Post-fabrication Modification Research Articles

Facile and controlled dual-step modification with enhanced anti-fouling performance in polyvinylidene fluoride membranes

Water scarcity and pollution pose significant challenges, necessitating advancements in water treatment technologies. Among various solutions, ultrafiltration membranes, especially those crafted from polyvinylidene fluoride (PVDF), are favored for their mechanical robustness and chemical stability. However, their practical application is often limited by severe membrane fouling due to the inherent hydrophobicity of PVDF. This project introduces a straightforward, controlled method to enhance the anti-fouling properties of PVDF membranes, utilizing a blend of cellulose acetate (CA). The process involves a two-step modification of hydrolysis followed by quaternization, effectively increasing hydroxyl group presence and facilitating subsequent chemical reactions. The optimized membranes achieve a dynamic water contact angle of 0° within 30 s and maintain an electroneutral surface at pH 7.1. With a mean pore size reduction from 28.6 nm to 23.9 nm and an impressive drop in the irreversible fouling ratio from 36.9 % to 0.3 %, these modifications markedly improve the anti-fouling performance. This research demonstrates significant potential for enhancing the functionality of PVDF ultrafiltration membranes through post-fabrication modifications, offering significant benefits for water treatment applications.

Manufacturing of 3D-Printed Hybrid Scaffolds with Polyelectrolyte Multilayer Coating in Static and Dynamic Culture Conditions.

Three-dimensional printing (3DP) has emerged as a promising method for creating intricate scaffold designs. This study assessed three 3DP scaffold designs fabricated using biodegradable poly(lactic) acid (PLA) through fused deposition modelling (FDM): mesh, two channels (2C), and four channels (4C). To address the limitations of PLA, such as hydrophobic properties and poor cell attachment, a post-fabrication modification technique employing Polyelectrolyte Multilayers (PEMs) coating was implemented. The scaffolds underwent aminolysis followed by coating with SiCHA nanopowders dispersed in hyaluronic acid and collagen type I, and finally crosslinked the outermost coated layers with EDC/NHS solution to complete the hybrid scaffold production. The study employed rotating wall vessels (RWVs) to investigate how simulating microgravity affects cell proliferation and differentiation. Human mesenchymal stem cells (hMSCs) cultured on these scaffolds using proliferation medium (PM) and osteogenic media (OM), subjected to static (TCP) and dynamic (RWVs) conditions for 21 days, revealed superior performance of 4C hybrid scaffolds, particularly in OM. Compared to commercial hydroxyapatite scaffolds, these hybrid scaffolds demonstrated enhanced cell activity and survival. The pre-vascularisation concept on 4C hybrid scaffolds showed the proliferation of both HUVECs and hMSCs throughout the scaffolds, with a positive expression of osteogenic and angiogenic markers at the early stages.

Osteogenic differentiation of human adipose-derived stem cells on polycaprolactone 3D-printed scaffolds containing bioactive bioceramic

Three-dimensional (3D) printing is a promising approach to fabricating bone tissue engineering scaffolds with desired geometry and properties. In this study, we hypothesized that a post-fabrication modification process with baghdadite as a bioactive glass can improve the osteoconductivity of PCL-based 3D-printed scaffolds. The main advantage of this study is the introduction of a cost-effective post-fabrication process for the treatment of 3D-printed porous scaffold for bone tissue engineering applications. The 3D-printed scaffolds were fabricated with circular four-layer and lay-down 0/90°patterns, before exposing them to three different concentrations of baghdadite (1 %, 5 %, and 10 %). The results showed that the addition of baghdadite to the PCL scaffolds did not alter the mechanical behavior of the scaffold. However, the hydrolytic degradation rate was higher for PCL/baghdadite than for plasma-treated scaffold. The biocompatibility of human adipose tissue-derived mesenchymal stem cells (hASCs) cultured on the scaffolds was evaluated by MTT and live/dead staining assays. The osteogenic differentiation ability of scaffolds was measured by evaluating alkaline phosphatase (ALP) activity, calcium deposition, and four bone-related gene expressions (osteocalcin, osteonectin, ALP, and RUNX). The results revealed that the surface treatment of printed scaffolds significantly improved the osteogenic differentiation of hASCs culture on scaffolds and therefore this method can be an effective approach for the treatment of bone tissue engineering scaffolds.

