Macrophage PET imaging in mouse models of cardiovascular disease and cancer with an apolipoprotein-inspired radiotracer

Macrophages are key inflammatory mediators in many pathological conditions, including cardiovascular disease (CVD) and cancer, the leading causes of morbidity and mortality worldwide. This makes macrophage burden a valuable diagnostic marker and several strategies to monitor these cells have been reported. However, such strategies are often high-priced, non-specific, invasive, and/or not quantitative. Here, we developed a positron emission tomography (PET) radiotracer based on apolipoprotein A1 (ApoA1), the main protein component of high-density lipoprotein (HDL), which has an inherent affinity for macrophages. We radiolabeled an ApoA1-mimetic peptide (mA1) with zirconium-89 (89Zr) to generate a lipoprotein-avid PET probe (89Zr-mA1). We first characterized 89Zr-mA1's affinity for lipoproteins in vitro by size exclusion chromatography. To study 89Zr-mA1's in vivo behavior and interaction with endogenous lipoproteins, we performed extensive studies in wildtype C57BL/6 and Apoe-/- hypercholesterolemic mice. Subsequently, we used in vivo PET imaging to study macrophages in melanoma and myocardial infarction using mouse models. The tracer's cell specificity was assessed by histology and mass cytometry (CyTOF). Our data show that 89Zr-mA1 associates with lipoproteins in vitro. This is in line with our in vivo experiments, in which we observed longer 89Zr-mA1 circulation times in hypercholesterolemic mice compared to C57BL/6 controls. 89Zr-mA1 displayed a tissue distribution profile similar to ApoA1 and HDL, with high kidney and liver uptake as well as substantial signal in the bone marrow and spleen. The tracer also accumulated in tumors of melanoma-bearing mice and in the ischemic myocardium of infarcted animals. In these sites, CyTOF analyses revealed that natZr-mA1 was predominantly taken up by macrophages. Our results demonstrate that 89Zr-mA1 associates with lipoproteins and hence accumulates in macrophages in vivo. 89Zr-mA1's high uptake in these cells makes it a promising radiotracer for non-invasively and quantitatively studying conditions characterized by marked changes in macrophage burden.

Acid ceramidase regulates innate immune memory

Innate immune memory, also called "trained immunity," is a functional state of myeloid cells enabling enhanced immune responses. This phenomenon is important for host defense, but also plays a role in various immune-mediated conditions. We show that exogenously administered sphingolipids and inhibition of sphingolipid metabolizing enzymes modulate trained immunity. In particular, we reveal that acid ceramidase, an enzyme that converts ceramide to sphingosine, is a potent regulator of trained immunity. We show that acid ceramidase regulates the transcription of histone-modifying enzymes, resulting in profound changes in histone 3 lysine 27 acetylation and histone 3 lysine 4 trimethylation. We confirm our findings by identifying single-nucleotide polymorphisms in the region of ASAH1, the gene encoding acid ceramidase, that are associated with the trained immunity cytokine response. Our findings reveal an immunomodulatory effect of sphingolipids and identify acid ceramidase as a relevant therapeutic target to modulate trained immunity responses in innate immune-driven disorders.

Multiparametric Immunoimaging Maps Inflammatory Signatures in Murine Myocardial Infarction Models

In the past 2 decades, research on atherosclerotic cardiovascular disease has uncovered inflammation to be a key driver of the pathophysiological process. A pressing need therefore exists to quantitatively and longitudinally probe inflammation, in preclinical models and in cardiovascular disease patients, ideally using non-invasive methods and at multiple levels. Here, we developed and employed in vivo multiparametric imaging approaches to investigate the immune response following myocardial infarction. The myocardial infarction models encompassed either transient or permanent left anterior descending coronary artery occlusion in C57BL/6 and Apoe-/-mice. We performed nanotracer-based fluorine magnetic resonance imaging and positron emission tomography (PET) imaging using a CD11b-specific nanobody and a C-C motif chemokine receptor 2-binding probe. We found that immune cell influx in the infarct was more pronounced in the permanent occlusion model. Further, using 18F-fluorothymidine and 18F-fluorodeoxyglucose PET, we detected increased hematopoietic activity after myocardial infarction, with no difference between the models. Finally, we observed persistent systemic inflammation and exacerbated atherosclerosis in Apoe-/- mice, regardless of which infarction model was used. Taken together, we showed the strengths and capabilities of multiparametric imaging in detecting inflammatory activity in cardiovascular disease, which augments the development of clinical readouts.

