A novel sensing platform for recognition and quantification of target microRNAs (miRNAs) was developed by combining an amylase-trapped DNA hydrogel, multicomponent nucleic acid enzymes (MNAzymes), and a portable glucometer (PGM) readout. First, the amylase was encapsulated inside the DNA hydrogel and physically separated from its substrate of amylose, which was in a solution outside the hydrogel. After addition of the target miRNA, the activity of the MNAzyme was restored, which cuts off the substrate linker strand. The active MNAzyme can catal...