Research Projects

The central goal in biology is to achieve a quantitative understanding of how diverse biomolecules within cells interact in space and time to orchestrate complex functions or drive pathological states. Fluorescence imaging, especially with the advent of super-resolution microscopy, has emerged as a powerful tool for visualizing these molecular events with high spatial and temporal precision. However, long-term imaging of specific biomolecules in live cells remains severely constrained by the fundamental problem of fluorophore photobleaching. This limitation is particularly pronounced in advanced techniques such as stimulated emission depletion (STED) and single-molecule localization microscopy (SMLM), which require intense laser illumination that accelerates fluorophore degradation. To overcome this critical bottleneck, we propose to develop a new class of hybrid macrocyclic supramolecular host-guest probes based on semi-cucurbituril–pillararene architectures, capable of enabling long-term, high-resolution imaging in live cells. This strategy leverages my expertise in organic synthesis and supramolecular chemistry, and will be developed in collaboration with the Sarit S. Agasti Lab at JNCASR, Bangalore. The key innovation of this proposal lies in exploiting the transient yet highly specific host–guest interactions intrinsic to these macrocycles, which can operate efficiently under physiological (aqueous) conditions. Unlike conventional probes that rely on permanently tethered fluorophores and suffer from irreversible photobleaching, the proposed supramolecular system will function via dynamic, reversible binding of fluorescent guest molecules to the macrocyclic hosts immobilized on target structures. These transient interactions will give rise to an autonomous ON–OFF blinking behavior, wherein a fluorophore becomes detectable on the camera upon binding (ON state) and becomes undetectable upon dissociation (OFF state). This blinking will be essential for SMLM, enabling nanometer-scale resolution imaging without the need for high-intensity laser excitation or specialized buffers. Crucially, because the fluorophores are not permanently bound, photobleached molecules will be continuously replaced by fresh ones from the surrounding medium through reversible host–guest exchange. This mechanism offers a powerful solution to the challenge of photobleaching, effectively allowing infinitely renewable fluorescence signals and thereby enabling prolonged imaging of dynamic cellular processes with nanoscale resolution. In addition to their bleaching immunity, the compact size, aqueous stability, and cell-permeability of these host–guest systems make them ideally suited for live-cell applications. By integrating the dynamic nature of supramolecular recognition with the precision of single-molecule imaging, this platform has the potential to transform long-term, high-resolution visualization of molecular events in complex biological environments.