Abstract
Near-infrared-II (NIR-II, 1000–1700 nm) fluorescence imaging boasts high spatial resolution and deep tissue penetration due to low light scattering, reduced photon absorption, and low tissue autofluorescence. NIR-II biological imaging is applied mainly in the noninvasive visualization of blood vessels and tumors in deep tissue. In the study, a stereo NIR-II fluorescence imaging system was developed for acquiring three-dimension (3D) images on tumor vasculature in real-time, on top of the development of fluorescent semiconducting polymer dots (IR-TPE Pdots) with ultra-bright NIR-II fluorescence (1000–1400 nm) and high stability to perform long-term fluorescence imaging. The NIR-II imaging system only consists of one InGaAs camera and a moving stage to simulate left-eye view and right-eye view for the construction of 3D in-depth blood vessel images. The system was validated with blood vessel phantom of tumor-bearing mice and was applied successfully in obtaining 3D blood vessel images with 0.6 mm- and 5 mm-depth resolution and 0.15 mm spatial resolution. The NIR-II stereo vision provides precise 3D information on the tumor microenvironment and blood vessel path.
Highlights
Fluorescence imaging is an essential tool for drug distribution monitoring, cancertargeting, or tumor therapy preclinical studies [1,2,3]
The phantom was used for mimicking the optical characteristics of biological tissues in the NIR-II window
The full-width half maximum (FWHM) values of belly vessels were 0.98 mm (1100 nm LP filter), 0.69 mm (1300 nm LP filter), and 0.56 mm (1400 nm LP filter), respectively. These results show that IR-TPE Pdots could be applied as fluorescence imaging agents in NIRII imaging, using a 1400 nm LP filter to achieve high resolution
Summary
Fluorescence imaging is an essential tool for drug distribution monitoring, cancertargeting, or tumor therapy preclinical studies [1,2,3]. In visible and NIR-I windows (400–900 nm), the imaging depth is restricted by high tissue scattering and absorption [5,6,7]. Light scattering suppression and low tissue absorption facilitate in vivo fluorescence imaging visualization of blood vessels with a high signal-to-noise ratio (SNR) [13,14], thereby detecting a tumor region according to blood vessel maturation or tumor-induced angiogenesis [15]. NIR-II fluorescent semiconducting polymer dots (IR-TPE Pdots) were developed to obtain high SNR NIR-II blood vessel imaging [22,23]
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