title: Ferric plasmonic nanoparticles, aptamers, and magnetofluidic chips: toward the development of diagnostic surface-enhanced Raman spectroscopy assays.
abstract: Conjugation of aptamers and their corresponding analytes onto plasmonic nanoparticles mediates the formation of nanoparticle assemblies: molecularly bound nanoclusters that cause a measurable change in the colloid’s optical properties. The optimization of a surface-enhanced Raman spectroscopy (SERS) competitive binding assay utilizing plasmonic “target” and magnetic “probe” nanoparticles for the detection of the toxin bisphenol-A (BPA) is presented. These assay nanoclusters were housed inside three types of optofluidic chips patterned with magnetically activated nickel pads, in either a straight or array pattern. Both Fe 2 O 3 and Fe 2 CoO 4 were compared as potential magnetic cores for the silver-coated probe nanoparticles. We found that the Ag @ Fe 2 O 3 particles were, on average, more uniform in size and more stable than Ag @ Fe 2 CoO 4 , whereas the addition of cobalt significantly improved the collection time of particles. Using Raman mapping of the assay housed within the magnetofluidic chips, it was determined that a 1 × 5 array of 50 ?? ? m square nickel pads provided the most uniform SERS enhancement of the assay (coefficient of variation ? 25 % ) within the magnetofluidic chip. Additionally, the packaged assay demonstrated the desired response to BPA, verifying the technology’s potential to translate magnetic nanoparticle assays into a user-free optical analysis.
authors.affiliation: Texas A&M University, Department of Biomedical Engineering, 101 Bizzell Street, College Station, Texas 77843, United StatesbUniversity of Strathclyde, Department of Pure and Applied Chemistry, 99 George Street, Glasgow G1 1RD, United Kingdom.
authors.forename: Haley
authors.initials: H
authors.lastname: Marks
authors.affiliation: Texas A&M University, Department of Materials Science and Engineering, 575 Ross Street, College Station, Texas 77843, United States.
authors.forename: Po-Jung
authors.initials: PJ
authors.lastname: Huang
authors.affiliation: University of Strathclyde, Department of Pure and Applied Chemistry, 99 George Street, Glasgow G1 1RD, United Kingdom.
authors.forename: Samuel
authors.initials: S
authors.lastname: Mabbott
authors.affiliation: University of Strathclyde, Department of Pure and Applied Chemistry, 99 George Street, Glasgow G1 1RD, United Kingdom.
authors.forename: Duncan
authors.initials: D
authors.lastname: Graham
authors.affiliation: Texas A&M University, Department of Electrical and Computer Engineering, 188 Bizzell Street, College Station, Texas 77843, United States.
authors.forename: Jun
authors.initials: J
authors.lastname: Kameoka
authors.affiliation: Texas A&M University, Department of Biomedical Engineering, 101 Bizzell Street, College Station, Texas 77843, United StateseTexas A&M University, Texas A&M Engineering Experiment Station Center for Remote Health Technologies and Systems, Department of Biomedical Engineering, 101 Bizzell Street, College Station, Texas 77843, United States.
authors.forename: Gerard
authors.initials: G
authors.lastname: Coté
mesh_terms: D052157:Aptamers, Nucleotide / Q000737:chemistry*; D004867:Equipment Design; D058185:Magnetite Nanoparticles / Q000737:chemistry*; D025202:Molecular Diagnostic Techniques; D012834:Silver / Q000737:chemistry; D013059:Spectrum Analysis, Raman / Q000379:methods*
chemical_list: D052157:Aptamers, Nucleotide; D058185:Magnetite Nanoparticles; C586932:colloidal silver; D012834:Silver