title: Asymmetric Colloidal Janus Particle Formation Is Core-Size-Dependent.
abstract: Colloidal particles with asymmetric surface chemistry (Janus particles) have unique bifunctional properties. The size of these particles is an important determinant for their applications in diverse fields from drug delivery to chemical catalysis. The size of Janus particles, with a core surface coated with carboxylate and a partially encapsulating silica shell, depends upon several factors, including the core size and the concentration of carboxylate coating. The role of the carboxylate coating on the Janus particle size is well-understood; however, the role of the core size is not well defined. The role of the carboxylated polystyrene (cPS) core size on the cPS-silica Janus particle morphology (its size and shape) was examined by testing two different silica sizes and five different cPS core sizes. Results from electron microscopy (EM) and dynamic light scattering (DLS) analysis indicate that the composite cPS-silica particle acquires two distinct shapes: (i) when the size of the cPS core is much smaller than the non-cPS silica (b-SiO2) sphere, partially encapsulated Janus particles are formed, and (ii) when the cPS core is larger than or equal to the b-SiO2 sphere, a raspberry-like structure rather than a Janus particle is formed. The cPS-silica Janus particles of ∼100-500 nm size were obtained when the size of the cPS core was much smaller than the non-cPS silica (b-SiO2) sphere. These scalable nanoscale Janus particles will have wide application in a multifunctional delivery platform and catalysis.
authors.affiliation: Department of Bioengineering, §Department of Mechanical and Aerospace Engineering, ∥Materials Science and Engineering Program, ⊥Department of Nanoengineering, and #Institute of Engineering in Medicine, University of California, San Diego , 9500 Gilman Drive, La Jolla, California 92093, United States.
authors.forename: Preston B
authors.initials: PB
authors.lastname: Landon
authors.affiliation: Department of Bioengineering, §Department of Mechanical and Aerospace Engineering, ∥Materials Science and Engineering Program, ⊥Department of Nanoengineering, and #Institute of Engineering in Medicine, University of California, San Diego , 9500 Gilman Drive, La Jolla, California 92093, United States.
authors.forename: Alexander H
authors.initials: AH
authors.lastname: Mo
authors.affiliation: Department of Bioengineering, §Department of Mechanical and Aerospace Engineering, ∥Materials Science and Engineering Program, ⊥Department of Nanoengineering, and #Institute of Engineering in Medicine, University of California, San Diego , 9500 Gilman Drive, La Jolla, California 92093, United States.
authors.forename: Adam D
authors.initials: AD
authors.lastname: Printz
authors.affiliation: Department of Bioengineering, §Department of Mechanical and Aerospace Engineering, ∥Materials Science and Engineering Program, ⊥Department of Nanoengineering, and #Institute of Engineering in Medicine, University of California, San Diego , 9500 Gilman Drive, La Jolla, California 92093, United States.
authors.forename: Chris
authors.initials: C
authors.lastname: Emerson
authors.affiliation: Department of Bioengineering, §Department of Mechanical and Aerospace Engineering, ∥Materials Science and Engineering Program, ⊥Department of Nanoengineering, and #Institute of Engineering in Medicine, University of California, San Diego , 9500 Gilman Drive, La Jolla, California 92093, United States.
authors.forename: Chen
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Department of Bioengineering, §Department of Mechanical and Aerospace Engineering, ∥Materials Science and Engineering Program, ⊥Department of Nanoengineering, and #Institute of Engineering in Medicine, University of California, San Diego , 9500 Gilman Drive, La Jolla, California 92093, United States.
authors.forename: Woraphong
authors.initials: W
authors.lastname: Janetanakit
authors.affiliation: Department of Bioengineering, §Department of Mechanical and Aerospace Engineering, ∥Materials Science and Engineering Program, ⊥Department of Nanoengineering, and #Institute of Engineering in Medicine, University of California, San Diego , 9500 Gilman Drive, La Jolla, California 92093, United States.
authors.forename: David A
authors.initials: DA
authors.lastname: Colburn
authors.affiliation: Department of Bioengineering, §Department of Mechanical and Aerospace Engineering, ∥Materials Science and Engineering Program, ⊥Department of Nanoengineering, and #Institute of Engineering in Medicine, University of California, San Diego , 9500 Gilman Drive, La Jolla, California 92093, United States.
authors.forename: Siddhartha
authors.initials: S
authors.lastname: Akkiraju
authors.affiliation: Department of Bioengineering, §Department of Mechanical and Aerospace Engineering, ∥Materials Science and Engineering Program, ⊥Department of Nanoengineering, and #Institute of Engineering in Medicine, University of California, San Diego , 9500 Gilman Drive, La Jolla, California 92093, United States.
authors.forename: Samuel
authors.initials: S
authors.lastname: Dossou
authors.affiliation: Department of Bioengineering, §Department of Mechanical and Aerospace Engineering, ∥Materials Science and Engineering Program, ⊥Department of Nanoengineering, and #Institute of Engineering in Medicine, University of California, San Diego , 9500 Gilman Drive, La Jolla, California 92093, United States.
authors.forename: Baxi
authors.initials: B
authors.lastname: Chong
authors.affiliation: Department of Bioengineering, §Department of Mechanical and Aerospace Engineering, ∥Materials Science and Engineering Program, ⊥Department of Nanoengineering, and #Institute of Engineering in Medicine, University of California, San Diego , 9500 Gilman Drive, La Jolla, California 92093, United States.
authors.forename: Gennadi
authors.initials: G
authors.lastname: Glinsky
authors.affiliation: Department of Bioengineering, §Department of Mechanical and Aerospace Engineering, ∥Materials Science and Engineering Program, ⊥Department of Nanoengineering, and #Institute of Engineering in Medicine, University of California, San Diego , 9500 Gilman Drive, La Jolla, California 92093, United States.
authors.forename: Ratnesh
authors.initials: R
authors.lastname: Lal
mesh_terms: D003102:Colloids; D016503:Drug Delivery Systems; D010316:Particle Size; D011137:Polystyrenes / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*
chemical_list: D003102:Colloids; D011137:Polystyrenes; D012822:Silicon Dioxide