A fluorescent colorimetric pH sensor and the influences of matrices on sensing performances.
A fluorescent colorimetric pH sensor was developed by a polymerization of a monomeric fluorescein based green emitter (SM1) with a monomeric 2-dicyanomethylene-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran derived red emitter (SM2) in poly(2-hydroxyethyl methacrylate)-co-polyacrylamide (PHEMA-co-PAM) matrices. PolymerizedSM1(PSM1) in the polymer matrices showed bright emissions at basic conditions and weak emissions at acidic conditions. PolymerizedSM2(PSM2) in the polymer matrices exhibited a vastly different response when compared toPSM1. The emissions ofPSM2are stronger under acidic conditions than those under basic conditions. WhenSM1andSM2were polymerized in the same polymer matrix, a dual emission sensor acting as a ratiometric pH sensor (PSM1,2) was successfully developed. Because thePSM1andPSM2exhibited different pH responses and separated emission windows, the changes in the emission colors were clearly observed in their dual color sensor ofPSM1,2, which changed emission colors dramatically from green at pH 7 to red at pH 4, which was detected visually and/or by using a color camera under an excitation of 488 nm. In addition to the development of the dual color ratiometric pH sensor, we also studied the effects of different matrix compositions, crosslinkers, and charges on the reporting capabilities of the sensors (sensitivity and pKa).
Center for Biosignatures Discovery Automation, Biodesign Institute, Arizona State University, Tempe, AZ 85287-6501, USA.
Yanqing
Y
Tian
Emily
E
Fuller
Summer
S
Klug
Fred
F
Lee
Fengyu
F
Su
Liqiang
L
Zhang
Shih-Hui
SH
Chao
Deirdre R
DR
Meldrum
charge; colorimetric sensors; crosslinkers; matrix; pH sensors