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. 2022 Dec 29;126(51):9605-9617.
doi: 10.1021/acs.jpca.2c05902. Epub 2022 Dec 16.

Scaling Up Magnetic Nanobead Synthesis with Improved Stability for Biomedical Applications

Nadja C Bigall  1   2 , Marina Rodio  1 , Sahitya Avugadda  1 , Manuel Pernia Leal  1   3 , Riccardo Di Corato  1   4 , John S Conteh  1 , Romuald Intartaglia  1 , Teresa Pellegrino  1
Affiliations

Scaling Up Magnetic Nanobead Synthesis with Improved Stability for Biomedical Applications

Nadja C Bigall et al. J Phys Chem A. .

Abstract

The growing interest in multifunctional nano-objects based on polymers and magnetic nanoparticles for biomedical applications motivated us to develop a scale-up protocol to increase the yield of polymeric magnetic nanobeads while aiming at keeping the structural features at optimal conditions. The protocol was applied to two different types of magnetic ferrite nanoparticles: the Mn-ferrite selected for their properties as contrast agents in magnetic resonance imaging and iron oxide nanostar shaped nanoparticles chosen for their heat performance in magnetic hyperthermia. At the same time, some experiments on surface functionalization of nanobeads with amino modified polyethyelene glycol (PEG) molecules have provided further insight into the formation mechanism of magnetic nanobeads and the need to cross-link the polymer shell to improve the stability of the beads, making them more suitable for further manipulation and use. The present work summarizes the most important parameters required to be controlled for the upscaling of nanobead synthesis in a bench protocol and proposes an alternative cross-linking strategy based on prefunctionalization of the polymer prior to the nanobead formation as a key parameter to improve the nanobead structural stability in solutions at different pHs and during surface functionalization.

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Conflict of interest statement

The authors declare no competing financial interest.

Figures

Figure 1
Figure 1
Schematic drawing of the nanobead formation in the presence of water. Initially (left), when dissolving the nanoparticles with the polymer, all maleic anhydride rings are closed. After adding a controlled amount of water and vortexing for a certain time (center), some of the maleic anhydride rings are opened while both the polymer and the nanoparticles remain in solution. Opening of the maleic anhydride of this polymer to a certain degree affects the solubility in more polar solvents, and on the other hand, the stability of the colloidal nanobeads formed owing to their resulting surface charge and hence electrostatic repulsion. Therefore, the nanobeads formed during the addition of acetonitrile (right) are colloidally stable in solution.
Figure 2
Figure 2
TEM images of nanobead synthesis under controlled water amount addition of (A) 2.5 μL (139 μmol), (B) 5 μL (278 μmol), and (C) 7.5 μL (417 μmol) of water added to the anhydrous reactants (polymer and Mn-IONPs in THF) followed by the addition of acetonitrile solvent. (Zoom D–F) Higher magnification of TEM image of the nanobeads. (G) Analysis of the nanobead diameters by TEM and by DLS as a function of the water amount added. The error bar indicates the standard deviation of the size distribution by TEM analysis on at least 200 nanobeads analyzed and the standard deviation of the DLS analysis from three independent measurements.
Figure 3
Figure 3
Modification of the upscale procedure from the water-controlled nanobead synthesis (left) and a 100-fold upscale procedure (right). The amounts of water, IONPs, and polymer solution were increased by 100-fold, while the amount of THF added to the polymer+IONPs+water solution was adjusted to reach a volume below 6 mL and the ACN solvent volume was fixed to 16 mL. Note that the volume of Mn-IONPs is always evaporated before addition of polymer solution, water, and THF.
Figure 4
Figure 4
TEM image (A,B) and higher magnification TEM image (zoom C and D) of nanobeads produced by a 100 times scale-up approach and at a water content of 500 μL (A) and 750 μL (B). (E) Analysis of the nanobead diameter by TEM (left columns) and by DLS (right columns) as a function of the water/polymer ratio. The error bar indicates the standard deviation from the size distribution by TEM and DLS analysis measured by three independent measurements. For those two nanobead samples, the PDIs as obtained from DLS measurements were 0.063 and 0.077, respectively. (F) Concentration of l Mn-IONPs measured on the nanobeads dispersion.
Figure 5
Figure 5
Implementation of the nanobeads scale-up protocol to another type of magnetic nanoparticles, the IONS with a star shape and a size of 13 ± 1 nm. (A) Photograph of magnetic nanobeads (MNB-IONS) solution. (B, C) TEM images of the magnetic nanobeads at low and high magnification. (E) TEM image of the individually coated IONS stabilized in water with TMAOH. (D) SAR values of MNBs-IONS and IONS solutions based on the hysteresis loops measured by AC magnetometry at frequency of 110 kHz and field range of 16–24 kA/m at a fixed concentration of 1 gFe/L in water.
Figure 6
Figure 6
Overview of the TEM image of magnetic nanobeads obtained from PMA-OD (A) before and (B) after modification with amino-PEG750 via EDC chemistry. (C) and (D) are TEM images of magnetic beads from PMA-OD prefunctionalized with a tertiary amine (N,N-dimethylethylenediamine), before and after amino-PEG750, respectively. (E) and (F) are TEM images of beads functionalized with an amino derivate of a pyridine (2-(2-pyridyl)ethylamine), before and after PEG-ylation. In all three cases, after the reaction of the shell with amino-PEG750, the polymer beads are not visible anymore and only groups of nanoparticles can be distinguished, indicating a loss of polymer structures around each bead due to PEG functionalization reaction.
Figure 7
Figure 7
(left) Zeta potential and (right) hydrodynamic diameter (dH) from the DLS curve as a function of the pH before and after monoamino PEG750 reaction of the solution for (A) nanobeads made from PMA-OD and (B–D) nanobeads made from PMA-OD prefunctionalized with primary amine side chain at 25%, 50%, and 75% of the polymer monomer units, respectively. Even though the nanobeads sizes are not discrete anymore after PEG-ylation, the colloidal stability of the beads seems to remain, and the net zeta potential has increased.
Figure 8
Figure 8
(Left column) TEM images of nanobeads prepared from diamine (2,2′-ethylendedioxy)bis(ethylamine) functionalized polymers with 25%, 50%, and 75% diamine molecules added with respect to the maleic anhydride monomer groups. (Right column) TEM images of the same nanobeads after functionalization with poly(ethylene glycol). In the bottom line, the pH dependency of the differently modified polymer nanobeads is shown (left) before and (right) after the monoamino-PEG750 functionalization. Key: polymer0, no amine functionalization; polymer3, functionalization with 25, 50, and 75% of the diamine molecules added with respect to the maleic anhydride groups.
See this image and copyright information in PMC