[French practical guidelines for the diagnosis and management of IPF - 2021 update, full version]

BACKGROUND

Since the previous French guidelines were published in 2017, substantial additional knowledge about idiopathic pulmonary fibrosis has accumulated.

METHODS

Under the auspices of the French-speaking Learned Society of Pulmonology and at the initiative of the coordinating reference center, practical guidelines for treatment of rare pulmonary diseases have been established. They were elaborated by groups of writers, reviewers and coordinators with the help of the OrphaLung network, as well as pulmonologists with varying practice modalities, radiologists, pathologists, a general practitioner, a head nurse, and a patients' association. The method was developed according to rules entitled "Good clinical practice" in the overall framework of the "Guidelines for clinical practice" of the official French health authority (HAS), taking into account the results of an online vote using a Likert scale.

RESULTS

After analysis of the literature, 54 recommendations were formulated, improved, and validated by the working groups. The recommendations covered a wide-ranging aspects of the disease and its treatment: epidemiology, diagnostic modalities, quality criteria and interpretation of chest CT, indication and modalities of lung biopsy, etiologic workup, approach to familial disease entailing indications and modalities of genetic testing, evaluation of possible functional impairments and prognosis, indications for and use of antifibrotic therapy, lung transplantation, symptom management, comorbidities and complications, treatment of chronic respiratory failure, diagnosis and management of acute exacerbations of fibrosis.

CONCLUSION

These evidence-based guidelines are aimed at guiding the diagnosis and the management in clinical practice of idiopathic pulmonary fibrosis.

Acidic nanoparticles protect against α-synuclein-induced neurodegeneration through the restoration of lysosomal function

Parkinson's disease (PD) is an age‐related neurodegenerative disorder characterized by the loss of dopaminergic neurons in the substantia nigra, associated with the accumulation of misfolded α‐synuclein and lysosomal impairment, two events deemed interconnected. Protein aggregation is linked to defects in degradation systems such as the autophagy‐lysosomal pathway, while lysosomal dysfunction is partly related to compromised acidification. We have recently proven that acidic nanoparticles (aNPs) can re‐acidify lysosomes and ameliorate neurotoxin‐mediated dopaminergic neurodegeneration in mice. However, no lysosome‐targeted approach has yet been tested in synucleinopathy models in vivo. Here, we show that aNPs increase α‐synuclein degradation through enhancing lysosomal activity in vitro. We further demonstrate in vivo that aNPs protect nigral dopaminergic neurons from cell death, ameliorate α‐synuclein pathology, and restore lysosomal function in mice injected with PD patient‐derived Lewy body extracts carrying toxic α‐synuclein aggregates. Our results support lysosomal re‐acidification as a disease‐modifying strategy for the treatment of PD and other age‐related proteinopathies.

[French practical guidelines for the diagnosis and management of IPF - 2021 update, short version]

BACKGROUND

Since the previous French guidelines were published in 2017, substantial additional knowledge about idiopathic pulmonary fibrosis has accumulated.

METHODS

Under the auspices of the French-speaking Learned Society of Pulmonology and at the initiative of the coordinating reference center, practical guidelines for treatment of rare pulmonary diseases have been established. They were elaborated by groups of writers, reviewers and coordinators with the help of the OrphaLung network, as well as pulmonologists with varying practice modalities, radiologists, pathologists, a general practitioner, a head nurse, and a patients' association. The method was developed according to rules entitled "Good clinical practice" in the overall framework of the "Guidelines for clinical practice" of the official French health authority (HAS), taking into account the results of an online vote using a Likert scale.

