Dual Energy Transfer-Based DNA/Graphene Oxide Nanocomplex Probe for Highly Robust and Accurate Monitoring of Apoptosis-Related microRNAs.

Fluorescent labeled single-stranded DNA (ssDNA) molecules physisorbed on graphene oxide (GO) have been extensively explored as a useful sensing platform. However, this approach faces challenges when applied to complex biological samples due to heavy nonspecific desorption of nontarget molecules from GO. To overcome this problem, we introduced a capture DNA (cDNA) fragment with a poly adenine (poly-A) extension into the physisorption system that greatly reduces nonspecific desorption and false positive signal due to strong binding between poly-A and GO. Fluorescence from the dye can be effectively quenched by BHQ, which thus provides a second guarantee of anti-interference to avoid possible nonspecific poly-A DNA displacement. As a proof of concept, we have successfully developed a novel DNA-adsorbing GO nanocomplex probe (DNA-GO nanocomplex probe). This probe has a high anti-interference capability and low background due to the presence of both GO and black hole quencher (BHQ) as a dual-quencher that reduces the background in live cell imaging due to resonance energy transfer (RET). We then employed the DNA-GO nanocomplex probe for simultaneous detection of miR-630 and miR-21 and also for simultaneous in situ dynamic monitoring of intracellular miR-630 and miR-21 in apoptotic cells. We discovered that miR-630 expression was up-regulated during the first 120 min. This simple but powerful protocol has great potential in precise detection and imaging of various substances in complex biological samples with improved accuracy.