title: Label-free and highly sensitive biomolecular detection using SERS and electrokinetic preconcentration.
abstract: In this paper, we present a method combining surface-enhanced Raman scattering (SERS) spectroscopy to detect biomolecules in a label-free way with an electrokinetic preconcentration technique (electrophoresis) to amplify biomolecular signals at low concentrations. A constant electric field is applied to charged biomolecules in solution, attracting them to an oppositely charged electrode, which is also used as a SERS substrate. Within 5 min, we observed that the SERS signal of 10 fM adenine was amplified to the level of the signal of non-preconcentrated 1 microM adenine (sensitivity improvement by 8 orders of magnitude) and the method was effective over a wide range of concentrations (10 fM to 1 microM). The signals were further amplified under stronger electric field and longer application: The increase of the signal intensity was observed to be 51 times at -0.6 V cm(-1) after 25 min. The effectiveness of this method allows the creation of label-free, target-specific, and highly sensitive monitoring applications.
authors.affiliation: Biomolecular Nanotechnology Center, Department of Bioengineering, University of California, Berkeley, California 94720, USA.
authors.forename: Hansang
authors.initials: H
authors.lastname: Cho
authors.forename: Brian
authors.initials: B
authors.lastname: Lee
authors.forename: Gang L
authors.initials: GL
authors.lastname: Liu
authors.forename: Ajay
authors.initials: A
authors.lastname: Agarwal
authors.forename: Luke P
authors.initials: LP
authors.lastname: Lee
mesh_terms: D000225:Adenine / Q000032:analysis*; D004586:Electrophoresis / Q000379:methods*; D012680:Sensitivity and Specificity; D013059:Spectrum Analysis, Raman / Q000379:methods*; D013499:Surface Properties
chemical_list: D000225:Adenine