Synthetic and Nanotechnological Approaches for a Diagnostic Use of Manganese

Abstract

The development of multimodal imaging techniques such as positron emission tomography (PET) and magnetic resonance imaging (MRI) allows the contemporary obtaining of metabolic and morphological information. To fully exploit the complementarity of the two imaging modalities, the design of probes displaying radioactive and magnetic properties at the same time could be very beneficial. In this regard, transition metals offer appealing options, with manganese representing an ideal candidate. As nanosized imaging probes have demonstrated great value for designing advanced diagnostic/theranostic procedures, this work focuses on the potential of liposomal formulations loaded with a new synthesized paramagnetic Mn(II) chelates. Negatively charged liposomes were produced by thin-layer hydration method and extrusion. The obtained formulations were characterized in terms of size, surface charge, efficiency of encapsulation, stability over time, relaxivity, effective magnetic moment, and in vitro antiproliferative effect on human cells by means of the MTT assay. The negatively charged paramagnetic liposomes were monodisperse, with an average hydrodynamic diameter not exceeding 200 nm, and they displayed good stability and no cytotoxicity. As determined by optical emission spectroscopy, manganese complexes are loaded almost completely on liposomes maintaining their paramagnetic properties.

Development and Evaluation of the Magnetic Properties of a New Manganese (II) Complex: A Potential MRI Contrast Agent

“…Hence, even considering the experimental error, the value of μ eff found for the Mn4 complex slightly exceeds that expected for the Mn 2+ ion, probably due to residual traces of the initial reagents in the sample. We obtained values of μ eff consistent with the high-spin state of Mn 2+ also for Mn2 and Mn3 [ 17 ].…”

“…The manganese complexes [Mn(II)(PTA)(Cl) 2 (H 2 O) 2 ] (Mn2) and [Mn(II)(C 7 H 12 O 2 -N-C(=S)S) 2 ] (Mn3) were prepared and characterized as described in the literature [ 15 , 16 , 17 ]. Briefly, all compounds were prepared by reacting the Mn(II)Cl 2 ·4H 2 O (Mn1) with the PTA or dithiocarbamate ligands, respectively.…”

Oldie but Goodie: Is Technetium-99m Still a Treasure Trove of Innovation for Medicine? A Patents Analysis (2000–2022)

“…Last but not least the rising interest in the design of specific combinations of magnetic resonance and nuclear imaging contrast agents for multimodal assessments (e.g., PET/MRI) may contribute to the diffusion in clinical practice of new diagnostic and, in general, new molecular imaging approaches. 68 , 69 …”

“…Last but not least the rising interest in the design of specific combinations of magnetic resonance and nuclear imaging contrast agents for multimodal assessments (e.g., PET/MRI) may contribute to the diffusion in clinical practice of new diagnostic and, in general, new molecular imaging approaches. 68,69 Another potential reason is the great impulse given by the consolidation of alternative technologies for sustaining the production of technetium-99m. As reported in Figure 9, patent productivity for alternative processes for implementing technetium-99m remained almost silent for several years and then started as a response to the 2008−2009 and 2012−2013 global shortages, until becoming established in more recent years (and being the most representative in 2019).…”

“…A number of new molecular carriers with favorable characteristics are already available for the development of new probes, not only for nuclear medicine applications. Last but not least the rising interest in the design of specific combinations of magnetic resonance and nuclear imaging contrast agents for multimodal assessments (e.g., PET/MRI) may contribute to the diffusion in clinical practice of new diagnostic and, in general, new molecular imaging approaches. , …”