Structure-related antibacterial activity of a titanium nanostructured surface fabricated by glancing angle sputter deposition

Mechanical, bactericidal and osteogenic behaviours of hydrothermally synthesised TiO2 nanowire arrays

The application of orthopaedic implants is associated with risks of bacterial infection and long-term antibiotic therapy. This problem has led to the study of implants with nano-textured surfaces as a method of inhibiting bacterial adhesion and reducing implant failure due to infection. In this research, various nano-textured surfaces of TiO₂ were synthesised using hydrothermal synthesis, by varying NaOH concentration, reaction time and reaction temperature. Their correlations to mechanical, morphological, bactericidal and osteogenic properties of the surfaces were investigated. It was found that high alkaline concentrations produced large nanowire mesh arrays, while short reaction time and low temperature produced comparatively smaller arrays. The highly dense morphology formed at higher NaOH concentrations has resulted in high elastic modulus and hardness values, compared to surfaces produced at lower NaOH concentrations. Viability tests of the TiO₂ nanowire array against gram-positive Staphylococcus aureus cells showed a bactericidal efficiency of 54% and 33% after 3 and 18 h, respectively. This nano-textured surface produces an osteoblast cellular metabolic activity of 71% after 24 h, compared to 67% when exposed to a flat Ti control surface. This preliminary work demonstrates an excellent outcome in producing bactericidal surfaces that promoted metabolic activity of human osteoblast cells for potential use in orthopaedic implants.

Nanodarts, nanoblades, and nanospikes: Mechano-bactericidal nanostructures and where to find them

Over the past ten years, a next-generation approach to combat bacterial contamination has emerged: one which employs nanostructure geometry to deliver lethal mechanical forces causing bacterial cell death. In this review, we first discuss advances in both colloidal and topographical nanostructures shown to exhibit such "mechano-bactericidal" mechanisms of action. Next, we highlight work from pioneering research groups in this area of antibacterials. Finally, we provide suggestions for unexplored research topics that would benefit the field of mechano-bactericidal nanostructures. Traditionally, antibacterial materials are loaded with antibacterial agents with the expectation that these agents will be released in a timely fashion to reach their intended bacterial metabolic target at a sufficient concentration. Such antibacterial approaches, generally categorized as chemical-based, face design drawbacks as compounds diffuse in all directions, leach into the environment, and require replenishing. In contrast, due to their mechanisms of action, mechano-bactericidal nanostructures can benefit from sustainable opportunities. Namely, mechano-bactericidal efficacy needs not replenishing since they are not consumed metabolically, nor are they designed to release or leach compounds. For this same reason, however, their action is limited to the bacterial cells that have made direct contact with mechano-bactericidal nanostructures. As suspended colloids, mechano-bactericidal nanostructures such as carbon nanotubes and graphene nanosheets can pierce or slice bacterial membranes. Alternatively, surface topography such as mechano-bactericidal nanopillars and nanospikes can inflict critical membrane damage to microorganisms perched upon them, leading to subsequent cell lysis and death. Despite the infancy of this area of research, materials constructed from these nanostructures show remarkable antibacterial potential worthy of further investigation.

Antimicrobial and Osseointegration Properties of Nanostructured Titanium Orthopaedic Implants

The surface design of titanium implants influences not only the local biological reactions but also affects at least the clinical result in orthopaedic application. During the last decades, strong efforts have been made to improve osteointegration and prevent bacterial adhesion to these surfaces. Following the rule of “smaller, faster, cheaper”, nanotechnology has encountered clinical application. It is evident that the hierarchical implant surface micro- and nanotopography orchestrate the biological cascades of early peri-implant endosseous healing or implant loosening. This review of the literature gives a brief overview of nanostructured titanium-base biomaterials designed to improve osteointegration and prevent from bacterial infection.

Nanofabrication of mechano-bactericidal surfaces

The search for alternatives to the standard methods of preventing bacterial adhesion and biofilm formation on biotic and abiotic surfaces alike has led to the use of biomimetics to reinvent through nanofabrication methods, surfaces, whereby the nanostructured topography is directly responsible for bacterial inactivation through physico-mechanical means. Plant leaves, insect wings, and animal skin have been used to inspire the fabrication of synthetic high-aspect-ratio nanopillared surfaces, which can resist bacterial colonisation. The adaptation of bacteria to survive in the presence of antibiotics and their ability to form biofilms on conventional antibacterial surfaces has led to an increase in persistent infections caused by resistant strains of bacteria. This presents a worldwide health epidemic that can only be mitigated through the search for a new generation of biomaterials.