3D-Printed PCL Scaffolds Coated with Nanobioceramics Enhance Osteogenic Differentiation of Stem Cells.

With advances in bone tissue engineering, various materials and methods have been explored to find a better scaffold that can help in improving bone growth and regeneration. Three-dimensional (3D) printing by fused deposition modeling can produce customized scaffolds from biodegradable polyesters such as polycaprolactone (PCL). Although the fabricated PCL scaffolds exhibited a lack of bioactivity and poor cell attachment on their surfaces, herein, using a simple postfabrication modification method with hydroxyapatite (HA) and bioglasses (BGs), we obtained better cell proliferation and attachment. Biological behavior and osteosupportive capacity of the 3D-printed scaffolds including PCL, PCL/HA, PCL/BG, and PCL/HA/BG were evaluated in this study, while human adipose tissue-derived mesenchymal stem cells (hADSCs) were cultured on the scaffolds. The cell morphology, attachment, and proliferation were investigated using scanning electron microscopy (SEM), 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, and 4′,6-diamidino-2-phenylindole (DAPI) staining. In the next step, the ability of stem cells to differentiate into osteoblasts was evaluated by measuring alkaline phosphatase (ALP) activity, calcium deposition, and bone-related gene and protein expression. In the end, the expression levels of miR-20a, miR-125a, and their target genes were also investigated as positive and negative regulators in osteogenesis pathways. The results showed that the coated scaffolds with bioceramics present a more appropriate surface for cell adhesion and proliferation, as well as efficient potential in inducing osteoconduction and osteointegration compared to PCL alone and control. The PCL/HA/BG scaffold exhibited higher in vitro cell viability and bone formation compared to the other groups, which can be due to the synergistic effect of HA and BG. On the whole, this tricomponent 3D-printing scaffold has a promising prospect for bone tissue engineering applications.

Soft Surface Nanostructure with Semi-Free Polyionic Components for Sustainable Antimicrobial Plastic.

Surface antimicrobial materials are of interest as they can combat the critical threat of microbial contamination without contributing to issues of environmental contamination and the development drug resistance. Most nanostructured surfaces are prepared by post fabrication modifications and actively release antimicrobial agents. These properties limit the potential applications of nanostructured materials on flexible surfaces. Here, we report on an easily synthesized plastic material with inherent antimicrobial activity, demonstrating excellent microbicidal properties against common bacteria and fungus. The plastic material did not release antimicrobial components as they were anchored to the polymer chains via strong covalent bonds. Time-kill kinetics studies have shown that bactericidal effects take place when bacteria come into contact with a material for a prolonged period, resulting in the deformation and rupture of bacteria cells. A scanning probe microscopy analysis revealed soft nanostructures on the submicron scale, for which the formation is thought to occur via surface phase separation. These soft nanostructures allow for polyionic antimicrobial components to be present on the surface, where they freely interact with and kill microbes. Overall, the new green and sustainable plastic is easily synthesized and demonstrates inherent and long-lasting activity without toxic chemical leaching.

Fabricating spatially functionalized 3D-printed scaffolds for osteochondral tissue engineering.

Three-dimensional (3D) printing of biodegradable polymers has rapidly become a popular approach to create scaffolds for tissue engineering. This technique enables fabrication of complex architectures and layer-by-layer spatial control of multiple components with high resolution. The resulting scaffolds can also present distinct chemical groups or bioactive cues on the surface to guide cell behavior. However, surface functionalization often includes one or more post-fabrication processing steps, which typically produce biomaterials with homogeneously distributed chemistries that fail to mimic the biochemical organization found in native tissues. As an alternative, our laboratory developed a novel method that combines solvent-cast 3D printing with peptide-polymer conjugates to spatially present multiple biochemical cues in a single scaffold without requiring post-fabrication modification. Here, we describe a detailed, stepwise protocol to fabricate peptide-functionalized scaffolds and characterize their physical architecture and biochemical spatial organization. We used these 3D-printed scaffolds to direct human mesenchymal stem cell differentiation and osteochondral tissue formation by controlling the spatial presentation of cartilage-promoting and bone-promoting peptides. This protocol also describes how to seed scaffolds and evaluate matrix deposition driven by peptide organization.

