Structural Reorganization and Fibrinogen Adsorption Behaviors on the Polyrotaxane Surfaces Investigated by Sum Frequency Generation Spectroscopy

Abstract

Polyrotaxanes, such as supramolecular assemblies with methylated α-cyclodextrins (α-CDs) as host molecules noncovalently threaded on the linear polymer backbone, are promising materials for biomedical applications because they allow adsorbed proteins possessing a high surface flexibility as well as control of the cellular morphology and adhesion. To provide a general design principle for biomedical materials, we examined the surface reorganization behaviors and adsorption conformations of fibrinogen on the polyrotaxane surfaces with comparison to several random copolymers by sum frequency generation (SFG) vibrational spectroscopy. We showed that the polyrotaxane (OMe-PRX-PMB) with methylated α-CDs as the host molecule exhibited unique surface structures in an aqueous environment. The hydrophobic interaction between the methoxy groups of the methylated α-CD molecules and methyl groups of the n-butyl methacrylate (BMA) side chains may dominate the surface restructuring behavior of the OMe-PRX-PMB. The orientation analysis revealed that the orientation of the fibrinogen adsorbed on the OMe-PRX-PMB surface is close to a single distribution, which is different from the adsorption behaviors of fibrinogen on other polyrotaxane or random copolymer surfaces.

Surface-Restructuring Differences between Polyrotaxanes and Random Copolymers in Aqueous Environment

“…30−33 Recently, we reported an SFG study on the structural reorganization of polyrotaxanes (containing 12 α-CDs or methylated α-CDs per molecule). 34 We found that the methylation of the α-CD moiety significantly affects the surface restructuring behaviors of the polyrotaxane in an aqueous solution and leads to different adsorption structures of human plasma fibrinogen molecules. 34 To gain further insight into the effects of α-CDs on the surface restructuring and biomolecular adsorption, we 1).…”

“…34 We found that the methylation of the α-CD moiety significantly affects the surface restructuring behaviors of the polyrotaxane in an aqueous solution and leads to different adsorption structures of human plasma fibrinogen molecules. 34 To gain further insight into the effects of α-CDs on the surface restructuring and biomolecular adsorption, we 1). These copolymers contain components of n-butyl methacrylate (BMA) and 2-methacryloyloxyethyl phosphorylcholine (MPC) similar to those in the polyrotaxanes.…”

Probing Molecular Behavior of Carbonyl Groups at Buried Nylon/Polyolefin Interfaces in Situ

“…Detailed information on the buried interfaces between the polymer thin films in the multilayer samples has seldom been investigated nondestructively at the molecular level due to the lack of appropriate analytical tools to probe this information. Sum frequency generation (SFG) vibrational spectroscopy is a second-order nonlinear optical technique and a powerful nondestructive, in situ tool to study the molecular structure of the buried interfacial structures, with sub-monolayer interface specificity. − SFG has been extensively applied to study many buried solid/solid interfaces involving a variety of polymers. − Recently, we have reported molecular orientation information, especially for methylene groups, at buried interfaces of nylon and functionalized polyolefin materials . In this study, we expand this to investigate the molecular structure of the nylon/MAH-grafted polyethylene buried interface, focusing on the polar CO groups of MAH-grafted polyethylene at buried CaF 2 and nylon interfaces in situ.…”

Sum Frequency Generation Vibrational Spectroscopy Using Evanescent Waves—Toward Probing Irregular and Complex Surfaces of Mesoscopic-Scale Materials

“…Sum frequency generation (SFG) vibrational spectroscopy, as a second order nonlinear optical technique developed for more than 30 years since the first series of papers were published in 1987 by Shen et al., − has shown significant advantages over the traditional ones due to its intrinsic surface selectivity and molecular orientation sensitivity. Surface and interfacial molecular-level structures for a wide range of materials have successfully been studied, − providing new knowledges and promoting our understanding on the materials’ surfaces and interfaces. It should be noted, as a coherent process, interaction of the two incident beams with molecules at a flat surface or interface leads to a third sum frequency beam with the defined output direction.…”