Aptamer-based detection and quantitative analysis of ricin using affinity probe capillary electrophoresis

Area of Science:

• Biochemistry
• Molecular Biology
• Analytical Chemistry

Background:

• Antibodies are commonly used for specific biomolecule detection.
• RNA aptamers offer similar specificity to antibodies but with potential advantages in assay simplification.
• Immunoassays often involve complex steps and may require specialized equipment.

Purpose of the Study:

• To demonstrate the detection of sub-nanomolar concentrations of ricin using fluorescently tagged RNA aptamers.
• To evaluate the specificity and sensitivity of RNA aptamers in detecting ricin.
• To explore the potential of aptamer-based assays for detecting biowarfare agents.

Main Methods:

• Development of fluorescently tagged RNA aptamers for ricin detection.
• Utilizing capillary electrophoresis for free-solution assays.
• Monitoring the dissociation constant (Kd) between RNA aptamer and ricin A-chain under nonequilibrium conditions.

Main Results:

• Demonstrated detection of ricin at sub-nanomolar concentrations (500 pM or 7.1 amol).
• Quantified a dissociation constant (Kd) of 134 nM for the RNA aptamer-ricin A-chain interaction.
• Showed no inhibition by interfering proteins (bovine serum albumin, casein) at sub-nanomolar concentrations.
• Confirmed detection down to 1 nM ricin even with significant aptamer degradation by RNase A.

Conclusions:

• RNA aptamers provide a sensitive and selective method for ricin detection, rivaling antibody performance.
• The developed free-solution assay simplifies detection processes and is robust against common interfering proteins.
• This aptamer-based approach is a promising tool for rapid, selective, and sensitive detection of biowarfare agents.