RESULTS

After analysis of the literature, 54 recommendations were formulated, improved, and validated by the working groups. The recommendations covered a wide-ranging aspects of the disease and its treatment: epidemiology, diagnostic modalities, quality criteria and interpretation of chest CT, indication and modalities of lung biopsy, etiologic workup, approach to familial disease entailing indications and modalities of genetic testing, evaluation of possible functional impairments and prognosis, indications for and use of antifibrotic therapy, lung transplantation, symptom management, comorbidities and complications, treatment of chronic respiratory failure, diagnosis and management of acute exacerbations of fibrosis.

CONCLUSION

These evidence-based guidelines are aimed at guiding the diagnosis and the management in clinical practice of idiopathic pulmonary fibrosis.

Embracing nanomaterials' interactions with the innate immune system

Immunotherapy has firmly established itself as a compelling avenue for treating disease. Although many clinically approved immunotherapeutics engage the adaptive immune system, therapeutically targeting the innate immune system remains much less explored. Nanomedicine offers a compelling opportunity for innate immune system engagement, as many nanomaterials inherently interact with myeloid cells (e.g., monocytes, macrophages, neutrophils, and dendritic cells) or can be functionalized to target their cell-surface receptors. Here, we provide a perspective on exploiting nanomaterials for innate immune system regulation. We focus on specific nanomaterial design parameters, including size, form, rigidity, charge, and surface decoration. Furthermore, we examine the potential of high-throughput screening and machine learning, while also providing recommendations for advancing the field. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Diagnostic Tools > In Vivo Nanodiagnostics and Imaging Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

[Epidemiology of fibrosing interstitial lung diseases in the department of Haute Garonne]

EPIDemio study is a multicenter, prospective and observational study. The objective is to estimate the prevalence and incidence of fibrosing interstitial lung diseases (ILDs) in the department of Haute Garonne (31) in France. Fifty-five pulmonologists from the Toulouse university hospital and 8 private establishments participated in this study. Two hundred and fifty-six cases of fibrosing ILDs were reported (gross overall prevalence: 22.8/100,000 and estimated 30.1/100,000. Idiopathic ILDs represent 55.8% of fibrosing ILDs ahead of systemic disease-related ILDs (24.6%) and ILDs associated with environmental exposure (13.3%). Idiopathic pulmonary fibrosis (IPF) represents 35.9% of fibrosing ILDs, which corresponds to a minimal prevalence of 8.2/100,000 and an estimated prevalence of 11.2/100,000. This study confirms epidemiological data collected in France and Europe.

[Parsonage-Turner syndrome following severe SARS-CoV-2 infection]

Introduction

Les complications de l’infection par le SARS-CoV-2 peuvent affecter la sphère neurologique ; il s’agit habituellement de cas de polyradiculonévrite aiguë inflammatoire ou de plexite.

Observation

Le cas clinique rapporté concerne un patient de 20 ans sans comorbidités, atteint d’une infection sévère à la COVID-19 compliquée d’un syndrome de détresse respiratoire aiguë, avec manifestations thromboemboliques et surinfection bactérienne. Ce patient souffrait également d’un trouble neurologique non spécifique lié au SARS-Cov-2 avec une paralysie pseudobulbaire (IRM, EMG et ponction lombaire étaient normaux), associé à des troubles neurologiques persistants 4 mois plus tard, caractérisés par un déficit à prédominance motrice de l’épaule gauche et une insuffisance respiratoire. Le bilan respiratoire et neurologique conclut à un syndrome de Parsonage-Turner, ou amyotrophie névralgique, affectant les racines nerveuses en C5-C6, le nerf pectoral latéral et le nerf phrénique à l’origine de l’amyotrophie de la ceinture scapulaire et de la paralysie du diaphragme gauche.

Conclusion

Ce cas montre que la dyspnée persistante après une infection à la COVID-19 doit faire rechercher une cause diaphragmatique et que celle-ci n’est pas toujours secondaire à la neuropathie de réanimation, mais peut aussi être le témoin d’une amyotrophie névralgique.

