A new method for non-labeling attomolar detection of diseases based on an individual gold nanorod immunosensor

Abstract

Herein, we present the use of a single gold nanorod sensor for detection of diseases on an antibody-functionalized surface, based on antibody-antigen interaction and the localized surface plasmon resonance (LSPR) λ(max) shifts of the resonant Rayleigh light scattering spectra. By replacing the cetyltrimethylammonium bromide (CTAB), a tightly packed self-assembled monolayer of HS(CH(2))(11)(OCH(2)CH(2))(6)OCH(2)COOH(OEG(6)) has been successfully formed on the gold nanorod surface prior to the LSPR sensing, leading to the successful fabrication of individual gold nanorod immunosensors. Using prostate specific antigen (PSA) as a protein biomarker, the lowest concentration experimentally detected was as low as 111 aM, corresponding to a 2.79 nm LSPR λ(max) shift. These results indicate that the detection platform is very sensitive and outperforms detection limits of commercial tests for PSA so far. Correlatively, its detection limit can be equally compared to the assays based on DNA biobarcodes. This study shows that a gold nanorod has been used as a single nanobiosensor to detect antigens for the first time; and the detection method based on the resonant Rayleigh scattering spectrum of individual gold nanorods enables a simple, label-free detection with ultrahigh sensitivity.

A nanoplasmonic biosensor for label-free multiplex detection of cancer biomarkers

“…These results indicate that gold nanoparticle were successfully conjugated with the monoclonal antibody (mAb) via amide bonds. The immunogolds are now ready for capturing target antigens for biosensing, indicating the successful attachment of the target protein layer onto the surface of gold nanoparticles (Truong et al, 2011;Nguyen et al, 2015).…”

“…As reported in previous studies, our group has developed an individual nanoplasmonic platform for detecting cancer biomarkers (Cao and Sim, 2007;Truong et al, 2011;Hwang et al, 2012;Jun et al, 2014). Nanoplasmonic biosensors based on a single gold particle have a sensing concentration in the attomolar range, which is well suited for detection of a single biomarker.…”

Development of Individual Plasmonic Nanosensors for Clinical Diagnosis

“…Using the PSA-ACT complex as a protein biomarker, the lowest concentration recorded was ∼ 110 aM. Compared to DNA biobarcode assays that require complicated instrumentation, multiple experimental steps, including microarrayer, complicated signal amplification, silver enhancement and light scattering measurements, single Au nanorod sensors can be fabricated with a low-cost and simple method, with label-free, attomolar detection limits [37]. In an effort to push single-nanoparticle measurement technique to its terminal detection limit, the sensitivity of Au nanorods with the various aspect ratios for single nanosensors was demonstrated and the Au nanorod with aspect ratio of ∼ 3.5 were proven optimal for LSPR sensing.…”

Applications of gold nanorods in biomedical imaging and related fields

“…In direct ligand exchange, thiolated biomolecules, such as PEG [29,30] and DNA [31], are directly linked to GNRs by Au-S bonds. In covalent coupling, small bifunctional molecules such as 11-mercaptoundecanoic acids [32] are used as a linker to introduce functional carboxyl groups for further bioconjugation with antibody and protein using carbodiimide coupling agent.…”