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Surface‐enhanced Raman scattering (SERS) is a powerful sensing technique. However, the employment of SERS sensors in practical applications is hindered by high fabrication costs from processes with limited scalability, poor batch‐to‐batch reproducibility, substrate stability, and uniformity. Here, highly scalable and reproducible flame aerosol technology is employed to rapidly self‐assemble uniform SERS sensing films. Plasmonic Ag nanoparticles are deposited on substrates as nanoaggregates with fine control of their interparticle distance. The interparticle distance is tuned by adding a dielectric spacer during nanoparticle synthesis that separates the individual Ag nanoparticles within each nanoaggregate. The dielectric spacer thickness dictates the plasmonic coupling extinction of the deposited nanoaggregates and finely tunes the Raman hotspots. By systematically studying the optical and morphological properties of the developed SERS surfaces, structure–performance relationships are established and the optimal hot‐spots occur for interparticle distance of 1 to 1.5 nm among the individual Ag nanoparticles, as also validated by computational modeling, are identified for the highest signal enhancement of a molecular Raman reporter. Finally, the superior stability and batch‐to‐batch reproducibility of the developed SERS sensors are demonstrated and their potential with a proof‐of‐concept practical application in food‐safety diagnostics for pesticide detection on fruit surfaces is explored. Robust surface‐enhanced Raman scattering (SERS) sensing surfaces are fabricated using one‐step flame nanoparticle deposition. The sensing surfaces exhibit superior stability and high batch‐to‐batch reproducibility, highlighting their potential in practical (bio)chemical sensing. The detection of pesticides on fruit surfaces demonstrates a proof‐of‐concept practical application in food safety diagnostics at the point of consumption.

The first observation of ultraviolet surface-enhanced Raman scattering (UV-SERS) was 20 years ago, yet the field has seen a slower development pace than its visible and near-infrared counterparts. UV excitation for SERS offers many potential advantages. These advantages include increased scattering intensity, higher spatial resolution, resonance Raman enhancement from organic, biological, and semiconductor analytes, probing UV photoluminescence, and mitigating visible photoluminescence from analytes or substrates. One of the main challenges is the lack of readily accessible, effective, and reproducible UV-SERS substrates, with few commercial sources available. In this review, we evaluate the reported UV-SERS substrates in terms of their elemental composition, substrate morphology, and performance. We assess the best-performing substrates with regard to their enhancement factors and limits of detection in both the ultraviolet and deep ultraviolet regions. Even though aluminum nanostructures were the most reported and best-performing substrates, we also highlighted some unique UV-SERS composition and morphology substrate combinations. We address the challenges and potential opportunities in the field of UV-SERS, especially in relation to the development of commercially available, cost-effective substrates. Lastly, we discuss potential application areas for UV-SERS, including cost-effective detection of environmentally and militarily relevant analytes, in situ and operando experimentation, defect engineering, development of materials for extreme environments, and biosensing.

Novel low‐cost materials to uptake and detect vestigial amounts of pesticides are highly desirable for water quality monitoring. Herein, are demonstrated, for the first time, surface‐enhanced Raman scattering (SERS) sensors enabled via additively manufactured lattices coated with plasmonic nanoparticles (NPs) for detecting pesticides in real water samples. The architected lattices comprising polypropylene (PP) and multiwall carbon nanotubes (MWCNTs) are realized via fused filament fabrication (FFF). In the first stage, the SERS performance of the PP/MWCNT filaments coated with distinct metallic NPs (Ag NPs and Au NPs) is evaluated using methylene blue (MB) as molecular probe. Thereafter, distinctly architected hybrid SERS sensors with periodic porous and fully dense geometries are investigated as adsorbents to uptake MB from aqueous solutions and subsequent detection using SERS. The spatial distribution of MB and Ag NPs on the FFF‐printed lattices is accomplished by SERS imaging. The best hybrid composite is used as SERS probing system to detect low amounts of pesticides (thiram and paraquat) and offers a detection limit of 100 nm for both pesticides. As a proof‐of‐concept, FFF‐enabled test strips are used to detect in loco paraquat molecules spiked on real water samples (Estuary Aveiro water and tap water) using a portable Raman spectrometer. For the first time, 3D printed architected nanocomposite lattices coated with Ag nanoparticles are demonstrated as hybrid sensors with high sensitivity and stability for detecting water pollutants in real water samples using Raman imaging coupled with surface‐enhanced Raman scattering. This research opens new opportunities for realizing additive manufacturing‐enabled low‐cost and highly active on‐site water quality monitoring sensors.

