Plasmonic Detection of a Model Analyte in Serum by a Gold Nanorod Sensor

• Published in: Analytical chemistry (Washington) 2007-07, Vol.79 (14), p.5278-5283
• Main Authors: Marinakos, Stella M, Chen, Sihai, Chilkoti, Ashutosh
• Format: Article
• Language: English
• Subjects: Analytical chemistry; Biological and medical sciences; Biosensing Techniques - methods; Biosensors; Biotechnology; Biotin - chemistry; Chemistry; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Glass - chemistry; Gold; Gold - chemistry; Humans; Metal Nanoparticles - chemistry; Methods. Procedures. Technologies; Nanotubes - chemistry; Proteins; Sensitivity and Specificity; Serum - chemistry; Spectrometric and optical methods; Streptavidin - chemistry; Surface Plasmon Resonance - methods; Various methods and equipments
• ISSN: 0003-2700; 1520-6882
• DOI: 10.1021/ac0706527

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 μg/mL (94 pM) in PBS and 1 μg/mL (19 nM) in serum, and the dynamic range spans 94 pM to 0.19 μM. 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.