Activation of epidermal growth factor receptors in triple-negative breast cancer cells by morphine; analysis through Raman spectroscopy and machine learning.

Triple negative breast cancer (TNBC) is a very aggressive form of breast cancer, and the analgesic drug morphine has been shown to promote the proliferation of TNBC cells. This article investigates whether morphine causes activation of epidermal growth factor receptors (EGFR), the roles of µ-opioid and EGFR receptors on TNBC cell proliferation and migration. While examining the changes with molecular techniques, we also aimed to investigate the analysis ability of Raman spectroscopy and machine learning-based approach. Effects of morphine on the proliferation and migration of MDA.MB.231 cells were evaluated by MTT and scratch wound-healing tests, respectively. Morphine-induced phosphorylation of the EGFR was analyzed by western blotting in the presence and absence of µ-receptor antagonist naltrexone and the EGFR-tyrosine kinase inhibitor gefitinib. Morphine-induced EGFR phosphorylation and cell migration were significantly inhibited by pretreatments with both naltrexone and gefitinib; however, morphine-increased cell proliferation was inhibited only by naltrexone. While morphine-induced changes were observed in the Raman scatterings of the cells, the inhibitory effect of naltrexone was analyzed with similarity to the control group. Principal component analysis (PCA) of the Raman confirmed the epidermal growth factor (EGF)-like effect of morphine and was inhibited by naltrexone and partly by gefitinib pretreatments. Our in vitro results suggest that combining morphine with an EGFR inhibitor or a peripherally acting opioidergic receptor antagonist may be a good strategy for pain relief without triggering cancer proliferation and migration in TNBC patients. In addition, our results demonstrated the feasibility of the Raman spectroscopy and machine learning-based approach as an effective method to investigate the effects of agents in cancer cells without the need for complex and time-consuming sample preparation. The support vector machine (SVM) with linear kernel automatically classified the effects of drugs on cancer cells with ∼95% accuracy.

pH Tunable Patterning of Quantum Dots.

Patterning of quantum dots (QDs) is essential for many, especially high-tech, applications. Here, pH tunable assembly of QDs over functional patterns prepared by electrohydrodynamic jet printing of poly(2-vinylpyridine) is presented. The selective adsorption of QDs from water dispersions is mediated by the electrostatic interaction between the ligand composed of 3-mercaptopropionic acid and patterned poly(2-vinylpyridine). The pH of the dispersion provides tunability at two levels. First, the adsorption density of QDs and fluorescence from the patterns can be modulated for pH > ≈4. Second, patterned features show unique type of disintegration resulting in randomly positioned features within areas defined by the printing for pH ≤ ≈4. The first capability is useful for deterministic patterning of QDs, whereas the second one enables hierarchically structured encoding of information by generating stochastic features of QDs within areas defined by the printing. This second capability is exploited for generating addressable security labels based on unclonable features. Through image analysis and feature matching algorithms, it is demonstrated that such patterns are unclonable in nature and provide a suitable platform for anti-counterfeiting applications. Collectively, the presented approach not only enables effective patterning of QDs, but also establishes key guidelines for addressable assembly of colloidal nanomaterials.

Food-Grade Physically Unclonable Functions.

Counterfeit products in the pharmaceutical and food industries have posed an overwhelmingly increasing threat to the health of individuals and societies. An effective approach to prevent counterfeiting is the attachment of security labels directly on drugs and food products. This approach requires the development of security labels composed of safely digestible materials. In this study, we present the fabrication of security labels entirely based on the use of food-grade materials. The key idea proposed in this study is the exploitation of food-grade corn starch (CS) as an encoding material based on the microscopic dimensions, particulate structure, and adsorbent characteristics. The strong adsorption of a food colorant, erythrosine B (ErB), onto CS results in fluorescent CS@ErB microparticles. Randomly positioned CS@ErB particles can be obtained simply by spin-coating from aqueous solutions of tuned concentrations followed by transfer to an edible gelatin film. The optical and fluorescence microscopy images of randomly positioned particles are then used to construct keys for a physically unclonable function (PUF)-based security label. The performance of PUFs evaluated by uniformity, uniqueness, and randomness analysis demonstrates the strong promise of this platform. The biocompatibility of the fabricated PUFs is confirmed with assays using murine fibroblast cells. The extremely low-cost and sustainable security primitives fabricated from off-the-shelf food materials offer new routes in the fight against counterfeiting.