A Nano-Emulsion Platform Functionalized with a Fully Human scFv-Fc Antibody for Atheroma Targeting: Towards a Theranostic Approach to Atherosclerosis

Atherosclerosis is at the onset of the cardiovascular diseases that are among the leading causes of death worldwide. Currently, high-risk plaques, also called vulnerable atheromatous plaques, remain often undiagnosed until the occurrence of severe complications, such as stroke or myocardial infarction. Molecular imaging agents that target high-risk atheromatous lesions could greatly improve the diagnosis of atherosclerosis by identifying sites of high disease activity. Moreover, a "theranostic approach" that combines molecular imaging agents (for diagnosis) and therapeutic molecules would be of great value for the local management of atheromatous plaques. The aim of this study was to develop and characterize an innovative theranostic tool for atherosclerosis. We engineered oil-in-water nano-emulsions (NEs) loaded with superparamagnetic iron oxide (SPIO) nanoparticles for magnetic resonance imaging (MRI) purposes. Dynamic MRI showed that NE-SPIO nanoparticles decorated with a polyethylene glycol (PEG) layer reduced their liver uptake and extended their half-life. Next, the NE-SPIO-PEG formulation was functionalized with a fully human scFv-Fc antibody (P3) recognizing galectin 3, an atherosclerosis biomarker. The P3-functionalized formulation targeted atheromatous plaques, as demonstrated in an immunohistochemistry analyses of mouse aorta and human artery sections and in an Apoe^-/- mouse model of atherosclerosis. Moreover, the formulation was loaded with SPIO nanoparticles and/or alpha-tocopherol to be used as a theranostic tool for atherosclerosis imaging (SPIO) and for delivery of drugs that reduce oxidation (here, alpha-tocopherol) in atheromatous plaques. This study paves the way to non-invasive targeted imaging of atherosclerosis and synergistic therapeutic applications.

A modular approach toward producing nanotherapeutics targeting the innate immune system

Immunotherapies controlling the adaptive immune system are firmly established, but regulating the innate immune system remains much less explored. The intrinsic interactions between nanoparticles and phagocytic myeloid cells make these materials especially suited for engaging the innate immune system. However, developing nanotherapeutics is an elaborate process. Here, we demonstrate a modular approach that facilitates efficiently incorporating a broad variety of drugs in a nanobiologic platform. Using a microfluidic formulation strategy, we produced apolipoprotein A1-based nanobiologics with favorable innate immune system-engaging properties as evaluated by in vivo screening. Subsequently, rapamycin and three small-molecule inhibitors were derivatized with lipophilic promoieties, ensuring their seamless incorporation and efficient retention in nanobiologics. A short regimen of intravenously administered rapamycin-loaded nanobiologics (mTORi-NBs) significantly prolonged allograft survival in a heart transplantation mouse model. Last, we studied mTORi-NB biodistribution in nonhuman primates by PET/MR imaging and evaluated its safety, paving the way for clinical translation.

Expectations about treatment of idiopathic pulmonary fibrosis: Comparative survey of patients, carers and physicians (the RESPIR French survey)

CONTEXT

Idiopathic pulmonary fibrosis (IPF) is a severe chronic disease during which anxiety and depression are frequent comorbidities. Better knowledge of patients' expectations is needed to inform an action plan to improve medical care.

AIM

To describe feelings and expectations of patients suffering from IPF and of their carers about antifibrotic therapy and compare them to what is perceived by their pulmonologist.

METHODS

National prospective study on practices and perceptions. Specific questionnaires were e-mailed to all 3276 pulmonologists in France who, in turn, invited patients and carers to participate in a survey.

RESULTS

147 pulmonologists, 161 patients and 144 carers participated in the survey. The role of the carer was evaluated as "important" or "very important" by more than 90% of participants, i.e. pulmonologists, patients or carers. Inconsistencies between how patients felt and how pulmonologists perceived them were identified: 88% of patients responded that they understood quite well what IPF is (vs. 75% of patients according to pulmonologists); 85.5% of patients said they were determined to fight the disease (vs. 68.0%); 61.7% of patients wanted to be kept informed of potential complications before they occurred (vs. 69.6%) and 81.2% wanted to be involved in therapeutic decisions (vs. 43.1%). Globally, patients had a more positive view of antifibrotic therapies than expected by pulmonologists: 41.5% evaluated their advantages superior to what they had expected (vs. 29.1% of patients according to pulmonologists) and 76.5% had a positive image of the benefits/disadvantages ratio (vs. 62.4%). Although pulmonologists had the impression that they were keeping their patients well-informed about exacerbations, hospital stays and the possible negative evolution of the disease despite antifibrotic therapies, 34.0%, 42.0% and 22.0% of patients respectively declared not being aware of these aspects.

