Bio-Inspired Nanostructured Ti-6Al-4V Alloy: The Role of Two Alkaline Etchants and the Hydrothermal Processing Duration on Antibacterial Activity

Bright, Richard; Hayles, Andrew; Wood, Jonathan; Ninan, Neethu; Palms, Dennis; Visalakshan, Rahul Madathiparambil; Burzava, Anouck; Brown, Toby D.; Barker, Dan; Vasilev, Krasimir

doi:10.3390/nano12071140

Cited by 26 publications

(30 citation statements)

References 59 publications

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“…Two sets of titanium (Ti-6Al-4V Grade-5) substrates sized 7 × 10 mm were used for the experiments. This chosen nanowire structure fabricated with a hydrothermal process on a Ti-6Al-4V alloy has been extensively studied by previous researchers for antibacterial property , and eukaryotic cell proliferation . The set of substrates that have undergone the hydrothermal synthesis process is referred to as treated substrates in this report.…”

Section: Materials and Methodologymentioning

confidence: 99%

Fluid Flow Induces Differential Detachment of Live and Dead Bacterial Cells from Nanostructured Surfaces

2022

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Nanotopographic surfaces are proven to be successful in killing bacterial cells upon contact. This non-chemical bactericidal property has paved an alternative way of fighting bacterial colonization and associated problems, especially the issue of bacteria evolving resistance against antibiotic and antiseptic agents. Recent advancements in nanotopographic bactericidal surfaces have made them suitable for many applications in medical and industrial sectors. The bactericidal effect of nanotopographic surfaces is classically studied under static conditions, but the actual potential applications do have fluid flow in them. In this study, we have studied how fluid flow can affect the adherence of bacterial cells on nanotopographic surfaces. Gram-positive and Gram-negative bacterial species were tested under varying fluid flow rates for their retention and viability after flow exposure. The total number of adherent cells for both species was reduced in the presence of flow, but there was no flowrate dependency. There was a significant reduction in the number of live cells remaining on nanotopographic surfaces with an increasing flowrate for both species. Conversely, we observed a flowrate-independent increase in the number of adherent dead cells. Our results indicated that the presence of flow differentially affected the adherent live and dead bacterial cells on nanotopographic surfaces. This could be because dead bacterial cells were physically pierced by the nano-features, whereas live cells adhered via physiochemical interactions with the surface. Therefore, fluid shear was insufficient to overcome adhesion forces between the surface and dead cells. Furthermore, hydrodynamic forces due to the flow can cause more planktonic and detached live cells to collide with nano-features on the surface, causing more cells to lyse. These results show that nanotopographic surfaces do not have self-cleaning ability as opposed to natural bactericidal nanotopographic surfaces, and nanotopographic surfaces tend to perform better under flow conditions. These findings are highly useful for developing and optimizing nanotopographic surfaces for medical and industrial applications.

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Section: Materials and Methodologymentioning

confidence: 99%

Fluid Flow Induces Differential Detachment of Live and Dead Bacterial Cells from Nanostructured Surfaces

2022

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“…The HTE-Ti nanoprotrusions were approximately perpendicular to the surface and measured 348 ± 152 nm in height and had a mean diameter of 98 ± 60 nm at midheight. Such nanostructures with heights greater than 200 nm and a high aspect ratio are required for optimal bactericidal activity. , The spacing between the nanostructures was 437 ± 46 nm. The arithmetic average (Ra) and mean square roughness (RMS) were determined from the AFM images to be 175.5 and 236.3 nm for HTE-Ti and 4.2 and 5.13 nm for AR-Ti (Figure C,D), respectively.…”

Section: Characterization and Cytocompatibility Of Hte-timentioning

confidence: 99%

“…The differences in the membrane composition between mammalian and bacterial cells lead to variations in membrane fluidity. Bacteria have a rigid peptidoglycan layer, rendering them susceptible to mechanobactericidal killing by the nanostructures. , Furthermore, as mammalian cells (10–100 μm) are much larger than bacterial cells (0.5–5 μm), mammalian cells are able to disperse downward pressure on the nanostructures over a larger surface. ,, …”

Section: Characterization and Cytocompatibility Of Hte-timentioning

confidence: 99%

“…19,31 Furthermore, as mammalian cells (10− 100 μm) are much larger than bacterial cells (0.5−5 μm), mammalian cells are able to disperse downward pressure on the nanostructures over a larger surface. 10,24,32 Vancomycin Treatment of Mature S. Aureus Biofilm on HTE-Ti. To understand the effect of the nanostructured surface on the susceptibility of S. aureus to antibiotics, first we cultured S. aureus on the AR-Ti and HTE-Ti surfaces for 3 days.…”

