The investigation of the organization, function, and dynamics of genomic DNA in chromatin is a challenging topic that can be addressed by fluorescence microscopy. Conventional DNA labeling methods employ metabolically active non-natural nucleoside analogs with subsequent secondary labeling with antibodies or fluorescent tags. But these methods do not allow for truly real-time monitoring of the nascent DNA in live cells due to the background signal of non-incorporated labeled nucleosides abundantly present in the intracellular space.
The researchers led by <a href="https://www.uochb.cz/en/directory/92/tomas-kraus">Tomáš Kraus</a> from IOCB Prague and <a href="https://hocek.group.uochb.cz/en">Michal Hocek</a> from IOCB Prague and Charles University designed and synthesized a novel 2′-deoxycytidine triphosphate (dCTP) nucleotide modified with a thiazole orange fluorophore, which can be incorporated into DNA strand by DNA polymerases in vitro as well as in live cells. Upon incorporation of the modified nucleotide into DNA, the fluorescence of thiazole orange moiety exhibits a shorter lifetime that differs significantly from the intercalated non-incorporated form.
Due to this measurable difference, DNA synthesis in live cells can be monitored in real-time using fluorescence lifetime imaging microscopy. This has allowed the scientists to distinguish and monitor cells which are actively synthesizing DNA from the very first moments after the probe treatment.
<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/UOCHB_Novel_fluorescent_probe_for_real_time_imaging_of_nascent_DNA_in_live_cells_Real_time_imaging_of_in_cellulo_incorporation_of_d_COTP_into_genomic_DNA_a0cb58c5a1.jpg" alt="IOCB Prague: Real-time imaging of in cellulo incorporation of dCOTP into genomic DNA."/>
This novel approach, published in Angewandte Chemie International Edition journal, can be exploited in studies of genomic DNA organization, dynamics, and function.

Novel fluorescent probe for real-time imaging of nascent DNA in live cells

Dr. Vojtěch Dočekal and <a href="https://orgchem.natur.cuni.cz/vesely/">Prof. Jan Veselý</a> from the <a href="https://lcms.labrulez.com/companies/257">Department of Organic Chemistry</a>, <a href="https://lcms.labrulez.com/companies/16">Faculty of Science, Charles University</a> described a new highly efficient method for the preparation of planar chiral compounds.
The method based on organocatalytic desymmetrization was published in the prestigious journal <a href="https://www.nature.com/articles/s41467-024-47407-0">Nature Communications</a>. Congratulations!
Planar chiral [2.2]paracyclophanes contain two suitably substituted benzene nuclei linked at the para positions by ethylene bridges. Such compounds have a wide range of applications either as ligands or catalysts in synthetic chemistry, but also in materials science or medicine. Despite the wide range of applications, only a limited number of studies have been described for their preparation in enantiomerically pure form.
The methodology developed in the asymmetric synthesis group is based on the highly efficient desymmetrization of prochiral [2.2]paracyclophanes substituted with two formyl groups in suitable positions. In a key transformation, one of the prochiral aldehyde groups is selectively transformed to an ester, leading to the formation of a planar chiral product using asymmetric synthesis methods. Methodologies using catalysis by low molecular weight chiral catalysts derived from natural amino acids, more specifically using so-called N-heterocyclic carbenes, have proven to be highly effective for such asymmetric esterification.
In addition to the optimization of the methodology, a study of the scope of application of the developed transformation, or a study of the synthetic applicability of the chiral products, the publication includes a detailed experimental mechanistic study that reveals interesting differences in the reactivity of the starting diformyl[2.2]paracyclophanes.

