Self-assembled Polyelectrolyte Multilayers Research Articles

Novel Anion-Exchange Blend Membranes Comprised of a Commercially Available & Water-Soluble Ionomer for All-Vanadium Redox Flow Batteries

The All-Vanadium Redox Flow Battery is a promising technology for solving the problem of cost-efficient and safe large-scale storage of renewable energies [1]. One key component of the batteries, which alters the performance and long-term stability of those systems, is the membrane. For this purpose, Nafion based membranes are often used. However, these membranes are high in cost and show a significant capacity fading and reduction of coulombic efficiency mainly due to crossover of vanadium species [2]. One way around this is to use commercially available, low-cost materials with positively charged ammonium groups, which can effectively repel positively charged vanadium species due to the Donnan exclusion effect [3, 4].In this work we present novel anion-exchange blend membranes comprised of a commercially available and water-soluble ionomer and a PBI blend matrix, which can be used in All-Vanadium Redox Flow batteries. For this approach the water-soluble ionomer was modified to achieve solubility in organic solvents and miscibility with the matrix polymer. The resulting membranes show good mechanical properties even at high IECs and can be modified in a wide range of properties by adjusting the amounts of ionomer and matrix polymer and/or by the addition of crosslinking agents.The above-mentioned membranes were characterised ex-situ by using EIS, NMR spectroscopy, IR spectroscopy, DMA, TGA, tensile tests and permeability tests. In addition, first promising in-situ characterisations were performed in a VRFB single-cell test station.Literature[1] Fan, X; Liu, B; Liu, J; Ding, J; Han, X; Deng, Y; Lv, X; Xie, Y; Chen, B; Hu, W; Zhong, C.: Battery Technologies for Grid-Level Large-Scale Electrical Energy Storage. Trans. Tianjin Univ. 2020, 92 – 103.[2] Düerkop, D; Widdecke, H; Schilde, C; Kunz, U; Schmiemann, A.: Polymer Membranes for All-Vanadium Redox Flow Batteries: A Review. Membranes 2021.[3] Xi, J; Wu, Z; Teng, X; Zhao, Y; Chen, L; Qiu, X.: Self-assembled polyelectrolyte multilayer modified Nafion membrane with suppressed vanadium ion crossover for vanadium redox flow batteries. J. Mater. Chem. 2008, 1232.[4] Mohammadi, T; Kazacos, M.: Modification of anion-exchange membranes for vanadium redox flow battery applications. Journal of Power Sources 1996, 179 – 186.

Fluorescence Signal Enhancement by a Spray-Assisted Layer-by-Layer Technique on Aluminum Tape Devices for Biosensing Applications

Layer-by-layer (LbL) self-assembled polyelectrolyte multilayer (PEM) films are a simple yet elegant bottom-up technology to create films at the nano-microscale. This low-cost technology has been widely used as a universal functionalization technique on a broad spectrum of substrates. Biomolecules under investigation can be incubated onto films based on complementary charge interactions between the films and biomolecules. There is a great demand for developing an ultralow-cost biosensing device, which can optimally enhance the fluorescence signal of the adsorbed biomolecules from the traditional labeled sensing platforms. In this work, we have incorporated a blend of the conventional metal enhanced fluorescence technology and the PEM as a dielectric spacer and functionalized film, coated on an aluminum paper (tape)-based substrate. These device has been found to be capable of holding biomolecules in three-dimensional PEM space. The devices fabricated by the proposed spray LbL technique provide significant fluorescence signal enhancement by holding a relatively higher mass per volume of the adsorbed biomolecules, when compared to traditional spin- and dip-coating techniques. Interestingly, our proposed device has expressed a fluorescence enhancement factor, which is 9 times higher than PEM-functionalized glass-based devices. To demonstrate the practical utility of our devices, we also compared our devices to Whatman FAST slides. Our experimental fluorescence results are almost comparable to Whatman FAST slides. Such PEM devices fabricated on top of low-cost aluminum tape using a spray LbL technique give new insights into the future development of ultralow-cost, high-throughput, and disposable lab-on-chip diagnostic applications.