Enhancing the Bactericidal Efficacy of Nanostructured Multifunctional Surface Using an Ultrathin Metal Coating

Insects and plants exhibit bactericidal behavior through nanostructures, which leads to physical contact killing that does not require antibiotics or chemicals. Also, certain metallic ions (e.g., Ag⁺ and Cu²⁺) are well-known to kill bacteria by disrupting their cellular functionalities. The aim of this study is to explore the improvement in bactericidal activity by combining extreme physical structure with surface chemistry. We have fabricated tall (8-9 μm high) nanostructures on silicon surfaces (NSS) having sharp tips (35-110 nm) using a single-step, maskless deep reactive ion etching technique inspired by dragonfly wing. Bactericidal efficacy of the nanostructured surfaces coated with a thin layer of silver (NSS_Ag) or copper (NSS_Cu) was measured quantitatively using standard viability plate-count method and flow cytometry. NSS_Cu surfaces kill bacteria very efficiently (killing 97% within 30 min) when compared to the uncoated NSS. This can be attributed to the addition of a surface chemistry to the nanostructures. The antibacterial activity of NSS_Cu is further indicated by the morphological differences of the dying/dead bacteria observed in the SEM images. The nanostructured surfaces demonstrate excellent superhydrophobic behavior, even with an ultrathin layer of metal (Ag/Cu) coating. The nanostructured surfaces exhibit static contact angle greater than 150° and contact hysteresis less than 10°. Moreover, reflectance is found to be <1% (for NSS_Cu < 0.5%) for all the nanostructured surfaces in the wavelength range 250-800 nm. The results obtained suggest that the fabricated nanostructured surfaces are multifunctional and can be used in various practical applications.

Bio-mimicking nano and micro-structured surface fabrication for antibacterial properties in medical implants

Orthopaedic and dental implants have become a staple of the medical industry and with an ageing population and growing culture for active lifestyles, this trend is forecast to continue. In accordance with the increased demand for implants, failure rates, particularly those caused by bacterial infection, need to be reduced. The past two decades have led to developments in antibiotics and antibacterial coatings to reduce revision surgery and death rates caused by infection. The limited effectiveness of these approaches has spurred research into nano-textured surfaces, designed to mimic the bactericidal properties of some animal, plant and insect species, and their topographical features. This review discusses the surface structures of cicada, dragonfly and butterfly wings, shark skin, gecko feet, taro and lotus leaves, emphasising the relationship between nano-structures and high surface contact angles on self-cleaning and bactericidal properties. Comparison of these surfaces shows large variations in structure dimension and configuration, indicating that there is no one particular surface structure that exhibits bactericidal behaviour against all types of microorganisms. Recent bio-mimicking fabrication methods are explored, finding hydrothermal synthesis to be the most commonly used technique, due to its environmentally friendly nature and relative simplicity compared to other methods. In addition, current proposed bactericidal mechanisms between bacteria cells and nano-textured surfaces are presented and discussed. These models could be improved by including additional parameters such as biological cell membrane properties, adhesion forces, bacteria dynamics and nano-structure mechanical properties. This paper lastly reviews the mechanical stability and cytotoxicity of micro and nano-structures and materials. While the future of nano-biomaterials is promising, long-term effects of micro and nano-structures in the body must be established before nano-textures can be used on orthopaedic implant surfaces as way of inhibiting bacterial adhesion.

Influence of nanoscale topology on bactericidal efficiency of black silicon surfaces

The nanostructuring of materials to create bactericidal and antibiofouling surfaces presents an exciting alternative to common methods of preventing bacterial adhesion. The fabrication of synthetic bactericidal surfaces has been inspired by the anti-wetting and anti-biofouling properties of insect wings, and other topologies found in nature. Black silicon is one such synthetic surfaces which has established bactericidal properties. In this study we show that time-dependent plasma etching of silicon wafers using 15, 30, and 45 min etching intervals, is able to produce different surface geometries with linearly increasing heights of approximately 280, 430, and 610 nm, respectively. After incubation on these surfaces with Gram-positive Staphylococcus aureus and Gram-negative Pseudomonas aeruginosa bacterial cells it was established that smaller, more densely packed pillars exhibited the greatest bactericidal activity with 85% and 89% inactivation of bacterial cells, respectively. The decrease in the pillar heights, pillar cap diameter and inter-pillar spacing corresponded to a subsequent decrease in the number of attached cells for both bacterial species.

