Self-assembled DNA micelles with Gold Nanoparticles for the Detection of miRNAs Associated with Alzheimer’s Disease

 

Alzheimer’s disease is a progressive neurodegenerative disorder that represents one of the greatest challenges in modern medicine. The disease is characterized by the abnormal accumulation of beta-amyloid (Aβ) plaques and tau protein in the brain, leading to inflammation, neuronal damage, and cognitive decline. One of the major challenges is that clinical symptoms typically emerge only after the brain is substantially damaged, thereby limiting the effectiveness of current treatments. Consequently, early detection has become a primary objective.

A research group in China developed an innovative strategy based on lateral flow assays (LFAs), a diagnostic tool for the sensitive, specific, and accessible detection of biomarkers, with the aim of identifying microRNA (miRNA) strands associated with the early stages of Alzheimer’s disease. miRNAs are small non-coding RNA molecules that regulate gene expression by binding to specific messenger RNAs and inhibiting their translation or promoting their degradation.

The proposed method employs DNA micelles functionalized with

gold nanoparticles (AuNPs) and equipped with miRNA strands.

A key feature of this approach is the use of self-assembled DNA micelles, namely nanostructures that spontaneously organize into spherical aggregates in aqueous solution. The DNA micelles were functionalized with gold nanoparticles (AuNPs) and mixed with strands of the target miRNA. When the sample is applied to the LFA test strip, the DNA–AuNP–miRNA complex migrates by capillary action toward the test line, where it is captured by a second probe containing a sequence complementary to the target miRNA and immobilized by a biotin/streptavidin interaction. The accumulation of AuNPs on the test strip produces a visible red band due to their plasmonic properties, with an intensity proportional to the concentration of miRNA present in the sample.

Since target miRNAs coexist with other miRNA species in real samples, it is essential for the system to exhibit high specificity toward the targets of interest. To evaluate this, the authors assessed cross-reactivity against other miRNAs and observed that no signal was produced at the test lines in the presence of interfering species. Red bands appeared only when the corresponding target miRNA (miR-34a, miR-125b, or miR-15a) was present.

Overall, the results demonstrate that the LFA enables the simultaneous detection of multiple miRNAs in serum with greater sensitivity and selectivity than conventional assays. This performance is attributed to the use of nanostructures that function as highly efficient recognition platforms capable of amplifying signals that would otherwise remain undetectable.

For further details, consult: Biosensors and bioelectronics