Surface‐enhanced Raman scattering (SERS) is a feasible and ultra‐sensitive method for biomedical imaging and disease diagnosis. SERS is widely applied to in vivo imaging due to the development of functional nanoparticles encoded by Raman active molecules (SERS nanoprobes) and improvements in instruments. Herein, the recent developments in SERS active materials and their in vivo imaging and biosensing applications are overviewed. Various SERS substrates that have been successfully used for in vivo imaging are described. Then, the applications of SERS imaging in cancer detection and in vivo intraoperative guidance are summarized. The role of highly sensitive SERS biosensors in guiding the detection and prevention of diseases is discussed in detail. Moreover, its role in the identification and resection of microtumors and as a diagnostic and therapeutic platform is also reviewed. Finally, the progress and challenges associated with SERS active materials, equipment, and clinical translation are described. The present evidence suggests that SERS could be applied in clinical practice in the future. The development of surface‐enhanced Raman scattering (SERS) materials and their applications in imaging and biosensing in vivo are summarized. The progress of SERS application in biomedical field are highlighted, including cancer detection, identifying tumor margins for intraoperative guidance, SERS sensor for disease diagnosis, SERS‐guided multifunctional theranostic platforms, and advance in equipment and clinical trials.

Surface‐enhanced Raman scattering (SERS) spectroscopy provides a noninvasive and highly sensitive route for fingerprint and label‐free detection of a wide range of molecules. Recently, flexible SERS has attracted increasingly tremendous research interest due to its unique advantages compared to rigid substrate‐based SERS. Here, the latest advances in flexible substrate‐based SERS diagnostic devices are investigated in‐depth. First, the intriguing prospect of point‐of‐care diagnostics is briefly described, followed by an introduction to the cutting‐edge SERS technique. Then, the focus is moved from conventional rigid substrate‐based SERS to the emerging flexible SERS technique. The main part of this report highlights the recent three categories of flexible SERS substrates, including actively tunable SERS, swab‐sampling strategy, and the in situ SERS detection approach. Furthermore, other promising means of flexible SERS are also introduced. The flexible SERS substrates with low‐cost, batch‐fabrication, and easy‐to‐operate characteristics can be integrated into portable Raman spectroscopes for point‐of‐care diagnostics, which are conceivable to penetrate global markets and households as next‐generation wearable sensors in the near future. Flexible surface‐enhanced Raman scattering (SERS) sensors have attracted great research attention owing to their distinct superiorities that the traditional rigid SERS substrates are not accessible to. Recent innovative strategies in developing flexible SERS sensors based on actively tunable plasmonic resonance, swab‐sampling route, and the in situ detection approach are highlighted, which affords unprecedented opportunities to realize point‐of‐care diagnostics in diverse applications.

This review article discusses progress in surface plasmon resonance (SPR) of two-dimensional (2D) and three-dimensional (3D) chip-based nanostructure array patterns. Recent advancements in fabrication techniques for nano-arrays have endowed researchers with tools to explore a material’s plasmonic optical properties. In this review, fabrication techniques including electron-beam lithography, focused-ion lithography, dip-pen lithography, laser interference lithography, nanosphere lithography, nanoimprint lithography, and anodic aluminum oxide (AAO) template-based lithography are introduced and discussed. Nano-arrays have gained increased attention because of their optical property dependency (light-matter interactions) on size, shape, and periodicity. In particular, nano-array architectures can be tailored to produce and tune plasmonic modes such as localized surface plasmon resonance (LSPR), surface plasmon polariton (SPP), extraordinary transmission, surface lattice resonance (SLR), Fano resonance, plasmonic whispering-gallery modes (WGMs), and plasmonic gap mode. Thus, light management (absorption, scattering, transmission, and guided wave propagation), as well as electromagnetic (EM) field enhancement, can be controlled by rational design and fabrication of plasmonic nano-arrays. Because of their optical properties, these plasmonic modes can be utilized for designing plasmonic sensors and surface-enhanced Raman scattering (SERS) sensors.

Recent achievements in semiconductor surface‐enhanced Raman scattering (SERS) substrates have greatly expanded the application of SERS technique in various fields. However, exploring novel ultra‐sensitive semiconductor SERS materials is a high‐priority task. Here, a new semiconductor SERS‐active substrate, Ta2O5, is developed and an important strategy, the “coupled resonance” effect, is presented, to optimize the SERS performance of semiconductor materials by energy band engineering. The optimized Mo‐doped Ta2O5 substrate exhibits a remarkable SERS sensitivity with an enhancement factor of 2.2 × 107 and a very low detection limit of 9 × 10−9 m for methyl violet (MV) molecules, demonstrating one of the highest sensitivities among those reported for semiconductor SERS substrates. This remarkable enhancement can be attributed to the synergistic resonance enhancement of three components under 532 nm laser excitation: i) MV molecular resonance, ii) photoinduced charge transfer resonance between MV molecules and Ta2O5 nanorods, and iii) electromagnetic enhancement around the “gap” and “tip” of anisotropic Ta2O5 nanorods. Furthermore, it is discovered that the concomitant photoinduced degradation of the probed molecules in the time‐scale of SERS detection is a non‐negligible factor that limits the SERS performance of semiconductors with photocatalytic activity. A semiconductor surface‐enhanced Raman scattering (SERS)‐active substrate Ta2O5 is developed, and an important strategy, the “coupled resonance” effect, is presented to optimize its SERS performance by energy band engineering. Furthermore, the unique photocatalytic degradation of probed molecules in the time‐scale of SERS detection by semiconductors is revealed as another non‐negligible factor that limits the SERS performance of some semiconductors with photocatalytic activity.

