Temperature plays a crucial role in many biological processes. Accurate temperature determination is important for diagnosis and treatment of diseases. Autofluorescence is an unavoidable interference in luminescent bioimaging. Hence, a large amount of research works has been devoted to reducing background autofluorescence and improving signal‐to‐noise ratio (SNR) in biodetection. Herein, a dual‐emissive phosphorescent polymeric thermometer has been developed by incorporating two long‐lived phosphorescent iridium(III) complexes into an acrylamide‐based thermosensitive polymer. Upon increasing temperature, this polymer undergoes coil‐globule transition, which leads to a decrease in polarity of the microenvironment surrounding the iridium(III) complexes and hence brings about emission enhancement of both complexes. Owing to their different sensitivity to surrounding environment, the emission intensity ratio of the two complexes is correlated to the temperature. Thus, the polymer has been used for temperature determination in vitro and in vivo via ratiometric luminescence imaging. More importantly, by using the long‐lived phosphorescence of the polymer, temperature mapping in zebrafish has been demonstrated successfully with minimized autofluorescence interference and improved SNR via time‐resolved luminescence imaging. To the best of our knowledge, this is the first example to use photoluminescent thermometer for in vivo temperature sensing.
Temperature plays an important part in many biochemical processes. Accurate diagnosis and proper treatment usually depend on precise measurement of temperature. In this work, a dual-emissive phosphorescent polymer temperature probe, composed of iridium(III) complexes as temperature sensitive unit with phosphorescence lifetime of ∼500 ns and europium(III) complexes as reference unit with lifetime of ∼400 μs, has been rationally designed and synthesized. Upon the increase of the temperature, the luminescence intensity from the iridium(III) complexes is enhanced, while that from the europium(III) complexes remains unchanged, which makes it possible for the ratiometric detection of temperature. Furthermore, the polymer also displays a significant change in emission lifetime accompanied by the temperature variation. By utilizing the laser scanning confocal microscope and time-resolved luminescence imaging systems, ratiometric and time-resolved luminescence imaging in Hela cells and zebrafish have been carried out. Notably, the intensity ratio and long-lifetime-based imaging can offer higher sensitivity, decrease the detection limit, and minimize the background interference from biosamples.
Drug-induced
liver injury (DILI) is a widespread clinical problem.
The pathophysiological mechanisms of DILI are complicated, and the
traditional diagnostic methods for DILI have their limitations. Owing
to its convenient operation, high sensitivity, and high specificity,
luminescent sensing and imaging as an indispensable tool in biological
research and clinical trials may provide an important means for DILI
study. Herein, we report the rational design and preparation of a
near-infrared dual-phosphorescent polymeric probe (P-ONOO) for exploring the DILI via specific imaging of peroxynitrite (ONOO–) elevation in vivo, which was one of early markers
of DILI and very difficult to be detected due to its short half-life
and high reactive activity. With the utilization of P-ONOO, the raised ONOO– was visualized successfully
in the drug-treated hepatocytes with a high signal-to-noise ratio
via ratiometric and time-resolved photoluminescence imaging. Importantly,
the ONOO– boost in the acetaminophen-induced liver
injury in real time was verified, and the direct observation of the
elevated ONOO– production in ketoconazole-induced
liver injury was achieved for the first time. Our findings may contribute
to understanding the exact mechanism of ketoconazole-induced hepatotoxicity
that is still ambiguous. Notably, this luminescent approach for revealing
the liver injury works fast and conveniently.
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