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

Truong Phuoc Long, Byung Woo Kim, Sang Jun Sim

Research output: Contribution to journalJournal articleResearchpeer-review

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) lambda(max) shifts. By experimentally measuring the refractive index sensitivity of Au nanorods, the Au nanorod with an aspect ratio of similar to 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)(6)OCH2COOH and HS(CH2)(11)(OCH2CH2)(3)OH 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 similar to 1 aM (similar to 6 x 10(5) molecules), corresponding to LSPR lambda max shifts of similar to 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.
Original languageEnglish
JournalLab on a Chip
Volume12
Issue number6
Pages (from-to)1102-1109
Number of pages8
ISSN1473-0197
DOIs
Publication statusPublished - 2012
Externally publishedYes

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