CONCLUSION

The feelings of patients suffering from IPF regarding their disease and treatment globally proved more positive compared with how pulmonologists perceived them. Taking into account the expectations and needs of patients may allow healthcare professionals to better address their needs and priorities.

Lung function in Birt-Hogg-Dubé syndrome: a retrospective analysis of 96 patients

Background

Birt-Hogg-Dubé syndrome (BHD) is a rare autosomal dominant disorder caused by mutations in the FLCN gene coding for folliculin. Its clinical expression includes cutaneous fibrofolliculomas, renal tumors, multiple pulmonary cysts, and recurrent spontaneous pneumothoraces. Data on lung function in BHD are scarce and it is not known whether lung function declines over time. We retrospectively assessed lung function at baseline and during follow-up in 96 patients with BHD.

Results

Ninety-five percent of BHD patients had multiple pulmonary cysts on computed tomography and 59% had experienced at least one pneumothorax. Mean values of forced expiratory volume in 1 second (FEV₁), forced vital capacity (FVC), FEV₁/FVC ratio, and total lung capacity were normal at baseline. Mean (standard deviation) residual volume (RV) was moderately increased to 116 (36) %pred at baseline, and RV was elevated > 120%pred in 41% of cases. Mean (standard deviation) carbon monoxide transfer factor (DLco) was moderately decreased to 85 (18) %pred at baseline, and DLco was decreased < 80%pred in 33% of cases. When adjusted for age, gender, smoking and history of pleurodesis, lung function parameters did not significantly decline over a follow-up period of 6 years.

Conclusions

Cystic lung disease in BHD does not affect respiratory function at baseline except for slightly increased RV and reduced DLco. No significant deterioration of lung function occurs in BHD over a follow-up period of 6 years.

Multimodal optical contrast agents as new tools for monitoring and tuning nanoemulsion internalisation into cancer cells. From live cell imaging to in vivo imaging of tumours

Tailor-made NIR emitting dyes were designed as multimodal optical probes. These asymmetric amphiphilic compounds show combined intense absorption in the visible region, NIR fluorescence emission, high two-photon absorption in the NIR (with the maximum located around 1000 nm) as well as large Stokes' shift values and second-harmonic generation ability. Thanks to their structure, high loading into nanoemulsions (NEs) could be achieved leading to very high one- and two-photon brightness. These dyes were demonstrated to act as multimodal contrast agents able to generate different optical modalities of interest for bioimaging. Indeed, the uptake and carrier behaviour of the dye-loaded NEs into cancer cells could be monitored by simultaneous two-photon fluorescence and second-harmonic generation optical imaging. Multimodal imaging provided deep insight into the mechanism and kinetics of dye internalisation. Quite interestingly, the nature of the dyes was also found to influence both the kinetics of endocytosis and the internalisation pathways in glioblastoma cancer cells. By modulating the charge distribution within the dyes, the NEs can be tuned to escape lysosomes and enter the mitochondria. Moreover, surface functionalization with PEG macromolecules was realized to yield stealth NIRF-NEs which could be used for in vivo NIRF imaging of subcutaneous tumours in mice.

