Triggered Release from Thermoresponsive Polymersomes with Superparamagnetic Membranes

Abstract

Magnetic polymersomes were prepared by self-assembly of the amphiphilic block copolymer poly(isoprene-b-N-isopropylacrylamide) with monodisperse hydrophobic superparamagnetic iron oxide nanoparticles (SPION). The specifically designed thermoresponsive block copolymer allowed for efficient incorporation of the hydrophobic nanoparticles in the membrane core and encapsulation of the water soluble dye calcein in the lumen of the vesicles. Magnetic heating of the embedded SPIONs led to increased bilayer permeability through dehydration of the thermoresponsive PNIPAM block. The entrapped calcein could therefore be released in controlled doses solely through exposure to pulses of an alternating magnetic field. This hybrid SPION-polymersome system demonstrates a possible direction for release applications that merges rational polymersome design with addressed external magnetic field-triggered release through embedded nanomaterials.

Thermoresponsive Polypeptoid‐Coated Superparamagnetic Iron Oxide Nanoparticles by Surface‐Initiated Polymerization

“…A dense, stably anchored polypeptoid shell should allow for colloidal stability of the SPION by steric repulsion, which was shown to be beneficial for SPION used as magnetic resonance contrast agent, potential drug delivery vehicle or magnetically actuated release vehicles . The initial ligand replacement of oleic acid with nitrodopamine yields SPION with high initiator density that should convert into a high grafting density of the brush …”

Magneto‐Thermal Release from Nanoscale Unilamellar Hybrid Vesicles

“…Sample preparation by solvent inversion indicated formation of LUV that paralleled that of the GUV preparation. The individual diblock copolymers assemble into vesicles with a sharp, bimodal size distribution for PBD‐ b ‐PEO or a broad, featureless one for PI‐ b ‐PNIPAM, as previously described . Vesicles formed at 2 mg mL −1 via solvent inversion frequently showed multilamellar and multivesicular assemblies both in optical microscopy and in TEM.…”

“…Efficient magnetically triggered and thermally actuated release requires the incorporation of magnetic nanoparticles in the vesicle membrane . The co‐self‐assembly behavior of the scaffold diblock copolymer PBD(1200)‐ b ‐PEO(600) with monodisperse hydrophobic USPION was therefore first investigated and optimized.…”

“…An elegant approach to achieve external control over the release profile is through structural incorporation of functional nanomaterials; these can act as efficient sensitizers for externally controlled electromagnetic fields that actuate the vesicle membrane, for example, through local heating . One such nanomaterial is ultra‐small superparamagnetic iron oxide nanoparticles (USPION) that can be used as sensitizers for magneto‐thermal actuation . Magnetic particles have been embedded in liposomes in various configurations to trigger release by thermal transitions in lipid membranes, and have been shown to be most efficient when USPION are positioned in the lipid membrane .…”

Агрегативная устойчивость и магнитные характеристики коллоидных частиц Fe-=SUB=-m-=/SUB=-O-=SUB=-n-=/SUB=--SiO-=SUB=-2-=/SUB=-, полученных золь-гель методом

“…Применение магнитных наночастиц (МНЧ) в ме-дицине требует изучения их агрегативной устойчи-вости в различных дисперсионных средах [4], вклю-чая воду [5,6], буферные растворы [7], растворы бел-ков [8,9], плазму крови и цельную кровь [10,11]. Синтез МНЧ включает их стабилизацию за счет использования поверхностно-активных веществ, что позволяет обеспе-чить агрегативную и седиментационную устойчивость водных коллоидных растворов [11].…”