Liver fibrosis, a progressive pathological condition triggered by chronic liver injury, often leads to cirrhosis and hepatocellular carcinoma if left untreated. Early diagnosis is critical for effective intervention and improved patient outcomes. However, current diagnostic methods such as liver biopsy are invasive, carry risks of complications, and lack repeatability. Non-invasive imaging techniques like ultrasound and CT suffer from poor sensitivity and specificity in detecting early-stage fibrosis. Therefore, there is an urgent need for accurate, non-invasive, and real-time diagnostic tools.
Monoamine oxidase B (MAO-B), a flavin-dependent enzyme overexpressed in early-stage liver fibrosis, has emerged as a promising biomarker. Its elevated activity correlates with hepatic stellate cell activation and excessive collagen deposition—hallmarks of fibrogenesis. Despite its potential, existing detection strategies for MAO-B are limited by slow reaction kinetics, low sensitivity, or poor spatial resolution, hindering their clinical utility.ANXA5 Antibody Purity
To address these challenges, we developed a novel two-photon fluorescence imaging platform based on a simple, rationally designed probe named BiPhAA. This probe consists of a benzylamine moiety linked to 2-aminobenzeneboronic acid via Suzuki coupling. Upon exposure to MAO-B, the benzylamine group is specifically oxidized to an aldehyde, which then reacts intramolecularly with the adjacent amino group to form a conjugated imine system. This structural transformation dramatically enhances fluorescence emission at 520 nm under 490 nm excitation, resulting in a bright turn-on signal within just 10 minutes—making it significantly faster than previously reported probes that require up to 2 hours.
The probe exhibits high selectivity for MAO-B over other enzymes, amino acids, metal ions, and reactive oxygen species, as confirmed through extensive control experiments. In vitro assays demonstrated a linear response to MAO-B concentrations ranging from 0 to 2.0 ng/L, with a detection limit as low as 0.02 ng/L. Moreover, BiPhAA showed excellent photostability and minimal cytotoxicity in both LX-2 hepatic stellate cells and HL7702 hepatocytes, indicating strong biocompatibility.hnRNP U Antibody Purity & Documentation
We further validated the probe’s performance in living cells using two-photon microscopy.PMID:35143137 Real-time imaging revealed a significant increase in fluorescence intensity in control cells incubated with BiPhAA, while pretreatment with the selective inhibitor D-penicillamine drastically reduced signal output. These results were corroborated by enzyme activity assays, confirming that fluorescence changes directly reflect MAO-B activity.
In vivo applications were conducted using a carbon tetrachloride (CCl₄)-induced mouse model of liver fibrosis. After tail vein injection of BiPhAA, two-photon imaging of deep liver tissues showed approximately six-fold higher fluorescence intensity in fibrotic mice compared to normal controls. The signal was effectively suppressed in mice pre-treated with D-penicillamine, confirming the specificity of the probe. Additionally, ex vivo imaging using the IVIS system confirmed the same trend, with strong fluorescence in fibrotic livers and weak signals in inhibitor-treated samples.
These findings demonstrate that BiPhAA enables rapid, sensitive, and specific two-photon fluorescence imaging of endogenous MAO-B activity in live animals. Its ability to distinguish early-stage liver fibrosis from normal tissue in real time offers a powerful tool for non-invasive diagnosis. By visualizing MAO-B dynamics in situ, this method not only facilitates early detection but also provides insights into the molecular mechanisms underlying liver fibrosis progression. We believe BiPhAA holds great promise for future translation into clinical diagnostics and therapeutic monitoring.MedChemExpress (MCE) offers a wide range of high-quality research chemicals and biochemicals (novel life-science reagents, reference compounds and natural compounds) for scientific use. We have professionally experienced and friendly staff to meet your needs. We are a competent and trustworthy partner for your research and scientific projects.Related websites: https://www.medchemexpress.com
