title: Enhancing the colloidal stability of detonation synthesized diamond particles in aqueous solutions by adsorbing organic mono-, bi- and tridentate molecules.
abstract: Colloidal stability of nanoparticles with particle sizes smaller than 100nm is a critical issue for various research areas, including material science, electronics and biomedicine. We propose a facile, fast and cost-efficient method to increase the colloidal stability by simply adding organic molecules as ligands, which adsorb to the nanoparticle surface subsequently. Citric acid, oxalic acid, glutamic acid and propylamine were found to stabilize the nanodiamond (ND) particles with a mean diameter of approx. 30-100nm. The charge of the particles could be controlled by the pH of the dispersions and by stabilizing with carboxylic acids or amino acids mentioned above. ND particles stabilized with citric acid and oxalic acid at a pH higher than 2.5 were negatively charged, while ND dispersions stabilized with glutamic acid were charged positively below a pH of 3.2. Furthermore, the stability of the dispersion was found to be dependent on the concentration of the stabilizing agent and the pH of the dispersion. Finally, we proposed the stabilizing mechanism of ND particles with propylamine. Glutamic acid and propylamine stabilized ND dispersions can be utilized for high seeding densities on negatively charged surfaces due to the amino-groups, which can be helpful for adsorption processes in electronics and material science. Due to the high biocompatibility, non-cytotoxicity and chemical inertness of ND particles, carboxylic acids and amino acids stabilized ND particles are envisaged to be useful in the biomedical field, i.e. bio-labels, drug delivery vehicles, and effective enterosorbent.
authors.affiliation: Functional Thin Films Research Center, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Wang
authors.affiliation: College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518060, China.
authors.forename: Stephan
authors.initials: S
authors.lastname: Handschuh-Wang
authors.affiliation: Functional Thin Films Research Center, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China.
authors.forename: Panpan
authors.initials: P
authors.lastname: Qin
authors.affiliation: Functional Thin Films Research Center, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Yang
authors.affiliation: College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518060, China.
authors.forename: Xuechang
authors.initials: X
authors.lastname: Zhou
authors.affiliation: Functional Thin Films Research Center, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China. Electronic address: tangyb@siat.ac.cn.
authors.forename: Yongbing
authors.initials: Y
authors.lastname: Tang
keywords: Adsorption; Colloidal stability; Diamond; Nanoparticle