Fluorescent Nanodiamonds: Effect of Surface Termination
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1203-J03-05
Fluorescent Nanodiamonds: Effect of Surface Termination I. Kratochvílová1, A. Taylor1, A. Kovalenko1, F. Fendrych1, V. Řezáčová1, V. Petrák1, S. Záliš2, J. Šebera2, M. Nesládek3 1
Institute of Physics, Academy of Sciences Czech Republic v.v.i, Na Slovance 2, CZ-182 21,
Prague 8, Czech Republic 2
J. Heyrovský Institute of Physical Chemistry, AS CR, v.v.i., Dolejškova 3, CZ-182 23 Prague 8,
Czech Republic 3
Hasselt University, Institute for Materials Research (IMO), Wetenschapspark 1, B-3590
Diepenbeek, Belgium ABSTRACT It has been reported that physico-chemical properties of diamond surfaces are closely related to the surface chemisorbed species on the surface. Hydrogen chemisorption on a chemical vapor deposition grown diamond surface is well-known to be important for stabilizing diamond surface structures with sp3 hybridization. It has been suggested that an H-chemisorbed structure is necessary to provide a negative electron affinity condition on the diamond surfaces. Negative electron affinity condition could change to a positive electron affinity by oxidation of the Hchemisorbed diamond surfaces. Oxidized diamond surfaces usually show characteristics completely different from those of the H-chemisorbed diamond surfaces. The unique electron affinity condition, or the surface potential, is strongly related to the chemisorbed species on diamond surfaces. The relationship between the surface chemisorption structure and the surface electrical properties, such as the surface potential of the diamond, has been modelled using DFT based calculations.
INTRODUCTION Nanodiamond is a novel promising material for in-vitro and in-vivo imaging in living cells. Specially, nanocrcystalline diamond (ND) and ultrananocrytslaine diamond (UND) particels [12] offer novel advantages for the drug delivery development [3]. Advantage of nano diamond is also the ability to penetrate into the cells without evoking a toxic cell response. The newly developed production, purification and functionalisation techniques enable the material to be widely used. The adsorption strength on nanodiamond due to hydrophilic and hydrophobic interactions is so high that a very efficient capture of proteins such as cytochrome c, myoglobin and albumin occurs. Recent studies have also initiated the use of ND/UNDs for in-vivo molecular imaging and bio-labelling. Additionally nanodiamond's offer properties such as the biocompatibility, nontoxicity and a possibility of the lable-free imaging, based on easily detected Raman signal and intrinsic fluorescence from nanoparticle point defect - Nitrogen-vacancy centres. In diamond the association of a vacancy with a nitrogen impurity leads to the formation
of a luminescent defect, called the NV colour centre and being either neutral (NV0) or negatively charged (NV-) [4,5]. Both of these centres are photostable and can be detected at the individual level which allows application of nanodiamonds for functional intracellular imaging on the molecular level based on tagging specific molecular sites. This
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