Fast and Sensitive Detection of Paramagnetic Species Using Coupled Charge and Spin Dynamics in Strongly Fluorescent Nanodiamonds.

Sensing of a few unpaired electron spins, such as in metal ions and radicals, is a useful but difficult task in nanoscale physics, biology, and chemistry. Single negatively charged nitrogen-vacancy (NV-) centers in diamond offer high sensitivity and spatial resolution in the optical detection of weak magnetic fields produced by a spin bath but often require long acquisition times on the order of seconds. Here, we present an approach based on coupled spin and charge dynamics in dense NV ensembles in strongly fluorescent nanodiamonds (NDs) to sense external magnetic dipoles. We apply this approach to various paramagnetic species, including gadolinium complexes, magnetite nanoparticles, and hemoglobin in whole blood. Taking advantage of the high NV density, we demonstrate a dramatic reduction in acquisition time (down to tens of milliseconds) while maintaining high sensitivity to paramagnetic centers. Strong luminescence, high sensitivity, and short acquisition time make dense NV- ensembles in NDs a potentially promising tool for biosensing and bioimaging applications.

Characterization of magnetic nanoparticles from Magnetospirillum Gryphiswaldense as potential theranostics tools.

We investigated the theranostic properties of magnetosomes (MNs) extracted from magnetotactic bacteria, promising for nanomedicine applications. Besides a physico-chemical characterization, their potentiality as mediators for magnetic fluid hyperthermia and contrast agents for magnetic resonance imaging, both in vitro and in vivo, are here singled out. The MNs, constituted by magnetite nanocrystals arranged in chains, show a superparamagnetic behaviour and a clear evidence of Verwey transition, as signature of magnetite presence. The phospholipid membrane provides a good protection against oxidation and the MNs oxidation state is stable over months. Using an alternate magnetic field, the specific absorption rate was measured, resulting among the highest reported in literature. The MRI contrast efficiency was evaluated by means of the acquisition of complete NMRD profiles. The transverse relaxivity resulted as high as the one of a former commercial contrast agent. The MNs were inoculated into an animal model of tumour and their presence was detected by magnetic resonance images two weeks after the injection in the tumour mass.

3D printing of rat salivary glands: The submandibular-sublingual complex.

The morphology and the functionality of the murid glandular complex, composed of the submandibular and sublingual salivary glands (SSC), were the object of several studies conducted mainly using magnetic resonance imaging (MRI). Using a 4.7 T scanner and a manganese-based contrast agent, we improved the signal-to-noise ratio of the SSC relating to the surrounding anatomical structures allowing to obtain high-contrast 3D images of the SSC. In the last few years, the large development in resin melting techniques opened the way for printing 3D objects starting from a 3D stack of images. Here, we demonstrate the feasibility of the 3D printing technique of soft tissues such as the SSC in the rat with the aim to improve the visualization of the organs. This approach is useful to preserve the real in vivo morphology of the SCC in living animals avoiding the anatomical shape changes due to the lack of relationships with the surrounding organs in case of extraction. It is also harmless, repeatable and can be applied to explore volumetric changes occurring during body growth, excretory duct obstruction, tumorigenesis and regeneration processes. 3D printing allows to obtain a solid object with the same shape of the organ of interest, which can be observed, freely rotated and manipulated. To increase the visibility of the details, it is possible to print the organs with a selected zoom factor, useful as in case of tiny organs in small mammalia. An immediate application of this technique is represented by educational classes.

Experimental protocol for activation-induced manganese-enhanced MRI (AIM-MRI) based on quantitative determination of Mn content in rat brain by fast T1 mapping.

In activation-induced manganese-enhanced MRI (AIM-MRI) experiments, differential accumulation of Mn in activated and silent brain areas is generally assessed using T(1)-weighted images and quantified by the enhancement of signal intensity (SI), calculated with reference to SI before Mn administration or to SI of brain regions unaffected by the specific stimulus. However, SI enhancement can be unreliable when animals are removed from and reinserted into the magnet. We have developed an experimental protocol based on repeated intraperitoneal (i.p.) injections of Mn, quantitative determination of T(1), and coregistration of images to a rat brain atlas that allows absolute quantification of Mn concentration in selected brain areas. Results showed that interanimal variability of postcontrast T(1) values was very low (compared to the experimental error in T(1) determinations) allowing detection of differential regional Mn uptake in stimulated and unstimulated animals. In addition we have determined in vivo relaxivity of Mn in brain tissue and its frequency dependence.

Normothermic perfusion and lung function after cardiopulmonary bypass: effects in pulmonary risk patients.

Fifty patients at risk for postoperative lung dysfunction and undergoing elective coronary revascularization have been randomly assigned to receive normothermic (36 degrees C) perfusion with warm heart protection (NP group) or hypothermic (28 degrees C) perfusion with cold heart protection (HP group). Lung function before and after cardiopulmonary bypass (CPB) was studied through the determination of the intrapulmonary shunt (Qs/Qt), the alveoloarterial oxygen gradient (A-a delta O2), and the artero-alveolar carbon dioxide gradient (a-A delta CO2). The Qs/Qt after CPB was significantly lower in the NP group (27.1 +/- 2.6 vs 35.7 +/- 2.3) as well as the A-a delta O2 (50.2 +/- 1.5 vs 57.6 +/- 2.4), both data returned to comparable between the groups after 3 h in the intensive care unit. The a-A delta CO2 was significantly lower after CPB in the NP group (5.2 +/- 0.74 vs 8.2 +/- 0.8). Hospital stay and mortality were comparable in the two groups; intubation time and rate of early extubation showed a trend in favour of the NP group; the rate of patients suffering hypoxia and/or hypercapnia after extubation was significantly lower in the NP group (12%) versus the HP group (44%). Normothermia seems to exert a protective effect against lung dysfunction after CPB. The absence of a rewarming injury associated with reperfusion, a limitation of the hypothermic-induced vasoconstriction due to local cooling of the lung and a better compliance of the normothermic lung are hypothesized as beneficial effects of the 'all-warm' strategy.