ElectroSens Platform with a Polyelectrolyte-Based Carbon Fiber Sensor for Point-of-Care Analysis of Zn in Blood and Urine.

In this paper, we describe an electrochemical sensing platform—ElectroSens—for the detection of Zn based on self-assembled polyelectrolyte multilayers on the carbon fiber (CF) electrode surface. The CF-extended surface facilitates the usage of a small volume electrochemical cell (1 mL) without stirring. This approach allows making a low-cost three-electrode platform. Working electrode modification with layer-by-layer assembly of polyethyleneimine (PEI), poly(sodium 4-styrenesulfonate) (PSS), and mercury nitrate layers eliminates solution toxicity and provides stable stripping voltammetry measurements. The stable, robust, sustainable, and even reusable Ag/AgCl reference electrode consists of adsorbed 32 PEI-KCl/PSS-KCl bilayers on the CF/silver paste separated from the outer solution by a polyvinyl chloride membrane. The polyelectrolyte-based sensor interface prevents adsorption of protein molecules from biological liquids on the CF surface that leads to a sensitivity increase of up to 2.2 μA/M for Zn2+ detection and provides a low limit of detection of 4.6 × 10–8 M. The linear range for Zn detection is 1 × 10–7 to 1 × 10–5 M. A portable potentiostat connected via wireless to a smartphone with an android-based software is also provided. The ElectroSens demonstrates reproducibility and repeatability of data for the detection of Zn in blood and urine without the digestion step.

Micro-Patterned Polystyrene Sheets as Templates for Interlinked 3D Polyelectrolyte Multilayer Microstructures

Polystyrene (PS) is currently mainly used as a sacrificial template during pattern release upon microcontact printing or for self-assembled flat free-standing films. We hereby present a method for creating 3D microstructured free-standing self-assembled polyelectrolyte multilayer (PEM) thin films. The approach presented utilizes a sacrificial microstructured PS template which can be coated with PEM thin films, whereby dissolution of the PS facilitates a free-standing 3D microstructured PEM film. The PS templating approach allows for omitting hot embossing on silicon masters, since PS templates can be prepared by drop casting on silicon masters. The prepared PEM film offers, if gold nanoparticles are incorporated, stimuli-responsive properties like light-induced chamber opening.

Electrophoretic Deposition of Ni(OH)2 Nanoplatelets Modified by Polyelectrolyte Multilayers: Study of the Coatings Formation in a Laminar Flow Cell

The electrophoretic deposition (EPD) of semiconductor ceramic nanoplatelets functionalized by self-assembled polyelectrolyte multilayers has been investigated. The influence of particle surface modification in the packing of the nanostructured film on a nickel cathode has been determined for different electrical conditions. A polymer multilayer shell has been fashioned onto β-Ni(OH)2 nanoplatelets surfaces by alternating the adsorption of Polyethylenimine (PEI) and Polyacrylic Acid (PAA). Two different core-shell systems with 1, 3 and 5 layers were considered using either linear or branched PEI as polycation to alternate with the anionic polyelectrolyte (PAA). The Layer by Layer, (LbL) build-up of polyanions and polycations was characterized both in terms of particle zeta potential measurements and in situ measurements of polyelectrolyte adsorption onto a flat substrate by optical fixed-angle reflectometry. The amount of polyelectrolyte required to build up each layer was determined from zeta potential measurements. Both data allowed the design of the in situ formation of the core-shell nanostructures as well as the shaping of the particulated coatings following the one-pot procedure, avoiding intermediate steps of drying or washing. The movement of the core-shell particles, their aggregation state and the coating growth during electrophoretic deposition were studied in situ using a laminar flow cell coupled to an optical microscope. The particle flux was calculated from the surface coverage of the cathode and compared to the values estimated by the EPD electrokinetic model, demonstrating the strong impact of the steric interactions between the core-shell particles in both the deposition rate of nanoplatelets and the coating morphology.

