High‐Density Hotspots Engineered by Naturally Piled‐Up Subwavelength Structures in Three‐Dimensional Copper Butterfly Wing Scales for Surface‐Enhanced Raman Scattering Detection

Abstract

Very recently, wing scales of natural Lepidopterans (butterflies and moths) manifested themselves in providing excellent three dimensional (3D) hierarchical structures for surface‐enhanced Raman scattering (SERS) detection. But the origin of the observed enormous Raman enhancement of the analytes on 3D metallic replicas of butterfly wing scales has not been clarified yet, hindering a full utilization of this huge natural wealth with more than 175 000 3D morphologies. Herein, the 3D sub‐micrometer Cu structures replicated from butterfly wing scales are successfully tuned by modifying the Cu deposition time. An optimized Cu plating process (10 min in Cu deposition) yields replicas with the best conformal morphologies of original wing scales and in turn the best SERS performance. Simulation results show that the so‐called “rib‐structures” in Cu butterfly wing scales present naturally piled‐up hotspots where electromagnetic fields are substantially amplified, giving rise to a much higher hotspot density than in plain 2D Cu structures. Such a mechanism is further verified in several Cu replicas of scales from various butterfly species. This finding paves the way to the optimal scale candidates out of ca. 175 000 Lepidopteran species as bio‐templates to replicate for SERS applications, and thus helps bring affordable SERS substrates as consumables with high sensitivity, high reproducibility, and low cost to ordinary laboratories across the world.

3-Dimensional Plasmonic Substrates Based on Chicken Eggshell Bio-Templates for SERS-Based Bio-Sensing

“…For the SM, the peak intensity for 100 nm Au is ~2.9 times stronger than that for the 60 nm Au. Variations in SERS intensity with respect to different metal thicknesses have also been reported in several previous studies regarding bio-inspired SERS substrates [ 34 , 35 ]. Thicker metal films effectively smoothen the surface nanostructures, which might cause the thickness dependent SERS performance variations.…”

Mesoporous Metal–Organic Frameworks: Synthetic Strategies and Emerging Applications

“…This method offers a perspective for the solution of global warming. Similar practices of composites based on MOFs and biomaterials taken directly from the nature have also been reported …”

From Zeolitic Imidazolate Framework‐8 to Metal‐Organic Frameworks (MOFs): Representative Substance for the General Study of Pioneering MOF Applications

“…This strategy opens a new window for global warming solutions. Similar practices of composing MOFs and biomaterials have also been reported . ZIF‐8 films have also exhibited potential in electronics, to which the engineering ZIF‐8 thin films devised in MOF‐based hybrid devices is also under research …”