A flexible wearable device coupled with injectable Fe3O4 nanoparticles for capturing circulating tumor cells and triggering their deaths.

Elimination of circulating tumor cells (CTCs) in the blood can be an effective therapeutic approach to disrupt metastasis. Here, a strategy is proposed to implement flexible wearable electronics and injectable nanomaterials to disrupt the hematogenous transport of CTCs. A flexible device containing an origami magnetic membrane is used to attract Fe3O4@Au nanoparticles (NPs) that are surface modified with specific aptamers and intravenously injected into blood vessels, forming an invisible hand and fishing line/bait configuration to specifically capture CTCs through bonding with aptamers. Thereafter, thinned flexible AlGaAs LEDs in the device offer an average fluence of 15.75 mW mm-2 at a skin penetration depth of 1.5 mm, causing a rapid rise of temperature to 48 °C in the NPs and triggering CTC death in 10 min. The flexible device has been demonstrated for intravascular isolation and enrichment of CTCs with a capture efficiency of 72.31% after 10 cycles in a simulated blood circulation system based on a prosthetic upper limb. The fusion of nanomaterials and flexible electronics reveals an emerging field that utilizes wearable and flexible stimulators to activate biological effects offered by nanomaterials, leading to improved therapeutical effects and postoperative outcomes of diseases.

Self-Healing of Biocompatible Superhydrophobic Coatings: The Interplay of the Size and Loading of Particles.

The broad application potential of superhydrophobic coatings is limited by the usage of environment-threatening materials and poor durability. The nature-inspired design and fabrication of self-healing coatings is a promising approach for addressing these issues. In this study, we report a fluorine-free and biocompatible superhydrophobic coating that can be thermally healed after abrasion. The coating is composed of silica nanoparticles and carnauba wax, and the self-healing is based on surface enrichment of wax in analogy to the wax secretion in plant leaves. The coating not only exhibits fast self-healing, just in 1 min under moderate heating, but also displays increased water repellency and thermal stability after healing. The rapid self-healing ability of the coating is attributed to the relatively low melting point of carnauba wax and its migration to the surface of the hydrophilic silica nanoparticles. The dependence of self-healing on the size and loading of particles provides insights into the process. Furthermore, the coating exhibits high levels of biocompatibility where the viability of fibroblast L929 cells was ∼90%. The presented approach and insights provide valuable guidelines in the design and fabrication of self-healing superhydrophobic coatings.

Scalable Fabrication of MXene-PVDF Nanocomposite Triboelectric Fibers via Thermal Drawing.

In the data-driven world, textile is a valuable resource for improving the quality of life through continuous monitoring of daily activities and physiological signals of humans. Triboelectric nanogenerators (TENG) are an attractive option for self-powered sensor development by coupling energy harvesting and sensing ability. In this study, to the best of the knowledge, scalable fabrication of Ti3 C2 Tx MXene-embedded polyvinylidene fluoride (PVDF) nanocomposite fiber using a thermal drawing process is presented for the first time. The output open circuit voltage and short circuit current show 53% and 58% improvement, respectively, compared to pristine PVDF fiber. The synergistic interaction between the surface termination groups of MXene and polar PVDF polymer enhances the performance of the fiber. The flexibility of the fiber enables the weaving of fabric TENG devices for large-area applications. The fabric TENG (3 × 2 cm2 ) demonstrates a power density of 40.8 mW m-2 at the matching load of 8 MΩ by maintaining a stable performance over 12 000 cycles. Moreover, the fabric TENG has shown the capability of energy harvesting by operating a digital clock and a calculator. A distributed self-powered sensor for human activities and walking pattern monitoring are demonstrated with the fabric.

Rational Integration of ZIF-8 and BiPO4 for Energy Storage and Environmental Applications.

