Magnetic Injection of Nanoparticles Into Rat Inner Ears at a Human Head Working Distance

Sarwar, Azeem; Lee, R.; Depireux, Didier A.; Shapiro, Benjamin

doi:10.1109/tmag.2012.2221456

Cited by 34 publications

(36 citation statements)

References 61 publications

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“…Permanent magnetic arrays materials have been used to assemble magnetic particle arrays, [31] to transport them across a magnetic array surface in rotating magnetic fields, [32] and to push magnetic fluids into the inner ear. [25, 33] To our knowledge, however, this is the first report of nanoparticle capture and release from a permanent magnetic structure. Compared to conventional approaches of capturing particles with soft magnetic materials by applying a field and release by removing the field, the advantage of our approach is that for biomedical applications, capture often occurs over long periods where application of a magnetic field is inconvenient, and release is often desired to be rapid and controlled.…”

Section: Resultsmentioning

confidence: 99%

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Synthesis of Brightly PEGylated Luminescent Magnetic Upconversion Nanophosphors for Deep Tissue and Dual MRI Imaging

Chen

Moore

et al. 2013

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We developed a novel method to fabricate monodispersed biocompatible Yb/Er or Yb/Tm doped β-NaGdF4 upconversion phosphors using polyelectrolytes to prevent irreversible particle aggregation during the conversion of the precursor (Gd2O(CO3)2•H2O:Yb/Er or Yb/Tm) to β-NaGdF4:Yb/Er or Yb/Tm. The polyelectrolyte on the outer surface of nanophosphors also provided an amine tag for PEGylation. This method is also employed to fabricate PEGylated magnetic upconversion phosphors with Fe3O4 as the core and β-NaGdF4 as a shell. These magnetic upconversion nanophosphors have relatively high saturation magnetization (7.0 emu g-1) and magnetic susceptibility (1.7×10-2 emu g-1 Oe-1), providing them with large magnetophoretic mobilities. We have studied their magnetic properties for separation and controlled release in flow, their optical properties for cell labeling, deep tissue imaging, and their T1 and T2-weighted magnetic resonance imaging (MRI) relaxivities. The magnetic upconversion phosphors display both strong magnetophoresis, dual MRI imaging (r1=2.9 mM-1 s-1, r2=204 mM-1 s-1), and bright luminescence under 1 cm chicken breast.

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Section: Resultsmentioning

confidence: 99%

“…Magnetic particles can be used as direct drug carriers to local sites in the human body, such as stents, [23] tumors, [24] the inner ear, [25] the retina of the eye, [26] and other regions. The magnetic force on these magnetic particles is given by (in cgs units):…”

Section: Resultsmentioning

confidence: 99%

Synthesis of Brightly PEGylated Luminescent Magnetic Upconversion Nanophosphors for Deep Tissue and Dual MRI Imaging

Chen

Moore

et al. 2013

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“…on the other side of the node, as shown by the orange dot and force arrow in Figure 4a. The design, optimization, and construction of such a push system are described elsewhere (136)(137)(138). Figure 4b shows the advantage of push versus pull for human patients.…”

Section: Figurementioning

confidence: 99%

“…For nanoparticles placed into the middle ear of a human patient, the push system will apply 20× more force than the pull system. Our magnetic push system, used at a human face-to-ear distance, has successfully delivered particles and drugs into rat inner ears (138). In our experiments, first rats were anesthetized and 300-nm-diameter red-fluorescent magnetic particles (nano-screenMAG-Chitosan, chemicell,…”

Section: Figurementioning

confidence: 99%

Shaping Magnetic Fields to Direct Therapy to Ears and Eyes

Shapiro

Kulkarni

Nacev

et al. 2014

Annu. Rev. Biomed. Eng.

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Magnetic fields have the potential to noninvasively direct and focus therapy to disease targets. External magnets can apply forces on drug-coated magnetic nanoparticles, or on living cells that contain particles, and can be used to manipulate them in vivo. Significant progress has been made in developing and testing safe and therapeutic magnetic constructs that can be manipulated by magnetic fields. However, we do not yet have the magnet systems that can then direct those constructs to the right places, in vivo, over human patient distances. We do not yet know where to put the external magnets, how to shape them, or when to turn them on and off to direct particles or magnetized cells-in blood, through tissue, and across barriers-to disease locations. In this article, we consider ear and eye disease targets. Ear and eye targets are too deep and complex to be targeted by a single external magnet, but they are shallow enough that a combination of magnets may be able to direct therapy to them. We focus on how magnetic fields should be shaped (in space and time) to direct magnetic constructs to ear and eye targets.

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“…It is also extensively used in real-time control of magnetic devices in medical sciences [10,25,28]. In addition, fixed location and direction of magnetic dipoles but variable intensity field, is considered in several applications such as microrobots micromanipulation [20] or magnetic drug targeting [32]. With such a configuration it is possible to reduce the numbers of free variables (fixed location and direction of dipoles) and the hardware involved.…”

Section: Minimization and Controlmentioning

confidence: 99%

Optimizing the Kelvin force in a moving target subdomain

Antil

Nochetto

Venegas

2017

Math. Models Methods Appl. Sci.

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In order to generate a desired Kelvin (magnetic) force in a target subdomain moving along a prescribed trajectory, we propose a minimization problem with a tracking type cost functional. We use the so-called dipole approximation to realize the magnetic field, where the location and the direction of the magnetic sources are assumed to be fixed. The magnetic field intensity acts as the control and exhibits limiting pointwise constraints. We address two specific problems: the first one corresponds to a fixed final time whereas the second one deals with an unknown force to minimize the final time. We prove existence of solutions and deduce local uniqueness provided that a second order sufficient condition is valid. We use the classical backward Euler scheme for time discretization. For both problems we prove the H 1 -weak convergence of this semi-discrete numerical scheme. This result is motivated by Γ-convergence and does not require second order sufficient condition. If the latter holds then we prove H 1 -strong local convergence. We report computational results to assess the performance of the numerical methods. As an application, we study the control of magnetic nanoparticles as those used in magnetic drug delivery, where the optimized Kelvin force is used to transport the drug to a desired location.

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Magnetic Injection of Nanoparticles Into Rat Inner Ears at a Human Head Working Distance

Cited by 34 publications

References 61 publications

Synthesis of Brightly PEGylated Luminescent Magnetic Upconversion Nanophosphors for Deep Tissue and Dual MRI Imaging

Synthesis of Brightly PEGylated Luminescent Magnetic Upconversion Nanophosphors for Deep Tissue and Dual MRI Imaging

Shaping Magnetic Fields to Direct Therapy to Ears and Eyes

Optimizing the Kelvin force in a moving target subdomain

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