Microwave-Accelerated Metal-Enhanced Fluorescence: Platform Technology for Ultrafast and Ultrabright Assays

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Abstract
We describe an exciting assay platform technology that promises to fundamentally address two underlying physical constraints of modern assays and immunoassays, namely, assay sensitivity and rapidity. By combining the use of metal-enhanced fluorescence with low-power microwave heating, we can indeed significantly increase the sensitivity of surface assays as well as >95 % kinetically complete the assay within a few seconds. Subsequently, this new technology promises to fundamentally change the way we currently employ immunoassays in clinical medicine. This new model platform system can be potentially applied to many other important assays, such as to the clinical assessment of myoglobin, where both assay speed and sensitivity is paramount for the assessment and treatment of acute myocardial infarction. To demonstrate the utility of microwave-accelerated metal-enhanced fluorescence (MAMEF), we show that a simple protein-based assay system can be optically amplified ∼10-fold by using silver nanostructures, while being kinetically complete in less than 20 s. This new platform approach is subsequently over 10-fold more sensitive and ∼90 times faster than a control assay that operates both at room temperature and without the use of metal-enhanced fluorescence. Finally, we show that low-power heating by microwaves in our model system does not denature proteins, as evidenced by no protein structural changes, probed by fluorescence resonance energy transfer.