Copper nanowire array as highly selective electrochemical sensor of nitrate ions in water

Preparation of CoFe@C composite modified electrode for neohesperidin dihydrochalcone sensing and its application in Chinese medicine

CoFe@C was first prepared by calcining the precursor of CoFe-metal-organic framework-74 (CoFe-MOF-74), then an electrochemical sensor for the determination of neohesperidin dihydrochalcone (NHDC) was constructed, which was stemmed from the novel CoFe@C/Nafion composite film modified glassy carbon electrode (GCE). The CoFe@C/Nafion composite was verified by field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). Electrochemical impedance spectroscopy (EIS) was used to evaluate its electrical properties as a modified material for an electrochemical sensor. Compared with CoFe-MOF-74 precursor modified electrode, CoFe@C/Nafion electrode exhibited a great synergic catalytic effect and extremely increased the oxidation peak signal of NHDC. The effects of various experimental conditions on the oxidation of NHDC were investigated and the calibration plot was tested. The results bespoken that CoFe@C/Nafion GCE has good reproducibility and anti-interference under the optimal experimental conditions. In addition, the differential pulse current response of NHDC was linear with its concentration within the range 0.08 ~ 20 µmol/L, and the linear regression coefficient was 0.9957. The detection limit was as low as 14.2 nmol/L (S/N = 3). In order to further verify the feasibility of the method, it was successfully used to determine the content of NHDC in Chinese medicine, with a satisfactory result, good in accordance with that of high performance liquid chromatography (HPLC).

Active Hydrogen Free, Z-Isomer Selective Isatin Derived "Turn on" Fluorescent Dual Anions Sensor

An efficient and anions fluorescence "on-off" sensor of 1-(prop-2-yn-1-yl)-3-(quinolin-3-ylimino)indolin-2-one (PQI) has been developed for the selective sensing of dual anions of F- and NO3- ions in aqueous medium. Active hydrogen and Lewis acidic binding sites free, Z- isomer of isatin based π-conjugated quinoline exhibited excellent sensing activity against F- and NO3- ions in UV light. The fluorescence turns on the process accomplished via the PET "on-off" mechanism. The interaction between probe molecule and anions is thought to be a non-covalent interaction of the low electron density covalently bonded N-methylene moiety of propargyl isatin (-N-CH2-) of probe molecule with F- ion and the terminal acidic proton of propargyl group of isatin (-C≡C-H) with NO3- ions. The modes of anions binding with PQI and plausible mechanisms are proposed by 1H and 13C NMR titrations. The selectivity of anions sensing may be offered by the bucked structure of the Z-isomer. The calculated association constant values for PQI and F- and NO3- are ions 2.5 × 104 M-1 and 2.2 × 103 M-1, respectively, indicating strong binding interaction between the PQI and anions. The association nature of anions and probes was analyzed by a Jobs plot and the finding indicates both F- and NO3- ions are in 1:1 complexation with PQI. The limit of detection (LOD) of the probe with F- and NO3- ions is calculated and is to be 6.91 × 10-7 M and 9.93 × 10-7 M, respectively. The proposed PQI fluorophore possesses a low limit of detection (LOD) for both F- and NO3- ions which is within the WHO prescribed detection limit.

Phosphate and Nitrate Electrochemical Sensor Based on a Bifunctional Boron-Doped Diamond Electrode

Phosphorus and nitrogen are important elements in both environmental cycles and biological growth, and their imbalance can lead to serious environmental and biological problems. It is important to be able to monitor the concentration of nitrate and phosphate in the water online. In this paper, a bifunctional boron-doped diamond (BDD) electrode with repeatable electrochemical renewal and modification ability has been developed and used as a shared working electrode for the determination of nitrate and phosphate. First, phosphate can be detected directly with a bare BDD electrode. After a thin copper (Cu) layer was electrodeposited on the BDD electrode, nitrate could be determined. The copper layer is then removed under a positive voltage, and the BDD electrode is renewed and can be used again for phosphate detection. This method enables the detection of both phosphate and nitrate while also improving the stability and repeatability through the renewal of the electrode surface. The segmented linear ranges for phosphate were 0.02-0.4 and 0.4-3 mg/L with a detection limit of 0.004 mg/L. The sensor detected nitrate in a wide concentration range, with segmented linear relationships in the ranges of 0.07-3 and 3-100 mg/L, with a detection limit of 0.065 mg/L. The electrochemical sensor based on the BDD electrode has a good reproducibility for phosphate and nitrate detection. The relative standard deviation (RSD) values of the current responses were 2.98, 2.79, 1.66, 1.81, and 1.23%, respectively, for 35 consecutive tests in 0.05, 0.2, 0.5, 1, and 1.5 mg/L phosphate solution. The RSD values of the current responses were 2.00, 0.97, and 1.03%, respectively, for 25 consecutive tests in 5, 7, and 10 mg/L nitrate solution.