References

    1. Gavilán H.; Avugadda S. K.; Fernández-Cabada T.; Soni N.; Cassani M.; Mai B. T.; Chantrell R.; Pellegrino T. Magnetic nanoparticles and clusters for magnetic hyperthermia: Optimizing their heat performance and developing combinatorial therapies to tackle cancer. Chem. Soc. Rev. 2021, 50 (20), 11614–11667. 10.1039/D1CS00427A. - DOI - PubMed
    1. Ho D.; Sun X.; Sun S. Monodisperse magnetic nanoparticles for theranostic applications. Accounts of chemical research 2011, 44 (10), 875–882. 10.1021/ar200090c. - DOI - PMC - PubMed
    2. Laurent S.; Forge D.; Port M.; Roch A.; Robic C.; Vander Elst L.; Muller R. N. Magnetic iron oxide nanoparticles: synthesis, stabilization, vectorization, physicochemical characterizations, and biological applications. Chem. Rev. 2008, 108 (6), 2064–2110. 10.1021/cr068445e. - DOI - PubMed
    3. Colombo M.; Carregal-Romero S.; Casula M. F.; Gutiérrez L.; Morales M. P.; Böhm I. B.; Heverhagen J. T.; Prosperi D.; Parak W. J. Biological applications of magnetic nanoparticles. Chem. Soc. Rev. 2012, 41 (11), 4306–4334. 10.1039/c2cs15337h. - DOI - PubMed
    1. Pereira C.; Pereira A. M.; Rocha M.; Freire C.; Geraldes C. F. Architectured design of superparamagnetic Fe 3 O 4 nanoparticles for application as MRI contrast agents: mastering size and magnetism for enhanced relaxivity. J. Mater. Chem. B 2015, 3 (30), 6261–6273. 10.1039/C5TB00789E. - DOI - PubMed
    1. Plank C.; Zelphati O.; Mykhaylyk O. Magnetically enhanced nucleic acid delivery. Ten years of magnetofection—Progress and prospects. Advanced drug delivery reviews 2011, 63 (14–15), 1300–1331. 10.1016/j.addr.2011.08.002. - DOI - PMC - PubMed
    2. Estelrich J.; Escribano E.; Queralt J.; Busquets M. A. Iron oxide nanoparticles for magnetically-guided and magnetically-responsive drug delivery. International journal of molecular sciences 2015, 16 (4), 8070–8101. 10.3390/ijms16048070. - DOI - PMC - PubMed
    1. Bigall N. C.; Parak W. J.; Dorfs D. Fluorescent, magnetic and plasmonic—Hybrid multifunctional colloidal nano objects. Nano Today 2012, 7 (4), 282–296. 10.1016/j.nantod.2012.06.007. - DOI
    2. Bruns O. T.; Ittrich H.; Peldschus K.; Kaul M. G.; Tromsdorf U. I.; Lauterwasser J.; Nikolic M. S.; Mollwitz B.; Merkel M.; Bigall N. C. Real-time magnetic resonance imaging and quantification of lipoprotein metabolism in vivo using nanocrystals. Nature Nanotechnol. 2009, 4 (3), 193–201. 10.1038/nnano.2008.405. - DOI - PubMed
    3. Tromsdorf U. I.; Bigall N. C.; Kaul M. G.; Bruns O. T.; Nikolic M. S.; Mollwitz B.; Sperling R. A.; Reimer R.; Hohenberg H.; Parak W. J. Size and surface effects on the MRI relaxivity of manganese ferrite nanoparticle contrast agents. Nano Lett. 2007, 7 (8), 2422–2427. 10.1021/nl071099b. - DOI - PubMed

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