Fig 6 - available via license: Creative Commons Attribution 4.0 International
Content may be subject to copyright.
Fourier transform infrared spectroscopy (FT-IR) spectra. Measured spectra of the major single component of the resin containing urethane acrylate monomer with PEG derivatives (A) and eluted components from the super-hydrophilic moth-eye film (B) and reference PEG (C). https://doi.org/10.1371/journal.pone.0185366.g006
Source publication
The antibacterial effect of a nanostructured film, known as “moth-eye film,” was investigated. The moth-eye film has artificially formed nano-pillars, consisting of hydrophilic resin with urethane acrylate and polyethylene glycol (PEG) derivatives, all over its surface that replicates a moth’s eye. Experiments were performed to compare the moth-eye...
Citations
... An irregular surface with a height of 620 nm, a width of 2 µm and a length of 5 µm (NIL-5, Figure 5c) and circular pillars with 600 nm height and a diameter of 1 µm (NIL-6, Figure 5d) were successfully replicated. Additionally, a moth eye array (NIL-7, Figure 5e) known for its antibacterial properties [62,63], with a height of 150 nm and a diameter of 200 nm, is presented. ...
Additive and lithographic manufacturing technologies using photopolymerisation provide a powerful tool for fabricating multiscale structures, which is especially interesting for biomimetic scaffolds and biointerfaces. However, most resins are tailored to one particular fabrication technology, showing drawbacks for versatile use. Hence, we used a resin based on thiol-ene chemistry, leveraging its numerous advantages such as low oxygen inhibition, minimal shrinkage and high monomer conversion. The resin is tailored to applications in additive and lithographic technologies for future biofabrication where fast curing kinetics in the presence of oxygen are required, namely 3D inkjet printing, digital light processing and nanoimprint lithography. These technologies enable us to fabricate scaffolds over a span of six orders of magnitude with a maximum of 10 mm and a minimum of 150 nm in height, including bioinspired porous structures with controlled architecture, hole-patterned plates and micro/submicro patterned surfaces. Such versatile properties, combined with noncytotoxicity, degradability and the commercial availability of all the components render the resin as a prototyping material for tissue engineers.
... This is consistent with the results of the abovementioned observations of bacterial morphology. The adherence of bacteria to material surfaces is usually considered to involve physical or chemical factors, such as surface morphology, 38 hydrophobic interaction, van der Waals forces, electrostatic interactions, 39 roughness, wettability, 40 and antiadhesive chemical composition. 41 After the EDM process, the microgrooved surface was coated with a layer of silver monomer that increased the roughness of the microgrooved surface, and the surface contact angle of the samples decreased from 78.67 ± 1.08°to 34.45 ± 7.14°after EDM silver deposition. ...
Infection caused by orthopedic titanium implants, which results in tissue damage, is a key factor in endosseous implant failure. Given the seriousness of implant infections and the limitations of antibiotic therapy, surface microstructures and antimicrobial silver coatings have emerged as prominent research areas and have displayed certain antimicrobial effects. Researchers are now working to combine the two to produce more effective antimicrobial surfaces. However, building robust and homogeneous coatings on complex microstructured surfaces is a tough task due to the limits of surface modification techniques. In this study, a novel flexible electrode brush (silver brush) instead of a traditional hard electrode was designed with electrical discharge machining, which has the ability to adapt to complex groove interiors. The results showed that the use of flexible electrode brush allowed silver to be deposited uniformly in titanium alloy microgrooves. On the surface of Ag-TC4, a uniformly covered deposit was visible, and it slowly released silver ions into a liquid environment. In vitro bacterial assays showed that a Ag-TC4 microstructured surface reduced bacterial adhesion and bacterial biofilm formation, and the antibacterial activity of Ag-TC4 against Staphylococcus aureus and Escherichia coli was 99.68% ± 0.002 and 99.50% ± 0.007, respectively. This research could lay the groundwork for the study of antimicrobial metal bound to microstructured surfaces and pave the way for future implant surface design.
... A quantifiable assessment of bacterial infection models within scaffolds is particularly challenging, as contemporary methods in microbiology usually focus on flat samples [165][166][167][168] . Methods such as the Japanese Film Method (JIS Z2801), adenosine triphosphate (ATP) bioluminescence assay, or LIVE/DEAD assays are widely used when assessing the bacterial behaviour on flat surfaces [169][170][171] , and the agar diffusion method is useful in assessing the antibacterial effect of substances eluted by the sample [172,173] , however they do not facilitate the analysis of 3D porous structures. Imaging of green fluorescent protein (GFP)-tagged bacterial cells with a confocal microscope 1.1 Literature review 33 allows for better analysis of larger surface structures [174] , but that too does not produce reliable results when faced with porous scaffolds. ...
