Bilayer Charge Reversal and Modification of Lipid Organization by Dendrimers as Observed by Sum-Frequency Vibrational Spectroscopy

T. Keszthelyi, Gábor Holló, G. Nyitrai, J. Kardos, László Héja

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

Polyamidoamine (PAMAM) dendrimers are hyperbranched, nanosized polymers with promising biomedical applications as nanocarriers in targeted drug delivery and gene therapy. For the development of safe dendrimer-based biomedical applications it is necessary to gain an understanding of the detailed mechanism of the interactions of both cationic and anionic dendrimers with cell membranes. To characterize dendrimer-membrane interactions we applied solid-supported lipid bilayers as biomembrane models and utilized infrared-visible sum-frequency vibrational spectroscopy to independently probe the interactions of cationic G5-NH2 and anionic G4.5-COONa dendrimers with the two leaflets of the lipid bilayers. Interaction with both dendrimers led to changes in the interfacial water structure and charge density as evidenced by the changes in the OH band intensities in the sum-frequency spectra of the bilayers. Interaction with the G5-NH2 dendrimer also led to a unique inversion of the sign of the OH-stretch amplitudes, in addition to a decrease in their absolute values. We suggest that the positively charged amino groups on the G5-NH2 dendrimer surface bind to the negatively charged bilayer, while uncompensated positive charges not involved in the binding cause a reversal of the electric field and thus an opposite orientation of the interfacial water molecules. More subtle but nonetheless significant changes were seen in the relative magnitudes of the CH amplitudes. The methyl antisymmetric to symmetric stretch amplitude ratios are altered, implying changes in the tilt angles of the phospholipid alkyl chains. The conformational order of the phospholipid alkyl chains of both leaflets is also influenced by the G5-NH2 dendrimer while G4.5-COONa has no effect on the alkyl chain conformation. (Figure Presented).

Original languageEnglish
Pages (from-to)7815-7825
Number of pages11
JournalLangmuir
Volume31
Issue number28
DOIs
Publication statusPublished - Jul 21 2015

Fingerprint

Dendrimers
Vibrational spectroscopy
dendrimers
Lipids
lipids
spectroscopy
Lipid bilayers
Phospholipids
interactions
Gene therapy
gene therapy
Water
Cell membranes
Charge density
Conformations
water
Polymers
therapy
delivery
Electric fields

ASJC Scopus subject areas

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

Cite this

Bilayer Charge Reversal and Modification of Lipid Organization by Dendrimers as Observed by Sum-Frequency Vibrational Spectroscopy. / Keszthelyi, T.; Holló, Gábor; Nyitrai, G.; Kardos, J.; Héja, László.

In: Langmuir, Vol. 31, No. 28, 21.07.2015, p. 7815-7825.

Research output: Contribution to journalArticle

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