Enzyme Release from Polyion Complex by Extremely Low Frequency Magnetic Field

Abstract

Remote nano-magneto-mechanical actuation of magnetic nanoparticles (Mnps) by non-heating extremely low frequency magnetic field (ELF MF) is explored as a tool for non-invasive modificationof bionanomaterials in pharmaceutical and medical applications. Here we study the effects of ELF MF (30-160 Hz, 8-120 kA/m) on the activity and release of a model enzyme, superoxide dismutase 1 (SOD1) immobilized by polyion coupling on dispersed Mnps aggregates coated with poly(L-lysine)-blockpoly(ethylene glycol) block copolymer (s-MNPs). Such fields do not cause any considerable heating of Mnps but promote their rotating-oscillating mechanical motion that produces mechanical forces and deformations in adjacent materials. We observed the changes in the catalytic activity of immobilized SOD1 as well as its release from the s-MNPs/SOD1 polyion complex upon application of the ELF MF for 5 to 15 min. At longer exposures (25 min) the s-MNPs/SOD1 dispersion destabilizes. The bell-shaped effect of the field frequency with maximum at f = 50 Hz and saturation effect of field strength (between 30 kA/m and 120 kA/m at f = 50 Hz) are reported and explained. The findings are significant as one early indication of the nano-magneto-mechanical disruption by eLf Mf of cooperative polyion complexes that are widely used for design of current functional healthcare bionanomaterials.Non-invasive functional control of bionanomaterials in inaccessible areas of a human body (e.g., biochemical reactions, drug release, gene expression, etc.) could greatly advance development of diagnostics and therapeutic modalities 1 . This control can be accomplished by remote actuation of nanoparticles by external fields 2-6 . In recent years magnetic nanoparticles (MNPs) have been investigated for cell separation, targeted drug delivery, and magnetic resonance imaging (MRI) 7-9 . Remote actuation of MNPs by radio frequency (200-800 kHz) magnetic fields has been used in hyperthermia for cancer therapy 10-12 . However, this approach has a risk of tissue overheating and damage. Recently an alternative nano-magneto-mechanical actuation of MNPs by non-heating extremely low frequency magnetic field (ELF MF) has attracted increasing attention in drug delivery and nanomedicine [13][14][15][16][17] .The phenomenon of nano-magneto-mechanical actuation is linked to the ability of MNPs to undergo mechanical motion in ELF MF and as a consequence produce mechanical forces and deformations in adjacent materials. It is well known, that a single-domain MNPs can relax in an external magnetic field, reducing an angle between the MNPs magnetic moment μ and the field vector H [18][19][20] . Two basic types of relaxation phenomena are dependent on the size of the magnetic core. MNPs with D m less than some critical value d* experience rotation of magnetic moments μ towards the vector H, which proceeds mainly by overcoming the crystallographic anisotropy of the lattice, without causing significant mechanical motion of the particle (Néel relaxation). MNPs with a diameter D m greater than d*...

Permeability of the Composite Magnetic Microcapsules Triggered by a Non-Heating Low-Frequency Magnetic Field

“…The appeared mechanical vibration and motion of the MNPs can make an impact on the particle environment and induce mechanical stress, which causes the efficient release of the model macromolecules [25,28]. The magneto-mechanic disruption of a highly specific protein-protein complex and a protein-polymer complex during the exposure to a low-frequency magnetic field has been previously shown [29,30]. In addition, structural changes in the lipid liposomal membrane due to magneto-mechanical actuation have been demonstrated [31,32].…”

CaCO3 Nanoparticles Coated with Alternating Layers of Poly-L-Arginine Hydrochloride and Fe3O4 Nanoparticles as Navigable Drug Carriers and Hyperthermia Agents

“…Imaging techniques include fluorescence molecular tomography, magnetic resonance imaging (MRI), optical coherence tomography, and the new ones such as optoacoustic microscopy and tomography . Many approaches have already been used for the remote release of encapsulated drugs, including laser irradiation, alternating magnetic fields, , and ultrasound including high-intensity focused ultrasound . Precise navigation can be implemented via optical and acoustic tweezers and the magnetic field gradient .…”

Magneto-Mechanical Approach in Biomedicine: Benefits, Challenges, and Future Perspectives

“…Unlike MHT, magneto-mechanics operates with non-heating low-frequency AMFs (LF AMF) with f < 10 kHz and B << 1 [ 6 , 30 ]. However, in practice, ultra-low frequency fields are most often used, i.e., when f < 100 Hz [ 24 , 31 , 32 , 33 , 34 , 35 ]. At such low frequencies, both the bulk heating of the medium at any MNP concentrations and the local overheating Δ T S on the MNP surface can be neglected.…”