Nitrate Sensor with a Wide Detection Range and High Stability Based on a Cu-Modified Boron-Doped Diamond Electrode

This paper describes an electrochemical sensor based on a Cu-modified boron-doped diamond (BDD) electrode for the detection of nitrate-contaminated water. The sensor utilizes the catalytic effect of copper on nitrate and the stability of the BDD electrode. By optimizing the electrolyte system, the linear detection range was expanded, allowing the sensor to detect highly concentrated nitrate samples up to 100 mg/L with a low detection limit of 0.065 mg/L. Additionally, the stability of the sensor was improved. The relative standard deviation of the current responses during 25 consecutive tests was only 1.03%. The wide detection range and high stability of the sensor makes it suitable for field applications and the on-site monitoring of nitrate-contaminated waters.

Copper Nanoparticles Confined in a Silica Nanochannel Film for the Electrochemical Detection of Nitrate Ions in Water Samples

The nitrate ion (NO3-) is a typical pollutant in environmental samples, posing a threat to the aquatic ecosystem and human health. Therefore, rapid and accurate detection of NO3- is crucial for both the aquatic sciences and government regulations. Here we report the fabrication of an amino-functionalized, vertically ordered mesoporous silica film (NH2-VMSF) confining localized copper nanoparticles (CuNPs) for the electrochemical detection of NO3-. NH2-VMSF-carrying amino groups possess an ordered perpendicular nanochannel structure and ultrasmall nanopores, enabling the confined growth of CuNPs through the electrodeposition method. The resulting CuNPs/NH2-VMSF-modified indium tin oxide (ITO) electrode (CuNPs/NH2-VMSF/ITO) combines the electrocatalytic reduction ability of CuNPs and the electrostatic attraction capacity of NH2-VMSF towards NO3-. Thus, it is a rapid and sensitive electrochemical method for the determination of NO3- with a wide linear detection range of 5.0-1000 μM and a low detection limit of 2.3 μM. Direct electrochemical detection of NO3- in water samples (tap water, lake water, seawater, and rainwater) with acceptable recoveries ranging from 97.8% to 109% was performed, demonstrating that the proposed CuNPs/NH2-VMSF/ITO sensor has excellent reproducibility, regeneration, and anti-interference abilities.

Electrochemical and Optical Sensors for Real-Time Detection of Nitrate in Water

The health and integrity of our water sources are vital for the existence of all forms of life. However, with the growth in population and anthropogenic activities, the quality of water is being impacted globally, particularly due to a widespread problem of nitrate contamination that poses numerous health risks. To address this issue, investigations into various detection methods for the development of in situ real-time monitoring devices have attracted the attention of many researchers. Among the most prominent detection methods are chromatography, colorimetry, electrochemistry, and spectroscopy. While all these methods have their pros and cons, electrochemical and optical methods have emerged as robust and efficient techniques that offer cost-effective, accurate, sensitive, and reliable measurements. This review provides an overview of techniques that are ideal for field-deployable nitrate sensing applications, with an emphasis on electrochemical and optical detection methods. It discusses the underlying principles, recent advances, and various measurement techniques. Additionally, the review explores the current developments in real-time nitrate sensors and discusses the challenges of real-time implementation.

