Enhanced stability of polyacrylate-coated magnetite nanoparticles in biorelevant media

Hajdú, Angéla; Szekeres, Márta; Tóth, Ildikó Y.; Bauer, Rita A.; Mihály, Judith; Zupkó, István; Tombácz, Etelka

doi:10.1016/j.colsurfb.2012.01.042

Cited by 75 publications

(126 citation statements)

References 54 publications

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“…1), neutralizing carboxylates, but not changing the surface charge of MNP. As a contrast, the charge of MNP was compensated almost quantitatively at the IEP in PAA adsorption, 35 The results of the cytotoxicity tests show that PAM@MNPs exerted no substantial action on the growth of cancer cells even at the highest concentration, seen on the right side of Figure 8 as the insignificant (less than 6 % for each cell lines) extent of proliferation inhibition. The MTT method applied here is widely used for investigation of potential anticancer agents.…”

Section: Charging Of Mnp and Pam The Ph-and Ionic Strength-dependentmentioning

confidence: 97%

Designed Polyelectrolyte Shell on Magnetite Nanocore for Dilution-Resistant Biocompatible Magnetic Fluids

et al. 2012

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Magnetite nanoparticles (MNPs) coated with poly(acrylic acid-co-maleic acid) polyelectrolyte (PAM) have been prepared with the aim of improving colloidal stability of core-shell nanoparticles for biomedical applications and enhancing the durability of the coating shells. FTIR-ATR measurements reveal two types of interaction of PAM with MNPs: hydrogen bonding and innersphere metal-carboxylate complex formation. The mechanism of the latter is ligand exchange between uncharged -OH groups of the surface and -COO -anionic moieties of the polyelectrolyte as revealed by adsorption and electrokinetic experiments. The aqueous dispersion of PAM@MNP particles (magnetic fluids -MFs) tolerate physiological salt concentration at composition corresponding to the plateau of the high-affinity adsorption isotherm. The plateau is reached at small amount of added PAM and at low concentration of non-adsorbed PAM, making PAM highly efficient for coating MNPs. The adsorbed PAM layer is not desorbed during dilution. The performance of the PAM shell is superior to that of polyacrylic acid (PAA), often used in biocompatible MFs. This is explained by the different adsorption mechanisms, namely metalcarboxylate cannot form in the case of PAA. Molecular-level understanding of the protective shell formation on MNPs presented here improves fundamentally the colloidal techniques used in coreshell nanoparticle production for nanotechnology applications. This is a PDF file of an unedited manuscript that has been accepted for publication. Final edited form is published in Langmuir 2012, 28, 16638−16646. http://dx

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Section: Charging Of Mnp and Pam The Ph-and Ionic Strength-dependentmentioning

confidence: 97%

Designed Polyelectrolyte Shell on Magnetite Nanocore for Dilution-Resistant Biocompatible Magnetic Fluids

et al. 2012

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“…We compared the effect of the adsorption of the different organic acids on the pH-dependent charging, salt tolerance and so the colloidal stability of magnetite nanoparticles. Some of the results used here can be found in our earlier publications [6][7][8][9]16], together with the detailed discussions on the mechanisms of adsorption. Therefore, we do not intend to go into those details, but we use our earlier conclusions to support the findings of the present comparative study on the stabilizing efficiencies of small and large molecular organic acids.…”

Section: Introductionmentioning

confidence: 99%

“…Besides our several years' experience with aqueous solutions of humic acids, their interaction with magnetite (Fe3O4, magnetic iron oxide) has been also studied [6,7]. The CA, PAA and PAM interactions with magnetite nanoparticles have been recently investigated [8,9,16]. Besides their environmental relevance, these are important from biomedical application point of view.…”

Section: Introductionmentioning

confidence: 99%

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Adsorption of organic acids on magnetite nanoparticles, pH-dependent colloidal stability and salt tolerance

