Dramatically Increased Binding Constant of Water-Soluble Cyclodextrin Hyperbranched Polymers: Explored with Diffusion Ordered NMR Spectroscopy (DOSY)

Anh Thi Ngoc Doan; Van Thi Hong Doan; Jun Katsuki; Shota Fujii; Hiroyuki Kono; Kazuo Sakurai

doi:10.1021/acsomega.1c06194

Dramatically Increased Binding Constant of Water-Soluble Cyclodextrin Hyperbranched Polymers: Explored with Diffusion Ordered NMR Spectroscopy (DOSY)

ACS Omega. 2022 Mar 25;7(13):10890-10900. doi: 10.1021/acsomega.1c06194. eCollection 2022 Apr 5.

Authors

Anh Thi Ngoc Doan¹, Van Thi Hong Doan¹, Jun Katsuki¹, Shota Fujii¹, Hiroyuki Kono², Kazuo Sakurai¹

Affiliations

¹ Department of Chemistry and Biochemistry, University of Kitakyushu, 1-1 Hibikino, Wakamatsu, Kitakyushu, Fukuoka 808-0135, Japan.
² Division of Applied Chemistry and Biochemistry, National Institute of Technology Tomakomai College, 443 Nishikioka, Tomakomai, Hokkaido 059-1275, Japan.

Abstract

We report that the polymerization of cyclodextrin (CD) with epichlorohydrin (ECH) dramatically increases the binding constant of CD to vanillin, from 55 to 8.4 × 10³ M^-1, by approximately 100 times, as determined by diffusion ordered spectroscopy (DOSY)-¹H NMR. The binding constant increased with an increase of the ECH content of the polymer, although ECH polymers without CDs showed no affinity at all, suggesting that the hydrophobicity of the ECH network outside of CDs helps to enhance the binding. This increased binding constant allows CD-ECH polymers to increase the drug loading ratio, which may be one of the most critical issues for drug delivery systems.