title: On-demand preparation of quantum dot-encoded microparticles using a droplet microfluidic system.
abstract: Optical barcoding technology based on quantum dot (QD)-encoded microparticles has attracted increasing attention in high-throughput multiplexed biological assays, which is realized by embedding different-sized QDs into polymeric matrixes at precisely controlled ratios. Considering the advantage of droplet-based microfluidics, producing monodisperse particles with precise control over the size, shape and composition, we present a proof-of-concept approach for on-demand preparation of QD-encoded microparticles based on this versatile new strategy. Combining a flow-focusing microchannel with a double T-junction in a microfluidic chip, biocompatible QD-doped microparticles were constructed by shearing sodium alginate solution into microdroplets and on-chip gelating these droplets into a hydrogel matrix to encapsulate CdSe/ZnS QDs. Size-controllable QD-doped hydrogel microparticles were produced under the optimum flow conditions, and their fluorescent properties were investigated. A novel multiplex optical encoding strategy was realized by loading different sized QDs into a single droplet (and thus a hydrogel microparticle) with different concentrations, which was triggered by tuning the flow rates of the sodium alginate solutions entrapped with different-colored QDs. A series of QD-encoded microparticles were controllably, and continuously, produced in a single step with the present approach. Their application in a model immunoassay demonstrated the potential practicability of QD-encoded hydrogel microparticles in multiplexed biomolecular detection. This simple and robust strategy should be further improved and practically used in making barcode microparticles with various polymer matrixes.
authors.affiliation: Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072, China.
authors.forename: Xing-Hu
authors.initials: XH
authors.lastname: Ji
authors.forename: Wei
authors.initials: W
authors.lastname: Cheng
authors.forename: Feng
authors.initials: F
authors.lastname: Guo
authors.forename: Wei
authors.initials: W
authors.lastname: Liu
authors.forename: Shi-Shang
authors.initials: SS
authors.lastname: Guo
authors.forename: Zhi-Ke
authors.initials: ZK
authors.lastname: He
authors.forename: Xing-Zhong
authors.initials: XZ
authors.lastname: Zhao
mesh_terms: D000464:Alginates / Q000737:chemistry; D020723:Glucuronic Acid / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry; D020100:Hydrogels / Q000737:chemistry; D007118:Immunoassay / Q000295:instrumentation / Q000379:methods; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation* / Q000379:methods*; D010316:Particle Size; D045663:Quantum Dots
chemical_list: D000464:Alginates; D006603:Hexuronic Acids; D020100:Hydrogels; D020723:Glucuronic Acid