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Fluorescence signal amplification by optical reflection in metal-coated nanowells

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Abstract 

A significant amplification in the fluorescence signal is demonstrated when measured in metal (aluminum)-coated fluidic wells with volumes on the order of a nanoliter or smaller (nanowells). Photolithographic and wet etching procedures were used to fabricate these nanowells on glass substrates followed by vapor deposition of an aluminum layer on them. The fluorescence signal recorded in these structures was enhanced due to the reflection of the incident and emitted radiation by the metal layer as well as focusing of this light by the curvature of the well surface. While the first effect amplified the background signal in the entire assay chamber, the latter one produced signal hotspots around the edges and center of the nanowell. In this work, we were able to realize over a 20-fold enhancement in the fluorescence signal upon quantitating it at the central hotspot of an aluminum-coated circular nanowell with a depth and photo-patterned diameter of 30 µm and 38 µm, respectively. More interestingly, our experiments indicate that this enhancement factor may be further improved by optimizing the curvature of the nanowell surface to merge all the signal hotspots within a smaller detection zone. Finally, quantitative assays using horseradish peroxidase samples were performed on the reported signal enhancement platform to further demonstrate its utility for making sensitive analytical measurements.

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Data Availability

The datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request.

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Funding

This research work was supported by funds from the National Science Foundation and Wyoming INBRE program through grants CHE-1808507 and P20GM103432, respectively.

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  1. Department of Chemistry, University of Wyoming, Laramie, WY, 82071, USA

    Sakur Mahmud & Debashis Dutta

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  1. Sakur Mahmud
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  2. Debashis Dutta
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Correspondence to Debashis Dutta.

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Mahmud, S., Dutta, D. Fluorescence signal amplification by optical reflection in metal-coated nanowells. Microchim Acta 189, 478 (2022). https://doi.org/10.1007/s00604-022-05577-y

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