Environmental pollution and energy storage are among the most pivotal challenges of today's world. The development of multifunctional materials is required to address these challenges. Our study presents the rational design and synthesis of a hybrid material (ZIF-8@BiPO4) with dual functionality: an outstanding supercapacitor electrode and an excellent photocatalyst. The ZIF-8@BiPO4 hybrid structure was obtained by conjoining zinc ions and 2-methylimidazole ligands toward BiPO4 by a one-pot stirring route at room temperature. The ZIF-8@BiPO4 resulted in considerably higher specific capacitance (Cs) (489 F g-1 at a scan rate of 5 mV s-1; 497 F g-1 at a current density of 1 A g-1) than that of pure BiPO4 (358; 443 F g-1) and ZIF-8 (185; 178 F g-1) under the same conditions in a three-electrode cell using the 2 M KOH aqueous electrolyte. Afterward, an asymmetric supercapacitor (ASC) device was fabricated with BiPO4 as the anode and ZIF-8@BiPO4 as the cathodes, acquiring an outstanding Cs of 255 F g-1 at a current density of 0.5 A g-1 with significant cycling stability (81% over 10,000 cycles). Moreover, the ASC has an energy density of 17.5 Wh kg-1and a power density of 13,695 W kg-1, which can be considered to be at the borderline between batteries and supercapacitors. The photocatalytic activity of ZIF-8@BiPO4 was further studied using a methylene blue (MB) dye and sildenafil citrate (SC) drug-active molecules. The degradation of MB was approximately 78% through the photocatalytic reduction after 180 min of UV irradiation. The outstanding characteristics together with the ecofriendly and low-cost preparation make ZIF-8@BiPO4 appealing for a broad range of applications.

One-step Green Fabrication of Antimicrobial Surfaces via In Situ Growth of Copper Oxide Nanoparticles.

Microorganisms such as pathogenic bacteria, fungi, and viruses pose a serious threat to human health and society. Surfaces are one of the major pathways for the transmission of infectious diseases. Therefore, imparting antipathogenic properties to these surfaces is significant. Here, we present a rapid, one-step approach for practical fabrication of antimicrobial and antifungal surfaces using an eco-friendly and low-cost reducing agent, the extract of Cedrus libani. Copper oxide nanoparticles were grown in situ on the surface of print paper and fabric in the presence of the copper salt and extract, without the use of any additional chemicals. The morphology and composition of the grown nanoparticles were characterized using field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction techniques. The analysis revealed that the grown particles consist of mainly spherical CuO nanoparticles with an average size of ∼14 nm and its clusters with an average size of ∼700 nm. The in situ growth process enables strong bonding of the nanoparticles to the surface, resulting in enhanced durability against wear and tear. Moreover, the fabricated surface shows excellent growth inhibition ability and bactericidal activity against both gram-negative and gram-positive bacteria, Escherichia coli and Staphylococcus aureus, as well as antifungal activity against Candida albicans, a common pathogenic fungus. The ability to grow copper oxide nanoparticles on different surfaces paves the way for a range of applications in wound dressings, masks, and protective medical equipment.

Mesoporous One-Component Gold Microshells as 3D SERS Substrates.

Surface-enhanced Raman scattering (SERS) is a powerful analytical tool for label-free analysis that has found a broad spectrum of applications in material, chemical, and biomedical sciences. In recent years, a great interest has been witnessed in the rational design of SERS substrates to amplify Raman signals and optionally allow for the selective detection of analytes, which is especially essential and challenging for biomedical applications. In this study, hard templating of noble metals is proposed as a novel approach for the design of one-component tailor-made SERS platforms. Porous Au microparticles were fabricated via dual ex situ adsorption of Au nanoparticles and in situ reduction of HAuCl4 on mesoporous sacrificial microcrystals of vaterite CaCO3. Elimination of the microcrystals at mild conditions resulted in the formation of stable mesoporous one-component Au microshells. SERS performance of the microshells at very low 0.4 µW laser power was probed using rhodamine B and bovine serum albumin showing enhancement factors of 2 × 108 and 8 × 108, respectively. The proposed strategy opens broad avenues for the design and scalable fabrication of one-component porous metal particles that can serve as superior SERS platforms possessing both excellent plasmonic properties and the possibility of selective inclusion of analyte molecules and/or SERS nanotags for highly specific SERS analysis.

Blood repellent superhydrophobic surfaces constructed from nanoparticle-free and biocompatible materials.

Durable and environment friendly superhydrophobic surfaces are needed for a set of important applications. Biomedical applications, in particular, impose stringent requirements on the biocompatibility of the materials used in the fabrication of superhydrophobic surfaces. In this study, we demonstrate the fabrication of mechanically durable superhydrophobic surfaces via an in-situ structuring strategy starting from natural carnauba wax and biocompatible polydimethylsiloxane (PDMS) materials. The transfer of the structure of the paper to a free-standing PDMS film provided the microscale structure. On top of this structured surface, the wax was spray-coated, initially resulting in a relatively homogeneous film with limited liquid repellence. The key in achieving superhydrophobicity was rubbing the surface for in-situ generation of a finely textured wax coating with a water contact angle of 169° and a sliding angle of 3°. The hierarchically structured surface exhibits mechanical robustness as demonstrated with water impact and linear abrasion tests. We finally demonstrate repellence of the surfaces against a range of blood products including platelet suspension, erythrocyte suspension, fresh plasma, and whole blood.