Reversible and irreversible pH induced conformational changes in self-assembled weak polyelectrolyte multilayers probed using etched fiber Bragg grating sensors

Polyelectrolytes are charged polymer species which electrostatically adsorb onto surfaces in a layer by layer fashion leading to the sequential assembly of multilayer structures. It is known that the morphology of weak polyelectrolyte structures is strongly influenced by environmental variables such as pH. We created a weak polyelectrolyte multilayer structure (∼100nm thick) of cationic polymer poly-allylamine hydrochloride (PAH) and an anionic polymer poly-acrylic acid (PAA) on an etched clad fiber Bragg grating (EFBG) to study the pH induced conformational transitions in the polymer multilayers brought about by the variation in charge density of weak polyelectrolyte groups as a function of pH. The conformational changes of the polyelectrolyte multilayer structure lead to changes in optical density of the adsorbed film which reflects in the shift of the Bragg wavelength from the EFBG. Using the EFBG system we were able to probe reversible and irreversible pH induced transitions in the PAH/PAA weak polyelectrolyte system.

Designing a Multicellular Organotypic 3D Liver Model with a Detachable, Nanoscale Polymeric Space of Disse

The design of in vitro models that mimic the stratified multicellular hepatic microenvironment continues to be challenging. Although several in vitro hepatic cultures have been shown to exhibit liver functions, their physiological relevance is limited due to significant deviation from in vivo cellular composition. We report the assembly of a novel three-dimensional (3D) organotypic liver model incorporating three different cell types (hepatocytes, liver sinusoidal endothelial cells, and Kupffer cells) and a polymeric interface that mimics the Space of Disse. The nanoscale interface is detachable, optically transparent, derived from self-assembled polyelectrolyte multilayers, and exhibits a Young's modulus similar to in vivo values for liver tissue. Only the 3D liver models simultaneously maintain hepatic phenotype and elicit proliferation, while achieving cellular ratios found in vivo. The nanoscale detachable polymeric interfaces can be modulated to mimic basement membranes that exhibit a wide range of physical properties. This facile approach offers a versatile new avenue in the assembly of engineered tissues. These results demonstrate the ability of the tri-cellular 3D cultures to serve as an organotypic hepatic model that elicits proliferation and maintenance of phenotype and in vivo-like cellular ratios.

Preparation and in vitro blood compatibility of chitosan/PLGA-heparin nanoparticles polyelectrolyte multilayers on titanium surface

Objective To improve the blood compatibility of titanium coated with chitosan/PLGAHep polyelectrolyte muhilayer films (CS/PLGA-Hep PEMs) on its surface.Methods (1) Double emulsion method was used to prepare PLGA-Heparin nanoparticles (PLGA-Hep NPs) ; (2) Polyelectrolyte multilayers containing chitosan and PLGA-Hep nanoparticles on titanium surface were prepared by using layer by layer self-assembly technique.The physical and chemical properties of the coatings on the titanium surface were analyzed ; (3) The in vitro blood compatibility of the polyelectrolyte multilayer films was evaluated.Results (1) Polyelectrolyte multilayers by using PLGA-Hep self-assembly had smooth surface and uniform structure; (2) The in vitro hemolysis rate of Chitosan/PLGA-Heparin polyelectrolyte multilayers was 0.737％,which was significantly lower than in control group (P ＜ 0.05) ; (3) The activated partial thromboplastin time was prolonged to (72.33 ± 1.95) s in Chitosan/PLGA-Heparin group as compared with control group (P ＜ 0.05).The plasma C3a level in Chitosan/PLGA-Heparin group was (1.23 ±0.39) mg/L,which was significantly lower than in control group (P ＜ 0.05).Platelet adhesion assay indicated this coatings could reduce platelet adhesion and activation.Conclusion Chitosan and PLGA-Hep NPs self-assembled polyelectrolyte multilayers can improve the in vitro blood compatibility of titanium. Key words: Heparin; Chitosan; Nanoparticles ; Biocompatibility

