1,721,134 research outputs found
A fistful of chemico-physical parameters crucial for 1H-NMR relaxation : the effect of size, shape and coating in iron oxides core-shell nanoparticles
No full textAn increasing awareness about novel medical applications of smaller, inorganic-based nanoparticles, possessing unique properties at the nanoscale, has led to a burst of research activities in the development of “nanoprobes” for diagnostic medicine and agents for novel, externally activated, therapies. In this research field, magnetic nanoparticles (MNPs) are prominent due to fundamental peculiar properties which make them particularly appealing to materials and biomedical applications.
In particular, much attention was devoted to MNPs useful as agents for Magnetic Resonance Imaging (MRI), Optical Imaging (OI) and Magnetic Fluid Hyperthermia (MFH), carriers for drugs and vectors for molecular targeting. The possibility to collect images of the regions where the MNPs are delivered through MRI and eventually OI (if functionalized with a luminescent molecule), is joint to their use under radio-frequency fields, with frequency of the order of 100 KHz, which causes a local release of heat directed to tumour cells (the MFH effect), possibly inducing their death. By such materials, theranostic agents can be obtained. On the other hand, in the field of drug delivery and molecular targeting, few examples of reproducible experiments using superparamagnetic nanoparticles are actually present in literature. Thus, the applications of MNPs to nanomedicine is currently of growing interest in the world.
The main objectives of my research group in the last decade was to contribute to the knowledge of physical mechanisms at the basis of MNPs used in biomedicine (especially MRI) and to propose some novel systems in strict collaboration with different research groups of chemists and biologists. I will present a mini-review of different case studies [1-4] where I show how the chemico-physical characteristics of MNPs are strictly correlated to their properties and can be partially interpreted with the most famous heuristic model [5] used in literature for NMR relaxivity profiles.
Key Words: magnetic nanoparticles, NMR relaxivity, nanomagnetism
References
1. F. Brero, M. Basini, M. Avolio, F. Orsini F., P. Arosio, C. Sangregorio, C. Innocenti, A. Guerrini, J Boucard, E. Ishow, M. Lecouvey, J. Fresnais, L. Lartigue, A. Lascialfari, Nanomaterials, 10 (2020) 1660-1672.
2. M. Basini, A. Guerrini, M. Cobianchi, F. Orsini, D. Bettega, M. Avolio, C. Innocenti, C. Sangregorio, A. Lascialfari, P. Arosio, Journal of Alloys and Compounds, 770 (2019), 58-66.
3. M. Basini, T. Orlando., P. Arosio, M.F. Casula, D. Espa, S. Murgia, C. Sangregorio, C. Innocenti, A. Lascialfari, J. Chem. Phys., 146 (2017), 034703.
4. Bordonali L., Kalaivani T., Sabareesh K.P.V., Innocenti C., Fantechi E., Sangregorio C., Casula M.F., Lartigue L., Larionova J., Guari Y., Corti M., Arosio P., Lascialfari A., Journal of Physics: Condensed Matter, 25 (2013), 066008
5. A. Roch, R.N. Muller, P. Gillis, J. Chem. Phys. 110 (1999) 5403-5411
Recent Developments in the Use of Magnetic Fluid Hyperthermia on Glioblastoma Multiforme Disease
Full text linkThe first evidence of the efficacy in the cancer treatment of hyperthermia, therapy focused on the heating of tumor masses to kill cells and tissues, went back almost a century and a half. One of the most promising techniques for increasing the cells and tissues temperature is based on the use of magnetic nanoparticles dispersed in concentrated colloidal suspensions and stimulated by an external alternating electromagnetic field, known as Magnetic Fluid Hyperthermia. Recently this technique has been used as coadjutant treatment of the most applied chemo and radio therapies in a series of different tumors, but in particular for Glioblastoma Multiforme till to clinical trials level. In this work, we report some of most significant progresses regarding the use of Magnetic Fluid Hyperthermia on Glioblastoma Multiforme disease published in literature during the last year, describing the more interesting outcomes for potential future clinical applications
Electrophoretic analysis of horse tissue ferritins at different pH values
No full textElectrophoretic mobilities of ferritins from horse heart, liver and spleen were compared in the pH range 3.5-10. Electrophoretic titrations and continuous buffer electrophoreses were used. The order of anionic mobilities was heart>liver>spleen at alkaline pH and this order was reversed in the neutral to acidic range. This order of mobilities, and the intermediate behavior of liver in respect to the other two ferritins correlate with the known subunit composition of the three ferritins, and strongly support the idea of different amino acid residues being exposed on the protein shell surfaces. From the analyses of differential mobility around the pK values of the various ionizable groups it was concluded that heart and spleen ferritins have a very similar number of acidic amino acid residues on their surfaces, whereas they differ in basic residues. Heart seems to have about 15% more Lys and Arg, and twice as many His as spleen