An innovative approach to planar chiral substances

A research team from <a href="https://icpms.labrulez.com/companies/62">IOCB Prague</a>, working in collaboration with the University of Tübingen, Germany, and the <a href="https://icpms.labrulez.com/companies/16">Faculty of Science, Charles University</a>, has developed a new type of contrast agent that can be used in both magnetic resonance imaging (MRI) and positron emission tomography (PET). This breakthrough resolves a major issue that previously hindered the integration of these two imaging techniques into a single device. Their discovery has the potential to significantly enhance diagnosis and subsequent treatment, particularly for kidney diseases and tumors. The research was published in Angewandte Chemie.
For a long time, medicine has been searching for new ways to refine and streamline available imaging methods. The ultimate goal was to combine the benefits of MRI and PET. While MRI is exceptional for imaging internal organs and tissues with high water content, PET can image even very small amounts of matter, making it capable of sensitively detecting molecular markers, for instance, in cancer cells. The fusion of both techniques was challenging because the strong magnetic field in MRI complicates the functioning of the electronics required for PET. However, this issue has been overcome, and hybrid PET/MRI machines are appearing in hospitals as the most advanced imaging technology. The remaining challenge was the development of a dual-purpose contrast agent that would work with PET and MRI simultaneously. The collaborative discovery by Czech and German researchers may be the solution.
<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/UOCHB_Nova_PET_MRI_kontrastni_latka_vyvinuta_v_UOCHB_slibuje_vcasne_odhaleni_skrytych_nemoci_Soucasne_PET_MRI_zobrazeni_zdravych_a_poskozenych_mysich_ledvin_pomoci_dualni_k_7492a0be78.jpg" alt="IOCB Prague: Current PET/MRI imaging of healthy and damaged mouse kidneys using the dual contrast agent [18F][Gd(FL1)]. The imaging provides consistent signals from both PET and MRI. In healthy kidneys, the center of the kidneys appears dark in the MRI image and very bright in the PET image, indicating normal excretion of the contrast agent. The onset of impaired function in one kidney is indicated by the accumulation of the contrast agent and its slow excretion. Precise mapping of MRI and PET data ensures detailed morphological and quantitative analysis of kidney impairment."/>
The described approach is simple and effective. <a href="https://lcms.labrulez.com/articles?search=Miloslav+Pol%C3%A1%C5%A1ek">Dr. Miloslav Polášek</a>, head of the <a href="https://polasek.group.uochb.cz/en">Coordination Chemistry group</a> at IOCB Prague, where the work started, explains: “Previous attempts to make PET/MRI probes aimed to achieve advanced and specialized functions, which led to complicated molecules with difficult synthesis and a narrow scope of use. We turned this around by designing a molecule that is simple to use and has broad applicability, one that radiologists will intuitively know how to use. It replicates all the favorable properties of current clinical MRI contrast agents and also provides a PET signal. This adds another dimension of information, improving accuracy and opening new diagnostic applications.”
“Our solution is a cleverly designed molecule that combines gadolinium and radioactive fluorine-18, which is commonly used in medical scans and is easy to obtain. Connecting these two parts required overcoming several problems, including the large difference in the amounts needed for MRI and PET images. We solved this by using an innovative technique to swap nonradioactive fluorine atoms in the MRI contrast agent for radioactive fluorine-18 atoms. The reaction is elegant, fast, and effective. In less than 30 minutes, we can use automated synthesis to prepare enough of this agent to treat five patients,” says Dr. Jan Kretschmer, one of Dr. Polášek’s former PhD students and the first co-author of the study, who currently works at the Werner Siemens Imaging Center at the University of Tübingen in the group of Prof. André Ferreira Martins.
<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/UOCHB_Nova_PET_MRI_kontrastni_latka_vyvinuta_v_UOCHB_slibuje_vcasne_odhaleni_skrytych_nemoci_Dr_Miloslav_Polasek_vedouci_skupiny_Koordinacni_chemie_UOCHB_AV_CR_5b95bcc5bc.jpg" alt="IOCB Prague: Dr. Miloslav Polášek, head of the Coordination Chemistry group at IOCB Prague."/>
Prof. Martins describes a potentially groundbreaking discovery made during testing in a mouse model: “Unexpectedly, we found that one seemingly healthy mouse had kidney problems. The right kidney showed systemic filtration patterns that could only be detected with the simultaneous detection of PET and MRI. This approach enabled us to monitor noninvasively, in real time, the biochemical behavior, distribution, and accumulation of the probe in living, healthy subjects, thereby explaining its unexpected behavior. This method represents a pioneering step toward personalized diagnostics, showcasing the significant diagnostic potential of our hybrid molecule. This is a revolutionary discovery in the field of precise imaging. We are on a path that will eventually allow us to determine not only what disease a patient has but also the stage, type, and aggressiveness of the condition.”
The new hybrid contrast agent is patented, and researchers are seeking potential investors. According to Dr. Polášek, this compound, originating from IOCB Prague, has properties that make it the first serious candidate for a PET/MRI agent usable in a clinical setting.
<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/UOCHB_Nova_PET_MRI_kontrastni_latka_vyvinuta_v_UOCHB_slibuje_vcasne_odhaleni_skrytych_nemoci_Dr_Miloslav_Polasek_Dr_Jan_Kretschmer_prvni_spoluautor_studie_Werner_Siemens_0962294d9a.jpg" alt="IOCB Prague / Tomáš Belloň: Dr. Miloslav Polášek, head of the Coordination Chemistry group at IOCB Prague (left), and Dr. Jan Kretschmer, Werner Siemens Imaging Center, University of Tübingen"/>

New PET/MRI probe developed by IOCB Prague promises early discovery of covert diseases

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The Department of Organic Chemistry, Faculty of Science, Charles University is engaged in teaching and scientific research in the fields of synthetic organic chemistry, bioorganic and medicinal chemistry, materials chemistry, and electrochemistry.

Department of Organic Chemistry, Faculty of Science, Charles University

The Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences (IOCB Prague) is a leading scientific institution in the Czech Republic, recognized internationally. Its primary mission is basic research in the fields of chemical biology and medicinal chemistry, organic and material oriented chemistry, chemistry of natural compounds, biochemistry and molecular biology, physical chemistry, theoretical chemistry, and analytical chemistry. 

Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences

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