Dual-colorimetric amplification biosensor based on GNPs and G-quadruplex/hemin DNAzyme for multiplexed microRNAs

The abnormal expression of microRNA (miRNA) is closely related to the occurrence and progression of diverse cancers. Accurate diagnosis of early-stage cancers via low-cost Point-of-Care Testing (POCT) remains highly desirable but challenging. Herein, a dual-colorimetric amplification biosensor has been developed for the simultaneous detection of two tumor-associated miRNAs. It enables the sensitive and accurate diagnosis of cancers without the requirement for complex procedures and expensive detection instruments. Specifically, the target miR-10b can initiate the Catalytic Hairpin Assembly (CHA) reaction between gold nanoparticles (GNPs) and magnetic beads (MBs), thereby leading to the coupling of GNPs onto MBs. Meanwhile, miR-21 can activate the Hybridization Chain Reaction (HCR) on MBs. After magnetic separation, the color of the supernatant changes from red to pale, and the G-quadruplex/hemin DNAzyme would form on the MBs sediment, which can further catalyze the colorless ABTS/H₂O₂ to green. Based on this, the concentrations of miR-10b and miR-21 could be visualized simultaneously. Under optimal conditions, the constructed biosensor demonstrates the feasibility, accuracy, and selectivity towards target miRNAs in both buffer solutions and real serum samples. The proposed strategy may offer a novel path for the precise diagnosis of cancers in POCT.