The Characterization of Binding between Aptamer and Bisphenol A and Developing Electrochemical Aptasensors for Bisphenol A with Rationally Engineered Aptamers

An Electrochemical Aptasensor for the Detection of Freshwater Cyanobacteria

Aphanizomenon is a genus of cyanobacteria that is filamentous and nitrogen-fixing and inhabits aquatic environments. This genus is known as one of the major producers of cyanotoxins that can affect water quality after the bloom period. In this study, an electrochemical aptasensor is demonstrated using a specific aptamer to detect Aphanizomenon sp. ULC602 for the rapid and sensitive detection of this bacterium. The principal operation of the generated aptasensor is based on the conformational change in the aptamer attached to the electrode surface in the presence of the target bacterium, resulting in a decrease in the current peak, which is measured by square-wave voltammetry (SWV). This aptasensor has a limit of detection (LOD) of OD750~0.3, with an extension to OD750~1.2 and a sensitivity of 456.8 μA·OD750-1·cm-2 without interference from other cyanobacteria. This is the first aptasensor studied that provides rapid detection to monitor the spread of this bacterium quickly in a targeted manner.

Fabrication of a Novel and Ultrasensitive Label-Free Electrochemical Aptasensor Based on Gold Nanostructure for Detection of Homocysteine

The current attempt was made to detect the amino acid homocysteine (HMC) using an electrochemical aptasensor. A high-specificity HMC aptamer was used to fabricate an Au nanostructured/carbon paste electrode (Au-NS/CPE). HMC at high blood concentration (hyperhomocysteinemia) can be associated with endothelial cell damage leading to blood vessel inflammation, thereby possibly resulting in atherogenesis leading to ischemic damage. Our proposed protocol was to selectively immobilize the aptamer on the gate electrode with a high affinity to the HMC. The absence of a clear alteration in the current due to common interferants (methionine (Met) and cysteine (Cys)) indicated the high specificity of the sensor. The aptasensor was successful in sensing HMC ranging between 0.1 and 30 μM, with a narrow limit of detection (LOD) as low as 0.03 μM.