Microfluidic Chip Integrated with Hydrogel Microparticles and CdS Cation Interfacial Exchange for the Sensitive Determination of miRNA

Abnormally expressed miRNAs have been employed as crucial indicators for the diagnosis and prognosis of disease. It is essential to develop quick, affordable, accurate, and multiplexed methods for miRNA detection. In this study, polyethylene glycol (PEG) hydrogel microparticles were used as solid-phase carriers for the hybridization chain reaction (HCR) in combination with cation-exchange fluorescence amplification, thus enabling the development of a new method for miRNA determination. The assay was sensitive with the detection limit for miRNA let7a equal to 46 pM. The assay was specific, the base-mismatched sequences of miRNA let7a were distinguished, and the serum matrix did not cause any interference. Moreover, by integration with a microfluidic chip, the throughput was significantly enhanced and the process was noticeably simplified. With further development, the developed method may be suitable for practical clinical analysis.