Bioinspired photonic barcodes for multiplexed target cycling and hybridization chain reaction.

Multiplexed detection of microRNA (miRNA) is of great value in clinical diagnosis. Here, a new type of polydopamine (PDA) encapsulated photonic crystal (PhC) barcodes are employed for target-triggering cycle amplification and hybridization chain reaction (HCR) to achieve multiplex miRNA quantification. The PDA-decorated PhC barcodes not only exhibit distinctive structural color for different encoding miRNAs, they also can immobilize biomolecules, allowing subsequent reaction with amino-modified hairpin probes (H1). When the PDA-decorated PhC barcodes are used in assays, target miRNAs can be circularly used to initiate HCR for cycle amplification. Therefore, by tuning the structural colors of the PDA-integrated PhC, the multiplexed miRNA quantification could be realized. We demonstrate that our strategy for multiplexed detection of miRNA is reasonably accurate, reliable and repeatable, with a detection limit as low as 8.0 fM. Our results show that PDA encapsulated PhC barcodes as a novel platform offer a pathway toward the multiplex analysis of low-abundance biomarkers for biomedical assays.