Broadband fluorescence enhancement on anodization-derived gold nanobowl arrays

Metal enhanced fluorescence offers enhanced sensitivity and signal-to-noise ratios and has opened up many new applications of fluorescence. However, the demand for efficient and robust substrates capable of consistently amplifying fluorescence signals across different spectral regions remains high. In response to this need, this work investigated the utilization of three-dimensional truncated plasmonic nanovoids, specifically gold nanobowl arrays, as substrates for enhancing fluorescence in the ultraviolet and visible spectral regions. The gold nanobowl arrays were fabricated using anodized aluminium substrates, a method enabling rapid production of robust and readily available nanobowl arrays. Serving as platforms for immobilizing fluorescent bovine serum albumin-encapsulated gold nanoclusters, these arrays were employed to investigate the fluorescence enhancement. Structural and angular analysis alongside finite-difference time-domain simulations elucidated the excitation-dependent plasmonic properties of the substrates. Our findings reveal significant fluorescence enhancement, reaching up to 34.5 fold compared to a gold thin film. Moreover, these substrates exhibit broadband optical activity and reduced reflectance across the ultraviolet-blue region, suggesting potential benefits for enhancing excitation efficiency in biomolecular fluorescence applications. This study sheds light on developing gold nanobowl arrays as efficient substrates for fluorescence enhancement, offering promising avenues for advancing metal enhanced fluorescence-based technologies.