title: Sculpting the internal architecture of fluorescent silica particles via a template-free approach.
abstract: Particles with an open, porous structure can be used to deliver payloads. It is often of interest to detect such particles in tissue or materials, which is facilitated by addition of dye. A straightforward approach leading to fluorescent, porous silica particles is described. The particles are etched with 3mM aqueous sodium hydroxide, taking advantage of the etching rate difference between normal silica and an interior band of silica that contains covalently attached dye. No additional steps, such as dye labeling or thermal annealing, are required. Etching modeled the internal structure of the fluorescent silica particles by creating meso/macropores and voids, as reflected by nitrogen absorption measurements. In order to investigate whether a polymer shell influences etching, certain composite particles are top-coated with poly(l-lysine) representing neutral or positive charged surfaces under typical pH conditions in living systems. The polypeptide-coated fluorescent silica cores exhibit the same porous morphology as uncoated homologs. The polypeptide topcoat does little to alter the permeation by the etching agent. Preservation of size during etching, confirmed by dynamic light scattering, transmission electron microscopy and small-angle X-ray scattering, simplifies the use of these template-free porous fluorescent particles as platforms for drug encapsulation, drug carriers and in vivo imaging.
authors: School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332, United States; Department of Chemistry and Macromolecular Studies Group, Louisiana State University, Baton Rouge, LA 70803, United States; Georgia Tech Polymer Network, GTPN, Georgia Institute of Technology, Atlanta, GA 30332, United States. Electronic address: cornelia.rosu@mse.gatech.edu.
authors: Cornelia
authors: C
authors: Rosu
authors: School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332, United States; Georgia Tech Polymer Network, GTPN, Georgia Institute of Technology, Atlanta, GA 30332, United States.
authors: Andrew J
authors: AJ
authors: Gorman
authors: Department of Chemistry and Macromolecular Studies Group, Louisiana State University, Baton Rouge, LA 70803, United States.
authors: Rafael
authors: R
authors: Cueto
authors: Cain Department of Chemical Engineering, Louisiana State University, Baton Rouge, LA 70803, United States.
authors: Kerry M
authors: KM
authors: Dooley
authors: School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332, United States; Department of Chemistry and Macromolecular Studies Group, Louisiana State University, Baton Rouge, LA 70803, United States; School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332, United States; Georgia Tech Polymer Network, GTPN, Georgia Institute of Technology, Atlanta, GA 30332, United States. Electronic address: paul.russo@mse.gatech.edu.
authors: Paul S
authors: PS
authors: Russo
mesh_terms: D004337:Drug Carriers / Q000737:chemistry; D005453:Fluorescence; D010316:Particle Size; D010455:Peptides / Q000737:chemistry; D016062:Porosity; D012822:Silicon Dioxide / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D004337:Drug Carriers; D010455:Peptides; D012822:Silicon Dioxide
keywords: Fluorescent silica; Mesoporous and macroporous silica; NaOH etching; Polypeptide composite particles; Stöber silica