Membrane Surface Modification by Electrospinning, Coating, and Plasma for Membrane Distillation Applications: A State‐of‐the‐Art Review

Membrane distillation (MD) is a thermally driven separation process where a hydrophobic and microporous membrane separates nonvolatile compounds. Because of its advantages, this process appears as an efficient way to recover water from industrial effluents. However, the commercial membranes used in the MD process still have operational troubles with complex industrial wastewater and against harsh operational conditions. Fouling, wetting, and low time of operation compromise the membrane function and make the total consolidation of MD technology difficult beyond the traditional application (desalination). Membrane modification can be key to mitigating these operational problems, allowing MD's expansion to complex separations. In this context, herein the main technologies to modify the membranes for MD applications of the last five years are comprehensively summarized. Three kinds of postfabrication modifications are focused on: electrospinning, coating, and plasma, including polymeric and ceramic membranes. A critical analysis of each technique is developed, discussing their potentialities and the properties achieved through them. This review enables the understanding of the operational problems of MD technology and leads to finding feasible alternatives to their mitigation. It also clarifies the evolution in membrane modification, discusses the development directions, and points out the future challenges of modifications.

Development of a modular, biocompatible thiolated gelatin microparticle platform for drug delivery and tissue engineering applications.

The field of biomaterials has advanced significantly in the past decade. With the growing need for high-throughput manufacturing and screening, the need for modular materials that enable streamlined fabrication and analysis of tissue engineering and drug delivery schema has emerged. Microparticles are a powerful platform that have demonstrated promise in enabling these technologies without the need to modify a bulk scaffold. This building block paradigm of using microparticles within larger scaffolds to control cell ratios, growth factors and drug release holds promise. Gelatin microparticles (GMPs) are a well-established platform for cell, drug and growth factor delivery. One of the challenges in using GMPs though is the limited ability to modify the gelatin post-fabrication. In the present work, we hypothesized that by thiolating gelatin before microparticle formation, a versatile platform would be created that preserves the cytocompatibility of gelatin, while enabling post-fabrication modification. The thiols were not found to significantly impact the physicochemical properties of the microparticles. Moreover, the thiolated GMPs were demonstrated to be a biocompatible and robust platform for mesenchymal stem cell attachment. Additionally, the thiolated particles were able to be covalently modified with a maleimide-bearing fluorescent dye and a peptide, demonstrating their promise as a modular platform for tissue engineering and drug delivery applications.

100th Anniversary of Macromolecular Science Viewpoint: Integrated Membrane Systems.

Membranes fabricated from self-assembled materials are one recent example of how polymer science has been leveraged to advance membrane technology. Due to their well-defined nanostructures, the performance of membranes made from these materials is pushing the boundaries of size-selective filtration. Still, there remains a need for higher performance and more selective membranes. The advent of functional membrane platforms that rely on mechanisms beyond steric hindrance (e.g., charge-selective membranes and membrane sorbents) is one approach to realize improved solute-solute selectivity and further advance membrane technology. To date, the lab-scale demonstration of these platforms has often relied on fabrication schemes that require extended processing times. However, in order to translate lab-scale demonstrations to larger-scale implementation, it is critical that the rate of the functionalization scheme is reconciled with membrane manufacturing rates. In this viewpoint, it is postulated that substrates lined by reactive moieties that are amenable to postfabrication modification would enable the production of membranes with controlled nanostructures while providing access to a diverse array of pore wall chemistries. A comparison of reaction and manufacturing rates suggests that mechanisms that exhibit second-order reaction rate constants of at least 1 M-1 s-1 are needed for roll-to-roll processing. Furthermore, for mechanisms that exhibit rate constants greater than 300 M-1 s-1, it may be possible to integrate multiple functional domains over the membrane surface such that useful properties emerge. These multifunctional systems can expand the capabilities of membranes when the patterned chemistries interact at the heterojunctions between domains (e.g., Janus and charge-patterned mosaic membranes) or if they exhibit cooperative responses to external operating conditions (e.g., membrane pumps).

