Comparative study on aptamers as recognition elements for antibiotics in a label-free all-polymer biosensor

Area of Science:

• Electrochemistry
• Materials Science
• Biosensing

Background:

• Development of sensitive and selective biosensors is crucial for detecting contaminants in food.
• Existing methods for antibiotic detection can be time-consuming and require complex sample preparation.
• There is a need for rapid, label-free detection platforms for antibiotics in real-world samples.

Purpose of the Study:

• To develop and validate an all-polymer electrochemical microfluidic biosensor for the detection of antibiotics.
• To functionalize conductive polymer electrodes with aptamers for specific antibiotic recognition.
• To assess the sensor's performance in detecting ampicillin and kanamycin A in both buffer solutions and real milk samples.

Main Methods:

• Fabrication of a microfluidic device using Topas® substrate.
• Creation of a conductive polymer bilayer electrode using PEDOT:TsO and PEDOT-OH:TsO.
• Covalent functionalization of electrodes with aptamers specific to ampicillin and kanamycin A.
• Detection of antibiotics using electrochemical impedance spectroscopy (EIS).
• Analysis of EIS data using an equivalent circuit model.

Main Results:

• The biosensor successfully detected ampicillin in the range of 100 pM to 1 μM and kanamycin A from 10 nM to 1 mM.
• EIS spectra were accurately modeled using an equivalent circuit, explaining the impedance signal.
• The sensor demonstrated functionality with real samples, detecting ampicillin in spiked milk below the EU maximum residue limit (MRL).

Conclusions:

• An all-polymer electrochemical microfluidic biosensor platform was successfully developed.
• The platform enables real-time, label-free, and selective impedimetric detection of antibiotics.
• The sensor shows promise for routine monitoring of antibiotic residues in food products.