Precision oncology, defined as the use of the molecular understanding of cancer to implement personalized patient treatment, is currently at the heart of revolutionizing oncology practice. Due to the need for repeated molecular tumor analyses in facilitating precision oncology, liquid biopsies, which involve the detection of noninvasive cancer biomarkers in circulation, may be a critical key. Yet, existing liquid biopsy analysis technologies are still undergoing an evolution to address the challenges of analyzing trace quantities of circulating tumor biomarkers reliably and cost effectively. Consequently, the recent emergence of cutting‐edge plasmonic nanomaterials represents a paradigm shift in harnessing the unique merits of surface‐enhanced Raman scattering (SERS) biosensing platforms for clinical liquid biopsy applications. Herein, an expansive review on the design/synthesis of a new generation of diverse plasmonic nanomaterials, and an updated evaluation of their demonstrated SERS‐based uses in liquid biopsies, such as circulating tumor cells, tumor‐derived extracellular vesicles, as well as circulating cancer proteins, and tumor nucleic acids is presented. Existing challenges impeding the clinical translation of plasmonic nanomaterials for SERS‐based liquid biopsy applications are also identified, and outlooks and insights into advancing this rapidly growing field for practical patient use are provided. In a bid to facilitate next‐generation plasmonic nanomaterials for clinical exploration of SERS‐based liquid biopsy applications, a detailed overview of up‐to‐date plasmonic nanomaterials that are designed for SERS applications and newly developed SERS technologies for liquid biopsies, is provided.

Plasmonic metal‐organic frameworks are composite nanoparticles comprising plasmonic metal nanoparticles (NPs) embedded within a metal‐organic framework (MOF) matrix. As a result, not only the functionalities of the individual components are retained, but synergistic effects additionally provide improved chemical and physical properties. Recent progress in plasmonic MOFs has demonstrated the potential for nanofabrication and various nanotechnology applications. Synthetic challenges toward plasmonic MOFs have been recently addressed, resulting in new opportunities toward practical applications, such as surface‐enhanced Raman scattering, therapy, and catalysis. The impact of key parameters (thermodynamic vs. kinetic) on the synthetic pathways of plasmonic MOFs is reviewed, while providing insight into related progress toward structure‐derived applications. Plasmonic metal‐organic frameworks hybrid nanocomposites feature improved chemical and physical properties, as compared with their individual components, due to synergistic performance. These materials show excellent opportunities toward practical applications, such as surface‐enhanced Raman scattering, therapy, and catalysis.

Contact lenses have become a popular health‐monitoring wearable device due to their direct contact with the eyes. By integrating biosensors into contact lenses, real‐time and noninvasive diagnoses of various diseases can be realized. However, current contact lens sensors often require complex electronics, which may obstruct the user's vision or even damage the cornea. Moreover, most of the reported contact lens sensors can only detect one analyte. Therefore, an optical‐based dual‐functional smart contact lens sensor has been introduced to monitor intraocular pressure (IOP) and detect matrix metalloproteinase‐9 (MMP‐9), both of which are key biomarkers in many eye‐related diseases such as glaucoma. Specifically, the elevated IOP is continuously monitored by applying an antiopal structure through color changes, without any complex electronics. Together with the peptide modified gold nanobowls (AuNBs) surface‐enhanced Raman scattering (SERS) substrate, the quantitative analysis of MMP‐9 at a low nanomolar range is achieved in real tear samples. The dual‐sensing functions are thus demonstrated, providing a convenient, noninvasive, and potentially multifunctional sensing platform for monitoring health and diagnostic biomarkers in human tears. Intraocular pressure (IOP) and matrix metalloproteinase‐9 (MMP‐9) are biomarkers closely associated with ocular diseases. A dual‐functional contact lens sensor for detections of both biomarkers, using structural colors and peptides modified surface‐enhanced Raman scattering (SERS) substrate, respectively is reported. This optical sensor, therefore, provides a potentially versatile, noninvasive sensing platform for detecting multibiomarkers of human eye diseases.