Ultra-wide linear MiRNA detection through diamond quantum charge state modulation

Accurate detection of microRNA concentrations is essential for early cancer diagnosis and monitoring. Existing methods typically provide a linear response within a limited concentration range, which hinders their precise clinical application. This study presents a novel sensing approach using the fluorescence properties of nitrogen vacancy (NV) centers. Magnetic particles capture and enrich fluorescent nanodiamonds (FNDs), and effectively address signal inconsistencies due to variations in FND particles by applying a voltage that regulates the NV center fluorescence. Our method achieves a linear response to microRNAs across a broad concentration range (10 fM to 1 μM), with the determination coefficient (R²) of the fluorescence signal, enhanced from 0.8711 to 0.9951 through voltage modulation. Additionally, optimizing experimental conditions and enhancing FND fluorescence increased the signal intensity, achieving a minimum detection limit of 7.17 fM. The combination of sensitive detection and an extensive linear range suggests the potential of this strategy as a universal detection method for the early diagnosis of various diseases.