Near-infrared fluorescence biosensors based on synergistic quenching effects for highly sensitive detection of miRNAs

Endometriosis is a chronic inflammatory disease that often occurs in women of childbearing age. Studies indicate that the abnormal expression of various miRNAs, such as miRNA-21, miRNA-122, miRNA-199a and miRNA-191, in patients with endometriosis, making them diagnostic biomarkers for early-stage detection. Herein, using miRNA-21 as the target model, a “turn-on” biosensor was developed, employing upconversion nanoparticle (UCNP) as stable fluorescent donor in complex biological samples, along with graphene oxide (GO) and BHQ2 as dual receptors that provide strong adsorption and efficient fluorescence quenching. The UCNP-H1 nanoprobes were fabricated by conjugating a specific miRNA-recognizing single-stranded DNA aptamer (H1) onto the UCNP. Upon binding to miRNA-21, UCNP-H1 nanoprobes are released from GO, leading to significant fluorescence restoration. The fluorescence intensity increased proportionally with the miRNA-21 concentration, establishing a highly accurate “turn-on” biosensing platform. Under optimal conditions, the biosensor demonstrated a linear response in the concentration range of 0.5–20 nM, with a detection limit as low as 0.83 nM. The recoveries of the spiked serum samples ranged from 98.18 % to 108.82 %, suggesting the applicability of the proposed biosensor for miRNA-21 detection in biological samples. Additionally, this biosensor can also be used to quantify other miRNAs related to endometriosis by altering complementary sequences to achieve accurate early diagnosis.