title: Conformational control of human transferrin covalently anchored to carbon-coated iron nanoparticles in presence of a magnetic field.
abstract: The control of the interactions of proteins with the support matrix plays a key role in medicine, drug delivery systems and diagnostics. Herein, we report that covalent anchoring of human transferrin to carbon-coated iron magnetic nanoparticles functionalized with carboxylic groups (Fe@C-COOH Nps) in the presence of magnetic field results in its conformational integrity and electroactivity. We have found that, the direct contact of human transferrin with Fe@C-COOH Nps does not lead to release of iron and in consequence to the irreversible conformational changes of the protein. Moreover, the examination of the direct electron transfer between Tf molecules from the conjugate and the electrode surface was possible. The quartz crystal microbalance with dissipation (QCM-D)- and thermogravimetric data (TGA) showed that under such conditions, in addition to a monolayer, an adlayer of the protein can be formed on Fe@C-COOH Nps at constant pH.
  
  
  
  To our best knowledge this is the first paper that reports on covalent anchoring of human transferrin (Tf) to carbon-coated iron magnetic nanoparticles functionalized with carboxylic groups (Fe@C-COOH Nps) in the presence of magnetic field, which results in its conformational integrity and electroactivity. We showed that it is possible to attach, without changing pH, more than one single layer of transferrin to the Fe@C-COOH Nps. This is a very rare phenomenon in the case of proteins. We proved, using various experimental techniques, that the proposed methodology does not lead to release of iron from Tf molecules, what was the major problem so far. We believe that this finding opens new possibilities in targeting drug delivery systems and medical diagnostics.
authors: Faculty of Chemistry, University of Warsaw, ul. Pasteura 1, PL-02-093 Warsaw, Poland. Electronic address: akowalczyk@chem.uw.edu.pl.
authors: Agata
authors: A
authors: Kowalczyk
authors: Faculty of Chemistry, University of Warsaw, ul. Pasteura 1, PL-02-093 Warsaw, Poland.
authors: Edyta
authors: E
authors: Matysiak-Brynda
authors: Faculty of Chemistry, University of Warsaw, ul. Pasteura 1, PL-02-093 Warsaw, Poland.
authors: Michal
authors: M
authors: Bystrzejewski
authors: Interdisciplinary Nanoscience Center (iNANO), Aarhus University, DK-8000 Aarhus, Denmark.
authors: Duncan S
authors: DS
authors: Sutherland
authors: Faculty of Chemistry, University of Warsaw, ul. Pasteura 1, PL-02-093 Warsaw, Poland.
authors: Zbigniew
authors: Z
authors: Stojek
authors: Faculty of Chemistry, University of Warsaw, ul. Pasteura 1, PL-02-093 Warsaw, Poland. Electronic address: anowicka@chem.uw.edu.pl.
authors: Anna M
authors: AM
authors: Nowicka
mesh_terms: D002244:Carbon / Q000737:chemistry*; D002942:Circular Dichroism; D055664:Electrochemical Techniques; D004566:Electrodes; D006046:Gold / Q000737:chemistry; D006801:Humans; D007501:Iron / Q000737:chemistry*; D060526:Magnetic Fields; D053758:Nanoparticles / Q000737:chemistry*; D011487:Protein Conformation; D058525:Quartz Crystal Microbalance Techniques; D013056:Spectrophotometry, Ultraviolet; D017550:Spectroscopy, Fourier Transform Infrared; D013818:Thermogravimetry; D014168:Transferrin / Q000737:chemistry*
chemical_list: D014168:Transferrin; D002244:Carbon; D006046:Gold; D007501:Iron
keywords: Core-shell ferromagnetic nanoparticles; Human transferrin; Magnetic field; Protein layers; Quartz crystal microbalance with dissipation