Breast cancer remains one of the most prevalent malignancies, where improved early detection can enhance treatment outcomes. MicroRNAs have emerged as promising minimally invasive biomarkers for cancer diagnosis and prognosis. This study presents a dual-mode colorimetric nanobiosensor specifically designed to detect two breast cancer-related microRNAs, miR-145 and miR-21, in a single analytical platform.
The platform aims to deliver simple, visible readouts by coupling nucleic-acid-triggered amplification with optical signal generation, enabling both single-target and multiplexed analyses suitable for screening contexts.
The sensor integrates two complementary mechanisms: a hybridization chain reaction (HCR) that yields G-quadruplex DNAzymes and an aggregation-based signal from gold nanoparticles (AuNPs). Target-triggered HCR assembles sequences capable of forming G-quadruplex/hemin DNAzyme structures; these DNAzymes catalyze oxidation of a chromogenic substrate (OPD), producing an absorbance signal measured at 425 nm.
Concurrently, target-induced hybridization events promote the aggregation of AuNPs, shifting their plasmonic peak and producing a colorimetric change monitored at 535 nm. The two mechanisms are leveraged to distinguish and quantify miR-145 and miR-21 signals.
Key components described in the study include DNA probes engineered for target recognition and HCR initiation, reagents to support G-quadruplex DNAzyme formation and activity, OPD as the chromogenic substrate for DNAzyme-driven oxidation, and colloidal gold nanoparticles as the aggregation-responsive reporter.
Readouts are optical absorbance measurements at two wavelengths: 425 nm (OPD oxidation mediated by the DNAzyme formed during HCR) and 535 nm (AuNP plasmon peak associated with nanoparticle dispersion or aggregation). These dual optical channels provide orthogonal information for each microRNA target.
When tested individually, the nanobiosensor achieved limits of detection (LOD) of 0.15 nM for miR-145 and 0.12 nM for miR-21. Linear response characteristics were strong for both targets, with reported correlation coefficients of R2 = 0.9887 for miR-145 and R2 = 0.9711 for miR-21, indicating reliable quantification across the tested concentration ranges.
Co-detection experiments (multiplexed format) reported LODs in the range of 0.01–0.4 nM, which the authors interpret as evidence of retained assay sensitivity and platform stability when both targets are present.
Specificity was assessed by including non-target microRNAs in the evaluation. The study used miR-195 and miR-155 as non-target controls and reported that the nanobiosensor effectively discriminated the intended targets from these non-target sequences, supporting the assay’s selectivity for miR-145 and miR-21.
In multiplexed analysis, the design yields partially overlapping signal contributions: miR-145 influences both the 425 nm DNAzyme-driven signal and contributes to the 535 nm AuNP-related readout, while miR-21 primarily modulates the 535 nm absorbance through AuNP aggregation. The authors leveraged this behavior to enable simultaneous quantification of both microRNAs within a single assay format.
Measured performance in co-detection experiments showed that the platform maintained low-nanomolar sensitivity and produced distinguishable optical responses for each microRNA, consistent with the assay’s dual-signal strategy.
The authors conclude that the developed dual-miRNA detection platform represents a promising assay for early breast cancer screening and has potential applicability in clinical multiplex diagnostic assays. The approach combines the simplicity of colorimetric readouts with nucleic acid amplification and plasmonic reporting, which may facilitate translation to point-of-care or laboratory workflows where rapid, low-cost miRNA screening is desirable.
It is important to note that the abstract reports analytic performance metrics and specificity testing using selected non-target microRNAs; details regarding clinical sample testing, sample preparation, or comparison to established clinical methods were not reported in the abstract.
This research was reported as supported by non-U.S. government research support. The article lists Maryam Keramati and Mahdi Rahaie from the Department of Nanobiotechnology and Biomimetics, School of Life Science Engineering, University of Tehran, Iran. The authors declared no known competing financial interests or personal relationships that could have influenced the work.
Note: The content above summarizes and restates results and experimental design as reported in the article abstract and PubMed entry. Additional experimental details, raw data, validation on clinical specimens, and procedural specifics were not provided in the source abstract and would require consulting the full text.