Coexistence of steady state and transient state in isoelectric focusing
No full textThe possibility of transforming a wide (pH 3.5-10) into a narrow pH gradient in isoelectric focusing (IEF) has been examined by the use of different amino acid terminators at the electrons, viz 50 mM Asp, 50 mM Trp, 45 mM Phe. 0.5 M Gly or 0.5 M Lys. The ph gradient formation and decay seem to be insensitive to the type of amino acid used or to its molarity. While Ampholine and protein samples reach equilibrium positions, large amounts of amino acids move as two wave fronts, from the anode and cathode, unsuccessfully trying to reach their pI positions. Thus, the steady state and transient state coexist in IEF and are quite insensitive to each other. The formation and stabilization of the pH gradient in IEF do not require a performed "pH-cage", nor can IEF be regarded as isotachophoresis, since the same ion acts simultaneously as the "leading" and "terminating" ion in our system. When the same buffer is used simultaneously at the anode and cathode, the gel loses its polarity so that the system becomes insensitive to the choice of electrode position, or to polarity reversal at any time during the IEF experiment
Aggregation mechanism of an IgG2 and two IgG1 monoclonal antibodies at low pH: From oligomers to larger aggregates
No full textISSN:0724-8741ISSN:1573-904XISSN:1573-904
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Population balance modeling of antibodies aggregation kinetics
No full textThe aggregates morphology and the aggregation kinetics of a model monoclonal antibody under acidic conditions have been investigated. Growth occurs via irreversible cluster-cluster coagulation forming compact, fractal aggregates with fractal dimension of 2.6. We measured the time evolution of the average radius of gyration, < R-g >, and the average hydrodynamic radius, < R-h >, by in situ light scattering, and simulated the aggregation kinetics by a modified Smoluchowski's population balance equations. The analysis indicates that aggregation does not occur under diffusive control, and allows quantification of effective intermolecular interactions, expressed in terms of the Fuchs stability ratio (W). In particular, by introducing a dimensionless time weighed on W, the time evolutions of < R-h > measured under various operating conditions (temperature, pH, type and concentration of salt) collapse on a single master curve. The analysis applies also to data reported in the literature when growth by cluster-cluster coagulation dominates, showing a certain level of generality in the antibodies aggregation behavior. The quantification of the stability ratio gives important physical insights into the process, including the Arrhenius dependence of the aggregation rate constant and the relationship between monomer-monomer and cluster-cluster interactions. Particularly, it is found that the reactivity of non-native monomers is larger than that of non-native aggregates, likely due to the reduction of the number of available hydrophobic patches during aggregation
Observing Xenopus laevis oocyte plasma membrane by Atomic Force Microscopy
No full textThis paper describes the use of Atomic Force Microscopy (AFM) to investigate the plasma membrane of Xenopus laevis oocyte. Different protocols of sample preparation to perform an AFM investigation of both external and intracellular sides of the oocyte plasma membrane are presented and discussed. Reproducible AFM images allowed visualization and dimensional characterization of protein complexes differently arranged on both sides of the oocyte plasma membrane. In particular, two different arrangements were visualized: (1) a heterogeneous and irregular distribution of the protein complexes and (2) in some cases a distribution of nanometer-sized membrane domains where protein complexes are densely packed and spatially arranged in an ordered hexagonal motif. In addition, a methodological approach based on the purification of oocyte plasma membrane by ultracentrifugation on sucrose gradient is also described in this work. The potential of AFM as a useful tool for the structural characterization of proteins in a native eukaryotic membrane was established and its relevance for describing the organization of protein complexes in native biological membranes was explored
- …
