Label-Free Detection of Saxitoxin with Field-Effect Device-Based Biosensor.

Area of Science:

• Biosensor development
• Analytical chemistry
• Environmental science

Background:

• Saxitoxin (STX) is a potent marine toxin causing paralytic shellfish poisoning (PSP), presenting significant environmental and human health risks.
• Existing STX detection methods often lack convenience, affordability, or sensitivity, necessitating novel approaches.
• Effective monitoring of STX is crucial for public health and marine ecosystem protection.

Purpose of the Study:

• To develop a novel, label-free aptasensor for the sensitive and selective detection of saxitoxin (STX).
• To utilize an electrolyte-insulator-semiconductor (EIS) platform functionalized with Poly(amidoamine) (PAMAM) dendrimers and STX-specific aptamers.
• To evaluate the performance of the aptasensor in terms of detection range, limit of detection, selectivity, stability, and applicability to real samples.

Main Methods:

• Fabrication of a label-free EIS sensor functionalized with PAMAM dendrimers for aptamer immobilization.
• Electrochemical characterization using capacitance-voltage and constant-capacitance measurements to monitor surface modifications and STX binding.
• Surface morphology analysis using atomic force microscopy (AFM) and scanning electron microscopy (SEM).
• Fluorescence microscopy to confirm aptamer immobilization.
• Testing the aptasensor's performance with varying STX concentrations and analyzing mussel tissue extracts.

Main Results:

• Successful fabrication of a PAMAM dendrimer-modified EIS sensor with electrostatically immobilized STX-specific aptamers.
• The aptasensor exhibited a linear detection range of 0.5-100 nM for STX with a low limit of detection (LOD) of 0.09 nM.
• Demonstrated high selectivity for STX and maintained stability for 9 days.
• Successful detection of STX in extracted mussel tissue, indicating potential for real-world applications.

Conclusions:

• The developed aptasensor provides a rapid, label-free, and sensitive method for STX detection.
• The use of PAMAM dendrimers facilitates aptamer immobilization, enhancing sensor performance.
• This aptasensor shows significant promise for monitoring marine toxins in real samples, contributing to food safety and environmental surveillance.