Production of natural chitin film from pupal shell of moth: Fabrication of plasmonic surfaces for SERS-based sensing applications.

Commercially available types of chitin or chitin isolate are usually in powder form and are nanofibrous in microstructure. However, the surface characteristics of natural chitin in the body of insects are currently understudied. Herein, natural chitin film was successfully produced from bio-waste of insect pupae of the Japanese giant silkworm. Two different surface morphologies of the chitin film were observed. We report for the first time a micropapillary surface structure of chitin which was observed on the dorsal side of the film. To further potential of the micropapillary structured natural chitin in sensing applications, we develop a protocol for generating a nanoscopic film of Ag using thermal evaporation. The Ag-deposited natural chitin films exhibited surface-enhanced Raman scattering (SERS) activity to an extent depending on the structure of the film. In conclusion, materials science has been expanded by addition of a natural, three-dimensional chitin film with utilizable properties.

Physically Unclonable Surfaces via Dewetting of Polymer Thin Films.

From anti-counterfeiting to biotechnology applications, there is a strong demand for encoded surfaces with multiple security layers that are prepared by stochastic processes and are adaptable to deterministic fabrication approaches. Here, we present dewetting instabilities in nanoscopic (thickness <100 nm) polymer films as a form of physically unclonable function (PUF). The inherent randomness involved in the dewetting process presents a highly suitable platform for fabricating unclonable surfaces. The thermal annealing-induced dewetting of poly(2-vinyl pyridine) (P2VP) on polystyrene-grafted substrates enables fabrication of randomly positioned functional features that are separated at a microscopic length scale, a requirement set by optical authentication systems. At a first level, PUFs can be simply and readily verified via reflection of visible light. Area-specific electrostatic interactions between P2VP and citrate-stabilized gold nanoparticles allow for fabrication of plasmonic PUFs. The strong surface-enhanced Raman scattering by plasmonic nanoparticles together with incorporation of taggants facilitates a molecular vibration-based security layer. The patterning of P2VP films presents opportunities for fabricating hybrid security labels, which can be resolved through both stochastic and deterministic pathways. The adaptability to a broad range of nanoscale materials, simplicity, versatility, compatibility with conventional fabrication approaches, and high levels of stability offer key opportunities in encoding applications.

Antibacterial, Antiviral, and Self-Cleaning Mats with Sensing Capabilities Based on Electrospun Nanofibers Decorated with ZnO Nanorods and Ag Nanoparticles for Protective Clothing Applications.

The COVID-19 pandemic has clearly shown the importance of developments in fabrication of advanced protective equipment. This study investigates the potential of using multifunctional electrospun poly(methyl methacrylate) (PMMA) nanofibers decorated with ZnO nanorods and Ag nanoparticles (PMMA/ZnO-Ag NFs) in protective mats. Herein, the PMMA/ZnO-Ag NFs with an average diameter of 450 nm were simply prepared on a nonwoven fabric by directly electrospinning from solutions containing PMMA, ZnO nanorods, and Ag nanoparticles. The novel material showed high performance with four functionalities (i) antibacterial agent for killing of Gram-negative and Gram-positive bacteria, (ii) antiviral agent for inhibition of corona and influenza viruses, (iii) photocatalyst for degradation of organic pollutants, enabling a self-cleaning protective mat, and (iv) reusable surface-enhanced Raman scattering substrate for quantitative analysis of trace pollutants on the nanofiber. This multi-functional material has high potential for use in protective clothing applications by providing passive and active protection pathways together with sensing capabilities.

SERS-active linear barcodes by microfluidic-assisted patterning.