This thesis reports on the development of quantifiable methods for the assessment of bacterial bioburden within three-dimensional orthopaedic scaffolds, and the subsequent investigation of the effects of exposure of their surfaces to proteins has on the observed biofouling. The lack of readily available methods for this purpose, and the rising cost (both human and financial) of biofilm infection of orthopaedic devices prompted the need for this research. Existing methods are identified during the literature review, such as Confocal Laser Scanning Microscopy (CLSM) and Micro-CT which are used in the research field are first investigated for efficacy as they have been used in some studies. The aim of this study is to develop and validate a new analysis method to provide quantifiable, accurate and reliable results for the measurement of bacterial biofouling on flat and three-dimensional samples alike. This method is then used to measure the bacterial biofouling of samples once inoculated and incubated with S. aureus in a protein-rich environment they would be exposed to in situ inside a patient. Analysis using SEM micrographs is adopted as a methodology and refined in this work. The standardised approach which takes readings in triplicate from each sample, and measures bacterial surface coverage of the imaged area through computational image analysis is used to study commercially-available orthopaedic scaffolds (Ta and Ti6Al4V), as well as samples containing elements known for their antibacterial properties (Cu and I). The reliability of the novel SEM methodology is shown through validation against the research standard of CLSM, which is readily used for analysis of flat, two-dimensional samples. Once validated, the SEM methodology is then used to study the effect a surface which has been pre-conditioned with protein has on bacterial biofouling compared to a clean surface, both when the substrate surface chemistry has known antibacterial properties or not. It is found that the physical shielding of bacterial cells from the antibacterial surface agent by the protein film reduces the antibacterial effect. The new method developed is of significance as it provides researchers a reliable way to measure biofouling in three-dimensional structures with a protocol made for that very purpose. It is hoped that this method will continue to be refined to further enable research within microbiological assessments within orthopaedic scaffolds which carry a risk of biofilm infection in a clinical setting. The protein conditioning studies go on to explain why samples, even when containing known antibacterial agents, are still susceptible to bacterial infection in a clinical setting.
... There are two types of TB: pulmonary TB, which typically affects the lung, and extrapulmonary TB, which might affect any other organ in the body. Urogenital TB is the third most common form of extrapulmonary TB after lymph node involvement and tuberculous pleural effusion [2]. Urogenital TB usually remains undiagnosed for years because it is a clinically silent disorder. ...
Background
Urinary tract tuberculosis (UTTB) is a common form of extrapulmonary tuberculosis (TB) which can infrequently present as renal carcinoma, leading to serious errors in the diagnosis and treatment of UTTB.
Case presentation
A 76-year-old Syrian man presented with gross hematuria as the main symptom. A urinary endoscopic examination and pelvic multi-slice computed tomography imaging increased the suspicion of a speared renal mass in the right urinary tract. The patient was treated for renal cancer. After nephrectomy and ureterctomy, the histopathology of the resected mass confirmed the diagnosis of UTTB and interstitial nephritis.
Conclusion
This case should serve to increase the attention of clinicians to perform an accurate diagnosis step by step. This is especially important if they have a patient similar to the case described here who presents with a renal mass, to avoid serious results such as the loss of an essential organ system.
... However, toxicity issues and the emergence of resistant bacteria strains are restricting their use and clinical efficacy. [1][2][3][4][5][6][7] As an alternative, nanostructured surfaces in nature, [8,9] such as cicada, [10,11] dragonfly, [12,13] damselfly, [14] planthopper wings, [15] gecko skin, [16,17] lotus leaf, [18] or moth-eye, [19,20] have emerged as a new strategy to deter bac-element models (FEM) [26,31,32] or molecular dynamic simulations [33] have been implemented to investigate the mechanobactericidal activity of surface nanostructures. ...
... These SEM images reveal that the moth-eye nanocones inflict a certain degree of damage to the bacteria attached compared to that seen on the flat counterparts, as previous works have shown before. [19,20] The dynamics of the bacteria death upon interaction with the moth-eye topography were evaluated using fluorescent probes. In this case, Syto9 was utilized to localize bacterial cells on the plane corresponding to the top nanocone surface, while PI was utilized to monitor the dynamics of the bactericidal process upon bacteria attachment to the surface by tracking the fluorescence signal of PI over time. ...