Electrochemical Quantification of H2O2 Released by Airway Cells Growing in Different Culture Media

Quantification of oxidative stress is a challenging task that can help in monitoring chronic inflammatory respiratory airway diseases. Different studies can be found in the literature regarding the development of electrochemical sensors for H2O2 in cell culture medium to quantify oxidative stress. However, there are very limited data regarding the impact of the cell culture medium on the electrochemical quantification of H2O2. In this work, we studied the effect of different media (RPMI, MEM, DMEM, Ham's F12 and BEGM/DMEM) on the electrochemical quantification of H2O2. The used electrode is based on reduced graphene oxide (rGO) and gold nanoparticles (AuNPs) and was obtained by co-electrodeposition. To reduce the electrode fouling by the medium, the effect of dilution was investigated using diluted (50% v/v in PBS) and undiluted media. With the same aim, two electrochemical techniques were employed, chronoamperometry (CH) and linear scan voltammetry (LSV). The influence of different interfering species and the effect of the operating temperature of 37 °C were also studied in order to simulate the operation of the sensor in the culture plate. The LSV technique made the sensor adaptable to undiluted media because the test time is short, compared with the CH technique, reducing the electrode fouling. The long-term stability of the sensors was also evaluated by testing different storage conditions. By storing the electrode at 4 °C, the sensor performance was not reduced for up to 21 days. The sensors were validated measuring H2O2 released by two different human bronchial epithelial cell lines (A549, 16HBE) and human primary bronchial epithelial cells (PBEC) grown in RPMI, MEM and BEGM/DMEM media. To confirm the results obtained with the sensor, the release of reactive oxygen species was also evaluated with a standard flow cytometry technique. The results obtained with the two techniques were very similar. Thus, the LSV technique permits using the proposed sensor for an effective oxidative stress quantification in different culture media and without dilution.

Copper Oxide Solution Sensor Formed on a Thin Film Having Nanowires for Detecting Ethanol in Water

Solution sensors are required to detect analytes in liquids with high sensitivity and response speed for environmental and health monitoring. In this study, we introduce the concept of a Cu oxide thin film having nanowires as a solution sensor for detecting ethanol in water. The Cu oxide sensor with grains and nanowires of different shapes was fabricated by a simple method of heating a Cu thin film and dropping an Ag conductive paste. Sensing parameters and mechanisms were evaluated by current-voltage and electrochemical impedance spectroscopy measurements. In the Cu oxide sensor formed on thin film having a large number of nanowires fabricated by heating at 400 °C for 5 h, the sensor sensitivity was 0.96 at 0.1 vol % ethanol concentration, and the response time was 313 s at a voltage of 0.1 V. The Cu oxide sensor detects ethanol by the change in electrical resistance caused by the reaction between ethanol molecules and the lattice oxygen on the Cu oxide surface. Therefore, the large nanowire surface area leads to a higher sensor sensitivity and a faster response time. Furthermore, the grain and nanowire regions on the thin film are represented by equivalent circuits. A high correlation was observed between the sensor sensitivity and the time constant calculated from the equivalent circuit. The proposed Cu oxide solution sensor and detection mechanism offer designs to improve the performance of chemical sensors.

Meeting the Water and Sanitation Challenges of Underbounded Communities in the U.S

Water and sanitation (wastewater) infrastructure in the United States is aging and deteriorating, with massive underinvestment over the past several decades. For many years, lack of attention to water and sanitation infrastructure has combined with racial segregation and discrimination to produce uneven access to water and wastewater services resulting in growing threats to human and environmental health. In many metropolitan areas in the U.S., those that often suffer disproportionately are residents of low-income, minority communities located in urban disadvantaged unincorporated areas on the margins of major cities. Through the process of underbounding (the selective expansion of city boundaries to exclude certain neighborhoods often based on racial demographics or economics), residents of these communities are disallowed municipal citizenship and live without piped water, sewage lines, and adequate drainage or flood control. This Perspective identifies the range of water and sanitation challenges faced by residents in these communities. We argue that future investment in water and sanitation should prioritize these communities and that interventions need to be culturally context sensitive. As such, approaches to address these problems must not only be technical but also social and give attention to the unique geographic and political setting of local infrastructures.

