Reproducible Flexible SERS Substrates Inspired by Bionic Micro‐Nano Hierarchical Structures of Rose Petals

Abstract

enlarge the signal of conventional Raman test, achieve trace detection, and even single-molecule detection. [4] Because of its unique fingerprint peak characteristics, non-destructive testing, fast response, and other advantages, [5,6] it is widely used in environmental monitoring, [7,8] food safety, [9][10][11] biomedicine, and other fields. [12][13][14] So far, there is no clear theoretical model that can explain the complex SERS phenomenon.However, electromagnetic enhancement (EM) and chemical enhancement (CM) are two kinds of SERS mechanisms that are generally accepted by the academic community. [15,16] The EM means that incident laser excites the surface of the precious metal nanostructure to form localized surface plasmon resonance, thereby amplifying the scattering signal. [17,18] The enhancement performance is the best in nanogaps (<10 nm) with small adjacent intervals, so these gaps are called hot spots, [19] which make it possible to detect single molecules. The enhancement factor (EF) of EM can reach 10 6 or higher, which is the dominant factor of signal enhancement. The CM mechanism is to form a chemical bond between adsorbed molecules and the surfaces of SERS substrate, resulting in charge transfer. The EF of CM is generally 10-100, [20] which is much smaller than EM. Meanwhile, the CM effect is often ignored in some experiments, because it just appears when the molecule is in contact with the substrate. [21] In summary, in order to design a high-performance SERS substrate, high-dimensional, and highdensity hot spots distribution must be considered.So far, a variety of SERS substrates have been reported. Most beginners build SERS substrates based on silver (Ag) nanoparticles. [22] Then 1D and 2D structures are introduced, such as nanorods, [23] nanowires, [24] graphene, [25] etc. Currently the most commonly used is the 3D hierarchical structures such as the nanoflowers array. [26][27][28] The ordered 3D structures can expand the distribution of hot spots, so that the SERS substrate has a larger enhancement factor. Besides, when used in practical applications, the uniformity and stability should not be ignored. Therefore, it is not only necessary to consider sufficient hot spots distribution, but also to precisely control the orderliness of the structures. Zhao et al. proposed a strategy to build the flexible SERS substrate, which was achieved by graphene oxide/Ag nanoparticles/pyramidal polymethyl methacrylate. [29] Zhu et al. used polystyrene sphere (PS) single-layer template electrodeposition to prepare a micro-bowl array assembled with Ag nanoparticles Surface-enhancement Raman scattering (SERS) is widely applied in environmental protection, biomedicine, origin traceability, food safety, and other fields as a crucial analysis and detection method. The construction strategy of excellent SERS substrates has always been a research hotspot. In this article, a 3D micro-lens array/wrinkle structures/silver nanoparticles SERS substrate (MLA/WS/AgNPs 3D-SERS) is prepared, which is enlightened by rose peta...

Highly Sensitive Exosome Detection for Early Diagnosis of Pancreatic Cancer Using Immunoassay Based on Hierarchical Surface‐Enhanced Raman Scattering Substrate

“…[26,27] Recent studies have shown that some 3D-array substrates with high specific surface area gradually appear in the field of SERS detection. [29,30] In this paper, we designed an ordered micro-nano structure array with a layer of AgNPs growing on the surface for exosome surface protein detection (GPC1-Exos, LRG1-Exos, or CD9-Exos), which could provide more hot spots and a larger surface area. To verify whether the H-SERS substrate could provide a stronger SESR intensity, we characterized the detection performance of different substrates by detecting MBs @ exosomes @ Ag-MBA-CD9 detection probes (MEDP-CD9).…”

Replica of Bionic Nepenthes Peristome-like and Anti-Fouling Structures for Self-Driving Water and Raman-Enhancing Detection

“…For example, aircraft coatings based on shark skin resistance [6,[14][15][16], radar sonar based on bats [17], solar applications inspired by photosynthesis, bullet train heads based on kingfisher beaks [18,19], antifouling coatings based on frog skins [20], etc. Biomaterials have also been widely applied in SERS substrates due to their 3D periodic microstructures, such as butterfly wings, cicada wings, and rose petals [21][22][23]. The best case for the continuation, this study focuses on the surface structure of nepenthes.…”

High Sensitivity and a Wide Sensing Range Flexible Strain Sensor Based on the V-Groove/Wrinkles Hierarchical Array

“…To balance sensitivity and the sensing range, researchers have conducted many studies. − Current methods primarily rely on the difference in the fracture toughness of sensitive conductive materials in different regions and forming cracks under different strains to achieve high sensitivity under a wide sensing range. For example, Liu et al took advantage of the self-pinning effect of the single-wall carbon nanotube solution to construct films of gradient thickness sensitive materials.…”