A Novel Electrochemical Sensing Platform for the Sensitive Detection and Degradation Monitoring of Methylene Blue

Abstract

Methylene blue is a toxic dye that is extensively used as a colorant in textile industries. Industrial effluent containing methylene blue, when drained into water bodies without proper treatment, poses a serious threat to aquatic and human lives. In order to protect the biocycle, various methods have been established to detect and remove hazardous dyes from aqueous systems. Electrochemical methods are preferred, owing to their characteristic features of simplicity, portability, potential selectivity, cost effectiveness, and rapid responsiveness. Based on these considerations, an electrochemical sensor consisting of amino-group-functionalized, multi-walled carbon nanotubes (NH2-fMWCNTs) immobilized on a glassy carbon electrode (GCE) was developed for the sensitive detection of methylene blue in aqueous solutions. The performance of the designed sensor was analyzed by electrochemical impedance spectroscopy, cyclic voltammetry, and square wave voltammetry. The developed sensing tool demonstrated promising features of sensitivity, selectivity, stability, fast responsiveness, and the ability to work with a very small volume of the analyte, i.e., in microliters, for analysis. Amino groups rich in electrons provide a negative charge to multi-walled carbon nanotubes, which significantly enhances the electrocatalytic activity of NH2-fMWCNTs for cationic dyes such as methylene blue. Using the designed sensing platform, a linear calibration plot with a limit of detection of 0.21 nM was obtained for methylene blue under optimized conditions. The designed sensor was also employed to monitor the extent and kinetics of the degradation of methylene blue. Titania nanoparticles were used for photocatalytic degradation, and the kinetics of degradation was monitored by both UV-Visible spectroscopic and electrochemical methods. The results revealed more than 95% removal of methylene blue in a time span of just 30 min.

Selective Aptamer Modification of Au Surfaces in a Microelectrode Sensor Array for Simultaneous Detection of Multiple Analytes

“…This result is in reasonable agreement with previously reported literature for this ATP E-AB sensor on a 2 mm Au disk electrode . It was also observed that the peak shifted to a more positive potential with increasing ATP concentration (Figure a), which was attributed to a decrease in the solution pH. , …”

Selective Aptamer Modification of Au Surfaces in a Microelectrode Sensor Array for Simultaneous Detection of Multiple Analytes

“…This result is in reasonable agreement with previously reported literature for this ATP E-AB sensor on a 2 mm Au disk electrode . It was also observed that the peak shifted to a more positive potential with increasing ATP concentration (Figure a), which was attributed to a decrease in the solution pH. , …”

MgO/NiCoFe 2 O 4 modified electrochemical sensor for simultaneous detection of ascorbic acid and levofloxacin

“…The pH of the solution plays a significant role in the electrocatalytic properties of sensors. 26 The pH was optimized from 4.0 to 8.0 of the BR electrolyte for the detection of AA and LEV using the developed MgO/NiCoFe 2 O 4 -NH/GCE/DPV method. The outcomes of the study showed that the maximum current response was observed at pH 7 ( Fig.…”

Nanoparticle-Assisted Liquid Crystal Droplet Sensors Enable Analysis of Low-Concentration Species in Aqueous Medium

“…We evaluate such concentration levels as significant and promising for potential applications of the nanoparticleassisted LC sensors when compared to the currently available literature on the sensing and detection of MB in aqueous environments showing the limit of detection in the order of 0.1 to 10 ppb levels. 61,62 Interestingly, such a low-concentration limit of detection corresponds to a value of ∼10 8 molecules per nanoparticle. Even at the extreme assumption limit of the adsorption of all of the molecules in the solution to the nanoparticle interfaces, a coverage of ∼20−30% of a monolayer can be estimated for 0.01 ppb of the MB case.…”

Selective Aptamer Modification of Au Surfaces in a Microelectrode Sensor Array for Simultaneous Detection of Multiple Analytes

“…This result is in reasonable agreement with previously reported literature for this ATP E-AB sensor on a 2 mm Au disk electrode . It was also observed that the peak shifted to a more positive potential with increasing ATP concentration (Figure a), which was attributed to a decrease in the solution pH. , …”

MgO/NiCoFe 2 O 4 modified electrochemical sensor for simultaneous detection of ascorbic acid and levofloxacin

“…The pH of the solution plays a significant role in the electrocatalytic properties of sensors. 26 The pH was optimized from 4.0 to 8.0 of the BR electrolyte for the detection of AA and LEV using the developed MgO/NiCoFe 2 O 4 -NH/GCE/DPV method. The outcomes of the study showed that the maximum current response was observed at pH 7 ( Fig.…”

Nanoparticle-Assisted Liquid Crystal Droplet Sensors Enable Analysis of Low-Concentration Species in Aqueous Medium

“…We evaluate such concentration levels as significant and promising for potential applications of the nanoparticleassisted LC sensors when compared to the currently available literature on the sensing and detection of MB in aqueous environments showing the limit of detection in the order of 0.1 to 10 ppb levels. 61,62 Interestingly, such a low-concentration limit of detection corresponds to a value of ∼10 8 molecules per nanoparticle. Even at the extreme assumption limit of the adsorption of all of the molecules in the solution to the nanoparticle interfaces, a coverage of ∼20−30% of a monolayer can be estimated for 0.01 ppb of the MB case.…”

Selective Aptamer Modification of Au Surfaces in a Microelectrode Sensor Array for Simultaneous Detection of Multiple Analytes

“…This result is in reasonable agreement with previously reported literature for this ATP E-AB sensor on a 2 mm Au disk electrode . It was also observed that the peak shifted to a more positive potential with increasing ATP concentration (Figure a), which was attributed to a decrease in the solution pH. , …”

MgO/NiCoFe 2 O 4 modified electrochemical sensor for simultaneous detection of ascorbic acid and levofloxacin

“…The pH of the solution plays a significant role in the electrocatalytic properties of sensors. 26 The pH was optimized from 4.0 to 8.0 of the BR electrolyte for the detection of AA and LEV using the developed MgO/NiCoFe 2 O 4 -NH/GCE/DPV method. The outcomes of the study showed that the maximum current response was observed at pH 7 ( Fig.…”

Nanoparticle-Assisted Liquid Crystal Droplet Sensors Enable Analysis of Low-Concentration Species in Aqueous Medium

“…We evaluate such concentration levels as significant and promising for potential applications of the nanoparticleassisted LC sensors when compared to the currently available literature on the sensing and detection of MB in aqueous environments showing the limit of detection in the order of 0.1 to 10 ppb levels. 61,62 Interestingly, such a low-concentration limit of detection corresponds to a value of ∼10 8 molecules per nanoparticle. Even at the extreme assumption limit of the adsorption of all of the molecules in the solution to the nanoparticle interfaces, a coverage of ∼20−30% of a monolayer can be estimated for 0.01 ppb of the MB case.…”