Sensitive multiplex detection of MicroRNAs based on liquid suspension nano-chip

Multiplex detection of microRNAs is highly desirable in trace analysis of clinical samples for early-stage disease diagnosis. In the present study, we report a new liquid suspension nano-chip technology for multiplex detection of microRNAs by detecting side scatter and fluorescence signals of molecular beacon-modified polystyrene nanoparticles, simultaneously. Polystyrene nanoparticles were encoded by distinguished intensity of scattered light with tunable sizes (120 nm, 200 nm and 280 nm). In the proposed detection system, the fluorescence of 5-carboxyfluorescein was recovered due to the structure change of molecular beacons from hairpin to rod-like shape caused by the hybridization of target microRNAs. The well-designed liquid suspension nano-chip system enabled quantitative detection of three colorectal cancer-related microRNAs with low limits of detection and high sensitivity. More importantly, for simulated clinical samples, three random mixed microRNAs were simultaneously detected by accurately decoding the scattering intensity of polystyrene nanoparticles of different sizes and quantitatively analyzed by fluorescence intensity. This technology provides a washing-free, sensitive, convenient and small loading volume strategy for detecting clinical multiplex nucleic acid samples.