Application of Nanoscale Zwitterionic Polyelectrolytes Brush with High Stability and Quantum Yield in Aqueous Solution for Cell Imaging

Zhiyong Zhang,Pengfei Sun,Xiaomei Lu,Minqiang Tan,Linghui Kong,Wei Huang,Hua Mo,Quli Fan

doi:10.1155/2020/1942791

Abstract

Cationic and zwitterionic polyelectrolytes are synthesized through atom transfer radical polymerization (ATRP), comprising a polyfluorene backbone with a small fraction of 2,1,3-benzothiadiazole and poly[2-(dimethylamino)ethyl methacrylate] (PDMAEMA) side chains. Due to higher charge density generated from grafted side chains, two polymers show higher water solubility and higher quantum yield. In comparison with cationic polyelectrolytes, zwitterionic polyelectrolytes are stable over a broad pH range from 1 to 13, even in 1 M NaCl solution. The absence of FRET between zwitterionic polymers and dye-labeled ssDNA indicates their ultralow nonspecific adsorption, while cationic polymer shows much stronger nonspecific interactions. The MTT assay of zwitterionic polymers exhibits their minimal cytotoxicity and potential in long-term clinical application. Most importantly, zwitterionic polymer could be efficiently taken up by cells, whereas cationic polymer stains the surface of cell due to membrane disruption generated from positive charges. The results illustrate that conjugated zwitterionic polymer could serve as a novel type of highly efficient ultralow fouling material with low cytotoxicity for labelling cell or potential biomedical applications.

Highlights

Cationic materials have been extensively used as transport materials crossing the cell membranes for labelling cell or gene delivery due to electrostatic attraction between positive charge of cationic materials and negative charge of cell membrane [1,2,3]
We find that due to the high charge density stemmed from poly[2-(dimethylamino)ethyl methacrylate] (PDMAEMA) graft side chains by atom transfer radical polymerization, both cationic and zwitterionic polymers exhibit excellent water-solubility and much higher quantum yield in aqueous solution
atom transfer radical polymerization (ATRP) of P2 with DMAEMA was performed in o-dichlorobenzene at 90°C for 12 h using 1,1,4,7,10,10-hexamethyl triethylenetetramine (HMTETA) as the ligand and CuBr as the catalyst. e resulting solution was purified through a column of neutral alumina and precipitated in n-hexane, yielding P3 as light yellow fibers

Summary

Introduction

Cationic materials have been extensively used as transport materials crossing the cell membranes for labelling cell or gene delivery due to electrostatic attraction between positive charge of cationic materials and negative charge of cell membrane [1,2,3]. Combining zwitterions with the nature of resistant to nonspecific adsorption and fluorescence conjugated polymer, it will develop conjugated polyelectrolytes as low cytotoxicity and nonfouling materials for various biological applications.

Results

Conclusion