Debabrata (Dev) Mukhopadhyay
Professor, Departments of Biochemistry and Molecular Biology and Biomedical Engineering;Mayo Clinic College of Medicine and Science,Florida, USA
Title: Single-walled carbon nanotubes as sensors of reactive species: Potential therapeutic implications
Biography
Biography: Debabrata (Dev) Mukhopadhyay
Abstract
Reactive species, specifically nitric oxide (NO) and hydrogen peroxide (H2O2), activate signal transduction pathways during angiogenesis and other biological systems and therefore play important roles in physiological development as well as various pathophysiologies. Herein, we utilize a near-infrared fluorescent single-walled carbon nanotube (SWNT) sensor array to measure the single-molecule efflux of NO and H2O2 from human umbilical vein endothelial cells (HUVEC) and cancer cells in response to angiogenic stimulation or chemotherapeutic drugs. The nanosensor array consists of a SWNT embedded within a collagen matrix that exhibits high selectivity and sensitivity to single molecules of specific reactive species. We observed that the production of H2O2 following VEGF stimulation is elevated outside of HUVEC, but not for stimulation via nanorods, while increased generation is observed in the cytoplasm for both cases, suggesting two distinct signaling pathways. In addition, we are able to detect the spatial resolution of NO in HUVEC cells in response to VEGF. Moreover, by employing transmission electron microscopy, confocal fluorescent microscopy, and UV-vis spectroscopic analysis, we have confirmed the internalization of DNA-SWCNT in HUVECs. Additionally, by using pharmacological inhibitors as well as genetic approaches, we have found that SWCNT is endocytosed through Rac1- GTPase mediated macropinocytosis in normal endothelial cells. Our work reveals a unique mode of entry of SWCNT in cells and might help to properly formulate SWCNT as nanovectors in biological systems. Moreover, the SWNT platform can be employed for early detection and therapeutic intervention of patients from liquid biopsies; this topic will be discussed as well.