UCLA researchers in the Department of Chemistry and Biochemistry have developed fluorescence imaging probes and methods to achieve multiplexed imaging in the shortwave infrared (SWIR, 1000 – 2000nm) region. The system and method developed allows high-contrast and resolution multiplexed imaging of whole animals in real-time.
BACKGROUND:
Real-time, fluorescence imaging is a non-invasive optical imaging modality that holds promise in image-guided surgery and molecular diagnostics. The shortwave infrared (SWIR, 1000 – 2000 nm) region of the electromagnetic spectrum has provided a means to real-time monitoring of whole mammals with high contrast and resolution due to deep penetration of light through tissue and low autofluorescence. While fluorophores have been developed for this region, multiplexed experiments have been limited due to near infrared (NIR, 700 – 1000 nm) excitation wavelengths of often broad and overlapping absorption profiles. To accomplish real-time multiplexed imaging in non-transparent animals, a method is needed in which 1) SWIR detection is employed for high contrast, resolution, and penetration depth; 2) fluorophores are excited at their absorbance maximum and all SWIR photons are collected to achieve ample signal and; 3) detection of each channel can occur in tandem. Custom, bright fluorophores are needed to meet requirements of excitation-multiplexing and “color-blind” detection.
INNOVATION: UCLA researchers have developed a set of bright polymethine dyes with diverse wavelength excitation. Along with the development of a triggered multi-excitation SWIR optical configuration, they have demonstrated multiplexed whole animal imaging with high spaciotemporal resolution on the millisecond time scale. Specifically, SWIR multiplexed imaging was enabled to monitor awake mice, hepatic clearance, and orthogonal detection of the lymph and circulatory systems. The technologies developed advance the ability to monitor orthogonal function in animals, a major advance in imaging methods. We envision that these methods as well as further exploration of the polymethine scaffold, and development of real-time imaging tools, will result in advanced surgical, therapeutic, and chemical biology studies by multiplexing in vivo.
POTENTIAL APPLICATIONS:
• Image-guided surgery
• Multiplexed optical imaging
• In vivo theranostic applications
• In vivo diagnostic platform
ADVANTAGES:
• Bright fluorophores
• Spectrally resolved fluorophores – allow multiplexing
• High spatiotemporal resolution
• Non-invasive imaging modality
• Novel multi-excitation SWIR optical configuration
• Highest frames per second recorded to-date
• Real-time monitoring of biological processes in vivo
DEVELOPMENT-TO-DATE:
The multiplexed SWIR optical configuration setup developed has allowed orthogonal biological function to be visualized noninvasively in real time. The method can achieve three color imaging up to 27.5 frames per second, the only method to-date to allow high resolution, multiplexed, real-time SWIR imaging.
Related Papers
Cosco, E. D.; et al, Nat. Chem. 2020, doi.org/10.1038/s41557-020-00554-5
Cosco, E. D.; et al, Angew. Chem. Int. Ed. 2017, 56, 13126–13129