Surface Modification of Graphite-Encapsulated Iron Compound Magnetic Nanoparticles by Radio Frequency Inductively-Coupled Plasma for Biomolecules Immobilization  

Oleh:

Saraswati, Teguh Endah ; Ogino, Akihisa ; Nagatsu, Masaaki

Jenis: Article from Journal - ilmiah nasional - terakreditasi DIKTI
Dalam koleksi: Makara Journal of Technology vol. 17 no. 3 (Dec. 2013), page 133-137.
Topik: Biomolecule Immobilization; Magnetic Nanoparticles; Surface Modification
Fulltext: 277-307-1-PB.pdf (481.94KB)

Isi artikel

We proposed the graphite-encapsulated iron compound magnetic nanoparticles as a candidate of nanomaterial due to their potential properties on physical, chemical and biological fields. This study was performed in three steps, starting from the nanoparticle fabrication, nanoparticle surface modification by plasma treatment, leading to biomolecules immobilization for testing the treated nanoparticles capabilities. After the plasma treatment, the surface of the outmost graphene layer is successfully covered by nitrogen-containing groups definitively assigned by XPS spectra and the STEM-EDS elemental mapping. The nitrogen-containing groups formed during the post-treatment plasma selectively attached on the outmost of graphene layer. The inner structure of inner graphene layer and the iron core are still found in stable condition which means that the applied plasma condition allows the efficient covalent functionalization of nitrogen-containing group to the surface particles without give any destruction. The results shows the highest values of N/C atomic ratio of 5.4% is obtained by applying 10 min of Ar plasma pre-treatment and 2 min of NH3 plasma post-treatment conducted in RF power of 80W and gas pressure of 50 Pa. Finally, in the biomolecules section, it is found that the primary amino groups grafted after Ar plasma pre-treatment followed by NH3 plasma post-treatment appeared to play an important role in dextran immobilization. The primary amines provide a high selective reaction between aldehyde group of oxidized dextran and amino groups of treated nanoparticles, hence the covalent immobilization was successfully achieved. The dextran immobilization was confirmed by XPS and HR-TEM analysis followed by amino group derivatization using TFBA. The deconvoluted peak at ~398.6 eV (C=N) (as an evidence for Schiff-base linkages between dextran and amino groups on the treated nanoparticles) increased with the increasing of the dextran concentration. This result is consistent with the decrease of free amino group percentage remaining on the nanoparticles surfaces which was evidenced when the dextran concentration increased. High magnification images obtained by HR-TEM allowed the visual observations of the differences between surface morphology of nanoparticles before and after dextran immobilization.

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