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Published on: February 5, 2019
Preparation and evaluation of MRI detectable poly (acrylic acid) microspheres loaded with superparamagnetic iron
Huan Wang1, Xiao-Ya Qin1, Zi-Yuan Li1
1The State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China; Beijing Key Laboratory of Molecular Pharmaceutics and New Drug Delivery Systems, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China.
Abstract:
To monitor the spatial distribution of embolic particles inside the target tissues during and after embolization, blank poly (acrylic acid) microspheres (PMs) were initially prepared by inverse suspension polymerization method and then loaded with superparamagnetic iron oxide (SPIO) nanoparticles by in situ precipitation method to obtain magnetic resonance imaging (MRI) detectable SPIO-loaded poly (acrylic acid) microspheres (SPMs). The loading of SPIO nanoparticles in SPMs was confirmed by vibrating sample magnetometer, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and infrared spectrum, respectively. The results showed that SPMs exhibited excellent superparamagnetism and the SPIO embedded in SPMs were proved to be inverse spinel magnetite. The content of SPIO loaded in wet SPMs of subgroups of 100-300, 300-500, 500-700 and 700-900μm was measured to be 11.84±0.07, 10.20±0.05, 9.98±0.00 and 8.79±0.01mg/ml, corresponding to the weight percentage in freeze-dried SPMs to be 18.07±0.28%, 18.54±0.13%, 18.66±0.01% and 18.50±0.07%, respectively. The SPMs were spherical in shape, had smooth surface, and were within the size range of clinical demands for embolization. The compression tests indicated that SPMs were more rigid than PMs and commercially used Embospheres (P<0.01). The MRI detectability of SPMs was evaluated with the SPMs embedded in gel phantom in vitro and injected subcutaneously into the back of mice in vivo. Both the results demonstrated that the SPMs could provide distinct negative contrast enhancement and be sensitively detected by T2-weighted MR imaging. All the results show that SPMs are potential MRI detectable embolic microspheres for the future embolotherapy.
Insights
Researchers developed superparamagnetic iron oxide (SPIO)-loaded poly (acrylic acid) microspheres (SPMs) for enhanced embolotherapy. These MRI-detectable SPMs allow real-time monitoring of embolic particle distribution during procedures.
Area of Science:
- Biomaterials Science
- Medical Imaging
- Interventional Radiology
Background:
- Embolization therapy requires precise monitoring of embolic agent distribution.
- Current methods lack real-time spatial tracking of microspheres within target tissues.
- Development of contrast-enhanced embolic agents is crucial for improved therapeutic outcomes.
Purpose of the Study:
- To synthesize and characterize superparamagnetic iron oxide (SPIO)-loaded poly (acrylic acid) microspheres (SPMs).
- To evaluate the magnetic properties, structural integrity, and MRI detectability of SPMs.
- To assess the potential of SPMs as MRI-detectable embolic agents for embolotherapy.
Main Methods:
- Poly (acrylic acid) microspheres (PMs) prepared via inverse suspension polymerization.
- SPIO nanoparticles loaded into PMs using in situ precipitation.
- Characterization using VSM, TEM, XRD, XPS, FTIR, and compression testing.
- In vitro (gel phantom) and in vivo (mouse model) MRI evaluation using T2-weighted imaging.
Main Results:
- SPMs exhibited excellent superparamagnetism with embedded inverse spinel magnetite SPIO.
- SPMs demonstrated spherical morphology, smooth surfaces, and suitable size for embolization.
- Compression tests showed SPMs are more rigid than PMs and Embospheres.
- T2-weighted MRI confirmed distinct negative contrast enhancement and sensitive detection of SPMs in vitro and in vivo.
Conclusions:
- Synthesized SPMs are MRI-detectable and possess suitable physical properties for embolization.
- SPMs enable sensitive detection and monitoring of embolic agent distribution via MRI.
- SPMs show significant potential as advanced embolic microspheres for future embolotherapy.
