Multifunctional Imaging of Vessels, Brown Adipose Tissue, and Bones in the Visible and Second Near-infrared Region Using Dual-Emitting Polymer Dots

Abstract

Dual-emitting polymer dots (dual-Pdots) in the visible and second near-infrared (NIR-II) region can facilitate the high-resolution imaging of the fine structure and improve the signal-to-noise ratio in in vivo imaging. Herein, combining high brightness of Pdots and multi-scale imaging, we synthesized dual-Pdots using a simple nano-coprecipitation method and performed multi-functional imaging of vessels, brown adipose tissue, and bones. Results showed that in vivo blood vessel imaging had a high resolution of up to 5.9 μm and bone imaging had a signal-to-noise ratio of 3.9. Moreover, dual-Pdots can accumulate in the interscapular brown adipose tissue within 2 min with a signal-to-noise ratio of 5.8. In addition, the prepared dual-Pdots can image the lymphatic valves and the frequency of contraction. Our study provides a feasible method of using Pdots as nanoprobes for multi-scale imaging in the fields of metabolic disorders, skeletal system diseases, and circulatory systems.

Fluorescent Pdots Facilitate High-Resolution Mapping of the Intact Meningeal Vascular Network and Eye–Brain Connections

“…The PFBT Pdots was prepared by the nanoprecipitation method according to our previous study. ,, Typically, a solution of 2 mL tetrahydrofuran (THF) containing 400 μg PFBT and 400 μg PS-PEG-COOH were prepared as a stock solution. Then, the mixture was quickly dispersed into 10 mL of purified water under vigorous sonication.…”

Mitochondrial-Targeted Ratiometric Near-Infrared Fluorescence Probe for Monitoring Nitric Oxide in Rheumatoid Arthritis

“…Molecular fluorescent probes have attracted much attention due to their high sensitivity and high selectivity, enabling accurate identification of target analytes and noninvasive real-time observation in vivo . − Reactive oxygen species (ROS) and reactive nitrogen species (RNS) levels increase during the progression of RA disease. − Several fluorescent probes for the detection of reactive oxygen and nitrogen species have been reported for the diagnosis and monitoring of arthritis. ,− In physiological disorders, activated macrophages produce high levels of nitric oxide (NO), which can upregulate osteoclasts, destroy cartilage, and recruit other immune cells to cause inflammation, and thus NO is often thought to be involved in joint damage. − Therefore, the detection of NO is of great significance for the early diagnosis of RA. , The reported NO probes are mainly composed of o -phenylenediamine and aromatic secondary amines, which specifically react with NO to produce fluorescent signals. − Among them, probes with o -phenylenediamine structure are typically based on photoinduced electron transfer (PET) that undergo enhanced fluorescence in the presence of NO. − Compared with to the single-channel imaging mode of the “turn-on” type probes, the ratio-metric fluorescent probes based on the intramolecular charge transfer (ICT) effect are preferred for NO imaging with high-resolution and self-calibration, which can be quantitatively detected by the ratio and effectively reduce the background signal interference to realize accurate spatial-temporal detection of NO. − However, ICT-based small molecule NIR fluorescent probes with o -phenylenediamine have not been reported.…”

Triglyceride-Rich Lipoprotein-Mediated Polymer Dots for Multimodal Imaging Interscapular Brown Adipose Tissue Capillaries

“…Compared with these organic probes, polymer dots (Pdots) brought many good optical properties and low cytotoxicity. They had a very short time interval from injection to imaging BAT clearly, even as short as 5 min without additional cold stimulation, which is a kind of excellent BAT fluorescence nanoprobe in the NIR-I region. − Therefore, the mechanism by which Pdots image BAT is necessary for further investigation.…”