Influence of SPION Surface Coating on Magnetic Properties and Theranostic Profile.

This study aimed to develop multifunctional nanoplatforms for both cancer imaging and therapy using superparamagnetic iron oxide nanoparticles (SPIONs). Two distinct synthetic methods, reduction-precipitation (MR/P) and co-precipitation at controlled pH (MpH), were explored, including the assessment of the coating's influence, namely dextran and gold, on their magnetic properties. These SPIONs were further functionalized with gadolinium to act as dual T1/T2 contrast agents for magnetic resonance imaging (MRI). Parameters such as size, stability, morphology, and magnetic behavior were evaluated by a detailed characterization analysis. To assess their efficacy in imaging and therapy, relaxivity and hyperthermia experiments were performed, respectively. The results revealed that both synthetic methods lead to SPIONs with similar average size, 9 nm. Mössbauer spectroscopy indicated that samples obtained from MR/P consist of approximately 11-13% of Fe present in magnetite, while samples obtained from MpH have higher contents of 33-45%. Despite coating and functionalization, all samples exhibited superparamagnetic behavior at room temperature. Hyperthermia experiments showed increased SAR values with higher magnetic field intensity and frequency. Moreover, the relaxivity studies suggested potential dual T1/T2 contrast agent capabilities for the coated SPpH-Dx-Au-Gd sample, thus demonstrating its potential in cancer diagnosis.

Peptide-Conjugated MRI Probe Targeted to Netrin-1, a Novel Metastatic Breast Cancer Biomarker.

Despite significant progress in cancer imaging and treatment over the years, early diagnosis and metastasis detection remain a challenge. Molecular magnetic resonance imaging (MRI), with its high resolution, can be well adapted to fulfill this need, requiring the design of contrast agents which target specific tumor biomarkers. Netrin-1 is an extracellular protein overexpressed in metastatic breast cancer and implicated in tumor progression and the appearance of metastasis. This study focuses on the design and preclinical evaluation of a novel Netrin-1-specific peptide-based MRI probe, GdDOTA-KKTHDAVR (Gd-K), to visualize metastatic breast cancer. The targeting peptide sequence was identified based on the X-ray structure of the complex between Netrin-1 and its transmembrane receptor DCC. Molecular docking simulations support the probe design. In vitro studies evidenced submicromolar affinity of Gd-K for Netrin-1 (KD = 0.29 µM) and good MRI efficacy (proton relaxivity, r1 = 4.75 mM-1 s-1 at 9.4 T, 37 °C). In vivo MRI studies in a murine model of triple-negative metastatic breast cancer revealed successful tumor visualization at earlier stages of tumor development (smaller tumor volume). Excellent signal enhancement, 120% at 2 min and 70% up to 35 min post injection, was achieved (0.2 mmol/kg injected dose), representing a reasonable imaging time window and a superior contrast enhancement in the tumor as compared to Dotarem injection.

["New Modalities in Cancer Imaging and Therapy" XVth edition of the workshop organized by the network "Tumor Targeting, Imaging, Radiotherapies" of the Cancéropôle Grand-Ouest, 5-8 October 2022, France]. / « New Modalities in Cancer Imaging and Therapy ¼ XVe édition de l'atelier organisé par le réseau « Vectorisation, Imagerie, Radiothérapies ¼ du Cancéropôle Grand-Ouest, 5­8 octobre 2022, Erquy, France.

The fifteenth edition of the international workshop organized by the "Tumour Targeting and Radiotherapies network" of the Cancéropôle Grand-Ouest focused on the latest advances in internal and external radiotherapy from different disciplinary angles: chemistry, biology, physics, and medicine. The workshop covered several deliberately diverse topics: the role of artificial intelligence, new tools for imaging and external radiotherapy, theranostic aspects, molecules and contrast agents, vectors for innovative combined therapies, and the use of alpha particles in therapy.

Optimized Methods for the Surface Immobilization of Collagens and Collagen Binding Assays.

