Magnetic Drive-Assisted DNA Reactor Based on the FRET Effect of Au Nanoparticles for Exosomal MUC1 Profiling and Breast Cancer Diagnosing

Cancer heterogeneity, low biomarker expression, and challenges in sample extraction impede the advancement of exosome protein detection technologies. To overcome these limitations, the study developed a simple and sensitive magnetically derived DNA reactor (MDDR) biosensor for quantifying breast cancer-related exosomal mucin 1 (MUC1), with potential applications for adjunctive breast cancer diagnosis. The MDDR comprised a magnetically responsive substrate and a DNA reactor; the two parts were connected by DNA hybridization. The target induced dissociation of the DNA reactor from the substrate by competitive binding to the aptamer, converting the target concentration into the number of DNA reactors. Specifically, the magnetically responsive substrate was constructed by coupling amine-functionalized magnetic nanoparticles (MNPs) with the MUC1 aptamer P1 for target capture and enrichment. The DNA reactor, with gold nanoparticles (Au NPs) serving as carriers, consisted of prehybridized double-stranded DNA (P2–P3) and the activator P4. Based on the Förster resonance energy transfer (FRET) effect of Au NPs and the strand displacement reaction mediated by an activator, signal transduction, amplification, and output were achieved. The MDDR biosensor, based on simple material design, offered a convenient and effective method for the sensitive detection of MUC1 protein in breast cancer exosomes and holds promise for advancing the clinical application of exosome-related biomedical research.