Thermo-Responsive Fluorescent Polymers with Diverse LCSTs for Ratiometric Temperature Sensing through FRET.

Zhaoyang Ding,Gang Feng,Chunfei Wang,Xuanjun Zhang

doi:10.3390/polym10030283

Abstract

Temperature is a significant parameter to regulate biological reactions and functions inside cells. Sensing the intracellular temperature with a competent method is necessary to understand life science. In this work, an energy-transfer polymeric thermometer was designed for temperature sensing. The thermometer was prepared from two thermo-responsive polymers with different lower critical solution temperatures (LCSTs) of 31.1 °C and 48.6 °C, coupling with blue and red fluorescent molecules, respectively, developed for ratiometric temperature sensing based on the Förster resonance energy transfer (FRET) mechanism. The polymers were synthesized from two monomers, N-isopropylacrylamide (NIPA) and N-isopropylmethacrylamide (NIPmA), which provided different temperature responses. The fluorescent intensity of each polymer (peaked at 436 and 628 nm, respectively) decreased upon the heating of the polymer aqueous solution. While these two polymer aqueous solutions were mixed, the fluorescent intensity decrease at 436 nm and substantial fluorescence enhancement at 628 nm was observed with the increasing temperature due to FRET effect. The cell imaging of HeLa cells by these thermo-responsive polymers was explored. The difference of LCSTs resulting in ratiometric fluorescence change would have a potential impact on the various biomedical applications.

Highlights

Temperature is an essential physiological parameter during all biochemical reactions in living cells.It has a close relationship with cellular functions, such as cell division, gene expression, metabolism, enzyme reaction, and so on [1,2]
The difference of lower critical solution temperatures (LCSTs) resulting in ratiometric fluorescence change would have a potential impact on the various biomedical applications
Two fluorescent polymers were synthesized via radical polymerization

Summary

Introduction

Temperature is an essential physiological parameter during all biochemical reactions in living cells. It has a close relationship with cellular functions, such as cell division, gene expression, metabolism, enzyme reaction, and so on [1,2]. Various abnormal medical phenomena, like cancer cell growth, are often accompanied by a temperature increase. Owing to these considerable demands, lots of promising approaches to fluorescent thermometers for cell temperature sensing have been studied [3]. A variety of stimuli-responsive polymers whose properties change in response to temperature, pH, ionic strength, light, and chemical stress have been investigated [13,14,15,16,17]

Methods

Results

Conclusion