Controlling Fibroblast Adhesion with Ph Modified Polyelectrolyte Multilayers

Tissue cells need to adhere to a biomaterial surface to promote their growth and differentiation and, thus, foster the integration of implants. As a result, surface features and their modification play an important role in biomedical applications. In this study, the layer-by-layer (LbL) technique was used to design self-assembled polyelectrolyte multilayer (PEM) coatings of polyethyleneimine (PEI) and heparin (HEP) on glass, which will control the adhesion of primary human dermal fibroblasts in a model system. The study showed that, among other surface features, the wettability of surfaces can be controlled by changing the conditions during multilayer self-assembly. Here, the pH value of the HEP solution was adjusted to acidic or alkaline values for terminal layers, which also led to a change in multilayer growth. Further, the study revealed that plain terminal layers were rather cytophobic. Upon pre-adsorption of fibronectin (FN), a clear effect on cell adhesion and morphology in dependence on the pH setup was evident. Proliferation studies clearly showed that terminal layers, which impaired cell adhesion, also inhibited growth of human fibroblasts under serum-conditions. On the other hand, on layers with pronounced cell adhesion an elevated cell growth was also observed. As a result, HEP terminated multilayers are interesting for applications requiring cell repellent properties, whereas PEI terminated multilayers could be used to promote cell adhesion and growth on implant surfaces.

Enhanced sucrose sensing sensitivity of long period fiber grating by self-assembled polyelectrolyte multilayers

The response laws of long period fiber grating (LPFG) coated with polyelectrolyte multilayers (PEMs) of poly(allylamine hydrochloride) (PAH)/poly(sodium-p-styrenesulfonate) (PSS) to a series of concentration of sucrose solutions were investigated. Experimental results showed that the central wavelengths of LPFG spectra move to short-wave as concentration of sucrose solution increase. Pure LPFGs show the optimal sensitivity to 55–60% of sucrose solutions. With increasing number of the layers, the most sensitive regions of LPFGs to sucrose solutions will shift from high concentration to low concentration by matching average refractive index of films and sucrose solutions with that of LPFG cladding. LPFGs assembled with 100 bilayers of PAH/PSS exhibited the optimal sensitivity to 20–25% of sucrose solutions. However, LPFGs coated with 115 bilayers were more sensitive to a lower concentration (<5%) of sucrose solution. Therefore, the sensitivity of LPFG to the small molecular weight analytes can be strongly improved by designing the refractive index and thickness of PEM overlay, as confirmed and interpreted by theoretical simulations.

Engineering the Extracellular Environment: Strategies for Building 2D and 3D Cellular Structures

Cell fate is regulated by extracellular environmental signals. Receptor specific interaction of the cell with proteins, glycans, soluble factors as well as neighboring cells can steer cells towards proliferation, differentiation, apoptosis or migration. In this review, approaches to build cellular structures by engineering aspects of the extracellular environment are described. These methods include non-specific modifications to control the wettability and stiffness of surfaces using self-assembled monolayers (SAMs) and polyelectrolyte multilayers (PEMs) as well as methods where the temporal activation and spatial distribution of adhesion ligands is controlled. Building on these techniques, construction of two-dimensional cell sheets using temperature sensitive polymers or electrochemical dissolution is described together with current applications of these grafts in the clinical arena. Finally, methods to pattern cells in three-dimensions as well as to functionalize the 3D environment with biologic motifs take us one step closer to being able to engineer multicellular tissues and organs.

