Engineered Organic Color Centers for Profiling Protein-Carbohydrate Recognition

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Protein-carbohydrate recognitions are crucial events in many biological processes including cell-cell communication, immune response, cancer development and metastasis. Understanding specific interactions between carbohydrates and carbohydrate-binding proteins has been a challenging task due to the lack of versatile probes. Organic color centers created on nanomaterial hosts with precise optical and carbohydrate functionalities are uniquely suited to profile protein-carbohydrate recognition, which can lead to clarifying functions of both molecules and their underlying molecular mechanism and discovering therapeutic and diagnostic mechanism as well. This project will promote the progress in science by advancing fundamental understanding of structure-property relationships of engineered organic color centers with biological functionalities and establishing the probing behavior of carbohydrate-functionalized color centers for specific biological targets in either physiological and pathological pathways. In addition to advancing an emerging frontier across nanotechnology, chemistry, glycoscience, and engineering, this work will positively impact the well-being of society. First, this work will contribute to the development of the next-generation multicolor fluorescent probes with precise functionalities for biomedical research and applications. Second, this project will provide exciting opportunities to students of all backgrounds through promoting engaged learning via hands-on research in an evolving interdisciplinary field of nanomaterial science and technology and glycosciences. It will further support the advancement of a broadly inclusive, next-generation science and engineering workforce, particularly in bio-nanotechnology.This project will focus on probing specific interactions between carbohydrates and proteins by engineered organic color centers with the goal of achieving new nanomaterial tools to detect targeted molecular interactions in biological processes with enhanced sensitivity and selectivity. The proposed color centers will be created through covalently functionalizing the sidewall of semiconducting, pure-chirality single-wall carbon nanotubes via oriented immobilization of glycopolymers that closely mimic the natural glycan structures and functions. There are many advantages for the proposed color centers. First, chirality-defined carbon nanotube hosts have defined structures and properties and color centers created on nanotubes further tune light in the near-infrared regime that has attenuated autofluorescence and deep tissue penetration, providing the ideal condition for high contrast fluorescence detection in complicated biological samples. Second, pure-chirality carbon nanotubes promote advances in ultra-low dose, high efficiency nanomedicines. Third, biomimetic, precision synthesized glycopolymers mimic the three-dimensional display of carbohydrates on the cell surfaces, thus warrant enhanced sensitivity and selectivity for proteins. Particularly, the proposed work will involve i) synthesizing organic color centers using galactose-containing glycopolymers with different carbohydrate ligand densities, ii) determining how the galactose pendent groups of glycopolymers mediate the specific interaction of color centers with asialoglycoprotein receptor of human hepatoma cells, and iii) assessing the basal toxicity and functionality of organic color centers for selectively identifying human hepatoma cells utilizing both two-dimensional and three-dimensional cell cultures. Here, microarray three-dimensional bioprinting of cell cultures provides in vivo-like microenvironments to better asses the toxicity and selectivity of nanomaterials-based color centers, which could be used as biocompatible, cancer cell-targeting multicolor fluorescent probes. Optical properties of engineered organic color centers and their specific interactions with proteins and human liver cancer cells will be characterized primarily by optical spectroscopy of color centers, high-content imaging assays, and near-infrared fluorescence imaging. The combinatorial diversity of nanotube structure and glycopolymer configuration offers vast potential for chemical innovation and biochemical sensing and imaging advancement. If successful, this work will provide a transformative approach to study the carbohydrate recognition in biology that is essential to uncover molecular mechanisms of many biological processes. This work will also open up possibilities to create a new class of multicolor fluorescent probes with distinct properties that are previously never achieved for many applications, such as biosensing and bioimaging.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.