Photomediated post-fabrication modification of azlactone-functionalized gels for the development of hydrogel actuators.

We report an approach for the photomediated post-fabrication modification of reactive, azlactone-containing gels using light-initiated deprotection of amines caged with 2-(nitrophenyl)propyloxycarbonyl (NPPOC). Photomediated modification of these gels can be used to generate a gradient in chemical functionality. When functionalized with tertiary amine groups, these gradient gels exhibit rapid and reversible shape deformations in response to changes in pH.

Hydroxyapatite nano bioceramics optimized 3D printed poly lactic acid scaffold for bone tissue engineering application

To achieve optimum functionality and mechanical properties of advanced manufacturing-based scaffolds for biomedical application, it is important to study their mechanical strength by 3D-printing at different orientations. This study examined the effects of printing at different orientations on the mechanical properties of synthesized 3D-polylactic acid (PLA) and hydroxyapatite-modified PLA (PLA-HAp) scaffolds. A total number of 30 samples were printed in three orientations on the XY plane: 0°, 45°, and 90°. Finite element modeling and simulation was employed to identify the strongest scaffold in terms of compression strength, which is the primary criterion for load bearing bone tissue scaffolds. These findings indicate that 3D-printing at an orientation of 90° on the XY plane resulted in a scaffold with the highest compression strength. Moreover, the fabricated PLA scaffolds showed very poor cell attachment and proliferation on their surface, which is not suitable for their biomedical application. This study additionally showed the optimization of a very simple post-fabrication modification technique with nano HAp for better cell attachment and proliferation with enhanced mechanical properties. The post-fabrication modification of PLA scaffolds by nano-HAp results in excellent cell attachment property with enhanced mechanical strength and stability of up to 47.16% for 90° 3D-printed PLA-HAp scaffolds.

Tunable and Selective Degradation of Amine-Reactive Multilayers in Acidic Media.

We report the design of reactive and hydrolytically degradable multilayers by the covalent layer-by-layer assembly of an azlactone-containing polymer, poly(2-vinyl-4,4-dimethylazlactone), with an acid-degradable, acetal-containing, small-molecule diamine linker. This approach yields cross-linked multilayers that contain (i) residual azlactone reactivity that can be used for further functionalization after fabrication and (ii) acid-labile cross-links that can undergo pH-triggered degradation. Thin films and hollow capsules fabricated using this approach were relatively stable in slightly basic media (pH = 7.4) but eroded and degraded gradually in mildly acidic environments (pH = 5). The residual azlactones in these materials could be functionalized by reaction with hydrophilic or hydrophobic amines to tune physicochemical properties, including surface wetting and rates of degradation/erosion. Interestingly, our results reveal that rates of degradation could be tuned over a broad range (from ∼4 h to ∼10 days) simply by post-fabrication modification of the parent reactive material. We further demonstrate the potential of acetal-containing microcapsules to be used for the acid-triggered release of encapsulated cargo. The results of in vitro experiments reveal that microcapsules loaded with fluorescently labeled dextran can be internalized by mammalian cells and that cell uptake and intracellular degradation were also influenced by the types of functional groups installed post-fabrication. The introduction of acid degradability expands the range of stimuli that can be used to trigger the destruction of these reactive materials to include changes in pH relevant to chemical and biological processes. Our results also introduce an approach to tuning degradation profiles that differs from past strategies used to design degradable multilayers. We conclude that this approach provides a new, useful, and modular platform for the design of stimuli-responsive nano/biointerfaces with transient environmental stability.

