Physiological and Environmental Impacts of Nanomaterials-Biomolecular Coronae

Engineered nanomaterials (ENMs) exhibit unique electronic and optical properties, which are suitable for the broad spectrum of applications including biomedical, aerospace, textiles, agriculture. Such unique properties of ENMs also raise significant concerns over their adverse ecological and physiological effects. In the past two decades, ENMs were found to exhibit complex interactions in biological milieu. It is expected that physicochemical properties of ENMs and their surrounding environment influence their environmental and physiological fate and transport. Indeed, a comprehensive understanding of interactions at the nano-bio interface is critical to designing environmentally and physiologically benign ENMs pivotal to the future growth of nanomedicine and its applications. To this end, the present work experimentally investigates nanomaterial-biomolecular corona (or biocorona) using spectroscopic techniques and biological assays. Specifically, the influence of defects, surface functionalization, and physiological environment on the formation of biocorona and ensuing biological responses is presented. The first two chapters (Chapters 1 and 2) provide a succinct introduction to nanotoxicity with focus on biocorona formation and various spectroscopic characterization techniques utilized. In Chapter 3, the variation in biocorona formation due to defects in the structure of single-walled and multi-walled carbon nanotubes (SWCNTs and MWCNTs) is presented. Briefly, it was found that defects result in significant changes in the nature and amount of proteins adsorbed on SWCNTs due to differences in their charge distribution. In case of MWCNTs, carboxylated MWCNTs with higher density of defects resulted in a stronger binding and efficient delivery of antigens. In Chapter 4, a unique study exploring the effect of diseased (hyperlipidemic) physiological state on the biocorona composition (instead of the normal healthy state) is presented. Our findings suggest that disease-induced variations in the physiological environment have a significant impact on nanomaterial-biomolecular corona, cell response, and cellular association. In Chapter 5 provides new spectroscopic insights into charge transfer interactions between biomolecules (aromatic amino acid complexes) and emerging two-dimensional (2D) ENMs like graphene, graphene oxide, and BN. The adsorption of amino acids on 2D materials was observed to considerably alter their biological response in terms of generation of reactive oxygen species. Also, the influence of different surface functional groups on Ag nanoparticles on conformational changes in apolipoprotein biocorona and ensuing biological is explored. Finally, Chapter 6 explores environmental effects of graphene, BN upon their interaction with natural organic matter (NOM). The results show that the delocalized π-electron cloud in graphene facilitated a significant charge transfer and chemisorption of NOM unlike BN. Also, BN was found to result in algal cell rupture and reduction in photosynthetic activity unlike graphene