NMR characterization of PAMAM-G5.NH2 entrapped atomic and molecular assemblies

Mónika Kéri, Chen Peng, Xiangyang Shi, István Bányai

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Abstract

High resolution NMR spectroscopy, NMR diffusiometry, and NMR cryoporometry have been used to investigate aqueous solution (D2O) of PAMAM-G5.NH2-(Au)25-100 and PAMAM-G5.NH2-(H2O)1000-(H2O)4000 systems. In the case of dendrimer entrapped gold nanoparticles, the detailed analysis of high resolution NMR spectra has shown that no precursor complex formation happens under the circumstances applied for reduction. Further PGSE results verify that gold nanoparticles of 1.9-2.6 nm size are entrapped in the outermost part of the dendrimers and probably more than one dendrimer molecule takes part in the stabilization process. This system looks like a transition state between dendrimer encapsulated nanoparticles (DENs) and dendrimer stabilized nanoparticles (DSNs), and we deal with it in details for what this means. NMR cryoporometry experiments were performed to detect the encapsulation of water molecules. The results show that, in the swelling PAMAM-G5.NH2 dendrimers, by adding water step by step, there are specific cavities for water with diameters of 3.6 and 5.2 nm. These cavities have a penetrable wall for water molecules and probably exist very close to the terminal groups. The permeability of the cavities is increasing with the increase of the water content. In dilute solution, the formation of nanoparticles is determined by the ratio of the rate of nucleation and aggregation and the latter is affected by the PAMAM-G5.NH2.

Original languageEnglish
Pages (from-to)3312-3319
Number of pages8
JournalJournal of Physical Chemistry B
Volume119
Issue number7
DOIs
Publication statusPublished - Feb 19 2015

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ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

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