A pH optical and fluorescent sensor based on rhodamine modified on activated cellulose paper

Abstract

A rhodamine-based colorimetric and fluorescent pH chemosensor (RhA) was designed and synthesized via a coupling reaction between rhodamine ethylenediamine and succinic anhydride. RhA showed excellent pH response in aqueous solutions. In addition, common cations (Na + , K + , Ag + , Mg 2+ , Ca 2+ , Pb 2+ , Co 2+ , Ni 2+ , Cu 2+ , Zn 2+ , Cd 2+ , Hg 2+ , Al 3+ , Cr 3+ , Fe 3+ , Au 3+ , Pt 2+ , and Ru 2+ ) did not interfere with the pH response. As it has the potential to be used as a portable pH sensor, RhA was immobilized on activated cellulose paper using N,N'dicyclohexylcarbodiimide (DCC) and N,N'-dimethylpyridin-4-amine (DMAP) as the coupling reagent to obtain a composite pH sensor (CP-RhA). CP-RhA was characterized by ATR-FTIR, UV-vis, and fluorescence spectroscopy, and by scanning electron microscopy (SEM). CP-RhA showed a rapid response in the pH range 1-8 through color and fluorescence changes. DFT calculations showed a blue-shifted spectrum in the protonated form compared to the neutral form. Moreover, the pH sensor paper could be reused by dipping in NaOH. Thus, our work demonstrates the potential of the rhodamine dye composite for visualizing pH changes in real systems.

Optical Sensing and Imaging of pH Values: Spectroscopies, Materials, and Applications

“…Several rhodamines that explore lactam formation have also been reported ( Figure 19 C). 410 , 454 − 460 The spirolactam form at neutral pH is colorless, whereas opening of the ring in acidic media yields a highly absorbing and fluorescent rhodamine. The p K a of spirolactam rhodamines can be tuned by varying the substitution of the group attached to the spirolactam group; the dyes with p K a values from 2.8 to 6.5 have been reported.…”

Recent Advances in Optical, Electrochemical and Field Effect pH Sensors

“…Although it had high precision (RSD < 0.30%), the sensor had a response time of about 3 min and could only be used in the acidic range (pH 0.5-5). Taweetanavanich et al described a rhodamine-based colorimetric and fluorimetric sensor that worked between pH 1 and 8 [30]. The interference of several metal cations (Na , K , Ag , Mg , Ca , Pb , Ni , Cu , Zn , Cd , Hg , Al , Cr , Fe , Au , Pt , Ru ) was negligible, thus confirming the selectivity of the sensor towards the hydronium ion.…”

Recent Progress in Small Spirocyclic, Xanthene-Based Fluorescent Probes

“…Live cell imaging was performed and the surface mobility and diffusion patterns of BACE1 were studied for the first time. nanoparticles [21,[73][74][75][76][77][78] or any other solid support [79][80][81][82] will be omitted, given the scope of this review.…”

“…The final section will summarize recent advances in the synthesis and understanding of their structure including novel computational approaches. Even though a lot of progress has been achieved, pH-sensing [ 60 , 61 , 62 , 63 , 64 ], metal ion detection [ 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 ], and the use of nanoparticles [ 21 , 73 , 74 , 75 , 76 , 77 , 78 ] or any other solid support [ 79 , 80 , 81 , 82 ] will be omitted, given the scope of this review.…”