title: A new approach to in-situ "micromanufacturing": microfluidic fabrication of magnetic and fluorescent chains using chitosan microparticles as building blocks.
abstract: An in situ microfluidic assembly approach is described that can both produce microsized building blocks and assemble them into complex multiparticle configurations in the same microfluidic device. The building blocks are microparticles of the biopolymer chitosan, which is intentionally selected because its chemistry allows for simultaneous intraparticle and interparticle linking. Monodisperse chitosan-bearing droplets are created by shearing off a chitosan solution at a microfluidic T-junction with a stream of hexadecane containing a nonionic detergent. These droplets are then interfacially crosslinked into stable microparticles by a downstream flow of glutaraldehyde (GA). The functional properties of these robust microparticles can be easily varied by introducing various payloads, such as magnetic nanoparticles and/or fluorescent dyes, into the chitosan solution. The on-chip connection of such individual particles into well-defined microchains is demonstrated using GA again as the chemical "glue" and microchannel confinement as the spatial template. Chain flexibility can be tuned by adjusting the crosslinking conditions: both rigid chains and semiflexible chains are created. Additionally, the arrangement of particles within a chain can also be controlled, for example, to generate chains with alternating fluorescent and nonfluorescent microparticles. Such microassembled chains could find applications as microfluidic mixers, delivery vehicles, microscale sensors, or miniature biomimetic robots.
authors.affiliation: Departments of Chemistry & Biochemistry, University of Maryland, College Park, MD 20742, USA.
authors.forename: Kunqiang
authors.initials: K
authors.lastname: Jiang
authors.forename: Chao
authors.initials: C
authors.lastname: Xue
authors.forename: Chanda
authors.initials: C
authors.lastname: Arya
authors.forename: Chenren
authors.initials: C
authors.lastname: Shao
authors.forename: Elijah O
authors.initials: EO
authors.lastname: George
authors.forename: Don L
authors.initials: DL
authors.lastname: DeVoe
authors.forename: Srinivasa R
authors.initials: SR
authors.lastname: Raghavan
mesh_terms: D040761:Biomimetic Materials; D001704:Biopolymers; D015374:Biosensing Techniques; D048271:Chitosan; D005456:Fluorescent Dyes; D005976:Glutaral; D060328:Magnetic Phenomena; D058185:Magnetite Nanoparticles; D046210:Microfluidic Analytical Techniques; D044085:Microfluidics; D055616:Microtechnology; D010316:Particle Size
chemical_list: D001704:Biopolymers; D005456:Fluorescent Dyes; D058185:Magnetite Nanoparticles; D048271:Chitosan; D005976:Glutaral