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In vivo detection and quantification of inflammation is a major goal in molecular imaging. Furthermore, cell-specific detection of inflammation would be a tremendous advantage in the characterization of many diseases. Here, we show how this goal can be achieved through the synergistic combination of nanotechnology and nuclear imaging. One of the most remarkable features of this hybrid approach is the possibility to tailor the pharmacokinetics of the nanomaterial-incorporated biomolecule and radionuclide. A good example of this approach is the covalent binding of a large amount of a neutrophil-specific, hydrophobic peptide on the surface of 68Ga core-doped nanoparticles. This new nano-radiotracer has been used for non-invasive in vivo detection of acute inflammation with very high in vivo labelling efficiency, i.e. a large percentage of labelled neutrophils. Furthermore, we demonstrate that the tracer is neutrophil-specific and yields images of neutrophil recruitment of unprecedented quality. Finally, the nano-radiotracer was successfully detected in chronic inflammation in atherosclerosis-prone ApoE−/− mice after several weeks on a high-fat diet. [ABSTRACT FROM AUTHOR]

Background: In vivo determination of regional pulmonary blood flow (PBF) is a valuable tool for the evaluation of many lung diseases. In this study, the use of Ga-DOTA PET for the in vivo quantitative determination of regional PBF is proposed. This methodology was implemented and tested in healthy pigs and validated using fluorescent microspheres. The study was performed on young large white pigs ( n = 4). To assess the reproducibility and consistency of the method, three PET scans were obtained for each animal. Each radiotracer injection was performed simultaneously to the injection of fluorescent microspheres. PBF images were generated applying a two-compartment exchange model over the dynamic PET images. PET and microspheres values were compared by regression analysis and Bland-Altman plot. Results: The capability of the proposed technique to produce 3D regional PBF images was demonstrated. The correlation evaluation between Ga-DOTA PET and microspheres showed a good and significant correlation ( r = 0.74, P < 0.001). Conclusions: Assessment of PBF with the proposed technique allows combining the high quantitative accuracy of PET imaging with the use of Ga/Ge generators. Thus, Ga-DOTA PET emerges as a potential inexpensive method for measuring PBF in clinical settings with an extended use. [ABSTRACT FROM AUTHOR]

Combination of complementary imaging techniques, like hybrid PET/MRI, allows protocols to be developed that exploit the best features of both. In order to get the best of these combinations the use of dual probes is highly desirable. On this sense the combination of biocompatible iron oxide nanoparticles and 68Ga isotope is a powerful development for the new generation of hybrid systems and multimodality approaches. Our objective was the synthesis and application of a chelator-free 68Ga-iron oxide nanotracer with improved stability, radiolabeling yield and in vivo performance in dual PET/MRI. We carried out the core doping of iron oxide nanoparticles, without the use of any chelator, by a microwave-driven protocol. The synthesis allowed the production of extremely small (2.5 nm) 68Ga core-doped iron oxide nanoparticles. The microwave approach allowed an extremely fast synthesis with a 90% radiolabeling yield and T1 contrast in MRI. With the same microwave approach the nano-radiotracer was functionalized in a fast and efficient way. We finally evaluated these dual targeting nanoparticles in an angiogenesis murine model by PET/MR imaging. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Contrast agents retaining high relaxivities at ultrahigh magnetic fields underpin an enhanced image sensitivity within derived MRI scans. By varying the Dy 3+ loading density inside a mesoporous silica architecture the dominant Curie effect can be effectively tuned so as to optimise T 2 contrast at magnetic fields as high as 11.7 T.

Background and Purpose: Non-invasive imaging methodologies, especially nuclear imaging techniques, have undergone an extraordinary development over the last years. Interest in the development of innovative tracers has prompted the emergence of new nanomaterials with a focus on nuclear imaging and therapeutical applications. Among others, organic nanoparticles are of the highest interest due to their translational potential related to their biocompatibility and biodegradability. Our group has developed a promising new type of biocompatible nanomaterials, sphingomyelin nanoemulsions (SNs). The aim of this study is to explore the potential of SNs for nuclear imaging applications., Methods: Ready-to-label SNs were prepared by a one-step method using lipid derivative chelators and characterized in terms of their physicochemical properties. Stability was assessed under storage and after incubation with human serum. Chelator-functionalized SNs were radiolabeled with 67 Ga and 68 Ga, and the radiochemical yield (RCY), radiochemical purity (RCP) and radiochemical stability (RCS) were determined. Finally, the biodistribution of 67/68 Ga-SNs was evaluated in vivo and ex vivo., Results: Here, we describe a simple and mild one-step method for fast and efficient radiolabeling of SNs with 68 Ga and 67 Ga radioisotopes. In vivo experiments showed that 67/68 Ga-SNs can efficiently and indistinctly be followed up by PET and SPECT. Additionally, we proved that the biodistribution of the 67/68 Ga-SNs can be conveniently modulated by modifying the surface properties of different hydrophilic polymers, and therefore the formulation can be further adapted to the specific requirements of different biomedical applications., Conclusion: This work supports 67/68 Ga-SNs as a novel probe for nuclear imaging with tunable biodistribution and with great potential for the future development of nanotheranostics., Competing Interests: The author reports no conflicts of interest in this work., (© 2021 Díez-Villares et al.)

