title: Surface modification of silica nanoparticles to reduce aggregation and nonspecific binding.
abstract: In this article, a systematic study of the design and development of surface-modification schemes for silica nanoparticles is presented. The nanoparticle surface design involves an optimum balance of the use of inert and active surface functional groups to achieve minimal nanoparticle aggregation and reduce nanoparticle nonspecific binding. Silica nanoparticles were prepared in a water-in-oil microemulsion and subsequently surface modified via cohydrolysis with tetraethyl orthosilicate (TEOS) and various organosilane reagents. Nanoparticles with different functional groups, including carboxylate, amine, amine/phosphonate, poly(ethylene glycol), octadecyl, and carboxylate/octadecyl groups, were produced. Aggregation studies using SEM, dynamic light scattering, and zeta potential analysis indicate that severe aggregation among amine-modified silica nanoparticles can be reduced by adding inert functional groups, such as methyl phosphonate, to the surface. To determine the effect of various surface-modification schemes on nanoparticle nonspecific binding, the interaction between functionalized silica nanoparticles and a DNA chip was also studied using confocal imaging/fluorescence microscopy. Dye-doped silica nanoparticles functionalized with octadecyl and carboxylate groups showed minimal nonspecific binding. Using these surface-modification schemes, fluorescent dye-doped silica nanoparticles can be more readily conjugated with biomolecules and used as highly fluorescent, sensitive, and reproducible labels in bioanalytical applications.
authors.affiliation: Center for Research at the Bio/Nano Interface, Department of Chemistry and Shands Cancer Center, UF Genetics Institute, University of Florida, Gainesville, Florida 32611, USA.
authors.forename: Rahul P
authors.initials: RP
authors.lastname: Bagwe
authors.forename: Lisa R
authors.initials: LR
authors.lastname: Hilliard
authors.forename: Weihong
authors.initials: W
authors.lastname: Tan
mesh_terms: D020099:Coated Materials, Biocompatible / Q000737:chemistry; D005456:Fluorescent Dyes; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D053758:Nanoparticles / Q000737:chemistry / Q000648:ultrastructure; D020411:Oligonucleotide Array Sequence Analysis; D012822:Silicon Dioxide / Q000737:chemistry*; D055672:Static Electricity; D013499:Surface Properties
chemical_list: D020099:Coated Materials, Biocompatible; D005456:Fluorescent Dyes; D012822:Silicon Dioxide