The performance of CoCrMo alloy in orthopaedic implants may be unfavourably affected by hyaluronic acid (HA) in synovial fluid. In this study, the authors aimed to understand the interactions between ...HA and CoCrMo using dedicated electrochemical experiments and surface analyses. A sequence of electrochemical measurements (open‐circuit potential, linear polarization resistance, potentiodynamic and potentiostatic polarizations) was run on LC‐CoCrMo (ASTM F1537) in Dulbecco's phosphate‐buffered saline (DPBS) solution with and without HA and in DPBS mixed with newborn calf serum (NCS) and HA, partially under simultaneous recording of surface pH using custom‐made microelectrodes. Samples were analysed by optical and electron microscopy. HA had no significant impact on the corrosion potential of CoCrMo alloy (ECORR = −173 ± 8, −211 ± 16, and −254 ± 30 mVAg/AgCl, in DPBS, DPBS + HA, and DPBS + NCS + HA, respectively). Average current density values at the transpassive domain were double in DPBS compared to DPBS + HA and DPBS + NCS + HA. At potentials above +0.6 VAg/AgCl, surface pH values decreased from 7.5 to 6.5 in DPBS and from 7.5 to below 4 in DPBS + HA. In conclusion, the presence of HA did not compromise the corrosion resistance of CoCrMo alloy at free potential, but it enhanced acidic conditions at the near surface under anodic‐applied potential in the transpassive domain.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Conventional methods for testing antibiotic susceptibility rely on bacterial growth on agar plates (diffusion assays) or in liquid culture (microdilution assays). These time-consuming assays use ...population growth as a proxy for cellular respiration. Herein we propose to use mediated extracellular electron transfer as a rapid and direct method to classify antibiotic-susceptible and -resistant bacteria. We tested antibiotics with diverse mechanisms of action (ciprofloxacin, imipenem, oxacillin, or tobramycin) with four important nosocomial pathogens (Acinetobacter baumannii, Staphylococcus aureus, Escherichia coli, and Klebsiella pneumoniae) by adding the bacterial culture to a custom-designed electrochemical cell with a glassy-carbon electrode and growth media supplemented with a soluble electron transfer mediator, phenazine methosulfate (PMS). During cell respiration, liberated electrons reduce PMS, which is then oxidized on the electrode surface, and current is recorded. Using this novel approach, we were able to consistently classify strains as antibiotic-resistant or -susceptible in <90 min for methodology development and <150 min for blinded tests.
•We developed an electrochemical assay to rapidly detect antibiotic susceptibility.•Current response was used to define antibiotic susceptibility index (ASI).•ASI along with an algorithm was used to classify antibiotic susceptible and resistant strains.•We tested the assay with four important nosocomial pathogens and diverse antibiotics.•The assay was validated using blind test and compared with conventional tests.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Chronic wound biofilm infections represent a major clinical challenge which results in a substantial burden to patients and healthcare systems. Treatment with topical antibiotics is oftentimes ...ineffective as a result of antibiotic‐resistant microorganisms and biofilm‐specific antibiotic tolerance. Use of biocides such as hypochlorous acid (HOCl) has gained increasing attention due to the lack of known resistance mechanisms. An HOCl‐generating electrochemical bandage (e‐bandage) is designed that delivers HOCl continuously at low concentrations targeting infected wound beds in a similar manner to adhesive antimicrobial wound dressings. A battery‐operated wearable potentiostat is developed that controls the e‐bandage electrodes at potentials suitable for HOCl generation. It is demonstrated that e‐bandage treatment is tunable by changing the applied potential. HOCl generation on electrode surfaces is verified using microelectrodes. The developed e‐bandage shows time‐dependent responses against in vitro Acinetobacter baumannii and Staphylococcus aureus biofilms, reducing viable cells to nondetectable levels within 6 and 12 h of treatment, respectively. The developed e‐bandage should be further evaluated as an alternative to topical antibiotics to treat wound biofilm infections.
Chronic wound biofilm infections represent a major clinical challenge due to the presence of antibiotic‐resistant pathogens and biofilm‐associated antibiotic tolerance. An electrochemical bandage controlled by a wearable potentiostat is designed to deliver electronically tunable low concentrations of hypochlorous acid to treat biofilm infections. The electrochemical bandage reduces the viable cell count of in vitro membrane biofilms in a time‐dependent manner.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Aims
Effects of H2O2 producing electrochemical‐bandages (e‐bandages) on methicillin‐resistant Staphylococcus aureus colonization and biofilm removal were assessed using a porcine explant biofilm ...model. Transport of H2O2 produced from the e‐bandage into explant tissue and associated potential toxicity were evaluated.
Methods and Results
Viable prokaryotic cells from infected explants were quantified after 48 h treatment with e‐bandages in three ex vivo S. aureus infection models: (1) reducing colonization, (2) removing young biofilms and (3) removing mature biofilms. H2O2 concentration‐depth profiles in explants/biofilms were measured using microelectrodes. Reductions in eukaryotic cell viability of polarized and nonpolarized noninfected explants were compared. e‐Bandages effectively reduced S. aureus colonization (p = 0.029) and reduced the viable prokaryotic cell concentrations of young biofilms (p = 0.029) with limited effects on mature biofilms (p > 0.1). H2O2 penetrated biofilms and explants and reduced eukaryotic cell viability by 32–44% compared to nonpolarized explants.
