title: Plasmonic detection of a model analyte in serum by a gold nanorod sensor.
abstract: We describe the fabrication of a label-free, chip-based biosensor based on the localized surface plasmon resonance (LSPR) of gold nanorods. Gold nanorods were chemisorbed onto a mercaptosilane-modified glass substrate, followed by conjugation of biotin to the nanorods. Streptavidin binding to biotin was monitored by the wavelength shift of the LSPR peak in the UV-vis extinction spectrum of the immobilized gold nanorods due to the change in local refractive index at the gold nanorod surface induced by streptavidin binding. The limit of detection of the sensor is 0.005 microg/mL (94 pM) in PBS and 1 microg/mL (19 nM) in serum, and the dynamic range spans 94 pM to 0.19 microM. The advantages of the nanorod-based sensor over an LSPR sensor that we had previously fabricated from gold nanospheres (Nath, N.; Chilkoti, A. Anal. Chem. 2002, 74, 504-509; J. Fluoresc. 2004, 14, 377-389; Anal. Chem. 2004, 76, 5370-5378) are the significantly lower detection limit and the internal self-reference that the signal of the nanorod sensor provides based on the measurement of peak wavelength shift.
authors.affiliation: Department of Biomedical Engineering, Center for Biologically Inspired Materials and Material Systems, Duke University, Durham, North Carolina 27708, USA.
authors.forename: Stella M
authors.initials: SM
authors.lastname: Marinakos
authors.forename: Sihai
authors.initials: S
authors.lastname: Chen
authors.forename: Ashutosh
authors.initials: A
authors.lastname: Chilkoti
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D001710:Biotin / Q000737:chemistry; D005898:Glass / Q000737:chemistry; D006046:Gold / Q000737:chemistry*; D006801:Humans; D053768:Metal Nanoparticles / Q000737:chemistry*; D043942:Nanotubes / Q000737:chemistry*; D012680:Sensitivity and Specificity; D044967:Serum / Q000737:chemistry; D019809:Streptavidin / Q000737:chemistry; D020349:Surface Plasmon Resonance / Q000379:methods*
chemical_list: D001710:Biotin; D006046:Gold; D019809:Streptavidin