Fibrosis occurs in various tissues as a reparative response to injury or damage. If excessive, however, fibrosis can lead to tissue scarring and organ failure, which is associated with high morbidity and mortality. Collagen is a key driver of fibrosis, with type I and type III collagen being the primary types involved in many fibrotic diseases. Unlike conventional protocols used to immobilize other proteins (e.g., elastin, albumin, fibronectin, etc.), comprehensive protocols to reproducibly immobilize different types of collagens in order to produce stable coatings are not readily available. Immobilizing collagen is surprisingly challenging because multiple experimental conditions may affect the efficiency of immobilization, including the type of collagen, the pH, the temperature, and the type of microplate used. Here, a detailed protocol to reproducibly immobilize and quantify type I and III collagens resulting in stable and reproducible gels/films is provided. Furthermore, this work demonstrates how to perform, analyze, and interpret in vitro time-resolved fluorescence binding studies to investigate the interactions between collagens and candidate collagen-binding compounds (e.g., a peptide conjugated to a metal chelate carrying, for example, europium [Eu(III)]). Such an approach can be universally applied to various biomedical applications, including the field of molecular imaging to develop targeted imaging probes, drug development, cell toxicity studies, cell proliferation studies, and immunoassays.

["Imaging of diagnostic and therapeutic biomarkers in oncology" XIIIth edition of the workshop organised by the « Vectorisation, Imagerie, Radiothérapies ¼ network of the Cancéropôle Grand-Ouest, September 25-28, 2019, Le Bono, France]. / "Imaging of diagnostic and therapeutic biomarkers in oncology" XIIIe édition du workshop organisé par le réseau « Vectorisation, Imagerie, Radiothérapies ¼ du Cancéropôle Grand-Ouest, 25­28 septembre 2019, Le Bono, France.

The thirteenth edition of the workshop focused on the last developments on oncologic imaging techniques. Our goal was purposely large, consisting in bringing together chemists, biologists, physicists, pharmacists and physicians to discuss these imaging developments. The meeting focused in four main topics: i) the evolution of imaging modalities such as photoacoustic or the latest PET (positrons emission tomography) imaging progress; ii) the improvements in imaging process; iii) the numerous contributions of chemistry towards medical imaging and iv) novel approaches of nuclear medicine in therapeutic monitoring strategies and theranostic aspects.

Doxorubicin-Sensitized Luminescence of NIR-Emitting Ytterbium Liposomes: Towards Direct Monitoring of Drug Release.

Drug-loaded liposomes are typical examples of nanomedicines. We show here that doxorubicin, the anti-cancer agent in the liposomal drug Doxil, can sensitize Ytterbium (Yb3+ ) and generate its near-infrared (NIR) emission. When doxorubicin and amphiphilic Yb3+ chelates are incorporated into liposomes, the sensitized emission of Yb3+ is dependent on the integrity of the particles, which can be used to monitor drug release. We also established the first demonstration that the NIR Yb3+ emission signal is observable in living mice following intratumoral injection of the Yb3+ -doxorubicin-liposomes, using a commercial macroscopic setup equipped with a NIR camera.

Concentration-Dependent Interactions of Amphiphilic PiB Derivative Metal Complexes with Amyloid Peptides Aß and Amylin*.

Metal chelates targeted to amyloid peptides are widely explored as diagnostic tools or therapeutic agents. The attachment of a metal complex to amyloid recognition units typically leads to a decrease in peptide affinity. We show here that by separating a macrocyclic GdL chelate and a PiB targeting unit with a long hydrophobic C10 linker, it is possible to attain nanomolar affinities for both Aß1-40 (Kd =4.4 nm) and amylin (Kd =4.5 nm), implicated, respectively in Alzheimer's disease and diabetes. The Scatchard analysis of surface plasmon resonance data obtained for a series of amphiphilic, PiB derivative GdL complexes indicate that their Aß1-40 or amylin binding affinity varies with their concentration, thus micellar aggregation state. The GdL chelates also affect peptide aggregation kinetics, as probed by thioflavin-T fluorescence assays. A 2D NMR study allowed identifying that the hydrophilic region of Aß1-40 is involved in the interaction between the monomer peptide and the Gd3+ complex. Finally, ex vivo biodistribution experiments were conducted in healthy mice by using 111 In labeled analogues. Their pancreatic uptake, ∼3 %ID g-1 , is promising to envisage amylin imaging in diabetic animals.

