Parallelized Manipulation of Adherent Living Cells by Magnetic Nanoparticles-Mediated Forces

The remote actuation of cellular processes such as migration or neuronal outgrowth is a challenge for future therapeutic applications in regenerative medicine. Among the different methods that have been proposed, the use of magnetic nanoparticles appears to be promising, since magnetic fields can act at a distance without interactions with the surrounding biological system. To control biological processes at a subcellular spatial resolution, magnetic nanoparticles can be used either to induce biochemical reactions locally or to apply forces on different elements of the cell. Here, we show that cell migration and neurite outgrowth can be directed by the forces produced by a switchable parallelized array of micro-magnetic pillars, following the passive uptake of nanoparticles. Using live cell imaging, we first demonstrate that adherent cell migration can be biased toward magnetic pillars and that cells can be reversibly trapped onto these pillars. Second, using differentiated neuronal cells we were able to induce events of neurite outgrowth in the direction of the pillars without impending cell viability. Our results show that the range of forces applied needs to be adapted precisely to the cellular process under consideration. We propose that cellular actuation is the result of the force on the plasma membrane caused by magnetically filled endo-compartments, which exert a pulling force on the cell periphery

Magnetic Core Shell Nanoparticles Trapping in a Microdevice Generating High Magnetic Gradient

Magnetic core shell nanoparticles (MCSNPs) 30 nm diameter with a magnetic weight of 10% are usually much too small to be trapped in microfluidic systems using classical external magnets. Here, a simple microchip for efficient MCSNPs trapping and release is presented. It comprises a bed of micrometric iron beads (6–8 mm diameter) packed in a microchannel against a physical restriction and presenting a low dead volume of 0.8 nL. These beads of high magnetic permeability are used to focus magnetic field lines from an external permanent magnet and generate local high magnetic gradients. The nanoparticles magnetic trap has been characterised both by numerical simulations and fluorescent MCSNPs imaging. Numerical simulations have been performed to map both the magnetic flux density and the magnetic force, and showed that MCSNPs are preferentially trapped at the iron bead magnetic poles where the magnetic force is increased by 3 orders of magnitude. The trapping efficiency was experimentally determined using fluorescent MCSNPs for different flow rates, different iron beads and permanent magnet positions. At a flow rate of 100 mL h1, the nanoparticles trapping/release can be achieved within 20 s with a preconcentration factor of 4000

Directional control of neurite outgrowth: emerging technologies for Parkinson's disease using magnetic nanoparticles and magnetic field gradients.

A challenge in current stem cell therapies for Parkinson's disease (PD) is controlling neuronal outgrowth from the substantia nigra towards the targeted area where connectivity is required in the striatum. Here we present progress towards controlling directional neurite extensions through the application of iron-oxide magnetic nanoparticles (MNPs) labelled neuronal cells combined with a magnetic array generating large spatially variant field gradients (greater than 20 T m-1). We investigated the viability of this approach in both two-dimensional and organotypic brain slice models and validated the observed changes in neurite directionality using mathematical models. Results showed that MNP-labelled cells exhibited a shift in directional neurite outgrowth when cultured in a magnetic field gradient, which broadly agreed with mathematical modelling of the magnetic force gradients and predicted MNP force direction. We translated our approach to an ex vivo rat brain slice where we observed directional neurite outgrowth of transplanted MNP-labelled cells from the substantia nigra towards the striatum. The improved directionality highlights the viability of this approach as a remote-control methodology for the control and manipulation of cellular growth for regenerative medicine applications. This study presents a new tool to overcome challenges faced in the development of new therapies for PD

