Solid-state probe based electrochemical aptasensor for cocaine: a potentially convenient, sensitive, repeatable, and...

Area of Science:

• Electrochemistry
• Biosensor Technology
• Nucleic Acid Aptamers

Background:

• Aptamers are artificial oligonucleotides used in developing novel biosensors (aptasensors).
• Electrochemical biosensors offer sensitive detection methods for various analytes.
• Label-free detection simplifies sensor design and reduces interference.

Purpose of the Study:

• To construct a label-free electrochemical aptasensor for sensitive and specific cocaine detection.
• To utilize a layer-by-layer (LBL) self-assembled multilayer for probe immobilization.
• To explore the potential of aptasensors for simultaneous multianalysis.

Main Methods:

• Fabrication of an indium tin oxide (ITO) array electrode with a ferrocene-appended poly(ethyleneimine) (Fc-PEI) and gold nanoparticle (AuNP) multilayer.
• Covalent labeling of cocaine aptamer fragments (SH-C2) onto the AuNP layer.
• Detection of cocaine using differential pulse voltammetry (DPV) by monitoring changes in the Fc-PEI signal upon target binding.

Main Results:

• The aptasensor achieved a low detection limit of 0.1 microM and a detection range up to 38.8 microM for cocaine.
• The sensor demonstrated high specificity for cocaine in complex biological fluids like human plasma and saliva.
• The sensing strategy showed general applicability, successfully detecting thrombin with a low detection limit.

Conclusions:

• The developed electrochemical aptasensor is a sensitive and specific tool for cocaine detection.
• The LBL self-assembly technique provides an effective method for aptasensor fabrication.
• The aptasensor platform shows promise for integration into multianalysis systems for simultaneous detection of multiple analytes.