Concentration-Dependent Interactions of Amphiphilic PiB Derivative Metal Complexes with Amyloid Peptides Aß and Amylin*.

Invited for the cover of this issue are Jean-François Morfin and Éva Tóth at the CNRS in Orléans, and their collaborators from University of Debrecen, University of Coimbra and Université de Toulouse. The image depicts that when an amphiphilic compound is intravenously injected, monomer, pre-micellar and micellar forms can co-exist in the blood and have different affinities for amyloid peptides. Read the full text of the article at 10.1002/chem.202004000.

Dual Imaging Gold Nanoplatforms for Targeted Radiotheranostics.

Gold nanoparticles (AuNPs) are interesting for the design of new cancer theranostic tools, mainly due to their biocompatibility, easy molecular vectorization, and good biological half-life. Herein, we report a gold nanoparticle platform as a bimodal imaging probe, capable of coordinating Gd3+ for Magnetic Resonance Imaging (MRI) and 67Ga3+ for Single Photon Emission Computed Tomography (SPECT) imaging. Our AuNPs carry a bombesin analogue with affinity towards the gastrin releasing peptide receptor (GRPr), overexpressed in a variety of human cancer cells, namely PC3 prostate cancer cells. The potential of these multimodal imaging nanoconstructs was thoroughly investigated by the assessment of their magnetic properties, in vitro cellular uptake, biodistribution, and radiosensitisation assays. The relaxometric properties predict a potential T1- and T2- MRI application. The promising in vitro cellular uptake of 67Ga/Gd-based bombesin containing particles was confirmed through biodistribution studies in tumor bearing mice, indicating their integrity and ability to target the GRPr. Radiosensitization studies revealed the therapeutic potential of the nanoparticles. Moreover, the DOTA chelating unit moiety versatility gives a high theranostic potential through the coordination of other therapeutically interesting radiometals. Altogether, our nanoparticles are interesting nanomaterial for theranostic application and as bimodal T1- and T2- MRI / SPECT imaging probes.

Gadolinium and Platinum in Tandem: Real-time Multi-Modal Monitoring of Drug Delivery by MRI and Fluorescence Imaging.

A novel dual-imaging cisplatin-carrying molecular cargo capable of performing simultaneous optical and MR imaging is reported herein. This long-lasting MRI contrast agent (r1 relaxivity of 23.4 mM-1s-1 at 3T, 25 oC) is a photo-activated cisplatin prodrug (PtGdL) which enables real-time monitoring of anti-cancer efficacy. PtGdL is a model for monitoring the drug delivery and anti-cancer efficacy by MRI with a much longer retention time (24 hours) in several organs such as renal cortex and spleen than GdDOTA and its motif control GdL. Upon complete release of cisplatin, all PtGdL is converted to GdL enabling subsequent MRI analyses of therapy efficacy within its reasonably short clearance time of 4 hours. There is also responsive fluorescence enhancement for monitoring by photon-excitation.

A novel tetraazamacrocycle bearing a thiol pendant arm for labeling biomolecules with radiolanthanides.

The novel tetraazamacrocycle 10-(2-sulfanylethyl)-1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid (H(4)DO3ASH) was synthesized and characterized by multinuclear NMR spectroscopy, 2D NMR techniques and mass spectrometry. The protonation constants of H(4)DO3ASH were determined by potentiometry at 25 degrees C in 0.1 M KCl ionic strength, and the protonation sequence was assigned based on (1)H- and (13)C-NMR titrations. The stability constants of the DO3ASH complexes with Ce(3+), Sm(3+) and Ho(3+) have been determined by potentiometry and UV-Vis spectroscopy. They are very similar, comprising a narrow range (logK(ML) = 21.0-22.0). UV-Vis spectrophotometric data on Ce(3+)-DO3ASH and relaxivity measurements on the Gd(3+)-DO3ASH complex suggest that the thiol group does not coordinate to the metal, even in its deprotonated form. For labeling with radioactive lanthanides(iii), various conditions were tested and both complexes, (153)Sm/(166)Ho-DO3ASH, were obtained in quantitative yield (> 98%) at pH = 6. At room temperature, formation kinetics were faster for the (153)Sm than for the (166)Ho complex (5 vs. 60 min, respectively, needed for complete labeling). The stability of these hydrophilic complexes ((153)Sm, logD = -2.1; (166)Ho, logD = -1.6) has been studied in different buffers, in human serum and in the presence of excess of cysteine and glutathione. (153)Sm-DO3ASH has shown a high stability under these conditions and a relatively low protein binding (2.1%), while (166)Ho-DO3ASH was less stable, including in the presence of cysteine and glutathione, and had a slightly higher protein binding (6.7%). In vivo studies have been performed only for the more stable (153)Sm-DO3ASH complex and its biological profile and in vivo stability has been compared to that of (153)Sm-DO3A in the same animal model. The biodistribution profile presents a similar trend with rapid total excretion from the whole animal body, mainly via the urinary pathway. The most striking difference found is related to a slightly slower clearance of (153)Sm-DO3ASH from organs like blood, bone and muscle as compared to (153)Sm-DO3A. Additionally, the fraction of (153)Sm-DO3ASH taken by the hepatobiliar tract is also modestly higher than that of (153)Sm-DO3A.