Simple, low-cost, robust, and scalable fabrication of microscopic linear barcodes with high levels of complexity and multiple authentication layers is critical for emerging applications in information security and anti-counterfeiting. This manuscript presents a novel approach for fabrication of microscopic linear barcodes that can be visualized under Raman microscopy. Microfluidic channels are used as molds to generate linear patterns of end-grafted polymers on a substrate. These patterns serve as templates for area-selective binding of colloidal gold nanoparticles resulting in plasmonic arrays. The deposition of multiple taggant molecules on the plasmonic arrays via a second microfluidic mold results in a linear barcode with unique Raman fingerprints that are enhanced by the underlying plasmonic nanoparticles. The width of the bars is as small as 10 µm, with a total barcode length on the order of 100 µm. The simultaneous use of geometric and chemical security layers provides a high level of complexity challenging the counterfeiting of the barcodes. The additive, scalable, and inexpensive nature of the presented approach can be easily adapted to different colloidal nanomaterials and applications.

Chemical Funneling of Colloidal Gold Nanoparticles on Printed Arrays of End-Grafted Polymers for Plasmonic Applications.

Spatially defined assembly of colloidal metallic nanoparticles is necessary for fabrication of plasmonic devices. In this study, we demonstrate high-resolution additive jet printing of end-functional polymers to serve as templates for directed self-assembly of nanoparticles into architectures with substantial plasmonic activity. The intriguing aspect of this work is the ability to form patterns of end-grafted poly(ethylene glycol) through printing on a hydrophobic layer that consists of fluoroalkylsilanes. The simultaneous dewetting of the underlying hydrophobic layer together with grafting of the printed polymer during thermal annealing enables fabrication of spatially defined binding sites for assembly of nanoparticles. The employment of electrohydrodynamic jet printing and aqueous inks together with reduction of the feature size during thermal annealing are critically important in achieving high chemical contrast patterns as small as ∼250 nm. Gold nanospheres of varying diameters selectively bind and assemble into nanostructures with reduced interparticle distances on the hydrophilic patterns of poly(ethylene glycol) surrounded with a hydrophobic background. The resulting plasmonic arrays exhibit intense and pattern-specific signals in surface-enhanced Raman scattering (SERS) spectroscopy. The localized seed-mediated growth of metallic nanostructures over the patterned gold nanospheres presents further routes for expanding the composition of the plasmonic arrays. A representative application in SERS-based surface encoding is demonstrated through large-area patterning of plasmonic structures and multiplex deposition of taggant molecules, all enabled by printing.

Usage of natural chitosan membrane obtained from insect corneal lenses as a drug carrier and its potential for point of care tests.

Chitosan is an indispensable biopolymer for use as a drug carrier thanks to its non-toxic, biodegradable, biocompatible, antimicrobial, and anti-oxidative nature. In previous studies, chitosan was first dissolved into weak acids and formed into gel, then used for carrying pharmaceutically active compounds such as nanoparticles, capsules, composites, and films. Using the produced chitosan gel after dissolving it in weak acids has advantages, such as ease of processing for loading the required amount of active substance and making the desired shape and size. However, dissolved chitosan loses some of its natural properties such as fibrous structure, crystallinity, and thermal stability. In this study, for the first time, three-dimensional chitosan lenses obtained from an insect's (Tabanus bovinus) compound eyes, with the original shape intact, were tested as a drug carrier. A model drug, quercetin, was loaded into chitosan membrane, and its release profile was examined. Also, a point-of-care test was conducted for both chitin and chitosan membranes. Chitin and chitosan membranes obtained from insect corneal lenses were characterized by using FTIR, TGA, elemental analysis, and surface wettability analysis as well as stereo, binocular, and scanning electron microscopies. It was observed that chitosan membrane could be used as a drug carrier material. Both chitin and chitosan membranes will be improved for lateral flow assay, and these membranes can be tested for other bioengineering applications in further studies.

Synthesis of Ag and TiO2 modified polycaprolactone electrospun nanofibers (PCL/TiO2-Ag NFs) as a multifunctional material for SERS, photocatalysis and antibacterial applications.

In this study, we reported the design and the fabrication of Ag and TiO2 modified polycaprolactone (PCL) electrospun nanofiber (NF) mats. The as-prepared NF mats were fabricated by one-step electrospinning and it was exploited for three different purposes (i) reusable SERS substrate for quantitative analysis to trace organic pollutants, (ii) photocatalyst for degradation of organic pollutants and (iii) antibacterial agent for killing of bacteria. Three different nanofiber mats, PCL, PCL-TiO2, PCL/TiO2-Ag NFs. were fabricated and further investigated. The morphologies and structures of the as-prepared nanofiber mats were carried out using X-ray diffraction spectroscopy (XRD), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX) and fourier transform infrared spectroscopy (FT-IR) techniques. PCL/TiO2-Ag NFs served as a highly effective SERS platform with a detection limit of 10 nM for the detection of methylene blue dye (MB). A remarkable feature of the presented platform is the ability to reuse the PCL/TiO2-Ag NFs for SERS analysis of MB; availing from its capability for self-cleaning under UV light. By employing PCL/TiO2-Ag NFs nanocatalyst, complete photocatalytic degradation of the probe analytes MB and ibuprofen (Ibu) under UV irradiation was accomplished not more than 180 min. Moreover, PCL/TiO2-Ag NF mats showed a highly promising bactericidal feature against gram-negative Escherichia coli and gram-positive Staphylococcus aureus bacteria, which immensely emerged due to the presence of Ag NPs. This new trending nanofiber is assumed to lead a bunch of changes in the field of photocatalytic, SERS and antibacterial studies.

