Dual Detection of microRNAs by a Signal-Off Colorimetric Nanobiosensor Based on Novel Split DNAzyme Nanostructure

Area of Science:

• Biomedical Engineering
• Nanotechnology
• Molecular Diagnostics

Background:

• Breast cancer is a leading cause of cancer death in women, necessitating early detection for improved survival rates.
• Early diagnosis of breast cancer is crucial, especially for women aged 20-59, to increase treatment efficacy.
• Specific microRNAs, such as miR-21 and miR-155, are implicated in breast cancer development and progression.

Purpose of the Study:

• To develop a novel nanobiosensor for the simultaneous early detection of miR-21 and miR-155 in breast cancer.
• To utilize a G-quadruplex (G4) DNA structure with peroxidase-like activity for a colorimetric detection method.
• To establish a simple, fast, and cost-effective diagnostic technique for breast cancer monitoring.

Main Methods:

• A nanobiosensor employing two probes (p1, p2) was designed to form a DNA-G4 structure upon binding with target microRNAs.
• The DNA-G4 structure exhibits peroxidase-like activity, catalyzing the oxidation of TMB to produce a blue color.
• A "signal-off" mechanism was implemented: hybridization with microRNAs prevents G4 formation and color development.

Main Results:

• The nanobiosensor successfully detected miR-21 and miR-155 simultaneously via a colorimetric response.
• The method demonstrated a linear response range of 2-10 nM.
• The limit of detection was determined to be 0.43 nM in buffer, 0.54 nM in blood, and 0.62 nM in urine, with R² = 0.98.

Conclusions:

• The developed nanobiosensor offers a promising approach for the simultaneous and early detection of breast cancer-related microRNAs.
• This colorimetric assay provides a simple, rapid, and cost-effective method for breast cancer diagnostics and monitoring.
• The nanobiosensor's effectiveness in buffer, blood, and urine samples highlights its potential for clinical application.