Label-Free and Redox Markers-Based Electrochemical Aptasensors for Aflatoxin M1 Detection

Area of Science:

• Analytical Chemistry
• Biosensor Technology
• Food Safety

Background:

• Mycotoxin contamination, particularly aflatoxin M₁ (AFM1), poses a significant risk to public health.
• Accurate and sensitive detection methods for AFM1 in food products like milk are crucial for regulatory compliance and consumer safety.
• Aptamer-based biosensors offer a promising alternative to traditional detection methods due to their specificity and potential for miniaturization.

Purpose of the Study:

• To comparatively analyze the sensitivity of DNA aptamer-based biosensors for AFM1 detection.
• To evaluate the impact of different DNA aptamer immobilization strategies on biosensor performance.
• To assess the suitability of label-free electrochemical techniques for AFM1 quantification.

Main Methods:

• Development and characterization of two aptasensor configurations utilizing different DNA aptamer immobilization techniques: amino-modified aptamers on polyamidoamine dendrimers (PAMAM G4) and biotin-modified aptamers on a neutravidin-coated gold surface.
• Label-free electrochemical detection using electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV).
• Validation of aptasensor performance using spiked milk samples to determine limit of detection (LOD) and recovery rates.

Main Results:

• Both immobilization methods yielded comparable and sensitive detection of AFM1, with limits of detection (LOD) of 8.47 ng/L and 8.62 ng/L, respectively.
• The determined LOD values are significantly below the maximum allowable limits for AFM1 in milk and dairy products.
• The aptasensors demonstrated good performance in real sample analysis, with recovery rates exceeding 78% in spiked milk samples.
• Comparative analysis indicated that the developed aptasensors exhibit sensitivity comparable to traditional immunoassays.

Conclusions:

• The study successfully developed and validated highly sensitive aptamer-based biosensors for AFM1 detection in milk.
• The choice of aptamer immobilization method has minimal impact on the overall sensitivity of the electrochemical detection system.
• These aptasensors represent a viable tool for rapid, sensitive, and reliable monitoring of AFM1 contamination in dairy products, contributing to enhanced food safety.