Developing strategies to assemble molecular components within the complexities of cells and tissues is of great interest in biology, such as in molecular imaging. However, the application of synthetic recognition motifs for programming molecular assemblies in living systems remains a challenging task due to the chemical complexities of the living system and lack of selectivity in conventional non-covalent interactions. We develop new strategies for programming molecular assemblies in the living system based on a synthetic host-guest system featuring Cucurbituril (CB). We recently demonstrated that highly selective and ultra-stable host-guest interaction in CB provides a non-covalent mechanism for assembling imaging agents in cells and tissues. We explored that the dynamic nature of the supramolecular interaction to develop a new technique for super-resolution imaging with ~20 nm resolution. This strategy exploits repetitive and transient binding of the fluorescently labeled guest to complementary CB host to obtain stochastic switching between fluorescence ON- and OFF-states. By connecting CB guest to targeting ligands, we demonstrated that this autonomous blinking enables two-dimensional (2D) and 3D super-resolution imaging of biomolecules in cells. We expect that these simple and easy to implement strategies will be easily applicable to address various questions in a wide range of biological and materials research.
In addition, are currently employing the programmable nature of DNA hybridization to generate probes for super-resolution microscopy. This imaging technique, called DNA-PAINT, accomplishes the necessary fluorescence ON/OFF switching for localization-based super-resolution microscopy by using transient DNA hybridization. Besides achieving ultra-high imaging resolution (~10 nm), this imaging technique has an intrinsically scalable multiplexing ability (>100✕). By integrating with molecularly targeted affinity ligand (e.g., antibodies), we are interested in situ proteomics imaging from single cells in the context of the tissue microenvironment.
Research activity in the area of imaging and super-resolution microscopy
1. Sasmal, R.; Das Saha, N.; Schueder, F.; Joshi, D.; Sheeba, V.; Jungmann, R.; Agasti, S. S., Dynamic host-guest interaction enables autonomous single molecule blinking and super-resolution imaging. Chem. Commun. 2019, 55 (96), 14430-14433.
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