Bactericidal performance of nanostructured surfaces by fluorocarbon plasma

This study presents the characterization and antibacterial activity of nanostructured Si by plasma treatment method using a tetrafluoromethane (CF₄) and hydrogen (H₂) mixture. Nanostructured-Si is a synthetic nanomaterial that contains high aspect ratio nanoprotrusions on its surface, produced through a reactive-ion etching process. We have shown that the nanoprotrusions on the surfaces produce a mechanical bactericidal effect. Nanostructured-Si exhibited notable activity against three different microorganisms: Gram-negative (Escherichia coli), Gram-positive (Staphylococcus aureus) and spore-forming bacteria (Bacillus cereus) producing a > 5 log₁₀ reduction after 24h of incubation. Scanning electron microscopy was used to analysis the structure and morphology character of different surfaces evidencing the physical bactericidal activity of the Nanostructured-Si. These results provide excellent prospects for the development of a new generation of antibacterial surfaces.

Combinatorial synthesis and high-throughput characterization of structural and photoelectrochemical properties of Fe:WO3 nanostructured libraries

Porous and photoelectrochemically active Fe-doped WO₃ nanostructures were obtained by a combinatorial dealloying method. Two types of precursor materials libraries, exhibiting dense and nano-columnar morphology were fabricated by using two distinct magnetron sputter deposition geometries. Both libraries were subjected to combinatorial dealloying enabling preparation and screening of a large quantity of compositions having different nanostructures. This approach allows identifying materials with interesting photoelectrochemical characteristics. The dealloying process selectively dissolved Fe from the composition gradient precursor W-Fe materials library, resulting in formation of monoclinic single crystalline nanoblade-like structures over the entire surface. Photoelectrochemical properties of nanostructured Fe:WO₃ films were found to be composition-dependent. The measurement region doped with ∼1.7 at % Fe and a film thickness of ∼ 900-1100 nm displayed highly porous WO₃ nanostructures and exhibited the highest photocurrent density of ∼ 72 μA cm^-2. This enhanced photocurrent density is attributed to the decreased bandgap values, suppressed recombination of electron-hole pairs, improved light absorption as well as efficient charge transport in the highly porous Fe-doped film with single crystalline WO₃ nanoblades.

Nanostructured Ti-Ta thin films synthesized by combinatorial glancing angle sputter deposition

Ti-Ta alloys are attractive materials for applications in actuators as well as biomedical implants. When fabricated as thin films, these alloys can potentially be employed as microactuators, components for micro-implantable devices and coatings on surgical implants. In this study, Ti_100-x Ta _x (x = 21, 30) nanocolumnar thin films are fabricated by glancing angle deposition (GLAD) at room temperature using Ti₇₃Ta₂₇ and Ta sputter targets. Crystal structure, morphology and microstructure of the nanostructured thin films are systematically investigated by XRD, SEM and TEM, respectively. Nanocolumns of ∼150-160 nm in width are oriented perpendicular to the substrate for both Ti₇₉Ta₂₁ and Ti₇₀Ta₃₀ compositions. The disordered α″ martensite phase with orthorhombic structure is formed in room temperature as-deposited thin films. The columns are found to be elongated small single crystals which are aligned perpendicular to the [Formula: see text] and [Formula: see text] planes of α″ martensite, indicating that the films' growth orientation is mainly dominated by these crystallographic planes. Laser pre-patterned substrates are utilized to obtain periodic nanocolumnar arrays. The differences in seed pattern, and inter-seed distances lead to growth of multi-level porous nanostructures. Using a unique sputter deposition geometry consisting of Ti₇₃Ta₂₇ and Ta sputter sources, a nanocolumnar Ti-Ta materials library was fabricated on a static substrate by a co-deposition process (combinatorial-GLAD approach). In this library, a composition spread developed between Ti_72.8Ta_27.2 and Ti_64.4Ta_35.6, as confirmed by high-throughput EDX analysis. The morphology over the materials library varies from well-isolated nanocolumns to fan-like nanocolumnar structures. The influence of two sputter sources is investigated by studying the resulting column angle on the materials library. The presented nanostructuring methods including the use of the GLAD technique along with pre-patterning and a combinatorial materials library fabrication strategy offer a promising technological approach for investigating Ti-Ta thin films for a range of applications. The proposed approaches can be similarly implemented for other materials systems which can benefit from the formation of a nanocolumnar morphology.

