Aug 29, 2012 - developing new applications based on this material. Minh D. Pham, Yi-Fang Tsai, Brian T.A. Chang, C.-C. Han, Sunney. I. Chan, Steve S.-F Yu*.
Surface chemistry of oxidative functionalized diamond nanoparticle: An x-ray absorption spectroscopy study Minh D. Pham, Yi-Fang Tsai, Brian T.A. Chang, C.-C. Han, Sunney. I. Chan, Steve S.-F Yu*
Introduction Applications of diamond nanoparticles have been quickly extended not only in materials engineering but also in biology. Transition metals - decorated nanodiamonds with tailored magnetic properties are promising advanced materials for applications in high density magnetic recording, molecular electronics, spin electronics and bio-imaging. Oxidative functionalized nanodiamonds exhibit exceptional affinity toward proteins, especially to membrane proteins through unidentified forces. Interestingly, transition metal ions such as copper (II) or iron (II/III) effectively disrupt these interactions. Understanding the surface chemistry of nanodiamonds doped with transition metals is therefore critically important for developing new applications based on this material. 2.0
Experiments and Results
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R (Å) 2 (Å2) 1.99(0) 0.005(6) [1.90, 11.25] [1.33 , 2.66] 0.11% 182 38
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Figure 3. (A) Extened X-ray Absorption Spectroscopy (EXAFS) of crude oxidative nanodiamond and (B) Table of parameters used in fitting the k3weighted EXAFS data 1.2
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+ Preparation of crude oxidative nanodiamond (ND): Diamond powders (100 nm) from Kay Industrial Diamond were firstly oxidized by a 9:1 (v/v) mixture of concentrated H2SO4 and HNO3 at 60˚C for 3 days. The material was then incubated in 0.1N NaOH aqueous solution at 90˚C for 2h, and finally in 0.1N HCl at 90˚C for 2hr. + Surface modification of ND by Cupper (II) ions: Oxidative nanodiamonds were thoroughly washed twice with 65% ultrapure HNO3 with the aid of microwave at 800W for 15 minutes in order to elimilate remaining metal ion impurities. The washed nanodiamonds were chemically modified with copper by mixing with 1M CuCl2 for 15 minutes, free copper ions were removed by washing twice with dH2O. All X-ray absorption spectroscopy experiments were performed on the solid phase of nanodiamonds collected by centrifugation at 12.500 rpm for 2.5 minutes. Intensity (arb. unites)
http://nano.materials.drexel.edu
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Figure 4. (A) EXAFS of nanodiamond washed by nitric acid and then treated by CuCl2; (B) Table of parameters used in fitting the k3-weighted EXAFS data
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Figure 1. (A) The X-ray Absorption Near Edge Structures (XANES) of the FeSO4 (black line); Fe2O3 (blue line); crude and oxidative nanodiamond –ND (red line); (B) The XANES of nanodiamond with/without treated with Copper (II) ions and Copper treated sample after washing with trong pure nitric acid. d
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Figure 2. Proposed model of the coordiations of Copper or Iron to the surface of ND
Conclusions and discussions + X-ray Absorption Near Edge Spectroscopy (XANES) showed that copper (II) and Fe (II or III) ions bind strongly to the surface of 100 nm oxidized nanoparticles but they can be washed out by concentrated nitric acid. + The interaction between these metal ions with nanodiamond surface comes from the exchanging of protons in carboxyl groups by metal cations. + The data presented here have confirmed that carboxyl groups play as ligands for the effective binding of metal ions to the surface. The best fits for Fe (III) and Cu (II) were obtained, and the result shows that the firstcoordination spheres are composed of 4 oxygen scatters at 1.99(0) and 1.96(1) Å, respectively. th 18
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+ Application of oxidative nanodiamond for membrane protein analysis: The mixture of membrane proteins from E.coli solubilized in various surfactant solutions were extracted by oxidized nanodiamonds with the ratio of protein:nanodiamond about 20:1. Three pH values (3, 7, 12) were tested for selective extraction of membrane proteins by the diamond nanoparticles. Superfast digestion (10minutes) of the hyrophobic proteins adhered in the surface of nanopartiles also obtained (data not shown). + Facilated analysis of membrane proteins can be obtained with the aid of the oxidative diamond nanopartiles.
Acknowledgements + Experiments of XANES and EXAFS were performed at BL17C beam line, National Synchrotron Radiation Center, Hsinchu, Taiwan. We thank Dr. ChiWen Pao and Dr. Jyh-Fu Lee for their kind helps. + This work is supported by Academia Sinica and grants from the National Science Council of the Republic of China (NSC).
Poster presented during The User’s Meeting & Workshops on Bio-image and Powder diffraction, National Synchrotron Radiation Research Center (NSRRC), Hsinchu City, Taiwan (2012 August 29-30).
