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.

Gold nanoparticle-based biosensors

“…Secondly, the height of analytical response was inverse related to the affinity of the respective antibodies, which was consistent with the inversely proportional relationship between antibody affinity and binding capacity [20]. Since then, numerous labs have put effort into the work for correlating peak intensity and position of the surface plasmon absorbance of GNPs with the local refractive index of the surrounding medium [21][22][23][24][25][26][27][28][29][30][31], which is termed the localized surface Plasmon resonance (LSPR).…”

Synthesis and Characterization of Gold Nanoparticles with Plasmon Absorbance Wavelength Tunable from Visible to Near Infrared Region

“…Among these geometries, nanorod is particularly interesting to us, because it provides an excellent platform with well-defined absorption spectrum for a labelfree bioanalytical assay [13][14][15][16][17][18]. The optical transduction by Au nanorods (GNRs) is based upon the phenomenon of localized surface plasmon resonance, that is, nanoSPR (or LSPR) [19][20][21].…”

Thermal and Chemical Stabilization of Silver Nanoplates for Plasmonic Sensor Application

“…4). It revealed that AgPLs@Au exhibit superior sensitivity to AgPLs prepared by colloidal lithography (19 nm RIU -1 ) 26 and AuNRs (231, 15 252, 27 and 206 28 nm RIU -1 ) even after TiO2-coating with the thermal stability. Although the sensitivity of the TiO2-coated AgPL@Au-deposited glass substrate decreased after TiOxovercoating with the chemical stability, the substrate could show satisfactory performance of LSPR sensing.…”