Development of a sustainable nanosensor using green Cu nanoparticles for simultaneous determination of antibiotics in drinking water

In this work, a novel, cost-effective, and eco-friendly electrochemical (EC) nanosensor was fabricated for the simultaneous detection of daptomycin (DAP) and meropenem (MEROP). EC methods have been developed for the determination of antibiotics. In this context, green synthesized copper nanoparticles (CuNPs) using Moringa oleifera plant extract were used as electrode modifiers. The incorporation of CuNPs was proposed to enhance the sensitivity and allow the simultaneous quantification of both antibiotics in water. Transmission electron microscopy (TEM), dynamic light scattering (DLS), attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, UV-visible spectroscopy, and field emission scanning electron microscopy with energy dispersive X-ray spectroscopy (FESEM-EDX) were employed to characterize CuNPs. Physical adsorption of 20.0 nm (±2.2 nm) spherical CuNPs on the surface of screen-printed carbon electrodes (SPCEs) induced a remarkable electrocatalytic effect. Indeed, the detection of both antibiotics exhibited a limit of detection (LOD) of 0.01 g L^-1. The response to various interfering species was assessed. Finally, the quantification of DAP and MEROP in drinking water was demonstrated, confirming the potential of the developed sensor for environmental monitoring applications.

Electrochemical Synthesis of Zinc Oxide Nanostructures on Flexible Substrate and Application as an Electrochemical Immunoglobulin-G Immunosensor

Immunoglobulin G (IgG), a type of antibody, represents approximately 75% of serum antibodies in humans, and is the most common type of antibody found in blood circulation. Consequently, the development of simple, fast and reliable systems for IgG detection, which can be achieved using electrochemical sandwich-type immunosensors, is of considerable interest. In this study we have developed an immunosensor for human (H)-IgG using an inexpensive and very simple fabrication method based on ZnO nanorods (NRs) obtained through the electrodeposition of ZnO. The ZnO NRs were treated by electrodepositing a layer of reduced graphene oxide (rGO) to ensure an easy immobilization of the antibodies. On Indium Tin Oxide supported on Polyethylene Terephthalate/ZnO NRs/rGO substrate, the sandwich configuration of the immunosensor was built through different incubation steps, which were all optimized. The immunosensor is electrochemically active thanks to the presence of gold nanoparticles tagging the secondary antibody. The immunosensor was used to measure the current density of the hydrogen development reaction which is indirectly linked to the concentration of H-IgG. In this way the calibration curve was constructed obtaining a logarithmic linear range of 10-1000 ng/mL with a detection limit of few ng/mL and good sensitivity.

Anodic Alumina Membranes: From Electrochemical Growth to Use as Template for Fabrication of Nanostructured Electrodes

The great success of anodic alumina membranes is due to their morphological features coupled to both thermal and chemical stability. The electrochemical fabrication allows accurate control of the porous structure: in fact, the membrane morphological characteristics (pore length, pore diameter and cell density) can be controlled by adjusting the anodizing parameters (bath, temperature, voltage and time). This article deals with both the fabrication and use of anodic alumina membranes. In particular, we will show the specific role of the addition of aluminum ions to phosphoric acid-based anodizing solution in modifying the morphology of anodic alumina membranes. Anodic alumina membranes were obtained at −1 °C in aqueous solutions of 0.4 M H3PO4 added with different amounts of Al(OH)3. For sake of completeness, the formation of PAA in pure 0.4 M H3PO4 in otherwise identical conditions was also investigated. We found that the presence of Al(OH)3 in solution highly affects the morphology of the porous layer. In particular, at high Al(OH)3 concentration (close to saturation) more compact porous layers were formed with narrow pores separated by thick oxide. The increase in the electric charge from 20 to 160 C cm−2 also contributes to modifying the morphology of porous oxide. The obtained anodic alumina membranes were used as a template to fabricate a regular array of PdCo alloy nanowires that is a valid alternative to Pt for hydrogen evolution reaction. The PdCo alloy was obtained by electrodeposition and we found that the composition of the nanowires depends on the concentration of two metals in the deposition solution.

Boosting electrocatalytic activity of carbon fiber@fusiform-like copper-nickel LDHs: Sensing of nitrate as biomarker for NOB detection