Synthesis and Intracellular Uptake of Rhodamine-Nucleolipid Conjugates into a Nanoemulsion Vehicle

Neurodegenerative diseases represent some of the greatest challenges for both basic science and clinical medicine. Due to their prevalence and the lack of known biochemical-based treatments, these complex pathologies result in an increasing societal cost. Increasing genetic and neuropathological evidence indicates that lysosomal impairment may be a common factor linking these diseases, demanding the development of therapeutic strategies aimed at restoring the lysosomal function. Here, we propose the design and synthesis of a nucleolipid conjugate as a nonviral chemical nanovector to specifically target neuronal cells and intracellular organelles. Herein, thymidine, appropriately substituted to increase its lipophilicity, was used as a model nucleoside and a fluorophore moiety, covalently bound to the nucleoside, allowed the monitoring of nucleolipid internalization in vitro. To improve nucleolipid protection and cellular uptake, these conjugates were formulated in nanoemulsions. In vitro biological assays demonstrated cell uptake- and internalization-associated colocalization with lysosomal markers. Overall, this nucleolipid-nanoemulsion-based formulation represents a promising drug-delivery tool to target the central nervous system, able to deliver drugs to restore the impaired lysosomal function.

Harnessing Lysosomal pH through PLGA Nanoemulsion as a Treatment of Lysosomal-Related Neurodegenerative Diseases

Most neurodegenerative disorders are characterized by deposits of misfolded proteins and neuronal degeneration in specific brain regions. Growing evidence indicates that lysosomal impairment plays a primary pathogenic role in these diseases, in particular, the occurrence of increased lysosomal pH. Thus, therapeutic development aiming at restoring lysosomal function represents a novel, precise, and promising strategy for the treatment of these pathologies. Herein we demonstrate that acidic oil-in-water nanoemulsions loaded with poly(dl-lactide- co-glycolide) (PLGA) are able to rescue impaired lysosomal pH in genetic cellular models of Parkinson's disease. For in vivo assays, nanoemulsions were labeled with an original synthetic hydrophobic far red-emitting dye to allow fluorescence monitoring. Following stereotaxic injection in the mouse brain, widespread diffusion of the nanocarrier was observed, up to 500 μm from the injection site, as well as internalization into the lysosomal compartment in brain cells. Finally, promising preliminary assays of systemic administration demonstrate that a fraction of the formulation crosses the blood brain barrier, penetrates the brain parenchyma, is internalized by cells, and colocalizes with lysosomal markers. Overall, these results suggest the feasibility and the therapeutic potential of this new nanoformulation as an effective drug delivery tool to the brain, with the potential to rescue pathological lysosomal deficits.

The mechanism for the stabilization and surfactant properties of epitaxial silicene

Using real-time in situ scanning tunneling microscopy and density functional theory simulations, we have studied the growth of Si films on Ag(111) beyond the silicene monolayer, evidencing the existence of metastable phases and an original growth mechanism. Above monolayer Si coverage, an initial structure forms, which is identified as an Ag-free Si bilayer with additional Si adatoms. With further deposition, this structure is replaced by a distinct bilayer structure covered by Si trimers and Ag atoms. The formation of these bilayers follows counterintuitive dynamics: they are partially inserted within the Ag substrate and form by expelling, from the underlying substrate, the atoms that reinsert below the adjacent silicene layer. The growth is therefore characterized by an unexpected "surfactant competition" between Ag and silicene: while silicene is a metastable surfactant for the Ag(111) surface, Ag plays the role of a surfactant for thicker diamond-like Si islands. In spite of being thermodynamically unfavoured, the silicene monolayer is, thus, a remarkably stable structure because of the high kinetic barrier for the growth of thicker layers.

Data on iron oxide core oil-in-water nanoemulsions for atherosclerosis imaging

The data presented in this article are related to the publication entitled "Iron oxide core oil-in-water nanoemulsion as tracer for atherosclerosis MPI and MRI imaging" (Prévot et al., 2017) [1]. Herein we describe the synthesis and the characteristics of the Superparamagnetic Iron Oxide Nanoparticles (SPION) loaded inside nanoemulsions (NEs). Focus was set on obtaining SPION with narrow size distribution and close to superparamagnetic limit (20 nm) in order to reach a reasonable magnetic signal. Nanoparticles (NPs) of three different sizes were obtained (7, 11 and 18 nm) and characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), diffuse reflectance infrared Fourier transform (DRIFT) and thermogravimetric analysis (TGA). SPION were coated with oleic acid (OA) in order to load them inside the oily core of NEs droplets. SPION loaded NEs were magnetically sorted using MACS® MS Column (Miltenyi Biotec) and iron quantification was performed by UV-spectrometry measurements.

