Hydroxypropyl Cellulose Assembled Microspheres as Structural Color Barcodes from Revolving Microfluidics

Optical barcodes are versatile information carriers widely applied for encryption, commercial anti-counterfeiting, and biomedical fields. Hydroxypropyl cellulose (HPC), as a natural derivative, exhibits excellent biocompatibility and can self-assemble into cholesteric liquid crystals (CLCs) with structure color. However, the high viscosity of HPC CLCs is a huge hurdle for material processing and thus limits their applications. In this study, a high-speed revolving microfluidic platform is developed for emulsifying high-viscosity methacrylate functionalized HPC (HPC-MA) solution to form droplets. HPC-MA molecules in the droplets can self-assemble into CLCs by water evaporation, and the resultant CLCs droplets can be cross-linked to form structural color barcode particles. The prepared HPC-MA CLCs barcoded particles exhibit well-defined and adjustable encoding information while maintaining excellent biocompatibility. Furthermore, the prepared barcode particles also demonstrate great potential in 3D cell culture and multiplex immunoassays. This work introduces an efficient way to continuously produce HPC-MA CLCs barcode particles with finely tunable size and uniformity. Such barcode particles are promising for widespread applications in bioanalysis and biodiagnostics.