: The use of nanoparticulate systems as contrast agents for magnetic resonance imaging (MRI) is well-established and known to facilitate an enhanced image sensitivity within scans of a particular pathological region of interest. Such a capability can enable both a non-invasive diagnosis and the monitoring of disease progression/response to treatment. In this review, magnetic nanoparticles that exhibit a bio-responsive MR relaxivity are discussed, with pH-, enzyme-, biomolecular-, and protein-responsive systems considered. The ability of a contrast agent to respond to a biological stimulus provides not only enriched diagnostic capabilities over corresponding non-responsive analogues, but also an improved longitudinal monitoring of specific physiological conditions., Competing Interests: The authors declare no conflict of interest.

In vivo detection and quantification of inflammation is a major goal in molecular imaging. Furthermore, cell-specific detection of inflammation would be a tremendous advantage in the characterization of many diseases. Here, we show how this goal can be achieved through the synergistic combination of nanotechnology and nuclear imaging. One of the most remarkable features of this hybrid approach is the possibility to tailor the pharmacokinetics of the nanomaterial-incorporated biomolecule and radionuclide. A good example of this approach is the covalent binding of a large amount of a neutrophil-specific, hydrophobic peptide on the surface of 68 Ga core-doped nanoparticles. This new nano-radiotracer has been used for non-invasive in vivo detection of acute inflammation with very high in vivo labelling efficiency, i.e. a large percentage of labelled neutrophils. Furthermore, we demonstrate that the tracer is neutrophil-specific and yields images of neutrophil recruitment of unprecedented quality. Finally, the nano-radiotracer was successfully detected in chronic inflammation in atherosclerosis-prone ApoE -/- mice after several weeks on a high-fat diet.

Combination of complementary imaging techniques, like hybrid PET/MRI, allows protocols to be developed that exploit the best features of both. In order to get the best of these combinations the use of dual probes is highly desirable. On this sense the combination of biocompatible iron oxide nanoparticles and 68Ga isotope is a powerful development for the new generation of hybrid systems and multimodality approaches. Our objective was the synthesis and application of a chelator-free 68Ga-iron oxide nanotracer with improved stability, radiolabeling yield and in vivo performance in dual PET/MRI. We carried out the core doping of iron oxide nanoparticles, without the use of any chelator, by a microwave-driven protocol. The synthesis allowed the production of extremely small (2.5 nm) 68Ga core-doped iron oxide nanoparticles. The microwave approach allowed an extremely fast synthesis with a 90% radiolabeling yield and T1 contrast in MRI. With the same microwave approach the nano-radiotracer was functionalized in a fast and efficient way. We finally evaluated these dual targeting nanoparticles in an angiogenesis murine model by PET/MR imaging. Copyright © 2016 John Wiley & Sons, Ltd., (Copyright © 2016 John Wiley & Sons, Ltd.)

Multifunctional nanoparticles are usually produced by sequential synthesis, with long multistep protocols. Our study reports a generic modular strategy for the parallel one-step multifunctionalization of different hydrophobic nanoparticles. The method was designed and developed by taking advantage of the natural noncovalent interactions between the fatty acid binding sites of the bovine serum albumin (BSA) and the aliphatic surfactants on different inorganic nanomaterials. As a general example of the approach, three different nanoparticles-iron oxide, upconverting nanophosphors, and gold nanospheres-were nanoemulsified in water with BSA. To support specific applications, multifunctional capability was incorporated with a variety of previously modified BSA modules. These modules include different conjugated groups, such as chelating agents for (68)Ga or (89)Zr and ligand molecules for enhanced in vivo targeting. A large library of 13 multimodal contrast agents was developed with this convergent strategy. This platform allows a highly versatile and easy tailoring option for efficient incorporation of functional groups. Finally, as demonstration of this versatility, a bimodal (PET/MRI) probe including a maleimide-conjugated BSA was selectively synthesized with an RGD peptide for in vivo imaging detection of tumor angiogenesis.