Morphological evolution of layered double hydroxides (LDHs) with preferential crystal facets has appealed gigantic attention of research community. Herein, we prepare hierarchical hybrid material by structurally integrating fusiform-like CuNiAl LDHs petals on conductive backbone of CF (CF@CuNiAl LDHs) and investigate electrocatalytic behavior in nitrate reduction over a potential window of -0.7 V to +0.7 V. The CF@CuNiAl LDHs electrode exhibits remarkable electrocatalytic aptitude in nitrate sensing including broad linear ranges of 5 nM to 40 µM and 75 µM to 2.4 mM with lowest detection limit of 0.02 nM (S/N = 3). The sensor shows sensitivity of 830.5 ± 1.84 µA mM^1- cm^2- and response time within 3 s. Owing to synergistic collaboration of improved electron transfer kinetics, specific fusiform-like morphology, presence of more catalytically active {111} facets and superb catalytic activity of LDHs, CF@CuNiAl LDHs electrode has outperformed as electrochemical sensor. Encouraged from incredible performance, CF@CuNiAl LDHs flexible electrode has been applied in real-time in-vitro detection of nitrite oxidizing bacteria (NOB) through the sensing of nitrate because NOB convert nitrite into nitrate by characteristic metabolic process to obtain their energy. Further, CF@CuNiAl LDHs based sensing podium has also been employed in in-vitro detection of nitrates from mineral water, tap water and Pepsi drink.

Electrochemical detection of chloride ions using Ag-based electrodes obtained from compact disc

In this work electrochemical sensors fabricated from compact disc material (waste or new) are used to quantify chloride ions in different types of samples. All three electrodes, working, counter, and pseudo-reference electrodes, were fabricated from the compact disc and directly used. Different parameters were studied in order to demonstrate the possibility of using this waste material for efficient and low-cost electrochemical sensors. Chloride sensing performance was evaluated using linear scan voltammetry as the detection technique. A sensitivity of 0.174 mA mM^-1 cm^-2 with a limit of detection of 20 μM and excellent selectivity against many interferents was observed. Selectivity and reproducibility tests were also carried out, showing excellent results. Sensors were also validated with real samples (drinking and sea water, milk, sweat and physiological solutions) with results comparable to conventional techniques. Our results show the applicability and suitability of these low-cost sensors, for detection of those analytes for which, silver, has high sensitivity and selectivity.

Nanomaterials for electrochemical detection of pollutants in water: A review

The survival of living beings, including humanity, depends on a continuous supply of clean water. However, due to the development of industry, agriculture, and population growth, an increasing number of wastewaters is discarded, and the negative effects of such actions are clear. The first step in solving this situation is the collection and monitoring of pollutants in water bodies to subsequently facilitate their treatment. Nonetheless, traditional sensing techniques are typically laboratory-based, leading to potential diminishment in analysis quality. In this paper, the most recent developments in micro- and nano-electrochemical devices for pollutant detection in wastewater are reviewed. The devices reviewed are based on a variety of electrodes and the sensing of three different categories of pollutants: nutrients and phenolic compounds, heavy metals, and organic matter. From these electrodes, Cu, Co, and Bi showed promise as versatile materials to detect a grand variety of contaminants. Also, the most commonly used material is glassy carbon, present in the detection of all reviewed analytes.

Electrochemical detection of dopamine with negligible interference from ascorbic and uric acid by means of reduced graphene oxide and metals-NPs based electrodes

Dopamine is an important neurotransmitter involved in many human biological processes as well as in different neurodegenerative diseases. Monitoring the concentration of dopamine in biological fluids, i.e., blood and urine is an effective way of accelerating the early diagnosis of these types of diseases. Electrochemical sensors are an ideal choice for real-time screening of dopamine as they can achieve fast, portable inexpensive and accurate measurements. In this work, we present electrochemical dopamine sensors based on reduced graphene oxide coupled with Au or Pt nanoparticles. Sensors were developed by co-electrodeposition onto a flexible substrate, and a systematic investigation concerning the electrodeposition parameters (concentration of precursors, deposition time and potential) was carried out to maximize the sensitivity of the dopamine detection. Square wave voltammetry was used as an electrochemical technique that ensured a high sensitive detection in the nM range. The sensors were challenged against synthetic urine in order to simulate a real sample detection scenario where dopamine concentrations are usually lower than 600 nM. Our sensors show a negligible interference from uric and ascorbic acids which did not affect sensor performance. A wide linear range (0.1-20 μm for gold nanoparticles, 0.1-10 μm for platinum nanoparticles) with high sensitivity (6.02 and 7.19 μA μM^-1 cm^-2 for gold and platinum, respectively) and a low limit of detection (75 and 62 nM for Au and Pt, respectively) were achieved. Real urine samples were also assayed, where the concentrations of dopamine detected aligned very closely to measurements undertaken using conventional laboratory techniques. Sensor fabrication employed a cost-effective production process with the possibility of also being integrated into flexible substrates, thus allowing for the possible development of wearable sensing devices.