Post-fabrication modifications of thermoplastic polymeric nanofiber membranes with electroactive polymers for triboelectric nanogenerators

With the development of wearable electronics, the demand for sustainable power supply has propelled the growth of garment-based triboelectric nanogenerators (TENGs). New approaches which can improve the electrical output performance while ensuring the comfort of wearing from a device are ongoing. In this investigation, a high-performance contact-separation TENG has been constructed with two triboelectric layers using the same thermoplastic polymeric materials. The above thermoplastic polymeric materials which are raw materials of clothing are used as substrate after developing them into nanofibers via melt-blending extrusion method. Post-fabrication modifications are applied to nanofiber membranes to achieve tribo-electronegative and tribo-electropositive for increasing the performance in terms of electrical output from the obtained devices. Driven by periodic motions, the triboelectric pair containing PTFE/PVDF/EVOH composite nanofiber membranes (PPECNMs) fabricated via facile non-solvent induced phase inversion and PEI/EVOH composite nanofiber membranes (PEI-ECNMs) obtained through effective grafting reaction realizes a continuous contact and separation to achieve a remarkable power density of 2.45 W/m2. In addition, the possibility of the developed TENG to harvest frictional energy between garment triggered by the body motions is successfully proved by sewing the triboelectric pair on clothes because of the compatibility between thermoplastic polymeric materials and clothing. Consequently, this study not only provides a novel way for the modification of micro-nanostructural triboelectric layers, but also demonstrates the practicality of all-fiber devices towards applications in smart garment.

Slippery Liquid-Infused Porous Surfaces (SLIPS) Using Layer-by-Layer Polyelectrolyte Assembly in Organic Solvent.

Slippery liquid-infused porous surfaces (SLIPS) have potential impact on a wide range of industries, including healthcare, food packaging, and automobile. A tremendouseffort has been focused on developing novel fabrication methods for making SLIPS. However, current fabrication methods usually involve harsh conditions and complicated postfabrication modifications or are limited to specific substrates. Presented here is a novel method for the fast and facile fabrication of SLIPS. Layer-by-layer (LBL) assembly of branched polyethylenimine and Nafion, a perfluorinated polyelectrolyte, is performed with methanol as the solvent. Hierarchically rough and superhydrophobic surface is obtained directly without further modification on various substrates. The surface properties are shown to highly depend on the LBL assembly parameters, including deposition cycles, dipping time, rinsing time, and drying time between baths. The polyelectrolyte multilayers obtained with this method are infused with Krytox 100 to form SLIPS surfaces, which show excellent omniphobic, antifouling, self-cleaning, flexible, and optical properties. The result of this study not only simplifies the fabrication of SLIPS surfaces, but also provides great insight for making LBL films with specific morphologies.

Feasibility of Clinician-Facilitated Three-Dimensional Printing of Synthetic Cranioplasty Flaps

Integration of three-dimensional (3D) printing and stereolithography into clinical practice is in its nascence, and concepts may be esoteric to the practicing neurosurgeon. Currently, creation of 3D printed implants involves recruitment of offsite third parties. We explored a range of 3D scanning and stereolithographic techniques to create patient-specific synthetic implants using an onsite, clinician-facilitated approach. We simulated bilateral craniectomies in a single cadaveric specimen. We devised 3 methods of creating stereolithographically viable virtual models from removed bone. First, we used preoperative and postoperative computed tomography scanner-derived bony window models from which the flap was extracted. Second, we used an entry-level 3D light scanner to scan and render models of the individual bone pieces. Third, we used an arm-mounted, 3D laser scanner to create virtual models using a real-time approach. Flaps were printed from the computed tomography scanner and laser scanner models only in a ultraviolet-cured polymer. The light scanner did not produce suitable virtual models for printing. The computed tomography scanner-derived models required extensive postfabrication modification to fit the existing defects. The laser scanner models assumed good fit within the defects without any modification. The methods presented varying levels of complexity in acquisition and model rendering. Each technique required hardware at varying in price points from $0 to approximately $100,000. The laser scanner models produced the best quality parts, which had near-perfect fit with the original defects. Potential neurosurgical applications of this technology are discussed.

