Preparation and photophysical behaviors of fluorescent chitosan bearing fluorescein: Potential biomaterial as temperature/pH probes

Abstract

A novel method for attaching fluorescein (via its epoxy derivative) to water-soluble chitosan, and the temperature/pH-sensitive qualities of fluorescence were investigated. 3-Epoxypropoxy fluorescein (EPF) was firstly synthesized by the reaction between fluorescein and epichlorohydrin, and then water-soluble chitosan bearing fluorescein (CS-EPF) was prepared via ring-opening reaction with EPF. They were characterized by the methods of 1 H NMR, MS, IR, UV-Vis, and luminescence spectra, respectively. The chemiluminescent and photophysical behaviors of EPF and CS-EPF were studied in detail. The results showed that the fluorescent chitosan could still provide temperature and pH sensitivities similar to that of fluorescein, achieving better long-term stability and fast equilibrium response. CS-EPF had an excellent linear response between relative fluorescence intensity and temperature in the range of 0-608C and two linear relationships between relative fluorescence intensity and pH in 0.0-4.14 and 8.15-13.20, respectively. This investigation may provide a convenient way to prepare low-cost and multifunctional macromolecule biomaterial to probe pH and temperature in biological systems.

Dual‐Emitting MOF⊃Dye Composite for Ratiometric Temperature Sensing

“…It needs to be mentioned that although numerous luminescent probes based on fluorescent dyes, quantum dots, and metal complexes or clusters have been developed for physiological temperature detection, such temperature sensors are usually based on temperature dependent luminescence intensity changes of single luminescence center in which the nonradiative decay rate was enhanced as the temperature increases. Because the luminescence intensity can be heavily affected by any changes in probe concentration, excitation, or detection efficiency, such luminescence temperature sensors have poor sensing accuracy.…”

Synthesis of hyperpolarizable biomaterials at molecular level based on pyridinium–chitosan complexes

“…In this context, typical modifications include N-alkylation by reduction 40 of imine derivatives, 16 formation of amides by coupling with carboxylic acids 17 and ring-opening oxirane. 18 These modifications greatly modulate the biopolymer physical and biological properties. Thus, lightly modified chitosan derivatives such as carboxymethyl 19 and quaternized 20 chitosans leave water- 45 soluble polymers that are able to increase their applications.…”

Facile preparation and potential application of water‐soluble polymeric temperature/pH probes bearing fluorescein

“…In our earlier works, different soluble polymeric pH indicators were synthesized by the reaction of functional dyes and polymers by a convenient method 25–29. However, the results show that it was difficult to control the content of fluorescence groups in the side chain of the polymer, and the reaction point was in complete disorder because the dyes were covalently bound to the surface of polymer.…”