining sensitivity and the flexibility of open fluorescence. To know more visit www.kaerlabs.com/nir-ii-kaer-imaging-systemor contact us