Visual and Electrochemical Detection of let-7a: A Tumor Suppressor and Biomarker

Area of Science:

• Biochemistry
• Molecular Biology
• Analytical Chemistry

Background:

• Let-7a microRNA is a low-expressed biomarker in cancer cells, significant for tumor suppression.
• Sensitive detection methods for let-7a are vital for cancer diagnosis and therapeutic strategies.
• Hybridization chain reaction (HCR) offers a promising platform for amplifying microRNA signals.

Purpose of the Study:

• To develop simple and sensitive detection methods for let-7a.
• To explore the utility of HCR initiated by let-7a for subsequent detection via Lateral Flow Assay (LFA) and Electrochemical Impedance Spectroscopy (EIS).
• To establish a quantitative detection range and limit for let-7a.

Main Methods:

• Initiation of HCR using let-7a and two hairpin primers (H1 and H2).
• Detection of HCR products using LFA with biotin-modified H1 (bio-H1) and free H2.
• Electrochemical detection using an H1'-AuNP-modified electrode to measure impedance changes (ΔRct) after HCR.

Main Results:

• LFA showed a color change on the T line that increased as let-7a concentration decreased.
• Electrochemical method detected let-7a in the range of 10.0 fM to 1.0 nM.
• The electrochemical method achieved a detection limit of 4.2 fM for let-7a.

Conclusions:

• The developed HCR-based methods provide sensitive and simple approaches for let-7a detection.
• Both LFA and EIS coupled with HCR are effective for quantifying let-7a, with EIS demonstrating a lower detection limit.
• These methods hold potential for advancing cancer diagnostics and monitoring therapeutic responses.