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FOx BIOSYSTEMS sandwich assays applications icon

The unique fiber-optic design of the FOx BIOSYSTEMS probe allows the implementation of sandwich-style bioassays using gold nanoparticles. This instantly amplifies the surface plasmon resonance signal without the lengthy enzymatic reaction incubations of an ELISA, providing increased detection sensitivity and speed.

Amplifying the signal in this way allows fast, physiologically relevant detection. Therefore, the FOx BIOSYSTEMS technology can detect physiologically active levels of biologicals and biomarkers quickly and accurately, allowing you to speed up your development.

Case study: FO-SPR amplification assay

Infliximab (IFX) is a monoclonal antibody used for the treatment of inflammatory bowel disease. Optimizing the therapeutic outcome requires concentration measurements which are currently obtained using the slow ELISA or less sensitive lateral flow-based immunotherapy techniques.

Tests using the FO-SPR probes and an IFX-specific capture antibody showed that surface plasmon resonance alone was unable to detect concentrations lower than 1 μg/ml. Using the same technology with SPR signal amplification via gold nanoparticles conjugated to detection antibody, a limit of detection (LOD) of 2.2 ng/ml was obtained in 100-fold diluted serum.

Sandwich bioassays on FO probe surface. The FOx BIOSYSTEMS instrument is capable of running standard bioassays that provide real-time, label-free data or gold nanoparticle sandwich assays to boost the sensitivity and speed of the surface plasmon resonance signal.

Multiplexed sandwich bioassays. Using sequential incubation of gold nanoparticle tagged antibodies, FO-SPR can accurately quantify two targets with co-immobilized bioreceptors.

Case study: Multiplexed FO-SPR sandwich assay

Multiplexing bioassays reduces the required sample volume, time, and cost of analysis.  It also allows to accurately determine ratios of target concentration. To achieve this, users developed a novel assay methodology using stable, oriented co-immobilization of autoimmune antibodies.

Using NTA probes allowed them to accurately quantify the two targets in both buffer and plasma with a gold nanoparticle (AuNP) signal amplification sandwich assay. The LoD for two antibodies against oriented fragements of ADAMTS13 in 200-fold diluted plasma were 3.38 and 2.31 ng/ml respectively.

Relevant publications

Found 16 Results
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Development and validation of an optical biosensor for rapid monitoring of adalimumab in serum of patients with Crohn’s disease


Bian et al. (2017) RPTH 7, doi: 10.1002/dta.2250 Therapeutic drug monitoring of adalimumab is recommended to improve therapeutic outcome in patients with Crohn’s disease. Performing an ELISA requires a rather…

January 29, 2024


Measuring ADAMTS-13 activity to diagnose thrombotic thrombocytopenic purpura: a novel, fast fiber-optic surface plasmon resonance immunoassay


Bonnez et al. (2023) RPTH 7,  DOI: 10.1016/j.rpth.2023.102171 Thrombotic thrombocytopenic purpura (TTP) is characterized by severe ADAMTS-13 activity deficiency (<10%). Diagnostic testing is challenging because of unavailability, high cost, and…

September 27, 2023


Integrated Signal Amplification on a Fiber Optic SPR Sensor Using Duplexed Aptamers


Dillen et al. (2023) ACS Sensors DOI: 10.1021/acssensors.2c02388 Throughout the past decades, fiber optic surface plasmon resonance (FO-SPR)-based biosensors have proven to be powerful tools for both the characterization of…

February 16, 2023


White paper: WP5 Extracellular vesicle quantification in complex matrices


White paper 5 | Version 2 | Kris Ver Donck, Filip Delport, Kim Stevens Based on original publication: Yildizhan et al. (2021) Journal of Extracellular Vesicles. 10 (4) ABSTRACT Fiber-optic...

December 15, 2021


Gold nanoparticle enhanced multiplexed biosensing on a fiber optic surface plasmon resonance probe


Qu et al. (2021) Biosensors and Bioelectronics 192, 113549  We present an innovative multiplexing concept on a fiber optic surface plasmon resonance (FO-SPR) platform and demonstrate for the first time…

August 24, 2021


White paper: WP3 Sensitive protein quantification in whole blood, dried blood spots, serum and plasma


White paper 3 | Version 2 | Kim Stevens, Kris Ver Donck, Filip Delport Based on original publication: Lu et al. (2017) Analytical Chemistry 89, 3664-3671. (1) ABSTRACT Fiber-optic surface...

June 29, 2021


White paper: WP2 sensitive protein quantification in serum – comparison of FO-SPR and ELISA


White paper 2 | Kim Stevens, Kris Ver Donck, Filip Delport Based on original publication: Lu et al. (2016) Biosensors and Bioelectronics 79, 173–179. (1) ABSTRACT This white paper demonstrates...

April 23, 2021


WHITE FOxTM technical specifications


You can find the technical specifications of the White FOxTM here: DOWNLOAD

April 8, 2021


FO-SPR biosensor calibrated with recombinant extracellular vesicles enables specific and sensitive detection directly in complex matrices


Yilidzhan et al. (2021) J. Extracell. Vesicles 10   Extracellular vesicles (EVs) have drawn huge attention for diagnosing myriad of diseases, including cancer. However, the EV detection and analyses procedures…

February 23, 2021


Real-time FO-SPR monitoring of solid-phase DNAzyme cleavage activity for cutting-edge biosensing


Peeters et al. (2019) ACS Appl. Mater. Interfaces 11, 7, 6759–6768   DNA nanotechnology has a great potential in biosensor design including nanostructuring of the biosensor surface through DNA origami,…

January 25, 2019


Immunoassay for detection of infliximab in whole blood using a fiber-optic surface plasmon resonance biosensor


Lu et al. (2017) Anal. Chem. 89, 3664−3671   Monitoring the concentration of a therapeutic drug antibody, infliximab (IFX), is recommended for enhancing its efficacy in patients with inflammatory bowel…

February 22, 2017


Competitive inhibition assay for the detection of progesterone in dairy milk using a fiber optic SPR biosensor


Daems et al. (2017) Analytica Chimica Acta 950, 1e6   Analytical methods that are often used for the quantification of progesterone in bovine milk include immunoassays and chromatographic techniques. Depending on the selected method,…

January 15, 2017


Fiber optic-SPR platform for fast and sensitive infliximab detection in serum of inflammatory bowel disease patients


Lu et al. (2016) Biosensors and Bioelectronics 79, 173–179    Infliximab (IFX) is a therapeutic monoclonal antibody used for treating patients with inflammatory bowel disease (IBD). In order to improve…

May 15, 2016


Real-time ligation chain reaction for DNA quantification and identification on the FO-SPR


Knez et al. (2015) Biosensors and Bioelectronics 65, 394-399   Different assays have been developed in the past years to meet point-of-care diagnostic tests requirements for fast and sensitive quantification…

May 15, 2015


Selection of aptamers against Ara h 1 protein for FO-SPR biosensing of peanut allergens in food matrices


Tran et al. (2013) Biosensors and Bioelectronics 43, 245–251    The rising prevalence to food allergies in the past two decades, together with the fact that the only existing therapy…

May 15, 2013


Fast and accurate peanut allergen detection with nanobead enhanced optical fiber SPR biosensor


Pollet et al. (2011) Talanta 83, 1436–1441   This paper is the first report of a fiber optic SPR biosensor with nanobead signal enhancement. We evaluated the system with a…

February 15, 2011


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For Research Use Only. Not for use in diagnostic procedures.