title: Surface functionalization of silica nanoparticles with cysteine: a low-fouling zwitterionic surface.
abstract: Herein, we report on the functionalization of silica nanoparticles with a small molecule, the amino acid cysteine, in order to create a low-fouling zwitterionic surface for nanomedicine applications. The cysteine functionalization was shown to impart the particles with excellent stability in both salt and single-protein solutions of lysozyme (positively charged) and bovine serum albumin (negatively charged). Bare silica particles precipitated immediately in a lysozyme solution, while cysteine-functionalized particles were stable for 20 h. Furthermore, the particles displayed excellent long-term stability in solutions of human serum showing no aggregation over a period of 14 days. The functionalized particles also possess multiple reactive surface groups for further coupling reactions. We believe that the surface functionalization schemes described in this report represent a versatile and effective method of stabilizing nanoparticle systems in biological media for their use in a variety of therapeutic and diagnostic applications.
authors.affiliation: Department of Chemical Engineering, University of Waterloo, Waterloo, Ontario, Canada.
authors.forename: Joshua E
authors.initials: JE
authors.lastname: Rosen
authors.forename: Frank X
authors.initials: FX
authors.lastname: Gu
mesh_terms: D000818:Animals; D057219:Biofouling / Q000517:prevention & control; D002417:Cattle; D003545:Cysteine / Q000737:chemistry*; D006801:Humans; D007477:Ions / Q000737:chemistry; D015394:Molecular Structure; D009113:Muramidase / Q000737:chemistry / Q000378:metabolism; D050997:Nanomedicine / Q000379:methods; D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D012710:Serum Albumin, Bovine / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry*; D055672:Static Electricity; D013499:Surface Properties
chemical_list: D007477:Ions; D012710:Serum Albumin, Bovine; D012822:Silicon Dioxide; D009113:Muramidase; D003545:Cysteine