Synthesis of nanostructured LiMn2O4 thin films by glancing angle deposition for Li-ion battery applications

The development of electric vehicles and portable electronic devices demands lighter and thinner batteries with improved specific charge and rate capabilities. In this work, thin films of LiMn₂O₄ were fabricated by rf magnetron sputtering. Glancing angle deposition is introduced as a promising approach for fabrication of porous cathode thin films with 2.6 times the capacity in comparison with conventionally sputtered films of the same thickness. Surface morphology and crystallinity of the films are studied along with their electrochemical performance in an aqueous electrolyte. The glancing angle deposited films can reach a rate capability of up to 4 mA cm^-2 with minimal energy loss, and a life cycle longer than 100 charge/discharge cycles.

Bactericidal mechanism of nanopatterned surfaces

The quest to design and fabricate new antibacterial surfaces is an important task to meet the urgent demands of biomedical applications. Recently, a mechanical mechanism for killing adherent bacteria was discovered on nanopatterned surfaces, but there is a lack of understanding of the bactericidal mechanism. Here we present a quantitative thermodynamic model to study the bactericidal mechanism of nanopatterned surfaces through analyzing the total free energy change of bacterial cells. By comparing the bacterial cells on a flat surface and nanopatterned surface, our theoretical results reveal that cicada wing-like nanopatterned surfaces have more effective bactericidal properties than flat surfaces because a patterned surface leads to a drastic increase of the contact adhesion area. Our model also reveals some details of the influence mechanism, and gives some important information about how to improve the bactericidal properties through designing the morphology of the patterned surface.

Cicada Wing Surface Topography: An Investigation into the Bactericidal Properties of Nanostructural Features

Recently, the surface of the wings of the Psaltoda claripennis cicada species has been shown to possess bactericidal properties and it has been suggested that the nanostructure present on the wings was responsible for the bacterial death. We have studied the surface-based nanostructure and bactericidal activity of the wings of three different cicadas (Megapomponia intermedia, Ayuthia spectabile and Cryptotympana aguila) in order to correlate the relationship between the observed surface topographical features and their bactericidal properties. Atomic force microscopy and scanning electron microscopy performed in this study revealed that the tested wing species contained a highly uniform, nanopillar structure on the surface. The bactericidal properties of the cicada wings were investigated by assessing the viability of autofluorescent Pseudomonas fluorescens cells following static adhesion assays and targeted dead/live fluorescence staining through direct microscopic counting methods. These experiments revealed a 20-25% bacterial surface coverage on all tested wing species; however, significant bactericidal properties were observed in the M. intermedia and C. aguila species as revealed by the high dead:live cell ratio on their surfaces. The combined results suggest a strong correlation between the bactericidal properties of the wings and the scale of the nanotopography present on the different wing surfaces.

Enhancement and suppression effects of a nanopatterned surface on bacterial adhesion

We present a quantitative thermodynamic model to elucidate the effects of a nanopatterned surface on bacterial adhesion. Based on the established model, we studied the equilibrium state of rodlike bacterial cells adhered to a nanopillar-patterned surface. Theoretical analyses showed the physical origin of bacterial adhesion on a nanopatterned surface is actually determined by the balance between adhesion energy and deformation energy of the cell membrane. We found that there are enhancement effects on bacterial adhesion to the patterned surface with large radius and small spacing of nanopillars, but suppression effects for nanopillars with a radius smaller than a critical value. In addition, according to our model, a phase diagram has been constructed which can clarify the interrelated effects of the radius and the spacing of nanopillars. The broad agreement with experimental observations implies that these studies would provide useful guidance to the design of nanopatterned surfaces for biomedical applications.

Strong Antibacterial Polydopamine Coatings Prepared by a Shaking-assisted Method

Strong antibacterial polydopamine (PDA) coatings prepared by a facile shaking-assisted method is reported for the first time. It was found that a minor modification made to the conventional synthesis procedure of PDA coatings, viz. replacing the static solution condition with a shaking solution condition by using a mechanical shaker, can produce the roughened polydopamine (rPDA) coatings at different substrates, e.g., glass, stainless steel, plastic, and gauze. The resulting rPDA coatings were characterized with Raman spectrum, zeta-potential analysis and contact angle measurement. The antibacterial activity of the rPDA coatings was evaluated by a shake flask test with gram-positive Staphylococcus aureus, and gram-negative Escherichia coli and Pseudomonas aeruginosa as bacteria models. Testing results revealed that, in the absence of any other antibacterial agents, the rPDA coatings exhibited remarkably enhanced antibacterial activities. In addition, such enhanced antibacterial activities of the rPDA coatings were found to be unimpaired by steam sterilization treatments.

