Professor Luis A. Colon of SUNY at Buffalo is supported by the Chemical Measurement and Imaging (CMI) Program in the Division of Chemistry to develop chromatographic separation media based on detonation nanodiamond (ND) material. NDs with a uniform particle size of 4-5 nm will be linked to the surface of monodispersed silica solid supports. The physicochemical properties of the resulting ND-silica material will be investigated with a battery of instrumental analysis techniques, including IR spectroscopy, elemental analysis, gas adsorption analysis and ESCA. The adsorptive characteristics of these relatively unexplored chromatographic separation media will be evaluated for applications in high performance liquid chromatography (HPLC), capillary electrophoresis (CE) and capillary electrochromatography (CEC).
There is a growing interest in the development of ND-based separation media because of the excellent chemical and thermal stability of NDs, which make them appealing from the stand point of chromatography. The proposed research will lead to efficient chromatographic ND-based separation media and will open up possibilities for their use in specific practical applications. HPLC, CE and CEC are indispensable analytical tools that facilitate advances in the chemical, biological, and relate sciences. The project will contribute to the education and training of graduate and undergraduate students, including members of traditionally underrepresented groups, in the synthesis and characterization of novel separation media and in chromatography and other analytical separations technologies.
The project was centered at the interface of separation science and nanomaterials research, investigating carbonaceous nanomaterials and their potential use as adsorbents (i.e., stationary phases) for liquid phase separations. The specific goals were to investigate detonation nanodiamonds (DND) and other carbon-based nanomaterials (i.e., carbon dots). Carbon dots (C-dots) were synthesized in bulk by the traditional top-down approach that produces a heterogeneous mixture of the carbonaceous nanomaterial. The properties reported in the past for such nanomaterials assumed that there is a high degree of homogeneity in the "as synthesized" bulk sample. The studies demonstrated that this is not the case. To have a more fundamental understanding of the material synthesized, methodology was developed to isolate/fractionate the carbon nanoparticles produced from bulk synthesis. The developed procedure provided for an unprecedented reduction in complexity that revealed fractions of carbon nanomaterials with unique chemical and luminescent properties. For example, it was discovered that the wavelength-dependent photoluminescence commonly ascribed as an inherent property of C-dots was not present in fractionated samples, indicating that well fractionated C-dots possess their unique spectroscopic properties. The fractionated C-dots were also shown to be brighter and displayed improved biological compatibility and usefulness as cellular imaging probes. The revealing findings underscored the importance of fractionation when synthesizing and studying nanomaterials to properly evaluate the material’s characteristics. It was clearly demonstrated that isolation from what can be a rather complicated mixture is critical to properly assess fundamental properties of nanomaterials before establishing their applicability. Chemical processing of commercially available carbonaceous clusters containing DND produced primary DND nanoparticles of about 5 nanometers in size. Surface hydrogenation of DND was accomplished at 900 °C under a flow of hydrogen gas. Procedures were developed to modify the surface of silica particles and monoliths with hydrogenated and non-hydrogenated DND. Silica monoliths were also modified with C-dots. The adsorptive characteristics of the nanoparticle-modified silicas were studied by producing columns packed with such material. It was demonstrated that the hydrogenated DND possess a hydrophobic character, adsorbing non-polar compounds preferentially over polar compounds. The non-hydrogenated DND, on the other hand, exhibited a hydrophilic character that induces adsorption of polar compounds over non-polar ones. The C-dots-modified silica monoliths were shown to possess a mix-mode of interactions where the adsorption of polar versus non-polar compounds could be varied by controlling the experimental conditions of the liquid phase. The characteristic of the materials studied were attributed to the surface chemistry of the nanomaterials and demonstrated to be applicable to the separation of chemical entities in chemical analysis. Under this project, 14 graduate students, 8 undergraduates, and 2 high school students had the opportunity to participate in one or more aspects of the research endeavors, contributing to their educational training, and development; within the grant period 7 PhDs and 4 Masters degrees have been earned. The students were trained in highly sophisticated techniques and instrumentation of modern science. The research work has lead to 12 journal articles and 45 presentations (26 invited, 19 contributed) at national and international conferences and universities. In all, this project has provided the means to study several important issues. The findings contribute to new knowledge in the fields of nanomaterials and separation science with immediate impact in chemical analysis. In addition, the project has provided the vehicle to train and educate students while they pursued an advanced degree in science, preparing them to join the technology and knowledge-driven workforce of their generation.
