Development of an Aptamer Based Luminescent Optical Fiber Sensor for the Continuous Monitoring of Hg2+ in Aqueous Media.

Nerea De Acha,César Elosúa,Francisco J Arregui

doi:10.3390/s20082372

Nerea De Acha, César Elosúa + Show 1 more

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https://doi.org/10.3390/s20082372

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Abstract

A fluorescent optical fiber sensor for the detection of mercury (Hg2+) ions in aqueous solutions is presented in this work. The sensor was based on a fluorophore-labeled thymine (T)-rich oligodeoxyribonucleotide (ON) sequence that was directly immobilized onto the tip of a tapered optical fiber. In the presence of mercury ions, the formation of T–Hg2+-T mismatches quenches the fluorescence emission by the labeled fluorophore, which enables the measurement of Hg2+ ions in aqueous solutions. Thus, in contrast to commonly designed sensors, neither a fluorescence quencher nor a complementary ON sequence is required. The sensor presented a response time of 24.8 seconds toward 5 × 10−12 M Hg2+. It also showed both good reversibility (higher than the 95.8%) and selectivity: the I0/I variation was 10 times higher for Hg2+ ions than for Mn2+ ions. Other contaminants examined (Co2+, Ag+, Cd2+, Ni2+, Ca2+, Pb2+, Mn2+, Zn2+, Fe3+, and Cu2+) presented an even lower interference. The limit of detection of the sensor was 4.73 × 10−13 M Hg2+ in buffer solution and 9.03 × 10−13 M Hg2+ in ultrapure water, and was also able to detect 5 × 10−12 M Hg2+ in tap water.

Highlights

Assuring a good quality of water is essential in order to guarantee the health of the population and the quality of the environment [1]
A 50 μM probe stock solution was prepared in a 10 mM phosphate buffered solution (PBS) (acquired from Merck (Darmstadt, Germany)) at pH 7.4, which was kept frozen at −22 ◦ C in the absence of light
The sensor was regenerated with 0.5% (w/w) sodium dodecyl sulfate (SDS) afterward

Summary

Introduction

Assuring a good quality of water is essential in order to guarantee the health of the population and the quality of the environment [1]. Public institutions are increasingly concerned about monitoring the presence of different water pollutants such as plastics [2], pesticides [3], or metal ions [4]. In aqueous media, even at trace levels. Among the different metal ions, mercury (Hg2+ ) is known to be one of the most toxic species of aqueous media [5]. Are non-degradable [8], so their monitoring is crucial in order to assure a good quality of water. The European Union (EU) has established the maximum allowable mercury concentration in surface water as 3.49 × 10−10 M [9]. The detection of this water contaminant has attracted the interest of scientists during the last few years, leading to the development of a wide variety of Hg2+ -sensitive devices [10,11,12]

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