Biocompatible, Detachable, and Free-Standing Polyelectrolyte Multilayer Films

Self-assembled polyelectrolyte multilayers have gained tremendous popularity over the past decade and have been incorporated in diverse applications. However, the fabrication of detachable and free-standing polyelectrolyte multilayers (PEMs) has proven to be difficult. We report the design of detachable, free-standing, and biocompatible PEMs comprised of hyaluronic acid (anionic PE) and chitosan (cationic PE). These PEMs can be detached from an underlying inert substrate without any postprocessing steps. Our approach enables the fabrication of detachable PEMs from a wide range of polyelectrolytes. Cross-linked PEMs exhibited greater than 95% weight retention when maintained in phosphate buffered saline at 37 °C over a seven day period. The PEM thickness was approximately 3 μm for dried films and increased 2-fold under hydration. A unique feature of the detachable, free-standing PEMs is their optical transparency in the 400-900 nm range under hydrated conditions. The Young's modulus of the cross-linked films ranged from 300-400 MPa, rendering these detachable free-standing multilayers ideal for biomaterial applications. BALB/c 3T3 fibroblasts adhered on the PEMs and colonized the entire surface over a six day period. The cellular responses, as well as the physical properties, demonstrate that the detachable PEM films exhibit tremendous potential for applications in biomaterials and tissue engineering.

Fabrication of selective anti-biofouling surface for micro/nanopatterning of proteins

This paper reports a simple method for creating a functionalized surface for the efficient micro/nanopatterning of proteins by micromolding in capillaries (MIMIC) of poly(ethylene glycol)-poly(lactide) diblock copolymer (PEG-PLA) and self-assembled polyelectrolyte multilayers (PEL). The fabricated surface consisted of two distinct regions: a PEL region to promote protein immobilization and a PEG-PLA background as a biological barrier to prevent the nonspecific binding of proteins. When the ability of anti-biofouling of PEG-PLA was compared with the most widely used blocking agents, such as bovine serum albumin (BSA) and skim milk, the PEG-PLA prevents the nonspecific adsorption of several proteins. The properties of a functionalized surface were characterized by the water contact angle and atomic force microscopy (AFM). Topological analysis clearly indicated that the MIMIC method provides a reliable surface regardless of the micro- and nanopattern size. Two different functionalities of the fabricated surface produce uniform protein patterns from the micro- to nanoscale with a high signal to noise ratio. The proposed method allows for flexibility in forming shapes, such as lines, squares, circles, triangles and stars, and can control the pattern size from 400 nm to 90 μm. Finally, the antigen-antibody assay showed good linearity over the range of 10 ng/mL to 25 μg/mL, indicating its feasibility for a quantitative measurement of the concentration of target proteins in a sample.

Mechanism of Surface Molecular Imprinting in Polyelectrolyte Multilayers

The combination of Layer-by-Layer (LbL) self-assembly of oppositely charged polymers with the concept of molecular imprinting in polymers promises faster loading/unloading as compared to bulk systems. Here, we monitor the construction of LbL self-assembled polyelectrolyte multilayers (PEM) including template molecules and the binding and release dynamics of the guest molecules in the imprinted sites employing a quartz crystal microbalance with dissipation measurement (QCM-D). It is found that pH-dependent removal and rebinding of the template leads to a simultaneous swelling of the film. Separating the swelling from the template kinetics is a task which can be carried out by careful interpretation of the obtained QCM-D data. Considering correlated frequency and dissipation changes, evidence is found that the film features binding sites that can be loaded with the template such that the major part of template uptake is due to selective binding into imprinted sites. Template uptake is causing an enhanced cross-linking, as monitored by a reduced dissipation. The mechanism of reversible template uptake and release is shown to be based on the charge equilibrium in the film, which is manipulated by pH variation.

Preparation of bacteria microarray using selective patterning of polyelectrolyte multilayer and poly(ethylene glycol)-poly(lactide) diblock copolymer

This study reports a simple but efficient method for create bacteria microarrays on a predesigned functional surface consisting of two distinctive regions; a bacterial immobilizing area and a nonimmobilizing region. The functionalized surface was fabricated by a combination of self-assembled polyelectrolyte multilayers (PEL) and micromolding in the capillaries (MIMIC) of poly(ethylene glycol)-poly(d,l-lactide) diblock copolymer (PEGPLA). The PEL region provides bacterial immobilization, and the nonspecific binding of bacteria was prevented using PEG-PLA as passivation molecules. The topological change in the functionalized surface was characterized by atomic force microscopy (AFM), which suggested the occurrence of a laterally homogeneous and well defined surface modification. An analysis of the fluorescence signals from the bacteria microarray indicates that the bacteria are viable and grow after immobilization on patterned surface features. The rapid fabrication of two different functionalities on the surface results in a uniform bacteria pattern with a high signal to noise ratio and shape flexibility, such as lines, squares, and circles. Moreover, the pattern size could be controlled from 20 to 100 μm.