13- and 14-membered macrocyclic ligands containing methylcarboxylate or methylphosphonate pendant arms: chemical and biological evaluation of their (153)Sm and (166)Ho complexes as potential agents for therapy or bone pain palliation.

The stability constants of La(3+), Sm(3+) and Ho(3+) complexes with 13- and 14-membered macrocycles having methylcarboxylate (trita and teta) or methylphosphonate (tritp and tetp) arms were determined. All the ligands were labelled with (153)Sm and (166)Ho in order to evaluate the effect of the macrocyclic cavity size and type of appended arms on their in vitro and in vivo behaviour. The radiolabelling efficiency was found to be higher than 98% for all the complexes, except for those of tetp. All radiocomplexes studied are hydrophilic with an overall negative charge and low plasmatic protein binding. Good in vitro stability in physiological media and human serum was found for all complexes, except the (153)Sm/(166)Ho-teta, which are unstable in phosphate buffer (pH 7.4). In vitro hydroxyapatite (HA) adsorption studies indicated that (153)Sm/(166)Ho-tritp complexes bind to HA having the (166)Ho complex the highest degree of adsorption (>80%, 10 mg). Biodistribution studies in mice demonstrated that (153)Sm/(166)Ho-trita complexes have a fast tissue clearance with more than 95% of the injected activity excreted after 2 h, value that is comparable to the corresponding dota complexes. In contrast, the (153)Sm-teta complex has a significantly lower total excretion. (153)Sm/(166)Ho-tritp complexes are retained by the bone, particularly (166)Ho-tritp that has 5-6% (% I.D./g) bone uptake and also a high rate of total excretion. Thus, these studies support the potential interest of (153)Sm/(166)Ho-trita complexes for therapy when conjugated to a biomolecule and the potential usefulness of the (166)Ho-tritp complex in bone pain palliation.

Radiopharmaceuticals for targeted radiotherapy.

This work intends to find specific radiopharmaceuticals for cancer therapy based on beta (153Sm and 166Ho) or Auger (99Tc(m)) emitter radionuclides, using cyclic and acyclic polyamines as bifunctional chelators. These chelators are designed to allow the binding of a tumour seeking biomolecule and/or a DNA intercalator. The cyclic amines, such as 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid, 1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetraacetic acid and 1,4,7,10-tetraazacyclotridecane-1,4,7,10-tetraacetic acid, were radiolabelled with 153Sm and 166Ho. The radiochemical and biological behaviour of the resulting complexes were evaluated in order to assess their potential as building blocks for the attachment of selected biomolecules, with the aim of further applying them for the development of specific therapeutic radiopharmaceuticals. Novel pyrazolyldiamines, bearing a DNA intercalating anthracenyl fragment, were also explored to synthesize radioactive complexes with the fac-[99Tc(m)(CO)]3]+ moiety. The identity of these 99Tc(m) tricarbonyl complexes was confirmed by high-performance liquid chromatography comparison with rhenium congeners fully characterized. By including a DNA intercalator into the chelator framework, we expect to induce more efficient and selective damage to the DNA of cancer cells by the action of the short-range Auger electrons emitted by 99Tc(m).