Robust Carbonated Structural Color Barcodes with Ultralow Ontology Fluorescence as Biomimic Culture Platform

Photonic crystal (PC) barcodes are a new type of spectrum-encoding microcarriers used in multiplex high-throughput bioassays, such as broad analysis of biomarkers for clinical diagnosis, gene expression, and cell culture. Unfortunately, most of these existing PC barcodes suffered from undesired features, including difficult spectrum-signal acquisition, weak mechanical strength, and high ontology fluorescence, which limited their development to real applications. To address these limitations, we report a new type of structural color-encoded PC barcodes. The barcodes are fabricated by the assembly of monodisperse polydopamine- (PDA-) coated silica (PDA@SiO₂) nanoparticles using a droplet-based microfluidic technique and followed by pyrolysis of PDA@SiO₂ (C@SiO₂) barcodes. Because of the templated carbonization of adhesive PDA, the prepared C@SiO₂ PC beads were endowed with simultaneous easy-to-identify structural color, high mechanical strength, and ultralow ontology fluorescence. We demonstrated that the structural colored C@SiO₂ barcodes not only maintained a high structural stability and good biocompatibility during the coculturing with fibroblasts and tumor cells capture but also achieved an enhanced fluorescent-reading signal-to-noise ratio in the fluorescence-reading detection. These features make the C@SiO₂ PC barcodes versatile for expansive application in fluorescence-reading-based multibioassays.