A novel ultrasensitive electrochemical genosensor based on PtNPs/EEGO-AGs/AuNPs nanoassembly for rapid detection of HCMV miRNA

MicroRNAs (miRNAs) are stable and accessible biomarkers for disease diagnosis. Elevated levels of human cytomegalovirus (HCMV)-encoded miRNA-UL22A-5p (miR-UL22A-5p) are associated with virologic recurrence in transplant patients with HCMV infection and can serve as a prognostic marker. Here, we introduce the first electrochemical genosensing platform for the sensitive and accurate detection of miR-UL22A-5p in serum samples. This platform employs a ratiometric strategy to improve probe specificity within complex serum matrices. A new nanocomposite consisting of platinum nanoparticles, effectively oxidised graphene oxide aerogels, and gold nanoparticles (PtNPs/EEGO-AGs/AuNPs) was electrodeposited onto a glassy carbon electrode (GCE). This design boosts sensor performance: PtNPs provide high electrocatalytic activity for signal amplification, EEGO-AGs offer antifouling properties to reduce interference from biological matrices while serving as a substrate for further modification, and AuNPs facilitate stable thiol-mediated attachment of single-stranded DNA probes. Under optimal conditions, the nanobiosensor demonstrated a linear detection range from 10^{- 12} to 10^{- 5} M, with a detection limit (LOD) of 6.1 × 10^{- 13} M and a quantification limit (LOQ) of 2 × 10^{- 12} M in human serum. Reproducibility was acceptable, with a standard deviation of 1.8%. To assess its quantitative ability and detection sensitivity, serum samples spiked with miR-UL22A-5p were analysed simultaneously with the biosensor and qRT-PCR, showing that the biosensor has a lower detection limit. This biosensor holds significant potential for clinical use as a sensitive tool for early HCMV detection in transplant patients. However, further validation through prospective clinical trials is necessary to confirm its effectiveness and impact on patient outcomes.