A General Procedure to Functionalize Agglomerating Nanoparticles Demonstrated on Nanodiamond

Abstract

Upon reduction of particle size to the nanometer range, one has to deal with the general issue of spontaneous agglomeration, which often obstructs postsynthesis modification of nanoparticle surfaces. A technique to cope with this phenomenon is required to realize a wide variety of applications using nanoparticles in solvents or as refined assemblies. In this article, we report on a new technique to facilitate surface chemistry of nanoparticles in a conventional glassware system. A beads-assisted sonication (BASD) process was examined to break up persistent agglomerates of nanodiamonds in two different reactions for simultaneous surface functionalization. The chosen reactions are the silanization with an acrylate-modified silane and the arylation using diazonium salts. The BASD process can be successfully applied even where the original material is not dispersible in the reaction solvent at all, as the formation of ever smaller, increasingly functionalized agglomerates is improving their solubility. We have confirmed that the presence of ceramic beads enables functionalization of each primary particle, while conventional magnetic stirring or beadless sonication can reach primary particles only when agglomeration is loose. Additionally, mechanical surface modification of nanodiamond was found to take place by BASD with high energy density, leading to sp(2)-hybridized surface patches on nanodiamond. This allowed for the efficient grafting of aryl groups to the surface of primary diamond nanoparticles. Stable, homogeneously functionalized nanodiamond particles in colloidal solution can be obtained by this method.

Antimicrobial activity of menthol modified nanodiamond particles

“…One of the advantages of NDs over other carbon-based materials such as fullerenes and carbon nanotubes is that they are completely inert, optically transparent, biocompatible and can be functionalized in many ways depending on their intended ultimate application [24], [25], [26], [27], [28], [29], [30] and [31]. Although their in vivo toxicity depends on their particular surface characteristics [32], ND particles do not induce significant cytotoxicity in a variety of cell types [32], [33], [34] and [35] and have been used in a variety of biomedical applications.…”

Colloidal Mesoporous Silica Nanoparticles

“…10 nm in size. 82 This novel sonication process could be used to redisperse aggregates of MSNs though the surface natures of silica and diamond are very different.…”

“…It should be noted that there must be some interparticle interactions among colloidal MSNs other than electrical repulsion forces because colloidal MSNs with almost neutral zeta potentials (+3.1 mV) can disperse stably. 82,102 However, there have been no investigations on these interparticle interactions of MSNs.…”

Luminescent nanodiamonds for biomedical applications

“…Acid treatments: Hydrogen plasma treatment (Thoms et al 1994;Strother et al 2002;Knickerbocker et al 2003) -Nitric and sulphuric acid (Kong et al 2005a;Huang and Chang 2004;Liu et al 2008;Chao et al 2007;Ushizawa et al 2002) Annealing in hydrogen gas (Härtl et al 2004;Christiaens et al 2006;Saini et al 2008) -Nitric acid Huang et al 2008;Sushchev et al 2008;Mitev et al 2007) Water vapour treatment (Ando et al 1996a) -Hydrochloric acid (Kossovsky et al 1995;Mitev et al 2007) Borane (BH3) (Krüger et al 2006;Neugart et al 2007;Liang et al 2009;Zhang et al 2009b) -Perchloric acid (Xu et al 2005) -Potassium dichromate and sulphuric acid (Mitev et al 2007) -Sulfuric acid and potassium permanganate (Xu et al 2005) Annealing in:…”

“…-apoobelin ) -aflatoxin B1 (AfB1) ) -DNA (Fu et al 2007) -luciferase Puzyr' et al 2004) -Alpha-bungarotoxin (Liu et al 2008 (Miller and Brown 1996;Knickerbocker et al 2003;Lu et al 2004;Strother et al 2002;Yang et al 2002;Takahashi et al 2003;Yeap et al 2008;Zhang et al 2009b;Zheng et al 2009;Chang et al 2010) (Strother et al 2002;Takahashi et al 2003;Ida et al 2003;Tsubota et al 2003;Härtl et al 2004;Christiaens et al 2006;Chang et al 2010) (Liu et al 2004;Ando et al 1996b;Khabashesku et al 2005;Ando et al 1996a;Ando et al 1993) (Ando et al 1996a;Ikeda et al 1998;Takahashi et al 2003;Miller and Brown 1996) Silanes Aryl Alkyl Amino (Zhang et al 2009b;Liang et al 2009;Krüger et al 2006;Yeap et al 2008 Zheng et al 2009) choice of biological buffer systems or media is also important, since both foetal bovine serum and phosphate buffered saline, two common biological buffer systems, tend to cause re-aggregation (Neugart et al 2007;Vaijayanthimala et al 2009). Despite the challenges involved in preparing and maintaining de-aggregated nanodiamonds, positive results strongly support their use in biological applications.…”