Antimicrobial performance of mesoporous titania thin films: role of pore size, hydrophobicity, and antibiotic release

Implant-associated infections are undesirable complications that might arise after implant surgery. If the infection is not prevented, it can lead to tremendous cost, trauma, and even life threatening conditions for the patient. Development of an implant coating loaded with antimicrobial substances would be an effective way to improve the success rate of implants. In this study, the in vitro efficacy of mesoporous titania thin films used as a novel antimicrobial release coating was evaluated. Mesoporous titania thin films with pore diameters of 4, 6, and 7 nm were synthesized using the evaporation-induced self-assembly method. The films were characterized and loaded with antimicrobial agents, including vancomycin, gentamicin, and daptomycin. Staphylococcus aureus and Pseudomonas aeruginosa were used to evaluate their effectiveness toward inhibiting bacterial colonization. Drug loading and delivery were studied using a quartz crystal microbalance with dissipation monitoring, which showed successful loading and release of the antibiotics from the surfaces. Results from counting bacterial colony-forming units showed reduced bacterial adhesion on the drug-loaded films. Interestingly, the presence of the pores alone had a desired effect on bacterial colonization, which can be attributed to the documented nanotopographical effect. In summary, this study provides significant promise for the use of mesoporous titania thin films for reducing implant infections.

Polyelectrolyte Multilayers: A Versatile Tool for Preparing Antimicrobial Coatings

The prevention of pathogen colonization of medical implants represents a major medical and financial issue. The development of antimicrobial coatings aimed at protecting against such infections has thus become a major field of scientific and technological research. Three main strategies are developed to design such coatings: (i) the prevention of microorganisms adhesion and the killing of microorganisms (ii) by contact and (iii) by the release of active compounds in the vicinity of the implant. Polyelectrolyte multilayer (PEM) technology alone covers the entire widespread spectrum of functionalization possibilities. PEMs are obtained through the alternating deposition of polyanions and polycations on a substrate, and the great advantages of PEMs are that (i) they can be applied to almost any type of substrate whatever its shape and composition; (ii) various chemical, physicochemical, and mechanical properties of the coatings can be obtained; and (iii) active compounds can be embedded and released in a controlled manner. In this article we will give an overview of the field of PEMs applied to the design of antimicrobial coatings, illustrating the large versatility of the PEM technology.

Antibacterial titanium nano-patterned arrays inspired by dragonfly wings

Titanium and its alloys remain the most popular choice as a medical implant material because of its desirable properties. The successful osseointegration of titanium implants is, however, adversely affected by the presence of bacterial biofilms that can form on the surface, and hence methods for preventing the formation of surface biofilms have been the subject of intensive research over the past few years. In this study, we report the response of bacteria and primary human fibroblasts to the antibacterial nanoarrays fabricated on titanium surfaces using a simple hydrothermal etching process. These fabricated titanium surfaces were shown to possess selective bactericidal activity, eliminating almost 50% of Pseudomonas aeruginosa cells and about 20% of the Staphylococcus aureus cells coming into contact with the surface. These nano-patterned surfaces were also shown to enhance the aligned attachment behavior and proliferation of primary human fibroblasts over 10 days of growth. These antibacterial surfaces, which are capable of exhibiting differential responses to bacterial and eukaryotic cells, represent surfaces that have excellent prospects for biomedical applications.

Modulation of human mesenchymal stem cell behavior on ordered tantalum nanotopographies fabricated using colloidal lithography and glancing angle deposition

