Gold nanoparticles have unique size and shape dependent physical properties that have made them attractive for a variety of biomedical applications. In particular, gold nanoparticles have a strong optical absorption due to their surface plasmon resonance (SPR), and this SPR can be easily tuned with NP size and shape. One use of NPs that has recently gained significant interest are paper based immunoassays, which are utilized as rapid diagnostics for infectious disease, clinical tests, drug testing, and food safety and many other applications. These are made of low-cost materials such as paper and can provide sample-to-answer times of minutes. Often they are able to provide a readout by eye because of the strong color due to the presence of gold nanoparticles. Consequently, these assays can be administered at point of care and out in the field. We will discuss how the unique properties of gold and silver NPs can be exploited to yield new capabilities of the device beyond presence of color. Because NPs can be synthesized with different colors, multicolor NPs can be used to multiplex the assay, where multiple antigens can be detected simultaneously. In addition, the NPs can be used to enhance Raman reporters, which can provide signal enhancements and thus enable lower limits of detection. Paper-based assays have numerous opportunities for non-specific adsorption, protein denaturation, and steric hindrance. Unfortunately the impact of these interface issues are false positives, and/or reduced sensitivity, which can have severe ramifications in a clinical setting. Here, we will discuss the interface issues and their impact on the paper diagnostic performance.

Using gold nanoparticles for diagnostics and sensing in low cost devices

2019 Spring National Meeting

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