A Waterborne Polyurethane‐Based Dye with Green Fluorescence Excited by Visible Light

Abstract

A waterborne aminofluorescein polyurethane-based dye (AF-WPU) with green fluorescence excited by visible light was synthesized by anchoring aminofluorescein (AF) to waterborne polyurethane chains. The structural characteristics of AF-WPU was confirmed by means of 1 H-NMR, FT-IR and UV-vis absorption. Compared with AF, there is a hypsochromic shift, and a new absorption peak generating in the UV-vis spectra of AF-WPU. Meanwhile, AF-WPU emited excellent fluorescence.The fluorescence intensity of AF-WPU increased five times at the same concentration. It is found that the fluorescence intensities of AF-WPU decreaseed with increased temperature, and increased first and then decreased with increasing concentration. The fluorescence of AF-WPU is very stable and insensitive to quenching agents. Moreover, AF-WPU which excited by visible light is less phototoxic to health, and has a broad prospect in practical applications.

Biodegradable Polyurethane Scaffolds in Regeneration Therapy: Characterization and In Vivo Real-Time Degradation Monitoring by Grafted Fluorescent Tracer

“…It was surprising that the intensity of the emission of PU-5 was dramatically higher than the same concentration of pristine calcein solution (3×) and CPU-5 (3×), and the emission maximum of PU-5 presented a hypsochromic shift (Figure C). Hu et al found that chemical grafting of fluorescent molecules (aminofluorescein) into the PU backbone would result in a hypsochromic shift of the emission wavelength of the fluorescent PU due to an increase in the polarity of the fluorescent molecule . In this study, a similar hypsochromic shift phenomenon was observed (from 445 nm in PU-5 to 437 nm in calcein, Figure C) and this hypsochromic shift could be additional evidence for the successful chemical grafting of calcein.…”

“…Hu et al found that chemical grafting of fluorescent molecules (aminofluorescein) into the PU backbone would result in a hypsochromic shift of the emission wavelength of the fluorescent PU due to an increase in the polarity of the fluorescent molecule. 35 In this study, a similar hypsochromic shift phenomenon was observed (from 445 nm in PU-5 to 437 nm in calcein, Figure 1C) and this hypsochromic shift could be additional evidence for the successful chemical grafting of calcein. In addition, the strengthened fluorescence performance can be explained by the structure-induced emission (SIE) effect.…”

“…Specifically, the SIE effect can be divided into two aspects. First, for fluorescent materials, the excited state energy can be lost due to intramolecular vibrations and rotations, which leads to a decrease in fluorescence emission . In this study, calcein was anchored to the PU backbone through the reaction of −OH groups with -NCO groups via urethane bonds.…”

“…First, for fluorescent materials, the excited state energy can be lost due to intramolecular vibrations and rotations, which leads to a decrease in fluorescence emission. 35 In this study, calcein was anchored to the PU backbone through the reaction of −OH groups with -NCO groups via urethane bonds. This chemical grafting helps to maintain the conformational stability of calcein and reduces the nonradiant energy transitions caused by the intramolecular vibrations and rotations, which in turn enhances the radiant energy transitions.…”

Blue fluorescent waterborne polyurethane‐based transition metal complexes with antibacterial activity

“…On the one hand, the photoinduced electron transfer process in Zn(5‐AQ) 2 ‐WPU, Cu(5‐AQ) 2 ‐WPU, and Cd(5‐AQ) 2 ‐WPU is inhibited 30 . On the other hand, after the reaction of NCO and NH 2 in the complexes, a large conjugated system is formed in the polyurethane chains, which restricts the intramolecular rotation and non‐radiative transition of the quinoline in the complexes 31 . It is worth noting that compared with the 495 nm emission peak of 5‐AQ at 495 nm, the fluorescence emission peaks of Zn(5‐AQ) 2 ‐WPU, Cu(5‐AQ) 2 ‐WPU, and Cd(5‐AQ) 2 ‐WPU are 462, 459, and 456 nm, respectively.…”