SYNTHESE ET CARACTERISATION DE NOUVEAUX COMPLEXANTS DES ELEMENTS F COMPORTANT UNE UNITE PYRIDINE INTRACYCLIQUE

CE TRAVAIL A ETE CONSACRE A LA SYNTHESE DE TETRAAZAMACROCYCLES COMPORTANT UNE UNITE PYRIDINE INTRACYCLIQUE ET A LA CARACTERISATION DE LEURS COMPLEXES VIS A VIS DE CERTAINS LANTHANIDES. L'INFLUENCE DE LA TAILLE DE LA CAVITE MACROCYCLIQUE ET DE LA TAILLE DES CYCLES DE CHELATION EXOCYCLIQUES SUR LES CONSTANTES DE COMPLEXATION VIS A VIS DES LANTHANIDES ETUDIES A PU ETRE EVALUEE. LE PREMIER CHAPITRE CONSISTE EN UNE PRESENTATION GENERALE DES LANTHANIDES ET DES TETRAAZAMACROCYCLES. DANS LE SECOND CHAPITRE EST PRESENTE LA SYNTHESE DU TETRAAZAMACROCYCLE DE REFERENCE, QUI A NOTAMMENT ETE REALISEE A L'AIDE D'UN GROUPEMENT CLIVABLE DANS DES CONDITIONS DOUCES, LE GROUPEMENT 2-NITROBENZENESULFONYLE. LA CARACTERISATION DES PROPRIETES COMPLEXANTES DE CE LIGAND, SELON UNE METHODE ORIGINALE, METTANT EN JEU LA LUMINESCENCE DE L'ION EUROPIUM III, EST EGALEMENT DEVELOPPEE. DANS LE TROISIEME CHAPITRE, LA SYNTHESE ET LA CARACTERISATION D'UN SECOND TETRAAZAMACROCYCLE A PERMIS D'EVALUER L'INFLUENCE DE LA TAILLE DE LA CAVITE MACROCYCLIQUE. UNE DIMINUTION D'UN FACTEUR 10 1 2 DES CONSTANTES DE COMPLEXATION VIS A VIS DES LANTHANIDES ETUDIES A AINSI ETE OBSERVEE. DANS LE QUATRIEME CHAPITRE, LA SYNTHESE ET LA CARACTERISATION DE DEUX TETRAZAMACROCYCLES A PERMIS DE METTRE EN EVIDENCE QUE LE PASSAGE DE CYCLES DE CHELATION DE 5 ATOMES A DES CYCLES DE CHELATION A 6 ATOMES AVAIT POUR CONSEQUENCE UNE DIMINUTION DES CONSTANTES DE COMPLEXATION VIS A VIS DES LANTHANIDES ETUDIES. LE CINQUIEME CHAPITRE EST CONSACRE A LA SYNTHESE DE MACROCYCLES SELECTIVEMENT N-FONCTIONNALISES. UNE METHODE ORIGINALE DE SYNTHESE, METTANT EN JEU LA SUBSTITUTION SELECTIVE DES FONCTIONS AMINES PRIMAIRES DE LA DIETHYLENETRIAMINE A L'AIDE DU GROUPEMENT 2-NITROBENZENESULFONYLE A ETE MISE AU POINT. LA SYNTHESE D'UN MACROCYCLE COMPORTANT DES CHAINES ALKYLCARBOXYLIQUES DE TAILLES DIFFERENTES A AINSI PU ETRE REALISEE POUR LA PREMIERE FOIS. LA CARACTERISATION DE SES PROPRIETES COMPLEXANTES A REVELEE UNE COMPLEXATION FAIBLE DU LANTHANE III.PARIS-BIUSJ-Thèses (751052125) / SudocCentre Technique Livre Ens. Sup. (774682301) / SudocPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF

Magnetic Hyperthermia on γ-Fe2O3@SiO2 Core-Shell Nanoparticles for mi-RNA 122 Detection

Magnetic hyperthermia on core-shell nanoparticles bears promising achievements, especially in biomedical applications. Here, thanks to magnetic hyperthermia, γ-Fe2O3 cores are able to release a DNA target mimicking the liver specific oncotarget miRNA-122. Our silica coated magnetic nanoparticles not only allow the grafting at their surface of a significant number of oligonucleotides but are also shown to be as efficient, by local heating, as 95 °C global heating when submitted to an alternative magnetic field, while keeping the solution at 28 °C, crucial for biological media and energy efficiency. Moreover, a slight modification of the silica coating process revealed an increased heating power, well adapted for the release of small oligonucleotides such as microRNA

Release and Detection of microRNA by Combining Magnetic Hyperthermia and Electrochemistry Modules on a Microfluidic Chip

The heating of a biologic solution is a crucial part in an amplification process such as the catalytic detection of a biological target. However, in many situations, heating must be limited in microfluidic devices, as high temperatures can cause the denaturation of the chip components. Local heating through magnetic hyperthermia on magnetic nano-objects has opened the doors to numerous improvements, such as for oncology where a reduced heating allows the synergy of chemotherapy and thermotherapy. Here we report on the design and implementation of a lab on chip without global heating of samples. It takes advantage of the extreme efficiency of DNA-modified superparamagnetic core–shell nanoparticles to capture complementary sequences (microRNA-target), uses magnetic hyperthermia to locally release these targets, and detects them through electrochemical techniques using ultra-sensitive channel DNA-modified ultramicroelectrodes. The combination of magnetic hyperthermia and microfluidics coupled with on-chip electrochemistry opens the way to a drastic reduction in the time devoted to the steps of extraction, amplification and nucleic acids detection. The originality comes from the design and microfabrication of the microfluidic chip suitable to its insertion in the millimetric gap of toric inductance with a ferrite core