Accumulation of harmful compounds by the composite of DNA and cyclodextrin: Effect on intramolecular cavity of cyclodextrin

Alpha-cyclodextrin (α-CD), β-CD, and γ-CD are composed of six, seven, and eight d-glucopyranose residues, respectively, and have a hydrophobic cavity in their molecules. In this study, the water-soluble cyclodextrin-immobilized poly(allylamine) (PCD) with various cavity sizes was synthesized. These α-PCD, β-PCD, and γ-PCD showed stability constants of 9.9 × 102 M−1, 4.5 × 103 M−1, and 6.2 × 103 M−1 to the 1,8-ANS molecule, respectively. Additionally, these PCD polymers formed water-insoluble composite materials by mixing with the double-stranded DNA, which can accumulate planar structure-containing harmful compounds, such as dioxin and polychlorobiphenyl (PCB). Therefore, we demonstrated the accumulation of various harmful compounds by the DNA–PCD composite materials having various cavity sizes. As a result, although the DNA–β-PCD composite material could encapsulate the non-planar structure-containing harmful compounds, such as bisphenol A and diethylstilbestrol, the DNA–α-PCD composite material did not interact with these molecules. These phenomena were due to the effect on the intramolecular cavity of the CD in the polymer. In contrast, all of the DNA–PCDs could accumulate the planar structure-containing compounds by an intercalation mechanism regardless of the cavity size in the CD.