Writing chemical patterns using electrospun fibers as nanoscale inkpots for directed assembly of colloidal nanocrystals.

Applications that range from electronics to biotechnology will greatly benefit from low-cost, scalable and multiplex fabrication of spatially defined arrays of colloidal inorganic nanocrystals. In this work, we present a novel additive patterning approach based on the use of electrospun nanofibers (NFs) as inkpots for end-functional polymers. The localized grafting of end-functional polymers from spatially defined nanofibers results in covalently bound chemical patterns. The main factors that determine the width of the nanopatterns are the diameter of the NF and the extent of spreading during the thermal annealing process. Lowering the surface energy of the substrates via silanization and a proper choice of the grafting conditions enable the fabrication of nanoscale patterns over centimeter length scales. The fabricated patterns of end-grafted polymers serve as the templates for spatially defined assembly of colloidal metal and metal oxide nanocrystals of varying sizes (15 to 100 nm), shapes (spherical, cube, rod), and compositions (Au, Ag, Pt, TiO2), as well as semiconductor quantum dots, including the assembly of semiconductor nanoplatelets.

Plasmonic assemblies of gold nanorods on nanoscale patterns of poly(ethylene glycol): Application in surface-enhanced Raman spectroscopy.

Approaches are needed for the tailored assembly of plasmonic building blocks on the surface of substrates to synergistically enhance their properties. Here we demonstrate selective immobilization and assembly of gold nanorods (NRs) on substrates modified and patterned with end-grafted poly(ethylene glycol) (PEG) layers. The ligand exchange from the initial cetyltrimethylammonium bromide to sodium citrate was necessary for the immobilization of gold NRs onto PEG grafted substrates. Linear nanopatterns of PEG were fabricated using electrospun nanofibers as masks in oxygen plasma etching. The selective immobilization of citrate-stabilized gold NRs with a length of ∼50 nm and a width of 20 nm on the nanopatterned PEG layers led to linear and registered arrays of rods. The number of gold NRs per line depended on the width of the patterns and approached 1 when the width of the patterns was comparable to the length of the rods. The confinement of the binding regions led to a ∼3 fold increase in the number of gold NRs immobilized per unit area. The selective and dense immobilization of gold NRs on the nanoscale patterns of PEG resulted in spatially defined and strong surface-enhanced Raman scattering activity enabling detection of molecules at concentrations as low as 1 nM.

Fabrication of Plasmonically Active Substrates Using Engineered Silver Nanostructures for SERS Applications.

Demanding applications in sensing, metasurfaces, catalysis, and biotechnology require fabrication of plasmonically active substrates. Herein, we demonstrate a bottom-up, versatile, and scalable approach that relies on direct growth of silver nanostructures from seed particles that were immobilized on polymer brush-grafted substrates. Our approach is based on (i) the uniform and tunable assembly of citrate-stabilized gold nanoparticles on poly(ethylene glycol) brushes to serve as seeds and (ii) the use of hydroquinone as a reducing agent, which is extremely selective to the presence of seed particles, confining the growth of silver nanostructures on the surface of the substrate. The diameter of the seed particles, concentration, as well as ratio of reactants and duration of the growth process are investigated for large-area growth of silver nanostructures with high surface coverage and plasmonic activity. The resulting silver nanostructures exhibit high levels of surface-enhanced Raman scattering activity at two different laser lines and allow detection of molecules at concentrations as low as 10 pM. The plasmonic properties of the silver nanostructures are further studied using ultrafast pump-probe spectroscopy. Spatially defined silver nanostructures are fabricated through the seed particles that are patterned via soft lithography, showing the capabilities of the presented approach in device applications.