Nanopatterning of proteins using composite nanomold and self-assembled polyelectrolyte multilayers

This paper describes the simple nanopatterning of proteins on polyelectrolyte surfaces using microcontact printing with a nanopatternable, hydrophilic composite nanomold. The composite nanomold was easily fabricated by blending two UV-curable materials composed of Norland Optical Adhesives (NOA) 63 and poly(ethylene glycol) dimethacrylate (PEG-DMA). NOA 63 provided stable nanostructure formation and PEG-DMA induced high wettability of proteins in the nanomold. Using the composite mold and functionalized surface with polyelectrolytes, the fluorescent, isothiocyanate-tagged, bovine serum albumin (FITC-BSA) was successfully patterned with 8 nm height and 500 nm width. To confirm the feasibility of the protein assay on a nanoscale, a glycoprotein-lectin assay was successfully demonstrated as a model system. As expected, the lectins correctly recognized the nano-patterned glycoproteins such as chicken ovalbumin. The simple preparation of composite nanomold and functionalized surface with a universal platform can be applied to various biomolecules such as DNA, proteins, carbohydrates, and other biomolecules on a nanoscale.

Formation of Self-Assembled Polyelectrolyte Multilayer Nanodots by Scanning Probe Microscopy

We demonstrate that patterned nanodots can be obtained from alternatively self-assembled polyelectrolytes which consist of poly(acrylic acid) (PAA) and poly(allylamine hydrochloride) (PAH) by using atomic force microscopy. The surface potentials are easily reversible as positive or negative depending on the kind of the top polyelectrolyte layer. With the layer by layer growth, the nanodots are formed exactly on the charged area and their thicknesses proportionally increase to the total number of monolayers with a uniform thickness of about 0.5 nm.

Self-assembled polyelectrolyte multilayered films on Nafion with lowered methanol cross-over for DMFC applications

The paper is concerned with the deposition of self-assembled polyelectrolyte multilayer on Nafion membrane by layer-by-layer (LbL) technique with lowered methanol cross-over for direct methanol fuel cell (DMFC) applications. The formation of self-assembled multilayered film on Nafion was characterized by UV–vis spectroscopy and it was found that the polyelectrolyte layers growth on the Nafion surface regularly. Furthermore, the proton conductivity and methanol cross-over measurements were carried out for characterization of the LbL self-assembled composite membranes. The results showed that the concentration and pH of the polyelectrolytes significantly affect the proton conductivity and methanol barrier properties of the composite membranes. 10 −1 monomol polyelectrolyte concentration and pH 1.8 was found to be optimum deposition conditions considering proton conductivity and methanol permeation properties of the LbL self-assembled composite membranes. The methanol permeability of the 10 bi-layers of PAH1.8/PSS1.8 deposited LbL self-assembly composite membrane was significantly suppressed and found to be 4.41 × 10 −7 cm 2/s while the proton conductivity value is in acceptable range for fuel cell applications.

Self-assembled polyelectrolyte multilayer modified Nafion membrane with suppressed vanadium ion crossover for vanadium redox flow batteries

The crossover of vanadium ions through proton-exchange membranes such as those of Nafion is the chief reason that results in the low energy efficiency and high self-discharge rate of vanadium redox flow batteries (VRB). With respect to applicability, the ideal proton-exchange membrane used in VRB should possess simultaneously high proton conductivity and low vanadium ion permeability. Here, we report a novel approach using a polyelectrolyte layer-by-layer self-assembly technique to fabricate a barrier layer onto the surface of Nafion membrane by alternate adsorption of polycation poly(diallyldimethylammonium chloride) (PDDA) and polyanion poly(sodium styrene sulfonate) (PSS), which can suppress the crossover of vanadium ions. The Nafion–[PDDA-PSS]n membrane (n = the number of multilayers) obtained shows much lower vanadium ion permeability compared with plain Nafion membrane. Accordingly, the VRB with Nafion–[PDDA-PSS]n membrane exhibits a higher coulombic efficiency (CE) and energy efficiency (EE) together with a slower self-discharge rate than that of Nafion system. The highest CE of 97.6% and EE of 83.9% can be achieved at charge–discharge current density of 80 mA cm−2 and 20 mA cm−2, respectively.

