Modified Nanodiamonds for Detoxification.

摘要

Nanodiamonds (NDs) are an emerging class of biomaterials that are reaching worldwide attention due to their biocompatible, nontoxic properties and abundant surface chemistries that lend them to a wide range of biomedical applications. Furthermore, surface functional groups of NDs can easily be tailored to exhibit desirable chemical, physical and biological properties. Such characteristics naturally allow for NDs' surface to be considered as ideal carriers for various molecules and biomolecules intended for the delivery or removal of molecules in vivo.;NDs have already shown to have a high affinity for various biological molecules, including DNA and proteins. This dissertation, however, expands NDs' use to the adsorption of carcinogenic mycotoxins, aflatoxin B1 (AfB1) and ochratoxin A (OTA). It has been estimated that myocotoxins are found in approximately 25 % of the world's crops each year. Ingestion of mycotoxins contaminated crops has been linked to hepatocellular carcinoma, disease and death. Therefore, we aim to develop ND enterosorbents, for the binding and removal of mycotoxins within the gastrointestinal (GI) tract, thereby eliminating the effects of these toxins.;While NDs are readily available, raw, unmodified NDs, like those typically received from vendors, possess inhomogeneous aggregate sizes and surface characteristics. Our research first explored several ND modification techniques to enhance ND's adsorption of AfB1 and OTA. Modification methods assessed in this research include size reduction techniques, plasma treatments, silane surface coatings and homogenous surface group termination, including carboxylation, hydrogenation and hydroxylation. The effectiveness of these NDs for mycotoxins removal was determined by calculations of maximum capacities and binding constants, as obtained through the Langmuir isotherm and related transform equations. Several of these treatments also showed heightening of the NDs' inherent zeta potentials (ZPs), which were essential for interacting with charged molecules, like OTA. Furthermore, the increased ZPs lead to improved colloidal stabilities over a wide range of pH, which is important for their interaction in the GI tract. While the dyes and OTA illustrated primarily electrostatic adsorption mechanisms, neutrally charged AfB1's adsorption was predominantly based upon the aggregate size of the ND substrate.;In addition to mycotoxins, fluorescent dyes, including propidium iodide, pyranine and 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS), were initially utilized during methodological development. Fluorescent dye investigations helped assesses the adsorption mechanisms of NDs and demonstrated the significance of electrostatic interactions. Beyond electrostatic adsorption mechanisms, surface functional groups were also responsible for the amount of dye adsorbed, as was also true in OTA adsorption. Therefore, surface characterization was carried out for several ND samples by FTIR, TOF-SIMS and TDMS analysis.;Final results of our studies show that our modified NDs perform better than yeast cells walls and other NDs but comparable to activated charcoal in the adsorption of AfB1, and outperform clay minerals in OTA studies. Moreover, it was demonstrated that adsorption can be maintained in a wide range of pH, thereby, increasing the possibility of NDs use in mycotoxins enterosorbent applications.