Molecular Recognition of Fluorescent Probe Molecules with a Pseudopolyrotaxane Nanosheet

Pseudopolyrotaxane nanosheets (PPRNS) are ultra-thin two-dimensional (2D) materials fabricated via supramolecular self-assembly of beta-cydodextrin (beta-CD) and polyethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) triblock copolymers. In this study, the molecular loading of various fluorescent probe molecules onto PPRNS was systematically investigated. H-1 NMR study for R6G absorption to PPRNS indicated that the small hydrophobic groups, such as the methyl group, of R6G were absorbed by PPRNS. Consistently, the fluorescent probes without methyl groups were not absorbed. These results indicate that PPRNS has a molecular recognition absorption property based on the host-guest interaction of the functional groups on probe molecules and molecular-sized spaces of PPRNS surfaces, which may be vacant beta-CDs and voids between beta-CD columns. The absorbed amount of the molecular probes onto PPRNS was investigated by UV-vis spectra, and the absorption behavior could be described well by the Langmuir absorption isotherm. This is consistent with the suggested model that the probes are absorbed onto the PPRNS surfaces. This study demonstrates that PPRNSs can be applied as adsorbents for toxic compounds, drug delivery systems, and 2D sensors.

Automated summary

Pseudopolyrotaxane nanosheets (PPRNS) are ultra-thin 2D materials fabricated through the supramolecular self-assembly of beta-CD and polyethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) triblock copolymers. These nanosheets exhibit a molecular recognition absorption property for fluorescent probes, making them suitable for adsorption of toxic compounds, drug delivery systems, and 2D sensors.