A label-free electrochemical biosensor based on a DNA aptamer against codeine.

Area of Science:

• Biotechnology
• Analytical Chemistry
• Nanotechnology

Background:

• Opium alkaloids, such as codeine, require sensitive detection methods.
• DNA aptamers offer high specificity and affinity for target molecules.
• Electrochemical biosensors provide a label-free and sensitive detection platform.

Purpose of the Study:

• To develop and characterize DNA aptamers for codeine detection.
• To create a novel electrochemical label-free aptamer biosensor for codeine.
• To evaluate the biosensor's specificity, sensitivity, stability, and regeneration capabilities.

Main Methods:

• Systematic evolution of ligands by exponential enrichment (SELEX) to generate DNA aptamers against codeine.
• Truncation-mutation assay for aptamer optimization.
• Fabrication of an electrochemical biosensor using gold-mesoporous silica nanoparticles (Au-MSN) and a redox probe ([Fe(CN)6](3-/4-)).

Main Results:

• A specific DNA aptamer (HL7-14) with a dissociation constant (Kd) of 0.91 μM was identified and optimized.
• The aptamer demonstrated high specificity for codeine over morphine and other small molecules.
• The developed electrochemical biosensor exhibited a linear detection range from 10 pM to 100 nM with a low detection limit of 3 pM.
• The biosensor showed good specificity, stability, and regeneration.

Conclusions:

• A highly specific and sensitive DNA aptamer against codeine was successfully developed.
• A novel electrochemical label-free aptamer biosensor for codeine detection was successfully fabricated and validated.
• The proposed biosensor holds promise for accurate and reliable codeine detection in various applications.