Nanowire-based sensor electronics for chemical and biological applications

Detection and recognition of chemical and biological species via sensor electronics are important not only for various sensing applications but also for fundamental scientific understanding. In the past two decades, sensor devices using one-dimensional (1D) nanowires have emerged as promising and powerful platforms for electrical detection of chemical species and biologically relevant molecules due to their superior sensing performance, long-term stability, and ultra-low power consumption. This paper presents a comprehensive overview of the recent progress and achievements in 1D nanowire synthesis, working principles of nanowire-based sensors, and the applications of nanowire-based sensor electronics in chemical and biological analytes detection and recognition. In addition, some critical issues that hinder the practical applications of 1D nanowire-based sensor electronics, including device reproducibility and selectivity, stability, and power consumption, will be highlighted. Finally, challenges, perspectives, and opportunities for developing advanced and innovative nanowire-based sensor electronics in chemical and biological applications are featured.

PANI-Based Wearable Electrochemical Sensor for pH Sweat Monitoring

Nowadays, we are assisting in the exceptional growth in research relating to the development of wearable devices for sweat analysis. Sweat is a biofluid that contains useful health information and allows a non-invasive, continuous and comfortable collection. For this reason, it is an excellent biofluid for the detection of different analytes. In this work, electrochemical sensors based on polyaniline thin films deposited on the flexible substrate polyethylene terephthalate coated with indium tin oxide were studied. Polyaniline thin films were abstained by the potentiostatic deposition technique, applying a potential of +2 V vs. SCE for 90 s. To improve the sensor performance, the electronic substrate was modified with reduced graphene oxide, obtained at a constant potential of −0.8 V vs. SCE for 200 s, and then polyaniline thin films were electrodeposited on top of the as-deposited substrate. All samples were characterized by XRD, SEM, EDS, static contact angle and FT-IR/ATR analysis to correlate the physical-chemical features with the performance of the sensors. The obtained electrodes were tested as pH sensors in the range from 2 to 8, showing good behavior, with a sensitivity of 62.3 mV/pH, very close to a Nernstian response, and a reproducibility of 3.8%. Interference tests, in the presence of competing ions, aimed to verify the selectivity, were also performed. Finally, a real sweat sample was collected, and the sweat pH was quantified with both the proposed sensor and a commercial pH meter, showing an excellent concordance.

Recent Advancement of Emerging Nano Copper-Based Printable Flexible Hybrid Electronics

Printed copper materials have been attracting significant attention prominently due to their electric, mechanical, and thermal properties. The emerging copper-based flexible electronics and energy-critical applications rely on the control of electric conductivity, current-carrying capacity, and reliability of copper nanostructures and their printable ink materials. In this review, we describe the growth of copper nanostructures as the building blocks for printable ink materials on which a variety of conductive features can be additively manufactured to achieve high electric conductivity and stability. Accordingly, the copper-based flexible hybrid electronics and energy-critical devices printed by different printing techniques are reviewed for emerging applications.

Surface Enhanced Raman Spectroscopy With Electrodeposited Copper Ultramicro-Wires With/Without Silver Nanostars Decoration

The electrochemical preparation of arrays of copper ultramicrowires (CuUWs) by using porous membranes as templates is critically revisited, with the goal of obtaining cheap but efficient substrates for surface enhanced Raman spectroscopy (SERS). The role of the materials used for the electrodeposition is examined, comparing membranes of anodized aluminum oxide (AAO) vs. track-etched polycarbonate (PC) as well as copper vs. glassy carbon (GC) as electrode material. A voltammetric study performed on bare electrodes and potentiostatic tests on membrane coated electrodes allowed the optimization of the deposition parameters. The final arrays of CuUWs were obtained by chemical etching of the template, with NaOH for AAO and CH₂Cl₂ for PC. After total etching of the template, SERS spectra were recorded on CuUWs using benzenethiol as SERS probe with known spectral features. The CuUW substrates displayed good SERS properties, providing enhancement factor in the 10³–10⁴ range. Finally, it was demonstrated that higher Raman enhancement can be achieved when CuUWs are decorated with silver nanostars, supporting the formation of SERS active hot-spots at the bimetallic interface.