Imaging Of Alkaline Phosphatase Activity Research Articles

Real-time imaging of alkaline phosphatase activity of diabetes in mice via a near-infrared fluorescent probe.

A novel water-soluble near-infrared fluorescent probe named QX-P with simple synthesis is developed. QX-P has high sensitivity and selectivity to ALP. Moreover, the probe can not only visualize ALP activity in four cell lines, but also real-time image ALP activity during the diagnosis and treatment of diabetes in mice.

Near-infrared mito-specific fluorescent probe for ratiometric detection and imaging of alkaline phosphatase activity with high sensitivity.

Fluorescent probe-based analytical methods for biological species have gained increasing attention for their powerful detection and imaging capabilities. However, it is still occasionally problematic for accurate analyses due to the influence of the probe concentration, intrinsic fluorescence, instrumental factors or environmental conditions, and intense laser irradiation is usually harmful to biological systems. An NIR ratiometric fluorescent probe can eliminate the influence of these factors and lead to a higher sensing performance. We propose the introduction of a reasonable masking group onto the meso oxygen atom of a cyanine framework (Cy-O) to achieve a NIR ratiometric probe by modulating the conjugated polymethine π-electron system of the cyanine dye. Herein, we report a proof-of-the-concept attempt for a highly sensitive and selective mito-specific NIR ratiometric fluorescent sensing strategy for ALP, and the phosphate group was chosen as the functional group for ALP catalyzed hydrolysis. Upon treatment with ALP, the probe Cy-OP exhibits excellent recognition properties such as high selectivity, high sensitivity (with a low detection limit of 0.16 mU mL-1), short response time (within 30 min) and a large spectral shift (from 736 to 516 nm in the absorption spectra and 766 to 616 nm in the emission spectra) with a low fluorescence background. Moreover, the ratio of emission (I616nm/I766nm) of the enzymatic residue was favorable for its application in a complex bio-system. Consequently, the well-designed probe was successfully applied for the detection of ALP in the living cells with satisfactory results.

A high-sensitivity fluorescent probe with a self-immolative spacer for real-time ratiometric detection and imaging of alkaline phosphatase activity

The probe APW uses a self-immolative mechanism to achieve a ratio response to ALP, which has the following advantages: fast response (in less than 15 min), high quantum yield (Φ = 0.6), low detection limit (0.46 U L−1) and excellent selectivity.

Simulation Analysis of Positional Relationship between Embryoid Bodies and Sensors on an LSI-based Amperometric Device for Electrochemical Imaging of Alkaline Phosphatase Activity.

In the present study, we monitored the alkaline phosphatase (ALP) activity of embryoid bodies (EBs) of mouse embryonic stem (ES) cells using a large-scale integration (LSI)-based amperometric device with 400 sensors and a pitch of 250 μm. In addition, a simulation analysis was performed to reveal the positional relationship between the EBs and the sensor electrodes toward more precise measurements. The study shows that simulation analysis can be applied for precise electrochemical imaging of three-dimensionally cultured cells by normalization of the current signals.

Imaging of Alkaline Phosphatase Activity in Bone Tissue

The purpose of this study was to develop a paradigm for quantitative molecular imaging of bone cell activity. We hypothesized the feasibility of non-invasive imaging of the osteoblast enzyme alkaline phosphatase (ALP) using a small imaging molecule in combination with 19Flourine magnetic resonance spectroscopic imaging (19FMRSI). 6, 8-difluoro-4-methylumbelliferyl phosphate (DiFMUP), a fluorinated ALP substrate that is activatable to a fluorescent hydrolysis product was utilized as a prototype small imaging molecule. The molecular structure of DiFMUP includes two Fluorine atoms adjacent to a phosphate group allowing it and its hydrolysis product to be distinguished using 19Fluorine magnetic resonance spectroscopy (19FMRS) and 19FMRSI. ALP-mediated hydrolysis of DiFMUP was tested on osteoblastic cells and bone tissue, using serial measurements of fluorescence activity. Extracellular activation of DiFMUP on ALP-positive mouse bone precursor cells was observed. Concurringly, DiFMUP was also activated on bone derived from rat tibia. Marked inhibition of the cell and tissue activation of DiFMUP was detected after the addition of the ALP inhibitor levamisole. 19FMRS and 19FMRSI were applied for the non-invasive measurement of DiFMUP hydrolysis. 19FMRS revealed a two-peak spectrum representing DiFMUP with an associated chemical shift for the hydrolysis product. Activation of DiFMUP by ALP yielded a characteristic pharmacokinetic profile, which was quantifiable using non-localized 19FMRS and enabled the development of a pharmacokinetic model of ALP activity. Application of 19FMRSI facilitated anatomically accurate, non-invasive imaging of ALP concentration and activity in rat bone. Thus, 19FMRSI represents a promising approach for the quantitative imaging of bone cell activity during bone formation with potential for both preclinical and clinical applications.