Characterization of zwitterion-modified poly(amidoamine) dendrimers in aqueous solution via a thorough NMR investigation

Jinyuan Liu,Mingwu Shen,Istvan Banyai,Zhijuan Xiong,Xiangyang Shi

doi:10.1140/epje/i2020-11931-6

Abstract

.Zwitterions are a class of unique molecules that can be modified onto nanomaterials to render them with antifouling properties. Here we report a thorough NMR investigation of dendrimers modified with zwitterions in terms of their structure, hydrodynamic size, and diffusion time in aqueous solution. In this present work, poly(amidoamine) (PAMAM) dendrimers of generation 5 (G5) were partially decorated with carboxybetaine acrylamide (CBAA), 2-methacryloyloxyethyl phosphorylcholine (MPC), and 1,3-propane sultone (1,3-PS), respectively with different modification degrees. The formed zwitterion-modified G5 dendrimers were characterized using NMR techniques. We show that the zwitterion modification leads to increased G5 dendrimer size in aqueous solution, suggesting that the modified zwitterions can form a hydration layer on the surface of G5 dendrimers. In addition, the hydrodynamic sizes of G5 dendrimers modified with different zwitterions but with the same degree of surface modification are discrepant depending on the type of zwitterions. The present study provides a new physical insight into the structure of zwitterion-modified G5 dendrimers by NMR techniques, which is beneficial for further design of different biomedical applications.Graphical abstract

Highlights

Reducing the adhesion of environmental molecules to surfaces has long been a goal of applied surface science
All samples were dissolved in deuterium oxide (D2O). 1H NMR, diffusion ordered spectroscopy (DOSY), and correlation spectroscopy (COSY) and diffusion time were analyzed by a Bruker DRX 400 NMR spectrometer (Karlsruhe, Germany) according to the standard pulse programs [26]
For the zwitterions of carboxybetaine acrylamide (CBAA) and methacryloyloxy ethyl phosphorylcholine (MPC), the higher modification degree on the surface of generation 5 (G5) dendrimers led to the larger hydrodynamic size of the G5 dendrimers

Summary

Introduction

Reducing the adhesion of environmental molecules to surfaces has long been a goal of applied surface science. The main methods to characterize the antifouling properties of zwitterion-modified nanoparticles (NPs) include nonspecific protein adsorption test, macrophage cellular uptake assay in vitro and pharmacokinetics in vivo [18,19,20] All of these detection methods require a complicated equipment, and cell and animal experiments, which require specialized experimental skills and instruments to obtain reliable experimental data. In another work [27], we employed NMR diffusiometry to examine the diffusion rate and hydrodynamic size of dendrimer/carbon dot nanhybrid materials to confirm the interaction between the multifunctional dendrimers and the carbon dots. These studies underscore the importance to use advanced NMR techniques to delineate functional dendrimers and hybrid materials. The obtained results are beneficial for a better understanding of the physical structure of the zwitterionic dendrimers for different biomedical applications

Materials

NMR techniques

NMR diffusiometry

Conclusion

Conflicts of interest