High-sensitivity small-molecule detection of microcystin-LR cyano-toxin using a terahertz-aptamer biosensor

Area of Science:

• Terahertz (THz) spectroscopy and sensing
• Biosensor development
• Analytical chemistry and toxin detection

Background:

• Microcystin-LR (MC-LR) is a harmful cyanotoxin requiring sensitive detection methods.
• Existing bio-sensing techniques like surface plasmon resonance (SPR) can be time-consuming and less sensitive.
• Aptasensors offer high specificity for target molecule detection.

Purpose of the Study:

• To demonstrate a rapid and highly sensitive aptasensor for MC-LR detection.
• To utilize terahertz (THz) emission technique via terahertz chemical microscope (TCM) for toxin sensing.
• To compare the performance of the TCM aptasensor with SPR for MC-LR detection.

Main Methods:

• Fabrication of a sensing plate with a silicon layer on a sapphire substrate, featuring a SiO2 layer.
• Immobilization of DNA aptamers onto the sensing plate surface using click chemistry.
• Detection of MC-LR by measuring changes in THz signal amplitude upon aptamer-toxin binding, optimized via aptamer concentration and buffer composition.

Main Results:

• The aptamer-based TCM achieved a rapid detection time of 15 minutes (10 min incubation, 5 min acquisition).
• An excellent MC-LR detection limit of 50 ng L-1 was obtained.
• The TCM method demonstrated 20 times higher sensitivity compared to SPR measurements for MC-LR.

Conclusions:

• The terahertz chemical microscope (TCM) coupled with an aptasensor provides a rapid, highly sensitive, and effective platform for MC-LR toxin detection.
• This approach significantly enhances sensitivity and reduces assay time compared to conventional methods like SPR.
• The TCM aptasensor shows great potential for real-time monitoring and early warning systems for harmful algal blooms and water quality assessment.