In recent years, the understanding of the bactericidal mechanisms of natural surfaces has received great attention to unravel their design principles for the development of next‐generation mechano‐bactericidal surfaces. Due to the difficulty in characterizing the bacteria–nanostructure interface, many aspects of the physical interaction between bacteria and the surface, and the underlying bactericidal mechanisms, remain unclear. This study focuses on evaluating the dynamics of the mechano‐bactericidal process in the case of the moth‐eye bioinspired topography in relation to the bacteria strain and mechanical characteristics of the surface. The bacteria–nanostructure interface is examined by measuring the deformations inflicted by the nanotopography on the bacterial wall upon attachment using two techniques, namely atomic force microscopy and stereometric analysis of scanning electron microscopy images. All data match well and are in accordance with the expected bacteria mechanical deformation calculated by finite element modeling. This represents a practical methodology to measure bacterial deformations inflicted by nanotopography. The methodology can be implemented to any other bacteria strain or bactericidal topography to verify the degree of mechanical stress and bactericidal efficacy related to the topography and surface stiffness and may serve as a design basis for the fabrication of effective antibacterial surfaces. A practical strategy to characterize the deformation inflicted on bacteria by bioinspired moth‐eye nanocones upon attachment to the surface is presented. Finite element simulations verify the accuracy of the measurements. The dynamics of the bactericidal process are followed to determine the time scale for bacterial death in relation to the nanotopography stiffness characteristics.
... Antibacterial effects of the artificial surface of nanoimprinted moth-eye film were investigated by Minoura et al. [210]. They find that moth-eye surfaces fabricated using UV-NIL in UV-curable PEG exhibit significant antibacterial effects when tested with Staphylococcus aureus and Esherichia coli. ...
Biomimetic micro- and nano- structures have attracted considerable interest over the last decades for various applications ranging from optics to life sciences. The complex nature of the structures, however, presents significant challenges for fabrication and their application in real-life settings. Nanoimprint lithography could provide an interesting opportunity in this respect. This article seeks to provide an overview of what has already been achieved using nanoscale replication technologies in the field of biomimetics and will aim to highlight opportunities and challenges for nanoimprinting in this respect in order to inspire new research.
... Nanoimprint lithography (NIL) [17] is a suitable candidate to realize bioinspired patterns, as it is a high-resolution lithographic method with generally low cost, high throughput and the ability to use different substrates materials, allowing surface structuring of transparent and flexible materials [18]. Several examples of bio-inspired topographies fabricated by batch-to-batch NIL can be found in the literature based on one-level nanocones [19], nanopillars [20][21][22][23][24], micro lines [25] and micro mushrooms [26]. Using NIL is possible to fabricate multi-scale topographies combining micro-and nano-structures, denoted as hierarchical structures [27][28][29][30][31][32][33]. ...
The development of antimicrobial surfaces has become a high priority in recent times. There are two ongoing worldwide health crises: the COVID-19 pandemic provoked by the SARS-CoV-2 virus and the antibiotic-resistant diseases provoked by bacteria resistant to antibiotic-based treatments. The need for antimicrobial surfaces against bacteria and virus is a common factor to both crises.
Most extended strategies to prevent bacterial associated infections rely on chemical based-approaches based on surface coatings or biocide encapsulated agents that release chemical agents. A critical limitation of these chemistry-based strategies is their limited effectiveness in time while grows the concerns about the long-term toxicity on human beings and environment pollution. An alternative strategy to prevent bacterial attachment consists in the introduction of physical modification to the surface. Pursuing this chemistry-independent strategy, we present a fabrication process of surface topographies [one-level (micro, nano) and hierarchical (micro+nano) structures] in polypropylene (PP) substrates and discuss how wettability, topography and patterns size influence on its antibacterial properties. Using nanoimprint lithography as patterning technique, we report as best results 82 % and 86 % reduction in the bacterial attachment of E. coli and S. aureus for hierarchically patterned samples compared to unpatterned reference surfaces. Furthermore, we benchmark the mechanical properties of the patterned PP surfaces against commercially available antimicrobial films and provide evidence for the patterned PP films to be suitable candidates for use as antibacterial functional surfaces in a hospital environment.
... coli) and Staphylococcus aureus, as a new technology using the surface nanostructure with biomimetics of cicada wings and lotus leaves. [6][7][8][9][10][11][12] Recently, the antibacterial activity of nanostructures with sharp protrusions and black silicon that are artificially produced by lithography in solar cells and by semiconductor manufacturing processes has attracted attention. In particular, the antibacterial activity of the products is expected to improve in response to increasing hygiene awareness. ...
... Sharp protrusion structures are known to exert antibacterial effects by piercing the bacterial cell wall upon contact or rupture of the bacterial cell wall, 7,10) whereas oligoglucosamine has been widely reported to exert antibacterial effects by promoting interactions with, and disruption of, the cell wall/membrane structure because of its cationic properties. 31,32) Thus, the antibacterial activity of the nanostructured cross-linked antibacterial film derived from oligoglucosamine in this study is likely to be caused by both physical and chemical mechanisms because of its surface structure and material, respectively, although further studies are required. ...
