Label-Free and Sensitive Determination of Cadmium Ions Using a Ti-Modified Co3O4-Based Electrochemical Aptasensor

Abstract

The current work demonstrates an electrochemical aptasensor for sensitive determination of Cd2+ based on the Ti-modified Co3O4 nanoparticles. In this unlabeled system, Ti-modified Co3O4 nanoparticles act as current signal amplifiers modified on the screen-printed carbon electrode (SPCE) surface, while the derivative aptamer of Cd2+ works as a target recognizer. In addition, the sensing is based on the increase in electrochemical probe thionine current signal due to the binding of aptamer to Cd2+ via specific recognition. In the current study, key parameters, including aptamer concentration, pH, and incubation time were optimized, respectively, to ensure sensing performance. Cyclic voltammetry was used not only to characterize each preparation and optimization step, but also to profile the bindings of aptamer to Cd2+. Under optimal conditions, Cd2+ can be determined in a linear range of 0.20 to 15 ng/mL, with a detection limit of 0.49 ng/mL, significantly below the maximum concentration limit set by the U.S. Environmental Protection Agency. Based on comparative analysis and the results of recovery test with real samples, this simple, label-free but highly selective method has considerable potential and thus can be used as an in-situ environmental monitoring platform for Cd2+ testing.

Highly sensitive biosensor based on aptamer and hybridization chain reaction for detection of cadmium ions

“…This result was identical to other reported method that also used a Cd 2+ aptamer to recognize Cd 2+ . [ 39–42 ]…”

“…This result was identical to other reported method that also used a Cd 2+ aptamer to recognize Cd 2+ . [39][40][41][42] F I G U R E 4 To investigate the reliability and potential application of the proposed new biosensor, recovery experiments were carried out in pond water samples that were collected from Yangtze University. Different Cd 2+ concentrations of pond water samples were prepared by adding 3, 7 or 9 nM Cd 2+ .…”

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

“…This could be ascribed to the specific recognition of FAM-aptamer to Cd 2+ . Since Cd 2+ was added in the aforementioned system, the FAM-aptamer disengaged themselves from the interaction with MOPS and was induced to form a stem-loop structure (partial hybridization by six base-pairs) to bind Cd 2+ with higher affinity simultaneously [ 37 ]. This formation prevented MOPS from approaching FAM fluorophore by steric effect, leading to reduced energy transfer and weak fluorescence.…”

A Review on Cyclic Voltammetric Investigation of Toxic Heavy Metals

“…Under optimized conditions, the electrochemical sensor showed a good linear relationship between Cd (II) concentration in the range of 1 to 50 ng/mL, with the limit of detection of 0.13 ng/mL respectively. [34]. Authors studied the effect of aptamer concentration, incubation time and pH of the solution to optimize the experimental condition to get good results.…”