Conclusions
H2O2 producing e‐bandages were most active when used to reduce colonization and remove young biofilms rather than to remove mature biofilms.
Significance and Impact of Study
The described e‐bandages reduced S. aureus colonization and young S. aureus biofilms in a porcine explant wound model, supporting their further development as an antibiotic‐free alternative for managing biofilm infections.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Chronic wound infections caused by biofilm‐forming microorganisms represent a major burden to healthcare systems. Treatment of chronic wound infections using conventional antibiotics is often ...ineffective due to the presence of bacteria with acquired antibiotic resistance and biofilm‐associated antibiotic tolerance. We previously developed an electrochemical scaffold that generates hydrogen peroxide (H2O2) at low concentrations in the vicinity of biofilms. The goal of this study was to transition our electrochemical scaffold into an H2O2‐generating electrochemical bandage (e‐bandage) that can be used in vivo. The developed e‐bandage uses a xanthan gum‐based hydrogel to maintain electrolytic conductivity between e‐bandage electrodes and biofilms. The e‐bandage is controlled using a lightweight, battery‐powered wearable potentiostat suitable for use in animal experiments. We show that e‐bandage treatment reduced colony‐forming units of Acinetobacter buamannii biofilms (treatment vs. control) in 12 h (7.32 ± 1.70 vs. 9.73 ± 0.09 log10CFU/cm2) and 24 h (4.10 ± 12.64 vs. 9.78 ± 0.08 log10CFU/cm2) treatments, with 48 h treatment reducing viable cells below the limit of detection of quantitative and broth cultures. The developed H2O2‐generating e‐bandage was effective against in vitro A. baumannii biofilms and should be further evaluated and developed as a potential alternative to topical antibiotic treatment of wound infections.
Chronic wound infections are difficult to treat using traditional approaches due to the frequent presence of bacteria with acquired antibiotic resistance alongside biofilm‐associated antibiotic tolerance. An electrochemical bandage controlled by a wearable potentiostat is designed to deliver low concentrations of hydrogen peroxide to manage wound infections. The activity of the electrochemical bandage is demonstrated in vitro against Acinetobacter baumannii biofilms.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Chronic wound biofilm infections represent a major clinical challenge which results in a substantial burden to patients and healthcare systems. Treatment with topical antibiotics is oftentimes ...ineffective as a result of antibiotic-resistant microorganisms and biofilm-specific antibiotic tolerance. Use of biocides such as hypochlorous acid (HOCl) has gained increasing attention due to the lack of known resistance mechanisms. We designed an HOCl-generating electrochemical bandage (e-bandage) that delivers HOCl continuously at low concentrations targeting infected wound beds in a similar manner to adhesive antimicrobial wound dressings. We developed a battery-operated wearable potentiostat that controls the e-bandage electrodes at potentials suitable for HOCl generation. We demonstrated that e-bandage treatment was tunable by changing the applied potential. HOCl generation on electrode surfaces was verified using microelectrodes. The developed e-bandage showed time-dependent responses against
and
biofilms, reducing viable cells to non-detectable levels within 6 and 12 hours of treatment, respectively. The developed e-bandage should be further evaluated as an alternative to topical antibiotics to treat wound biofilm infections.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Microliter volumes are used in electrochemical detection and preconcentration of radionuclides to reduce the dose received by researchers and equipment. Unfortunately, there is a lack of analysis of ...radionuclides with coupled electrochemical techniques and microliter volume reactors. The goals of this work are (1) to develop a miniaturized micro-electrochemical quartz crystal microbalance (μeQCM) reactor for use in small volume (50–200 μL) electrogravimetric experiments and (2) to use this reactor to characterize the preconcentration of neptunium on carbon electrodes via electroprecipitation. We successfully deposited neptunium in the new μeQCM reactor and verified its operation. We found that preconcentration of neptunium on carbon coated electrodes was possible by chronoamperometry at − 1.6 V
Ag/AgCl
. The mass shift of the resulting precipitate was indicative of the amount of neptunium on the electrode, although the correlation between the mass increase and activity of the preconcentrated material was not linear. Neptunium precipitate reduced electron transfer to the solution as evidenced by the increase in charge transfer resistance compared to bare electrodes.
We developed a new microelectrode with a tip made of a hematite film for the detection of flavin using pulse voltammetry. Hematite has been used as a reducing agent for many metals and an ...electrochemical sensor for Riboflavin, hydroquinone, and dopamine because of its excellent adsorption capacity. Potentially, a thin hematite film can be used for microelectrodes for sensor development. We prepared hematite films on a microelectrode with a carbon fiber tip. Colloidal hematite was synthesized from iron nitrate and characterized using FTIR and EDX. In addition to microelectrode work, a hematite film was deposited on to a glassy carbon electrochemical quartz crystal microbalance (eQCM) to characterize the mechanism of deposition and physical sorption in a pH range of 5-8. Lastly, electrochemical impedance spectroscopy (EIS) was used to characterize the electrochemical processes. We found that the hematite film exhibited capacitive and resistive characteristics. We also found that the hematite film microelectrode detection limit improved compared to bare carbon fiber.
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