Tombácz

Tóth

Nesztor

et al. 2013

Colloids and Surfaces A: Physicochemical and Engineering Aspect

115

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Graphical abstractH-type isotherms HA, PAM, GA, and CA Highlights  Organic acids either stabilize or destabilize oxide nanoparticles in natural waters.  The stabilizing/destabilizing effect depends on pH, salinity and organic concentration.  Specific configuration of carboxylic groups is necessary to surface complexation.  Surface complexation leads to high affinity adsorption isotherms.  Higher molecular weight organic acids provide better stability than smaller ones. AbstractThe adsorption of different organic acids and their influence on the pH-dependent charging, salt tolerance and so the colloidal stability of magnetite nanoparticles are compared. Adsorption isotherms of citric acid -CA, gallic acid -GA, poly(acrylic acid) -PAA, poly(acrylic-co-maleic acid) -PAM and humic acid -HA were measured. The pH-dependent charge state of MNPs was characterized by electrophoretic mobility and their aggregation by dynamic light scattering. The salt tolerance was tested in coagulation kinetic experiments. Although the adsorption capacities, the type of bonding (either H-bonds or metal ioncarboxylate complexes) and so the bond strengths are significantly different, the following general trends have been found. Small amount of organic acids at pH < ~8 (the pH of PZC of magnetite) -relevant condition in natural waters -only neutralizes the positive charges, and so promotes the aggregation and sedimentation of nanoparticles. Greater amounts of organic acid, above the charge neutralization, cause the sign reversal of particle charge, and at high

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“…After 1 day of GA adsorption, the hydrodynamic diameter of the GA-coated particles at high pH is close to that of naked MNPs (100 nm) published by us earlier. 12 However, it approaches the value of 170 nm four weeks after the preparation, characteristic to that of polyelectrolyte (polyacrylic acid 50 and poly(acrylicco-maleic acid 43 ) coated MNPs. This reveals that the surface polymerization of GA proceeds with time.…”

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Mechanism of in Situ Surface Polymerization of Gallic Acid in an Environmental-Inspired Preparation of Carboxylated Core–Shell Magnetite Nanoparticles

et al. 2014

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Corresponding authorsM. Szekeres (szekeres@chem.u-szeged.hu) and E. Tombácz (tombacz@chem.u-szeged.hu) Graphical abstract AbstractMagnetite nanoparticles (MNPs) with biocompatible coatings are good candidates for MRI (magnetic resonance imaging) contrasting, magnetic hyperthermia treatments and drug delivery systems. The spontaneous surface induced polymerization of dissolved organic matter on environmental mineral particles inspired us to prepare carboxylated core-shell MNPs by using a ubiquitous polyphenolic precursor. Through the adsorption and in-situ surface polymerization of gallic acid (GA), a polygallate (PGA) coating is formed on the nanoparticles (PGA@MNP) with possible antioxidant capacity. The Polygallate on magnetite nanoparticles Humic matter on clays 2This is a PDF file of an unedited manuscript that has been accepted for publication. Final edited form is published in Langmuir, 2014, 30:15451−15461. http://dx.doi.org/10.1021/la5038102 present work explores the mechanism of polymerization with the help of potentiometric acid-base titration, dynamic light scattering (for particle size and zeta potential determination), UV-Vis (UVvisible light spectroscopy), FTIR-ATR (Fourier-transformed infrared spectroscopy by attenuated total reflection) and XPS (X-ray photoelectron spectroscopy) techniques. We observed the formation of ester and ether linkages between gallate monomers both in solution and in the adsorbed state. Higher polymers were formed in the course of several weeks both on the surface of nanoparticles and in the dispersion medium. The ratio of the absorbances of PGA supernatants at 400 and 600 nm (i.e., the E4/E6 ratio commonly used to characterize the degree of polymerization of humic materials) was determined to be 4.3, similar to that of humic acids. Combined XPS, dynamic light scattering and FTIR-ATR results revealed that prior to polymerization, the GA monomers became oxidized to polycarboxylic acids due to ring opening while Fe 3+ ions reduced to Fe 2+ . Our published results on the colloidal and chemical stability of PGA@MNPs are referenced thoroughly in the present work. Detailed studies on biocompatibility, antioxidant property and biomedical applicability of the particles will be published.

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Enhanced stability of polyacrylate-coated magnetite nanoparticles in biorelevant media

Cited by 75 publications

References 54 publications

Designed Polyelectrolyte Shell on Magnetite Nanocore for Dilution-Resistant Biocompatible Magnetic Fluids

Designed Polyelectrolyte Shell on Magnetite Nanocore for Dilution-Resistant Biocompatible Magnetic Fluids

Adsorption of organic acids on magnetite nanoparticles, pH-dependent colloidal stability and salt tolerance

Mechanism of in Situ Surface Polymerization of Gallic Acid in an Environmental-Inspired Preparation of Carboxylated Core–Shell Magnetite Nanoparticles

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