Morphology-controllable synthesis of highly ordered nanoporous diamond films

The remarkable functional properties of diamond depend not only on its physical and chemical properties but also on its surface morphology. Ordered porous diamond with hierarchical structures is used in various applications in the fields of environment and energy management. However, obtaining such micro- and nanostructures via conventional techniques has proven to be challenging because of the superhardness and extreme chemical inertness of diamond. In this study, a strategy to create highly textured diamond films structured by vertical columnar crystals was developed. The mechanism of shape-evolution of diamond grains was proposed to account for the changes in the crystal shape from octahedron through cubo-octahedron to cube, followed by oxidation and hydrogenation. Shape evolution of diamond crystals during the initial fabrication stages was assessed by scanning electron microscopy, which revealed that the surfaces of fabricated diamond consisted of rough octahedral {111} and smooth cubic {100} faces. The variation of the crystal shape depended on the relative growth rate of {111} faces to that of {100} faces during the growth process. Finally, highly ordered porous diamond films with switchable wettability properties were obtained by post-fabrication modification involving thermal etching in air followed by etching in hydrogen plasma.

Post-fabrication modification of electrospun nanofiber mats with polymer coating for membrane distillation applications

Post-treatment of electrospun nanofibers is a versatile and scalable approach for the fabrication of membranes with controlled pore size, porosity, and morphology. In this study, we demonstrate a novel solution-based approach for the fabrication of membrane distillation (MD) membranes with adjustable pore size and performance through non-solvent induced phase separation of a polymeric solution over an electrospun fiber mat. Poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) was dissolved in a blend of acetone and dimethylacetamide and used to produce a highly porous electrospun fiber mat with an average pore diameter of ~1.2µm. Surface coating of the PVDF-HFP nanofibers with polyvinylidene fluoride (PVDF) through phase separation enabled control of the membrane pore size by filling the empty domains between the fibers. The coated fiber mats were characterized for their surface hydrophobicity, porosity, and structure. The PVDF polymeric coating layer integrated within the electrospun mat decreased the average pore diameter to <0.6µm without compromising the surface hydrophobicity. By controlling the depth of the PVDF coating layer within the substrate, we were able to fabricate robust membranes with near complete salt rejection (>99.9%) and a water flux of 30Lm−2h−1 in direct contact MD experiments with 40°C temperature difference between the feed and permeate solutions. This coating procedure is compatible with current roll-to-roll membrane fabrication processes, making it a viable approach for large-scale fabrication of electrospun membranes with exceptional performance for MD applications.

Helium Ion Microscope-Assisted Nanomachining of Resonant Nanostrings.

Helium ion microscopy has recently emerged as a potent tool for the in-situ modification and imaging of nanoscale devices. For example; finely focused helium ion beams have been used for the milling of pores in suspended structures. We here report the use of helium ion milling for the post-fabrication modification of nanostrings machined from an amorphous SiCN material. The modification consisted of milling linear arrays of holes along the length of nanostrings. This milling results in a slight decrease of resonant frequency while increasing the surface to volume ratio of the device. The frequency decrease is attributed to a reduction of the effective Young’s modulus of the string, which in turn reduces the tension the string is under. Such experimental observations are supported by the finite element analysis of milled and non-milled strings.