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Surfaces Containing Sharp Nanostructures Enhance Antibiotic Efficacy

et al. 2022

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The ever-increasing rate of medical device implantations is met by a proportionately high burden of implantassociated infections. To mitigate this threat, much research has been directed toward the development of antibacterial surface modifications by various means. One recent approach involves surfaces containing sharp nanostructures capable of killing bacteria upon contact. Herein, we report that the mechanical interaction between Staphylococcus aureus and such surface nanostructures leads to a sensitization of the pathogen to the glycopeptide antibiotic vancomycin. We demonstrate that this is due to cell wall damage and impeded bacterial defenses against reactive oxygen species. The results of this study promise to be impactful in the clinic, as a combination of nanostructured antibacterial surfaces and antibiotics commonly used in hospitals may improve antimicrobial therapy strategies, helping clinicians to prevent and treat implant-associated infections using reduced antibiotic concentrations instead of relying on invasive revision surgeries with often poor outcomes.

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“…[ 24 ] Structures with comparable dimensions have previously been shown to be effective at eliminating S. aureus and P. aeruginosa at 10 5 and 10 6 colony forming units (CFU) mL −1 , respectively. [ 19b,25 ] Atomic force microscopy (AFM) analysis supported the topography observed by SEM imaging, as machining marks were present on the otherwise smooth AR‐Ti, while nanoscale protrusions were clearly visualized on the HTE‐Ti surface. The nanoscale roughness (R a ) of the AR‐Ti and HTE‐Ti surfaces was determined from 5 × 5 µm AFM scans, which measured 42 nm on the AR‐Ti and 175 nm on the HTE‐Ti surface.…”

Section: Resultsmentioning

confidence: 88%

Dual Species Bacterial Challenge of a Biomimetic Nanostructured Surface

Hayles

Bright

Hasan

et al. 2022

Adv Materials Inter

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The occurrence of IAI is predominately triggered during surgery, when bacteria from the surgical site transfer to the implant surface and initiate a sequence of attachment, proliferation, and maturation. [2] This sequence leads to the establishment of a biofilm, which is characterized by an aggregation of bacterial cells attached to the implant surface and embedded in a matrix of extracellular polymeric substance (EPS). [3] The biofilm lifestyle affords bacteria an improved ability to avoid clearance by the host immune system and antibacterial drugs. [4] It is well established that bacterial biofilms enhance antibiotic resistance by up to 1000-fold, [5] and in most cases, antibiotics alone are insufficient to eliminate IAI. [6] Further, complications arise when multiple pathogenic species co-aggregate, as biofilm formation can be enhanced depending on the species composition. [7] This is concerning because polymicrobial infections account for a considerable proportion of IAI. For example, ≈15-19% of orthopedic implant infections involve more than one pathogenic species. [2,8] Staphylococcus aureus is the most common pathogen identified in IAI, [9] among other culprits such as Pseudomonas aeruginosa, Escherichia coli, Enterococcus faecalis, Klebsiella pneumoniae, and Candida albicans, among others. [8b] Mixed species biofilms can also promote the emergence of drug resistant bacteria, as biofilm-associated cells share genetic elements through horizontal gene transfer. [10] Beyond this, crossspecies interactions can benefit one or more species within the composition by mitigating unfavorable environmental conditions. [11] An example of this is seen during infection, when the host limits iron availability as a defense mechanism. [12] When E. faecalis is co-localized with E. coli, these iron limiting conditions trigger E. faecalis to induce the upregulation of siderophore biosynthesis by E. coli, enhancing its iron uptake, and supporting it to overcome the host defense mechanism. [13] This seemingly altruistic behavior of E. faecalis may ultimately cycle back to a realized benefit for itself if the E. coli isolate in the composition is carbapenemase-producing, as E. faecalis benefits from the presence of this drug resistance enzyme. [14] These mutually beneficial interactions lead to a concerning outcome, as co-infections of E. faecalis and E. coli have been shown to be significantly more virulent than their single-species counterparts. [15] An ever-present risk of medical device associated infection has driven a significant body of research toward development of novel anti-infective materials. Surfaces bearing sharp nanostructures are an emerging technology to address this concern. The in vitro efficacy of antimicrobial nanostructures has previously been verified using single species cultures, but there remains a paucity of data to address the threat of infections containing more than one species. Polymicrobial infections are a concerning threat because they can complicate treatment, promote drug resistance, and ...

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Bio-Inspired Nanostructured Ti-6Al-4V Alloy: The Role of Two Alkaline Etchants and the Hydrothermal Processing Duration on Antibacterial Activity

Cited by 26 publications

References 59 publications

Fluid Flow Induces Differential Detachment of Live and Dead Bacterial Cells from Nanostructured Surfaces

Fluid Flow Induces Differential Detachment of Live and Dead Bacterial Cells from Nanostructured Surfaces

Surfaces Containing Sharp Nanostructures Enhance Antibiotic Efficacy

Dual Species Bacterial Challenge of a Biomimetic Nanostructured Surface

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