Molecular rotor (MR) is a group of special fluorophores that typically consist of an electron donor, an electron receptor, and a π-conjugation system (denoted as the D-π-A motif). After being excited, a MR has two distinct states: (1) a planar conformation termed as locally exited state (LE) and (2) a twisted conformation termed as twisted intramolecular charge transfer state (TICT) (Haidekker & Theodorakis, 2010. <i>Journal of Biological Engineering</i>, 4: 11). Each excited MR molecule can relax through either the LE or TICT state. If the MR is in a free space, it relaxes through TICT state by releasing heat without emitting any photon. If the MR is in a local environment with spatial restriction, the transition from LE to TICT state is blocked and the relaxation is completed through the photon emission from LE state. For a given polymeric matrix, the overall spatial restriction governs the amount of MR molecules undergoing fluorescent emission. Therefore, the measurement of the fluorescence intensity of MR in a specific polymeric system can help to characterize the structural properties of this polymer. In this seminar, we will introduce our work of using MR to differentiate the supramolecular structures of two types of highly-branched carbohydrate polymer from plants, that is, amylopectin and phytoglycogen. In addition, we will describe our work on creating a micro-analysis method of using MR to rapidly evaluate the physical properties of starch materials at the milligram level. Using carbohydrate polymers as models, our overall goal is to establish MR as a unique approach in the study of biopolymers.

Characterization of carbohydrate polymers using molecular rotor as a structural probe

2019 Fall National Meeting

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