Research Projects

Real-time monitoring of biological processes in complex media is essential for advancing point-of-care diagnostics. However, optical probes in the UV-visible spectral region often encounter background interference from molecules that scatter, absorb, and emit in this range, making biological signal detection less reliable. Thus, there is a pressing need for the development of optical probes that operate without such interference. Single-walled carbon nanotubes (SWCNTs), derived from rolled-up graphene sheets, present a promising solution. SWCNTs exhibit unique electronic properties, including near-infrared (NIR) fluorescence, advantageous for biological imaging due to deep tissue penetration and minimal interference. Commercial SWCNTs are multichiral, leading to multiple emission peaks, whereas monochiral SWCNTs have a single emission peak due to their nearly uniform chirality. My laboratory's primary goal is to establish a NIR fluorescence spectroscopy facility to utilize SWCNTs as real-time fluorescent probes for studying biological processes, particularly protein aggregation in neurodegenerative diseases like Alzheimer’s and Parkinson’s. Unlike traditional UV-visible spectroscopy, which suffers from interference from biomolecules, NIR fluorescence offers a clearer, and more reliable method for monitoring biological processes in complex environments. To achieve this, we will first functionalize hydrophobic multichiral SWCNTs with proteins, leveraging their amphiphilic nature for π-π stacking and stability in aqueous environments, thus enhancing compatibility for biological applications. We will introduce aggregating agents to the protein-stabilized SWCNT dispersion to induce protein aggregation, with changes reflected in the NIR fluorescence signals of the SWCNTs (owing changes in the surface composition of the SWCNTs), providing insights into aggregation dynamics. Complementary techniques such as electron microscopy, circular dichroism, and protein assays will be done to corroborate findings from the SWCNTs optical platforms with standard observations. Additionally, we will investigate the role of rationally incorporated covalent defects in monochiral SWCNTs to control interactions with external molecules and modify their optical properties. Specifically, we will introduce aryl defects into suspended SWCNTs, generating an additional peak from E₁₁* transitions alongside the existing E₁₁ peak from pristine monochiral SWCNTs, creating a dual-emitting probe. Interaction of biologically relevant analytes with the SWCNTs will alter the E11 peak characteristics, while the defects peak will serve as a reference. This ratiometric fluorescent biosensing approach enhances sensitivity and overcomes single-wavelength sensing limitations through internal calibration. Ultimately, we aim to use defect-engineered monochiral SWCNTs for real-time ratiometric monitoring of protein aggregation, contributing to new insights in neurodegenerative disease research.