Post-fabrication modification of forward osmosis membranes with a poly(ethylene glycol) block copolymer for improved organic fouling resistance

Facile and effective strategies are needed to modify forward osmosis (FO) membranes for improved resistance to organic fouling. Fouling resistant FO membranes will advance the commercial implementation of FO for treating feed waters with high fouling potential, such as wastewater and brines. We report a membrane modification technique for post-fabrication grafting of a poly(ethylene glycol) (PEG) block copolymer to the surface of commercial thin-film composite (TFC) FO membranes via an amide coupling reaction. The PEG concentration for membrane modification is optimized based on increased membrane hydrophilicity and reduced water permeability that result from increasing PEG concentrations during modification. Modified membranes exhibit improved resistance to organic fouling compared to unmodified control membranes when exposed to an aggressive synthetic wastewater mixture. The fouling resistance is achieved despite the non-uniform grafting of PEG, which is attributed to the limited accessibility of carboxylic group binding sites on the membrane surface. The fouling resistance of membranes modified using this post-fabrication technique compares favorably to TFC-FO membranes modified using other procedures. The modification technique we report in this work has the advantages of being relatively inexpensive, easy to implement, and applicable to commercial membranes.

Study of Potassium-Rich Prussian Blue and MoO3 Aqueous Secondary Cell with Nanoscale TiO2 Coatings

1. Introduction – Lithium-ion batteries are regarded as the current benchmark for new battery designs. While lithium-ion batteries offer both high energy densities and large cell potentials, they also possess many inherent disadvantages such as flammability and high material costs [1, 2]. Potassium-ion (K+) batteries can be of great environmental and economic importance. Potassium possesses an oxidation/ reduction potential closest to lithium among all alkali metals, only 0.12 V lower than that of lithium [3]. Furthermore, nanoscale coatings of transition metal oxides are known to behave as inhibitors to cell capacity degradation [4]. 2. Fabrication procedures – Prussian blue (Fe4[Fe(CN)6]3) cathode is fabricated by dissolution of 4 mmol K4Fe(CN)6•3H2O in 50 ml of 0.1 M HCl solution followed by vigorous mixing at 500 rpm at 80 °C overnight until dry. Resulting powder is ground, washed and separated by centrifugation and at 80 °C overnight. α MoO3 anode is fabricated by titration of 0.7 mmol (NH4)6Mo7O24•4H2O in 10 ml of 5 M (NH4)2CO3 with Nitric acid until a white precipitate is formed. Solution is aged overnight, dried at 80 °C, washed with HCl solution and separated by centrifugation, and then annealed at 500 °C for 20 hrs. Electrolyte of 0.5 M aqueous KPF6 is used. Atomic Layer Deposition technique is used to deposit thin TiO2 films of 5 and 10 nm on the Prussian blue cathode surface. 3. Experimental setup and results –XRD and SEM is done to study the crystallinity and morphology of both pristine and TiO2 coated cathodes. XRD spectrum of Prussian blue cathode and α-MoO3 anode is shown in Figure 1. Cycling performance is studied using a charge/discharge current of 2 mA and 0.5 mA respectively and voltage range of 0 to 1 V. Discharge capacity and capacity retention performance of aqueous cells of pristine, 5 nm and 10 nm TiO2 coated Prussian blue cathodes and α MoO3 anode is shown in Figures 2 and 3 respectively. 4. Conclusions and future work – A decrease in initial discharge capacity and increase in capacity retention is observed for cells utilizing a TiO2 coated cathode. Initial discharge capacities of the 5 nm and 10 nm TiO2 coated cathodes are observed to be less than that of the pristine cathode. After 10 cycles all three cell configurations are observed to approach approximately the same discharge capacity. Both TiO2 coated cathode materials show considerable increase in capacity retention with respect to the pristine cathode. Future work aims to increase cell capacity by post-fabrication modification of anode and cathode. Post-cycling changes in electrode structure and morphology are also of interest. 5. References – [1] D. Lisbona, T. Snee, Process Safety and Environmental Protection, 89 (2011) 434-442.[2] M.D. Slater, D. Kim, E. Lee, C.S. Johnson, Advanced Functional Materials, 23 (2013) 947-958.[3] A. Eftekhari, Journal of Power Sources, 126 (2004) 221-228.[4] X. Li, J. Liu, X. Meng, Y. Tang, M.N. Banis, J. Yang, Y. Hu, R. Li, M. Cai, X. Sun, Journal of Power Sources, 247 (2014) 57-69. Figure 1