Search

Accurate visualization of tumor microenvironment is of great significance for personalized medicine. Here, we develop a near‐infrared (NIR) fluorescence/photoacoustic (FL/PA) dual‐mode molecular probe (denoted as NIR−CE) for distinguishing tumors based on carboxylesterase (CE) level by an analyte‐induced molecular transformation (AIMT) strategy. The recognition moiety for CE activity is the acetyl unit of NIR−CE, generating the pre‐product, NIR−CE−OH, which undergoes spontaneous hydrogen atom exchange between the nitrogen atoms in the indole group and the phenol hydroxyl group, eventually transforming into NIR−CE−H. In cellular experiments and in vivo blind studies, the human hepatoma cells and tumors with high level of CE were successfully distinguished by both NIR FL and PA imaging. Our findings provide a new molecular imaging strategy for personalized treatment guidance. [ABSTRACT FROM AUTHOR]

Fluorescence sensing is crucial to studying biological processes and diagnosing diseases, especially in the second near‐infrared (NIR‐II) window with reduced background signals. However, it's still a great challenge to construct "off‐on" sensors when the sensing wavelength extends into the NIR‐II region to obtain higher imaging contrast, mainly due to the difficult synthesis of spectral overlapped quencher. Here, we present a new fluorescence quenching strategy, which utilizes steric hindrance quencher (SHQ) to tune the molecular packing state of fluorophores and suppress the emission signal. Density functional theory (DFT) calculations further reveal that large SHQs can competitively pack with fluorophores and prevent their self‐aggregation. Based on this quenching mechanism, a novel activatable "off‐on" sensing method is achieved via bio‐analyte responsive invalidation of SHQ, namely the Steric Hindrance Invalidation geNerated Emission (SHINE) strategy. As a proof of concept, the ClO−‐sensitive SHQ lead to the bright NIR‐II signal release in epileptic mouse hippocampus under the skull and high photon scattering brain tissue, providing the real‐time visualization of ClO− generation process in living epileptic mice. [ABSTRACT FROM AUTHOR]

Early detection of kidney disease is of vital importance due to its current prevalence worldwide. Fluorescence imaging, especially in the second near‐infrared window (NIR‐II) has been regarded as a promising technique for the early diagnosis of kidney disease due to the superior resolution and sensitivity. However, the reported NIR‐II organic renal‐clearable probes are hampered by their low brightness (ϵmaxΦf>1000 nm<10 M−1 cm−1) and limited blood circulation time (t1/2<2 h), which impede the targeted imaging performance. Herein, we develop the aza‐boron‐dipyrromethene (aza‐BODIPY) brush macromolecular probes (Fudan BDIPY Probes (FBP 912)) with high brightness (ϵmaxΦf>1000 nm≈60 M−1 cm−1), which is about 10‐fold higher than that of previously reported NIR‐II renal‐clearable organic probes. FBP 912 exhibits an average diameter of ≈4 nm and high renal clearance efficiency (≈65 % excretion through the kidney within 12 h), showing superior performance for non‐invasively diagnosis of renal ischemia‐reperfusion injury (RIR) earlier than clinical serum‐based protocols. Additionally, the high molecular weight polymer brush enables FBP 912 with prolonged circulation time (t1/2≈6.1 h) and higher brightness than traditional PEGylated renal‐clearable control fluorophores (t1/2<2 h), facilitating for 4T1 tumor passive targeted imaging and renal cell carcinoma active targeted imaging with higher signal‐to‐noise ratio and extended retention time. [ABSTRACT FROM AUTHOR]

Organic dyes emitting in the second near‐infrared (NIR‐II, 900–1700 nm) window, with high molar extinction coefficients (MEC) and quantum yields (QY) in aqueous, are essential for in vivo bioimaging and biosensing. In this work, we developed a dibodipy‐based aggregation‐induced emission (AIE) fluorescent probe, THPP, to meet this aim. THPP exhibits a high MEC and has intensified absorption and emission in J‐aggregated state, which significantly enhance the fluorescence intensity (≈55 folds) and extend the maximal absorption/emission wavelengths to 970/1010 nm in NIR‐II region. Based on the bright THPP, imaging with a high frame rate (34 frames per second) at a deep "valid penetration depth" up to 6 mm can be achieved. This enabled simultaneous and dynamic imaging of vasculatures and deep tissues. Besides, we succeeded in monitoring the respiratory rate of acute‐lung‐injury mice and tracing the collateral circulation process with a high frame rate. [ABSTRACT FROM AUTHOR]