Mechanism of in situ surface polymerization of gallic acid in an environmental-inspired preparation of carboxylated core-shell magnetite nanoparticles

Ildikó Y. Tóth, M. Szekeres, Rodica Turcu, Szilárd Sáringer, E. Illés, Dániel Nesztor, E. Tombácz

Research output: Contribution to journalArticle

25 Citations (Scopus)

Abstract

Magnetite 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 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 (UV-visible 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 poly(carboxylic acid)s due to ring opening while Fe3+ ions reduced to Fe2+. 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.

Original languageEnglish
Pages (from-to)15451-15461
Number of pages11
JournalLangmuir
Volume30
Issue number51
DOIs
Publication statusPublished - Dec 30 2014

Fingerprint

Magnetite Nanoparticles
Magnetite nanoparticles
Gallic Acid
Polymerization
magnetite
polymerization
nanoparticles
preparation
acids
Acids
Photoelectron Spectroscopy
Spectrum Analysis
Dynamic light scattering
Antioxidants
Nanoparticles
antioxidants
Infrared spectroscopy
X ray photoelectron spectroscopy
Monomers
light scattering

ASJC Scopus subject areas

  • Electrochemistry
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Materials Science(all)
  • Spectroscopy
  • Medicine(all)

Cite this

Mechanism of in situ surface polymerization of gallic acid in an environmental-inspired preparation of carboxylated core-shell magnetite nanoparticles. / Tóth, Ildikó Y.; Szekeres, M.; Turcu, Rodica; Sáringer, Szilárd; Illés, E.; Nesztor, Dániel; Tombácz, E.

In: Langmuir, Vol. 30, No. 51, 30.12.2014, p. 15451-15461.

Research output: Contribution to journalArticle

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