A Facile Aptasensor for Instantaneous Determination of Cadmium Ions Based on Fluorescence Amplification Effect of MOPS on FAM-Labeled Aptamer

Abstract

Analytical performance and efficiency are two pivotal issues for developing an on-site and real-time aptasensor for cadmium (Cd2+) determination. However, suffering from redundant preparations, fabrications, and incubation, most of them fail to well satisfy the requirements. In this work, we found that fluorescence intensity of 6-carboxyfluorescein(FAM)-labeled aptamer (FAM-aptamer) could be remarkably amplified by 3-(N-morpholino)propane sulfonic acid (MOPS), then fell proportionally as Cd2+ concentration introduced. Importantly, the fluorescence variation occurred immediately after addition of Cd2+, and would keep stable for at least 60 min. Based on the discovery, a facile and ultra-efficient aptasensor for Cd2+ determination was successfully developed. The sensing mechanism was confirmed by fluorescence pattern, circular dichroism (CD) and intermolecular interaction related to pKa. Under the optimal conditions, Cd2+ could be determined rapidly from 5 to 4000 ng mL−1. The detection limit (1.92 ng mL−1) was also lower than the concentration limit for drinking water set by WHO and EPA (3 and 5 ng mL−1, respectively). More than a widely used buffer, MOPS was firstly revealed to have fluorescence amplification effect on FAM-aptamer upon a given context. Despite being sensitive to pH, this simple, high-performance and ultra-efficient aptasensor would be practical for on-site and real-time monitoring of Cd2+.

Silicon ameliorates cadmium (Cd) toxicity in pearl millet by inducing antioxidant defense system

“…The investigative enzymes like CAT, POD, APX and SOD perform an essential function in the metabolic responses of environmental stress function in crop [ [53] , [64] , [71] ]. Liu et al [ 72 ] reported that the increased in the activities of SOD and CAT in Si treated plants present enhanced modification of O to H 2 O 2 as similar to Si treatment in Refs. [ 73 , 74 ].…”

Graphene oxide aptasensor droplet assay for detection of metabolites secreted by single cells applied to synthetic biology

“…The quenching efficiency was determined by the formula ( F 1 − F 0 )/ F 1 , where F 1 and F 0 are the fluorescence signals of ATP aptamers before and after adding GO. 31 The signal-to-noise ratio (SNR) was determined by the formula SNR = F / F 0 , where F represents the recovered fluorescence intensity and F 0 is the quenched fluorescence intensity before adding the target compounds. 32 The correlation between GO concentration and quenching efficiency was obtained by recording the plateau quenching at different GO concentrations.…”

Design and Synthesis of Novel Squaraine-Based Fluorescent Probe for Far-Red Detection of Chymotrypsin Enzyme

“…Fluorescence quenching efficiency was calculated using the formula below [ 47 ]: where F PC is the emission intensity of SQ-122 PC, and F dye is the emission intensity of the SQ-122 dye at the same concentration in H 2 O (30%).…”