A time-resolved luminescent competitive assay to detect L-selectin using aptamers as recognition elements

Area of Science:

• Biomedical Engineering
• Analytical Chemistry
• Molecular Diagnostics

Background:

• L-selectin is a protein implicated in various diseases.
• Accurate detection of L-selectin is crucial for diagnosing and monitoring conditions such as Alzheimer's disease.
• Existing diagnostic methods, like ELISA, can be time-consuming and complex.

Purpose of the Study:

• To develop a novel aptamer-based luminescent assay for sensitive L-selectin detection.
• To establish a rapid, homogeneous assay as an alternative to conventional diagnostic techniques.
• To investigate the assay's potential for detecting L-selectin in disease-relevant concentrations.

Main Methods:

• Development of a Förster Resonance Energy Transfer (FRET) based sensing system.
• Utilizing a terbium complex (TbC) as a donor and a cyanine dye (Cy5) as an acceptor.
• Employing a biotinylated aptamer conjugated with Cy5-labelled streptavidin (Apta-Cy5-Strep) and L-selectin conjugated with TbC (L-selectin-TbC).

Main Results:

• The assay demonstrated FRET from TbC to Cy5 upon aptamer-L-selectin binding.
• A dose-dependent decrease in FRET signal was observed with increasing L-selectin concentrations.
• The assay detected L-selectin in the range of 10-500 ng/mL, relevant for Alzheimer's disease, with a limit of detection (LOD) of 10 ng/mL.

Conclusions:

• The developed aptasensor assay provides a sensitive and rapid method for L-selectin detection.
• This homogeneous assay can be completed within one hour, offering an advantage over ELISA.
• The assay shows potential as a valuable tool for clinical diagnostics, particularly for neurological disorders.