Fluorescence Signal Amplification Based on Arginine-Glycine-Aspartate-Gold-Nanoparticle Conjugates for <i>in</i> <i>Situ</i> Monitoring of microRNAs

With the rising incidence of cancer-related deaths worldwide, the highly sensitive in situ monitoring of tumor biomarkers is becoming increasingly crucial for the early diagnosis of cancer. For instance, fluctuations in microRNA levels may contribute to tumor inhibition or promotion, which are closely linked to the onset and progression of various cancers. In this context, we developed a one-pot synthesis strategy for arginine-glycine-aspartate (RGD)-conjugated gold nanoparticles (RGD-AuNPs). This approach generates charge-loaded, tumor-targeting nanocarriers that facilitate the intracellular transfer of a target-triggered enzyme-free amplification (TEFA) platform, enabling fluorescent signal amplification through the in vivo self-assembly of hairpin DNA probes. Utilizing this strategy, live-cell miRNA imaging was successfully conducted in three tumor cell lines: HepG2, A549, and MDA-MB-231. Additionally, the charge-loaded AuNP carrier proved to be an effective medium for in vivo TEFA. Furthermore, imaging of tumor tissues in mice demonstrated that charge-loaded AuNP carriers can be employed in a tumor-labeling strategy. These carriers were utilized to efficiently perform in vivo TEFA, representing a significant technical advancement in the field of live-cell native miRNA monitoring and target-triggered tumor labeling.