Aptamers as affinity reagents in an integrated electrophoretic lab-on-a-chip platform

Area of Science:

• Biochemistry
• Analytical Chemistry
• Biotechnology

Background:

• Nucleic acid aptamers present advantages over antibodies, including cost-effectiveness, enhanced stability, and suitability for rapid electrophoretic analysis due to their low molecular weight and high negative charge.
• Integrated aptamer-based assay platforms are crucial for developing low-cost point-of-care diagnostics, especially for remote or resource-limited settings where reagent cost and ambient stability are critical.

Purpose of the Study:

• To evaluate the efficacy of aptamer-based affinity assays within an integrated electrophoretic gel-shift platform for clinically relevant analytes.
• To demonstrate the feasibility of automating key assay steps, including sample mixing, buffer exchange, and preconcentration, for rapid, sample-to-answer analysis.

Main Methods:

• An integrated electrophoretic gel-shift platform was developed, incorporating aptamer-based affinity assays for immunoglobulin E (IgE) and NF-κB.
• Key steps were integrated on-chip upstream of fluorescence-based gel-shift analysis, utilizing a size-exclusion membrane for aptamer retention and sample preconcentration.
• Strategies to mitigate nonspecific interference from serum proteins, such as adding nucleic acid competitors, were implemented.

Main Results:

• The integrated platform successfully automated sample preparation and analysis, delivering results in 10 minutes or less.
• Nanomolar sensitivities were achieved for target analytes, with integrated preconcentration further enhancing detection limits.
• Aptamers demonstrated superior performance compared to antibodies, offering improved speed and resolution in gel-shift analysis of specific binding events.

Conclusions:

• Aptamer-based affinity assays integrated into an electrophoretic platform provide a rapid, sensitive, and cost-effective solution for analyte detection.
• The developed platform enables automated sample-to-answer analysis, paving the way for accessible point-of-care diagnostics.
• Aptamers exhibit significant advantages over traditional antibody reagents, particularly in speed, resolution, and stability for electrophoretic-based assays.