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Updated: Jun 4, 2026
Biofunctionalization of Magnetic Nanomaterials
Published on: July 16, 2020
Surface functionalization of superparamagnetic nanoparticles for the development of highly efficient magnetic
Chao Huang1, Koon Gee Neoh, Liang Wang
1Department of Chemical and Biomolecular Engineering, National University of Singapore, Kent Ridge, Singapore 119260.
Abstract:
In vivo magnetic resonance imaging (MRI) tracking of macrophages plays an important role in monitoring and understanding numerous human diseases with high macrophage activity. In this work, superparamagnetic iron oxide nanoparticles (SPIONs) of ∼12 nm were surface-functionalized with poly(DL-lactic acid-co-malic acid) copolymer (PLMA) via a nanoprecipitation method. The r(1), r(2) and r(2) /r(1) values of the PLMA-SPIONs obtained at a magnetic field of 3 T were 0.38, 196 and 516 mM(-1) s(-1) , respectively. The high r(2)/r(1) ratio can be expected to provide enhanced MR contrast. The PLMA-SPIONs were readily taken in by macrophages and the high iron uptake was confirmed via Prussian Blue staining and quantified by inductively coupled plasma mass spectrometry (ICP-MS). No significant cytotoxicity was found even at a high nanoparticle loading of 67.7 pg Fe per cell. A linear relationship between R(2) and R2* values and the number of PLMA-SPIONs labeled cells was observed in vitro. As a result of the significantly higher R2* than R(2) effects, an in vitro detection threshold of about 2820 labeled cells was achieved with short labeling time and low nanoparticle concentration using a clinical 3 T MRI scanner. Thus, the PLMA-SPIONs can be potentially useful as magnetic resonance probes for targeting and tracking macrophages.
Insights
Superparamagnetic iron oxide nanoparticles (SPIONs) coated with poly(DL-lactic acid-co-malic acid) (PLMA) show promise for tracking macrophages in vivo using magnetic resonance imaging (MRI). These PLMA-SPIONs offer enhanced contrast and detect low numbers of labeled cells with minimal toxicity.
Area of Science:
- Biomedical Engineering
- Materials Science
- Nanotechnology
Background:
- In vivo magnetic resonance imaging (MRI) is crucial for monitoring diseases with high macrophage activity.
- Developing effective contrast agents for macrophage tracking is essential for disease diagnosis and management.
Purpose of the Study:
- To synthesize and characterize poly(DL-lactic acid-co-malic acid)-coated superparamagnetic iron oxide nanoparticles (PLMA-SPIONs).
- To evaluate the efficacy of PLMA-SPIONs as contrast agents for in vitro and potentially in vivo macrophage tracking using MRI.
Main Methods:
- Surface functionalization of superparamagnetic iron oxide nanoparticles (SPIONs) with PLMA using nanoprecipitation.
- Characterization of PLMA-SPIONs' relaxivity (r(1), r(2), r(2)/r(1)) at 3 T.
- Assessment of cellular uptake, iron quantification (ICP-MS), and cytotoxicity in macrophages.
- Evaluation of MRI contrast enhancement and detection limits using a clinical 3 T MRI scanner.
Main Results:
- PLMA-SPIONs exhibited a high r(2)/r(1) ratio (516 mM(-1) s(-1)), indicating enhanced MR contrast potential.
- Macrophages readily internalized PLMA-SPIONs with no significant cytotoxicity observed.
- A linear correlation was found between R(2)/R(2*) values and the number of labeled cells.
- An in vitro detection threshold of approximately 2820 labeled cells was achieved.
Conclusions:
- PLMA-SPIONs are effective MRI contrast agents for macrophage labeling and tracking.
- The developed nanoparticles demonstrate low cytotoxicity and high cellular uptake.
- These findings suggest PLMA-SPIONs hold potential for targeted macrophage imaging in disease monitoring.
