Poster abstracts
Poster number 23 submitted by Sagarika Taneja
A pH-responsive rhodamine nanotube capable of self-reporting the assembly State
Sagarika Taneja (Chemistry and Biochemistry, The Ohio State University), Ziyuan Meng (Chemistry and Biochemistry, The Ohio State University), Reham Hassan (Chemistry and Biochemistry, The Ohio State University), Jon R. Parquette (Chemistry and Biochemistry, The Ohio State University)
Abstract:
Cancer, a global healthcare challenge, demands innovative approaches in drug delivery and intracellular imaging. This research focuses on the development of two pH-responsive self-assembled probes, Rho-KK and Rho-KE, derived from Rhodamine B and incorporating a β-sheet-forming dipeptide motif. The primary objective is to assess the probes' capability to be uptaken by liver cancer HepG2 cells and then to self-report its assembly state (nanotube vs monomer). Rho-KK/Rho-KE can exist either in a monomeric, open-ring state (λmax 580 nm) at low pH (4.1/4.2) or in the assembled nanotubular state which exhibits aggregation-induced emission (λmax 460 nm) at pH> (5.8/6.3). Between pH (4.1-5.8/4.2-6.2) respectively for Rho-KK/Rho-KE, the transition from fluorescent open-ring Rhodamine form to monomeric, non-fluorescent spirolactam form occurs. The probes upon entering the cancer cells would emit fluorescence corresponding to their location within the cells as intracellular organelles are known to have different pH values, from the early (pH 6.3) to the late endosome (pH 5.5) and ultimately the lysosome (pH 4.7). Structural validation involved a comprehensive analysis through UV-Vis, circular dichroism (CD), and fluorescence spectroscopy, complemented by imaging nanotubes via Atomic Force Microscopy (AFM) and Transmission Electron Microscopy (TEM). Confocal microscopy has been utilized for in vitro cellular imaging, allowing for a correlation between changes in emitted wavelength and the specific cellular compartments. In summary, developed probes have demonstrated the ability to emit wavelength corresponding to the pH-dependent structural state in in vitro cellular imaging.
Keywords: live-cell imaging, self-assembly, pH-responsivity