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Journal > MAKARA Journal of Technology Series > Surface Modification of Graphite-Encapsulated Iron Compound Magnetic Nanoparticles by Radio Frequency Inductively-Coupled Plasma for Biomolecules Immobilization

 

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MAKARA Journal of Technology Series
##issue.vol## 17, ##issue.no## 3 (2013): Desember
Surface Modification of Graphite-Encapsulated Iron Compound Magnetic Nanoparticles by Radio Frequency Inductively-Coupled Plasma for Biomolecules Immobilization
Teguh Endah Saraswati ( Department of Chemistry, Faculty of Mathematics and Natural Sciences, Sebelas Maret University, Surakarta 57126, Indonesia)
Akihisa Ogino ( Graduate School of Science and Technology, Shizuoka University, 3-5-1, Johoku, Naka-ku, Hamamatsu 432-8561, Japan)
Masaaki Nagatsu ( Graduate School of Science and Technology, Shizuoka University, 3-5-1, Johoku, Naka-ku, Hamamatsu 432-8561, Japan)
Article Info   ABSTRACT
Published date:
24 Feb 2014
 
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.Keywords: biomolecule immobilization, magnetic nanoparticles, surface modification
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