Selective Assembly of Colloidal Particles on a Nanostructured Template Coated with Polyelectrolyte Multilayers

The development of twoand three-dimensional (2D/3D) structures made up of colloidal particles has received considerable attention with respect to their potential applications in biochip devices and sensors, optoelectronic devices, and photonic bandgap materials. These device applications require precisely controlled and uniformly self-assembled structures over large areas. Template-assisted organization with a physically or chemically patterned substrate has been a promising approach due to its advantages in creating longrange order with fewer defects, and the engineering of a new crystalline structure. Microor nanoscale physical patterns on a template can be prepared with photolithography, electron-beam lithography, and ion-beam etching. The resulting template allows accurate positioning and control of colloidal clusters on the nanoscale. For example, Yin et al. and Xia et al. fabricated well controlled sizes and shapes of colloidal clusters by combining topological templating and capillary forces. Cui et al. demonstrated that the physical template can be applied to the integration of nanoparticles, and developed colloidal nanocrystals on lithographically patterned substrates. However, these methods are limited to arrays of monofunctional particles due to their deficiency in differentiating between different functionalized particles. On the other hand, chemical templating has been achieved by developing self-assembled monolayers and polyelectrolyte multilayers using soft lithographic and photolithographic techniques, and these approaches can allow the introduction of two or more different functional groups on the substrate for creating multicomponent particle arrays. For example, Zheng et al. demonstrated the fabrication of two differently charged particle arrays on patterned polyelectrolyte multilayer templates; however, these processes still have some limitations with respect to the precise spatial control of particles on the chemically patterned template. As particle size is decreased, there are also challenges with flat 2D chemical patterns due to the limited region of contact between the particle and surface. Here, we examine a combination of physical and chemical patterning to achieve an optimized degree of spatial control, pattern stability, and selectivity. In this work, we present a technique for preparing chemically modified nanotemplates and their use in the development of sub-micrometer-scale particle arrays via self-organization on the surface. Recently, we developed nanostructured polymer molds using high-modulus (∼ 2 GPa at 25 °C) UV-curable photopolymers with favorable mechanical properties and excellent replication characteristics. In this previous work, we introduced this material for the preparation of physical templates of nanostructures and created functional chemical patterns on the template, using electrostatic layer-by-layer (LBL) assembly and polymer-on-polymer stamping processes. In the LBL assembly process, thin bilayers on the template are created via alternate adsorption of oppositely charged polyelectrolytes. Figure 1 illustrates the sample fabrication process employed to realize the nanotemplating and selective assembly of colloidal particles on the surface. A nanostructured template was prepared by molding the UV-curable polyurethanebased photopolymers on a silicon master substrate. Then, the template was coated with polyelectrolyte multilayers using the LBL deposition process to provide a charged functionality. The polyelectrolytes used here were poly(allylamine hydrochloride) (PAH) or poly(diallyldimethylammonium chloride) (PDAC) as polycations and sulfonated polystyrene (SPS) as a polyanion. The photopolymer surface was plasma treated prior to assembly and the polycation was absorbed first on the surface. The LBL process was repeated until 10.5 bilayers of (PAH–SPS) or (PDAC–SPS) were constructed, finishing with an outermost layer of PAH or PDAC to create a positively charged surface (layer thickness = 10.2 or 4.2 nm). Next, a flat sheet of poly(dimethylsiloxane) (PDMS) was immersed in an aqueous solution of SPS to allow adsorption of a layer of polyanion on the surface. Although C O M M U N IC A TI O N