1. Immunoassay Development 

 

The detection of specific biomarkers for applications such as medical diagnostics, pathogen detection and environmental monitoring relies on the formation of highly specific antibody-antigen interactions. Innovative approaches to improving the speed of response, sensitivity of the test, simplicity of use and cost-effectiveness are the core goal of our team. Our focus is on the antibody conjugate label, which is a key component of the immunoassay for signal transduction (e.g. colorimetric, fluorometric, photoacoustic) of the antibody-antigen interaction. Suitable labels for antibodies include metal nanoparticles and enzymes. 

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Metal Nanoparticle Labels 

Gold nanoparticles appear red in colour due to absorption of light in the visible region as a result of surface plasmon resonance. This makes gold nanoparticles highly attractive as colorimetric labels. They are commonly used in point-of-care tests such as lateral flow assays where their colour can be visualised on a membrane surface if the sample contains the target analyte. These assays offer qualitative or semi-qualitative results but can be improved through systematic design of the size, shape and metal composition of the nanoparticles. 

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Metal nanoparticles can be readily conjugated with antibodies. Antibody surface coverage and orientation on a surface are important considerations when it comes to choice of conjugation method. Physical adsorption of antibodies is the most direct and straightforward approach which relies on charge attraction of antibodies to a gold surface. When a high degree of oriented antibodies is required, covalent attachment can result in increased sensitivity. Furthermore, amplification strategies using biotin-avidin chemistry can be adopted. 

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