Data on atherosclerosis specific antibody conjugation to nanoemulsions

This article present data related to the publication entitled “Iron oxide core oil-in-water nanoemulsion as tracer for atherosclerosis MPI and MRI imaging” (Prévot et al., 2017) [1]. Herein we describe the engineering in the baculovirus-insect cell system and purification processes of the human scFv-Fc TEG4-2C antibody, specific of platelets within the atheroma plaque. For molecular targeting purpose, atheroma specific antibody was conjugated to nanoemulsions (NEs) using a heterobifunctional linker (DSPE-PEG-maleimide). Atheroma labelling was assayed by immunochemistry on arterial sections from rabbits.

Iron oxide core oil-in-water nanoemulsion as tracer for atherosclerosis MPI and MRI imaging

PURPOSE

For early atherosclerosis imaging, magnetic oil-in-water nanoemulsion (NE) decorated with atheroma specific monoclonal antibody was designed for Magnetic Particle Imaging (MPI) and Magnetic Resonance Imaging (MRI). MPI is an emerging technique based on direct mapping of superparamagnetic nanoparticles which may advantageously complement MRI.

METHODS

NE oily droplets were loaded with superparamagnetic iron oxide nanoparticles of 7, 11 and 18nm and biofunctionalized with atheroma specific scFv-Fc TEG4-2C antibody.

RESULTS

Inclusion of nanoparticles inside NE did not change the hydrodynamic diameter of the oil droplets, close to 180nm, nor the polydispersity. The droplets were negatively charged (ζ=-30mV). In vitro MPI signal was assessed by Magnetic Particle Spectroscopy (MPS). NE displayed MRI and MPS signals confirming its potential as new contrast agent. NE MPS signal increase with NPs size close to the gold standard (Resovist). In MRI, NE displayed R₂* transversal relaxivity of 45.45, 96.04 and 218.81mM^-1s^-1 for 7, 11 and 18nm respectively. NE selectively bind atheroma plaque both in vitro and ex vivo in animal models of atherosclerosis.

CONCLUSION

Magnetic NE showed reasonable MRI/MPS signals and a significant labelling of the atheroma plaque. These preliminary results support that NE platform could selectively image atherosclerosis.

A stress-controlled shear cell for small-angle light scattering and microscopy

We develop and test a stress-controlled, parallel plates shear cell that can be coupled to an optical microscope or a small angle light scattering setup, for simultaneous investigation of the rheological response and the microscopic structure of soft materials under an imposed shear stress. In order to minimize friction, the cell is based on an air bearing linear stage, the stress is applied through a contactless magnetic actuator, and the strain is measured through optical sensors. We discuss the contributions of inertia and of the small residual friction to the measured signal and demonstrate the performance of our device in both oscillating and step stress experiments on a variety of viscoelastic materials.

An efficient scheme for sampling fast dynamics at a low average data acquisition rate

We introduce a temporal scheme for data sampling, based on a variable delay between two successive data acquisitions. The scheme is designed so as to reduce the average data flow rate, while still retaining the information on the data evolution on fast time scales. The practical implementation of the scheme is discussed and demonstrated in light scattering and microscopy experiments that probe the dynamics of colloidal suspensions using CMOS or CCD cameras as detectors.

Critical Au Concentration for the Stabilization of Au-Cu Nanoparticles on Rutile against Dissociation under Oxygen

Controlling aging of catalysts is of crucial importance to preserve their properties, in particular for bimetallic nanoparticles (NPs) where reaction can modify the composition. Herein, we have studied the stability upon oxygen exposure of gold-copper NPs supported on rutile. We have used in situ scanning tunneling microscopy to follow the evolution of individual Au, Cu and Au-Cu NPs with various compositions grown on the TiO2(110) surface, during each step from their nucleation to their modification with oxygen. We demonstrated a direct relation between the stability of the nanoparticles and their Au concentration. Whereas pure Cu nanoparticles dissociate under O2, Au-Cu NPs containing at least 20% Au are stable. This is explained by a modification of the local density of states of Cu atoms upon alloying.