Rhodamine-immobilized optical hydrogels with shape deformation and Hg2+-sensitive fluorescence behaviors

Zixiang Qu,Lizhen Wang,Dawei Qin,Xia Meng,Hongdong Duan

doi:10.1038/s41598-020-64549-5

Zixiang Qu, Lizhen Wang + Show 3 more

Open Access

https://doi.org/10.1038/s41598-020-64549-5

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Abstract

A highly effective method for the research and development of a novel macroscopic hydrogel sensor and bilayer hydrogel is reported. Based on Rhodamine 6G, an Hg2+ sensitive fluorescent functional monomer was synthesized, then the monomer was utilized to synthesize hydrogel sensors and bilayer hydrogels. Hydrogel sensor has prominent selectivity to Hg2+, the bilayer hydrogel has shape changing function additionally. By combining a thermoresponsive hydrogel layer, poly N-isopropylacrylamide (PNIPAM), with an Hg2+ selective hydrogel layer via macroscopic supramolecular assembly, a bilayer hydrogel is obtained that can be tailored and reswells. The bilayer hydrogel sensor can show complex shape deformation caused by the PNIPAM layer and the Hg2+-responsive characteristic of hydrogel sensor layer can be observed under visible light or UV light. This work will provide novel insights for the design and synthesis of novel smart materials with synergistic functions.

Highlights

A highly effective method for the research and development of a novel macroscopic hydrogel sensor and bilayer hydrogel is reported
Absorption band rarely appeared or completely did not appear by adding other metal ions, which proved the prominent selectivity of R6GLA toward Hg2+ with the possible reason of the complexed property of R6GLA toward Hg2+ and the photoinduced electron transfer (PET)
The free solution of R6GLA in DMSO and H2O (7/3, v/v) showed no obvious fluorescence emission, while the addition of Hg2+ induced a significant fluorescence enhancement with the significant fluorescence appearance at 581 nm. These results should be ascribed to the blocked photoinduced electron transfer (PET) process and the chelation-enhanced fluorescence (CHEF)

Summary

Introduction

A highly effective method for the research and development of a novel macroscopic hydrogel sensor and bilayer hydrogel is reported. A transparent hydrogel sensor that shows fluorescence in response to sensing Hg2+ was reported, and based on this hydrogel sensor, a bilayer hydrogel was synthesized that characterized by Hg2+-response and shape-changing. Aiming at integration of properties of fluorescence color-changing and shape deformation into one hydrogel system, we synthesized a bilayer hydrogel by the hydrogel sensor and PNIPAM.

Results

Conclusion