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Issue 6, 2012
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Rational aspect ratio and suitable antibody coverage of gold nanorod for ultra-sensitive detection of a cancer biomarker

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Abstract

We report a simple, ultra-sensitive, and straightforward method for non-labeling detection of a cancer biomarker, using Rayleigh light scattering spectroscopy of the individual nanosensor based on antibody–antigen recognition and localized surface plasmon resonance (LSPR) λmax shifts. By experimentally measuring the refractive index sensitivity of Au nanorods, the Au nanorod with an aspect ratio of ∼3.5 was proven optimal for the LSPR sensing. To reduce the steric hindrance effect as well as to immobilize a large amount of ligand on the nanoparticle surface, various mixtures containing different molar ratios of HS(CH2)11(OCH2CH2)6OCH2COOH and HS(CH2)11(OCH2CH2)3OH were applied to form different self-assembled monolayer surfaces. The results showed that the best molar ratio for antibody conjugation was 1 : 10. When using individual Au nanorod sensors for the detection of prostate specific antigen (PSA), the lowest concentration recorded was ∼1 aM (∼6 × 105 molecules), corresponding to LSPR λmax shifts of ∼4.2 nm. These results indicate that sensor miniaturization down to the nanoscale level, the reduction of steric hindrance, and optimization of size, shape, and aspect ratio of nanorods have led to a significant improvement in the detection limit of sensors.

Graphical abstract: Rational aspect ratio and suitable antibody coverage of gold nanorod for ultra-sensitive detection of a cancer biomarker

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Publication details

The article was received on 03 Jul 2011, accepted on 14 Dec 2011 and first published on 01 Feb 2012


Article type: Paper
DOI: 10.1039/C2LC20588B
Citation: Lab Chip, 2012,12, 1102-1109

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    Rational aspect ratio and suitable antibody coverage of gold nanorod for ultra-sensitive detection of a cancer biomarker

    P. L. Truong, B. W. Kim and S. J. Sim, Lab Chip, 2012, 12, 1102
    DOI: 10.1039/C2LC20588B

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