Ordered surface nanostructures have attracted much attention in biotechnology and biomedical engineering because of their potential to modulate cell-surface interactions in a controllable manner. However, the ability to fabricate large area ordered nanostructures is limited because of high costs and low speed of fabrication. Here, we have fabricated ordered nanostructures with large surface areas (1.5 × 1.5 cm(2)) using a combination of facile techniques including colloidal self-assembly, colloidal lithography and glancing angle deposition (GLAD). Polystyrene (722 nm) colloids were self-assembled into a hexagonally close-packed (hcp) crystal array at the water-air interface, transferred on a biocompatible tantalum (Ta) surface and used as a mask to generate an ordered Ta pattern. The Ta was deposited by sputter coating through the crystal mask creating approximately 60-nm-high feature sizes. The feature size was further increased by approximately 200-nm-height respectively using GLAD, resulting in the fabrication of four different surfaces (FLAT, Ta60, GLAD100, and GLAD200). Cell adhesion, proliferation, and osteogenic differentiation of primary human adipose-derived stem cells (hADSCs) were studied on these ordered nanostructures for up to 2 weeks. Our results suggested that cell spreading, focal adhesion formation, and filopodia extension of hADSCs were inhibited on the GLAD surfaces, while the growth rate was similar between each surface. Immunostaining for type I collagen (COL1) and osteocalcin (OC) showed that there was higher osteogenic components deposited on the GLAD surfaces compared to the Ta60 and FLAT surfaces after 1 week of osteogenic culture. After 2 weeks of osteogenic culture, alkaline phosphatase (ALP) activity and the amount of calcium was higher on the GLAD surfaces. In addition, osteoblast-like cells were confluent on Ta60 and FLAT surfaces, whereas the GLAD surfaces were not fully covered suggesting that the cell-cell interactions are stronger than cell-substrate interactions on GLAD surfaces. Visible extracellular matrix deposits decorated the porous surface can be found on the GLAD surfaces. Depth profiling of surface components using a new Ar cluster source and X-ray photoelectron spectroscopy (XPS) showed that deposited extracellular matrix on GLAD surfaces is rich in nitrogen. The fabricated ordered surface nanotopographies have potential to be applied in diverse fields, and demonstrate that the behavior of human stem cells can be directed on these ordered nanotopographies, providing new knowledge for applications in biomaterials and tissue engineering.

Nanocolumnar coatings with selective behavior towards osteoblast and Staphylococcus aureus proliferation

Bacterial colonization and biofilm formation on orthopedic implants is one of the worst scenarios in orthopedic surgery, in terms of both patient prognosis and healthcare costs. Tailoring the surfaces of implants at the nanoscale to actively promote bone bonding while avoiding bacterial colonization represents an interesting challenge to achieving better clinical outcomes. Herein, a Ti6Al4V alloy of medical grade has been coated with Ti nanostructures employing the glancing angle deposition technique by magnetron sputtering. The resulting surfaces have a high density of nanocolumnar structures, which exhibit strongly impaired bacterial adhesion that inhibits biofilm formation, while osteoblasts exhibit good cell response with similar behavior to the initial substrates. These results are discussed on the basis of a "lotus leaf effect" induced by the surface nanostructures and the different sizes and biological characteristics of osteoblasts and Staphylococcus aureus.

A facile method for fabrication of buckled PDMS silver nanorod arrays as active 3D SERS cages for bacterial sensing

We have successfully demonstrated a simple and facile method to increase the SERS signal of bacteria due to the formation of high density hotspots among the AgNRs and the increase in the area for better interaction of bacteria with the metal surface.

Silver nanoparticle-doped zirconia capillaries for enhanced bacterial filtration

Membrane clogging and biofilm formation are the most serious problems during water filtration. Silver nanoparticle (Ag_nano) coatings on filtration membranes can prevent bacterial adhesion and the initiation of biofilm formation. In this study, Ag_nano are immobilized via direct reduction on porous zirconia capillary membranes to generate a nanocomposite material combining the advantages of ceramics being chemically, thermally and mechanically stable with nanosilver, an efficient broadband bactericide for water decontamination. The filtration of bacterial suspensions of the fecal contaminant Escherichia coli reveals highly efficient bacterial retention capacities of the capillaries of 8 log reduction values, fulfilling the requirements on safe drinking water according to the U.S. Environmental Protection Agency. Maximum bacterial loading capacities of the capillary membranes are determined to be 3 × 10⁹ bacterial cells/750 mm² capillary surface until back flushing is recommendable. The immobilized Ag_nano remain accessible and exhibit strong bactericidal properties by killing retained bacteria up to maximum bacterial loads of 6 × 10⁸ bacterial cells/750 mm² capillary surface and the regenerated membranes regain filtration efficiencies of 95–100%. Silver release is moderate as only 0.8% of the initial silver loading is leached during a three-day filtration experiment leading to average silver contaminant levels of 100 μg/L.

•

Silver nanoparticle-doped zirconia capillary membrane for water filtration purposes

•

Characterization of the silver loading capacity of the capillary membrane

•

Excellent bacteria filtration performances of log reduction values of 8

•

Efficient killing of 6 × 10⁸  filtrated bacteria/750 mm² capillary surface

•

Back flushing enables the regeneration of the membrane by removing dead bacteria.