title: Analysis of the surface density and reactivity of perfluorophenylazide and the impact on ligand immobilization.
abstract: Perfluorophenylazide (PFPA) chemistry is a novel method for tailoring the surface properties of solid surfaces and nanoparticles. It is general and versatile, and has proven to be an efficient way to immobilize graphene, proteins, carbohydrates, and synthetic polymers. The main thrust of this work is to provide a detailed investigation on the chemical composition and surface density of the PFPA tailored surface. Specifically, gold surfaces were treated with PFPA-derivatized (11-mercaptoundecyl)tetra(ethylene glycol) (PFPA-MUTEG) mixed with 2-[2-(2-mercaptoethoxy)ethoxy]ethanol (MDEG) at varying solution mole ratios. Complementary analytical techniques were employed to characterize the resulting films including Fourier transform infrared spectroscopy to detect fingerprints of the PFPA group, x-ray photoelectron spectroscopy and ellipsometry to study the homogeneity and uniformity of the films, and near edge x-ray absorption fine structures to study the electronic and chemical structure of the PFPA groups. Results from these studies show that the films prepared from 90:10 and 80:20 PFPA-MUTEG/MDEG mixed solutions exhibited the highest surface density of PFPA and the most homogeneous coverage on the surface. A functional assay using surface plasmon resonance with carbohydrates covalently immobilized onto the PFPA-modified surfaces showed the highest binding affinity for lectin on the PFPA-MUTEG/MDEG film prepared from a 90:10 solution.
authors.affiliation: National ESCA and Surface Analysis Center for Biomedical Problems, Departments of Bioengineering and Chemical Engineering, University of Washington , Box 351653, Seattle, Washington 98195-1653.
authors.forename: Gilad
authors.initials: G
authors.lastname: Zorn
authors.affiliation: National ESCA and Surface Analysis Center for Biomedical Problems, Departments of Bioengineering and Chemical Engineering, University of Washington , Box 351653, Seattle, Washington 98195-1653.
authors.forename: David G
authors.initials: DG
authors.lastname: Castner
authors.affiliation: Department of Chemistry, Portland State University , Portland, Oregon 97207-0751.
authors.forename: Anuradha
authors.initials: A
authors.lastname: Tyagi
authors.affiliation: Department of Chemistry, Portland State University , Portland, Oregon 97207-0751.
authors.forename: Xin
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Chemistry, Portland State University , Portland, Oregon 97207-0751.
authors.forename: Hui
authors.initials: H
authors.lastname: Wang
authors.affiliation: Department of Chemistry, Portland State University , Portland, Oregon 97207-0751.
authors.forename: Mingdi
authors.initials: M
authors.lastname: Yan