title: Layer-by-layer modification of high surface curvature nanoparticles with weak polyelectrolytes using a multiphase solvent precipitation process.
abstract: The layer-by-layer modification of ≈5 nm mercaptocarboxylic acid stabilized gold nanoparticles was studied in an effort to illustrate effective means to overcome practical issues in handling and performing surface modification of such extremely small materials. To accomplish this, each layer deposition cycle was separated into a multi-step process wherein solution pH was controlled in two distinct phases of polyelectrolyte adsorption and centrifugation. Additionally, a solvent precipitation step was introduced to make processing more amenable by concentrating the sample and exchanging solution pH before ultracentrifugation. The pH-dependent assembly on gold nanoparticles was assessed after each layer deposition cycle by monitoring the plasmon peak absorbance location, surface charge, and the percentage of nanoparticles recovered. The selection of solution pH during the adsorption phase was found to be a critical parameter to enhance particle recovery and maximize surface charge when coating with weak polyelectrolytes. One bilayer was deposited with a high yield and the modified particles exhibited enhanced colloidal stability across a broad pH range and increased ionic strength. These findings support the adoption of this multi-step processing approach as an effective and generalizable approach to improve stability of high surface curvature particles.
authors.affiliation: Department of Biomedical Engineering, Texas A&M University, College Station, TX 77843, United States.
authors.forename: Ashvin T
authors.initials: AT
authors.lastname: Nagaraja
authors.affiliation: Department of Materials Science and Engineering, Texas A&M University, College Station, TX 77843, United States.
authors.forename: Yil-Hwan
authors.initials: YH
authors.lastname: You
authors.affiliation: Department of Materials Science and Engineering, Hongik University, 121-791 Seoul, South Korea.
authors.forename: Jeong-Wan
authors.initials: JW
authors.lastname: Choi
authors.affiliation: Department of Materials Science and Engineering, Hongik University, 121-791 Seoul, South Korea.
authors.forename: Jin-Ha
authors.initials: JH
authors.lastname: Hwang
authors.affiliation: Department of Biomedical Engineering, Texas A&M University, College Station, TX 77843, United States; Department of Materials Science and Engineering, Texas A&M University, College Station, TX 77843, United States.
authors.forename: Kenith E
authors.initials: KE
authors.lastname: Meissner
authors.affiliation: Department of Biomedical Engineering, Texas A&M University, College Station, TX 77843, United States; Department of Materials Science and Engineering, Texas A&M University, College Station, TX 77843, United States. Electronic address: mcshane@tamu.edu.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: McShane
keywords: Electrosteric stabilization; Gold nanoparticle; Layer-by-layer; Poly(4-styrenesulfonic acid-co-maleic acid); Poly(acrylic acid); Poly(allylamine hydrochloride); Quantum dot; Solvent precipitation