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| A nanoscale optical blosensor: Sensitivity and selectivity of an approach based on the localized surface plasmon resonance spectroscopy of triangular silver nanoparticles |
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| Author(s): Haes AJ, Van Duyne RP |
| Source: JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Volume: 124 Issue: 35 Pages: 10596-10604 Published: SEP 4 2002 |
| Times Cited: 573 References: 99 |
| Abstract: Triangular silver nanoparticles (similar to100 nm wide and 50 nm high) have remarkable optical properties. In particular, the peak extinction wavelength, lambda(max) of their localized surface plasmon resonance (LSPR) spectrum is unexpectedly sensitive to nanoparticle size, shape, and local (similar to10-30 nm) external dielectric environment. This sensitivity of the LSPR lambda(max) to the nanoenvironment has allowed us to develop a new class of nanoscale affinity biosensors. The essential characteristics and operational principles of these LSPR nanobiosensors will be illustrated using the well-studied biotin-streptavidin system. Exposure of biotin-functionalized Ag nanotriangles to 100 nM streptavidin (SA) caused a 27.0 nm red-shift in the LSPR lambda(max). The LSPR lambda(max) shift, DeltaR/DeltaR(max), versus [SA] response curve was measured over the concentration range 10(-15) M < [SA] < 10(-6) M. Comparison of the data with the theoretical normalized response expected for 1:1 binding of a ligand to a multivalent receptor with different sites but invariant affinities yielded approximate values for the saturation response, DeltaR(max) = 26.5 nm, and the surface-confined thermodynamic binding constant K-a,K-surf = 10(11) M-1. At present, the limit of detection (LOD) for the LSPR nanobiosensor is found to be in the low-picomolar to high-femtomolar region. A strategy to amplify the response of the LSPR nanobiosensor using biotinylated Au colloids and thereby further improve the LOD is demonstrated. Several control experiments were performed to define the LSPR nanobiosensor's response to nonspecific binding as well as to demonstrate its response to the specific binding of another protein. These include the following: (1) electrostatic binding of SA to a nonbiotinylated surface, (2) nonspecific interactions of prebiotinylated SA to a biotinylated surface, (3) nonspecific interactions of bovine serum albumin to a biotinylated surface, and (4) specific binding of anti-biotin to a biotinylated surface. The LSPR nanobiosensor provides a pathway to ultrasensitive biodetection experiments with extremely simple, small, light, robust, low-cost instrumentation that will greatly facilitate field-portable environmental or point-of-service medical diagnostic applications. |
| Document Type: Article |
| Language: English |
| Reprint Address: Van Duyne, RP (reprint author), Northwestern Univ, Dept Chem, 2145 Sheridan Rd, Evanston, IL 60208 USA |
Addresses:
1. Northwestern Univ, Dept Chem, Evanston, IL 60208 USA |
| Publisher: AMER CHEMICAL SOC, 1155 16TH ST, NW, WASHINGTON, DC 20036 USA |
| Subject Category: Chemistry, Multidisciplinary |
| IDS Number: 591LH |
| ISSN: 0002-7863 |
| DOI: 10.1021/ja020393x |
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