title: Gold nanomaterials for the selective capturing and SERS diagnosis of toxins in aqueous and biological fluids.
abstract: A highly sensitive nanosensing method for the combined selective capture and SERS detection of Microcystin-LR (MC-LR) in blood plasma has been developed. The new method utilizes gold coated magnetic nanoparticles that are functionalized with anti MC-LR antibody Fab' fragments for the selective capture of MC-LR from aqueous media and blood plasma. Using an oriented immobilization approach, the Fab' fragments are covalently attached to gold surface to form a monolayer with high capture efficiency towards the toxin. After the selective capture, the purified MC-LR molecules were released from the extractor nanoparticles within 5min by manipulating the pH environment of the nanoparticles. The regenerated extractor nanoparticles maintained their capture efficiency and, therefore, were re-used to capture of MC-LR from successive samples. The released purified toxin was screened within 10min on gold coated silicon nanopillars and a new paper-based SERS substrate by handheld Raman spectrometer. The SERS enhancement factors of the nanopillars and the new paper-based substrate were 2.5×106and 3×105respectively. The lower limit of quantification (LOQ) of MC-LR by SERS on the nanopillar substrate was 10fM (R2=0.9975) which is well below the clinically required detection limit of the toxin. The SERS determination of MC-LR was cross validated against ELISA. By using antibody fragments that are specific to the target biomolecule, the new methodology can be extended to the rapid extraction and detection of other toxins and proteins.
authors.affiliation: Nanotechnology and Molecular Science Discipline, School of Chemistry, Physics and Mechanical Engineering, Science and Engineering Faculty, Queensland University of Technology, 2 George Street, Brisbane 4001, Australia.
authors.forename: Waleed A
authors.initials: WA
authors.lastname: Hassanain
authors.affiliation: Nanotechnology and Molecular Science Discipline, School of Chemistry, Physics and Mechanical Engineering, Science and Engineering Faculty, Queensland University of Technology, 2 George Street, Brisbane 4001, Australia. Electronic address: kiriakous@qut.edu.au.
authors.forename: Emad L
authors.initials: EL
authors.lastname: Izake
authors.affiliation: DTU Nanotech, Technical University of Denmark, Department of Micro-Micro, and Nanotechnology, Ørsteds Plads, Building 345 east, 2800 Kgs. Lyngby, Denmark.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Schmidt
authors.affiliation: Nanotechnology and Molecular Science Discipline, School of Chemistry, Physics and Mechanical Engineering, Science and Engineering Faculty, Queensland University of Technology, 2 George Street, Brisbane 4001, Australia.
authors.forename: Godwin A
authors.initials: GA
authors.lastname: Ayoko
mesh_terms: D055910:Antibodies, Immobilized / Q000737:chemistry*; D015374:Biosensing Techniques / Q000379:methods*; D006046:Gold / Q000737:chemistry*; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000737:chemistry; D057230:Limit of Detection; D008387:Marine Toxins; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D052998:Microcystins / Q000097:blood* / Q000302:isolation & purification; D013059:Spectrum Analysis, Raman / Q000379:methods*
chemical_list: D055910:Antibodies, Immobilized; D007140:Immunoglobulin Fab Fragments; D008387:Marine Toxins; D052998:Microcystins; D006046:Gold; C057862:cyanoginosin LR
keywords: Antibody fragments; Biological fluids; Functionalized nanoparticles; Microcystin-LR; Molecular diagnosis; Paper SERS substrate