This study aims to expand the antibacterial activity of the cross-linked film derived from oligoglucosamine by processing sharp protrusion nanostructures on the film surface in ultraviolet nanoimprint lithography using a solvent-permeable template. The solvent-permeable template was able to remove the dilution solvent contained in the flowable liquid derived from oligoglucosamine for life science and medical healthcare, which is the cause of molding failure, resulting in nanostructures of sharp protrusions. The nanostructured cross-linked antibacterial film derived from oligoglucosamine indicated 1.6 times the antibacterial activity compared to that of the flat comparative antibacterial film before the fabrication of the nanostructures.
... Ivanova et al. was first to report the bactericidal properties of protruding nanostructured surfaces found on the cicada wing against P. aeruginosa [34]. As opposed to natural antifouling surfaces that are usually found on marine or aquatic organisms [35][36][37], natural bactericidal surfaces are mostly found on insect wings [34,[38][39][40][41]. Several species of cicada [34,39] and dragonfly [38,40] have been shown to possess wings with bactericidal activity (Figure 1). ...
... As opposed to natural antifouling surfaces that are usually found on marine or aquatic organisms [35][36][37], natural bactericidal surfaces are mostly found on insect wings [34,[38][39][40][41]. Several species of cicada [34,39] and dragonfly [38,40] have been shown to possess wings with bactericidal activity (Figure 1). Butterfly and moth eyes [41], as well as gecko skin [42], which all have distinct nanostructured surfaces, have also been reported to possess bactericidal properties. Several studies have shown similar or enhanced bactericidal effects mediated by biomimetic nanotopographies on synthetic materials [43][44][45][46][47][48]. ...
... Coatings 2020, 10, x FOR PEER REVIEW 4 of 20 have been shown to possess wings with bactericidal activity (Figure 1). Butterfly and moth eyes [41], as well as gecko skin [42], which all have distinct nanostructured surfaces, have also been reported to possess bactericidal properties. Several studies have shown similar or enhanced bactericidal effects mediated by biomimetic nanotopographies on synthetic materials [43][44][45][46][47][48]. ...
Protruding nanostructured surfaces have gained increasing interest due to their unique wetting behaviours and more recently their antimicrobial and osteogenic properties. Rapid development in nanofabrication techniques that offer high throughput and versatility on titanium substrate open up the possibility for better orthopaedic and dental implants that deter bacterial colonisation while promoting osteointegration. In this review we present a brief overview of current problems associated with bacterial infection of titanium implants and of efforts to fabricate titanium implants that have both bactericidal and osteogenic properties. All of the proposed mechano-bactericidal mechanisms of protruding nanostructured surfaces are then considered so as to explore the potential advantages and disadvantages of adopting such novel technologies for use in future implant applications. Different nanofabrication methods that can be utilised to fabricate such nanostructured surfaces on titanium substrate are briefly discussed.
... The combination of topographical modification and coatings has been reported to increase its effectiveness. For instance, Yamada et al. [42] coated a PET film with nanoscale moth-eye cone-shaped protrusions from a hydrophilic resin made of urethane acrylate and polyethylene glycol (PEG) derivatives [43] with a size of approximately 200 nm in depth and diameter. Bacteria counts were reduced significantly with the use of moth-eye film compared to uncoated PET substrate due to specific structure of motheye film. ...
Polyethylene terephthalate (PET) is one of the most used polymeric materials in the health care sector mainly due to its advantages that include biocompatibility, high uniformity, mechanical strength and resistance against chemicals and/or abrasion. However, avoiding bacterial contamination on PET is still an unsolved challenge and two main strategies are being explored to overcome this drawback: the anti-adhesive and biocidal modification of PET surface. While bacterial adhesion depends on several surface properties namely surface charge and energy, hydrophilicity and surface roughness, a biocidal effect can be obtained by antimicrobial compounds attached to the surface to inhibit the growth of bacteria (bacteriostatic) or kill bacteria (bactericidal). Therefore, it is well known that granting antibacterial properties to PET surface would be beneficial in the prevention of infectious diseases. Different modification methods have been reported for such purpose. This review addresses some of the strategies that have been attempted to prevent or reduce the bacterial contamination on PET surfaces, including functionalisation, grafting, topographical surface modification and coating. Those strategies, particularly the grafting method seems to be very promising for healthcare applications to prevent infectious diseases and the emergence of bacteria resistance.
