RESEARCH PAPER Electrostatically mediated adsorption by nanodiamond and nanocarbon particles Natalie M. Gibson • Tzy-Jiun Mark Luo • Olga Shenderova • Alexey P. Koscheev • Donald W. Brenner Received: 15 June 2011 / Accepted: 26 December 2011 Ó Springer Science+Business Media B.V. 2012 Abstract Nanodiamond (ND) and other nanocarbon particles are popular platforms for the immobilization of molecular species. In the present research, factors affecting adsorption and desorption of propidium iodide (PI) dye, chosen as a charged molecule model, on ND and sp 2 carbon nanoparticles were studied, with a size ranging from 75 to 4,305 nm. It was found that adsorption of PI molecules, as characterized by ultra- violet–visible spectroscopy, on ND particles is strongly influenced by sorbent-sorbate electrostatic interactions. Different types of NDs with a negative zeta potential were found to adsorb positively charged PI molecules, while no PI adsorption was observed for NDs with a positive zeta potential. The type and density of surface groups of negatively charged NDs greatly influenced the degree and capacity of the PI adsorbed. Ozone-purified NDs had the highest capacity for PI adsorption, due to its greater density of oxygen containing groups, i.e., acid anhydrides and carboxyls, as assessed by TDMS and TOF–SIMS. Single wall nanohorns and carbon onion particles were found to adsorb PI regardless of their zeta potential; this is likely due to p bonding between the aromatic rings of PI and the graphitic surface of the materials and the internal cavity of the horns. Keywords Adsorption Á Diamonds Á Surface characterization Á Surface modification Á Nanoparticles Á Drug delivery Á Biomedical application Introduction Nanodiamonds (NDs) have recently attracted tremen- dous attention in the fields of nanotechnology and biomedicine due to their biocompatibility (Schrand et al. 2007b; 2008; Vaijayanthimala et al. 2009; Shenderova 2010), nontoxicity (Liu et al. 2007; Puzyr et al. 2007a; Schrand et al. 2007a; Zhu et al. 2009; Mohan et al. 2010), chemical inertness, and environ- mental stability (Mohan et al. 2010). NDs have high specific surface areas (SSAs) (typically 300–400 m 2 /g for NDs produced by detonation synthesis), which can be easily functionalized with a variety of surface groups to enhance binding selectivity toward target Electronic supplementary material The online version of this article (doi:10.1007/s11051-011-0700-9) contains supplementary material, which is available to authorized users. N. M. Gibson Á T.-J. M. Luo (&) Á O. Shenderova Á D. W. Brenner Department of Materials Science and Engineering, North Carolina State University, 911 Partners Way, Raleigh, NC, USA 27695 e-mail: tluo@ncsu.edu O. Shenderova International Technology Center, P.O. Box 13740, Research Triangle Park, NC, USA 27617 A. P. Koscheev State Scientific Center of Russian Federation, Karpov Institute of Physical Chemistry, ul. Vorontzovo Pole, 10, Moscow, Russia 105064 123 J Nanopart Res (2012) 14:700 DOI 10.1007/s11051-011-0700-9