An in situ antimicrobial susceptibility testing method based on in vivo measurements of chlorophyll α fluorescence

Heliopoulos, Nikolaos S.; Galeou, Angeliki; Papageorgiou, Sergios K.; Favvas, Evangelos P.; Katsaros, Fotios K.; Stamatakis, Kostas

doi:10.1016/j.mimet.2015.03.011

Cited by 10 publications

(18 citation statements)

References 19 publications

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“…nm thick coating. Their antibacterial behavior was studied according to an in situ method of fluorescence measurement, which has recently been developed and described in previous works 35,36 (see section 2.6 and the Supporting Information). Figure 4 shows the comparison of these two metals.…”

Section: Comparison Of the Antibacterial Action Of Silver Andmentioning

confidence: 99%

Is There a Threshold in the Antibacterial Action of Superhydrophobic Surfaces?

Ellinas

Kefallinou

Stamatakis

et al. 2017

ACS Appl. Mater. Interfaces

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110

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The realization of antibacterial surfaces is an important scientific problem, which may be addressed by the use of superhydrophobic surfaces, reducing bacterial adhesion. However, there are several limitations and contradicting reports on the antibacterial efficacy of such surfaces. Moreover, achieving antibacterial action through minimization of adhesion does not ensure complete protection against bacteria. Here, we identify the important factors affecting antibacterial action on superhydrophobic surfaces, emphasizing the role of bacterial concentration, and observing an upper concentration threshold above which antibacterial action of any surface is compromised. Finally, we propose metal enriched, superhydrophobic surfaces, as the "ultimate" "hybrid" antibacterial surfaces for in vitro applications.

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Section: Comparison Of the Antibacterial Action Of Silver Andmentioning

confidence: 99%

Is There a Threshold in the Antibacterial Action of Superhydrophobic Surfaces?

Ellinas

Kefallinou

Stamatakis

et al. 2017

ACS Appl. Mater. Interfaces

Self Cite

110

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“…where F 0 0 is the fluorescence value at zero contact time and F 0 i is the fluorescence value after 1, 2, ..., i days. Of notice, F 0 has been proved to be directly correlated to the bacterial population and the M i evolution to the increase/decrease of the population [48]. In particular, negative values of the M i index are indicative of a decline in bacterial population, therefore of an antibacterial behavior of the testing surface.…”

Section: Antibacterial Susceptibility Testing Methodsmentioning

confidence: 97%

“…An in situ quantitative method for the assessment of the antibacterial properties of the fabricated surfaces was used, based on in vivo measurements of chlorophyll (Chl α) fluorescence of cyanobacteria directly deposited on the surfaces, as a faithful representation of their real life conditions [48,49]. The method has been tested and evaluated for its accuracy compared to the AATCC 100-2004 method, which is used as a standard for the evaluation of the antibacterial properties [48]. More specifically, it has been demonstrated [49] that this method employing cyanobacteria can monitor the behavior of either phototrophic or heterotrophic bacterial metabolic pathways on antibacterial surfaces.…”

Section: Antibacterial Susceptibility Testing Methodsmentioning

confidence: 99%

“…In all cases, 50 µL of the corresponding concentration of Synechococcus sp. PCC 7942 were deposited on each surface and their antibacterial behavior was measured according to the Chl α fluorescence emission, as captured by the in situ antimicrobial susceptibility testing method [48] throughout the exponential bacterial growth period. The resulting M i index evolution of the two different metallic sputtered surfaces is presented separately for each bacterial concentration, with respect to an untreated pristine PMMA surface in Figure 4.…”

Section: Bactericidal Activity Of Copper and Silvermentioning

confidence: 99%

“…Its superiority in dry contact can be interpreted by its three-stage attack to bacteria [56], which involves primarily cell membrane rupture and loss of cytoplasmic content due to both released copper ions and applied stress, followed by generation of toxic reactive oxygen species (ROS) by a Fenton-type reaction [59] that damage cell functionality by inhibiting respiration and inactivating proteins, and finally, leading to DNA degradation. Added to the above, copper exhibits enhanced bactericidal performance towards specifically autotrophic photosynthetic organisms, due to the Cu 2+ copper ion's ability to obstruct the photosynthetic procedure by obstructing the electron transport in Photosystem II [48]. However, in our study, its bactericidal activity cannot be exhausted to its capacity to impede photosynthesis, as reaffirmed by the universality of the as here used chlorophyll α fluorescence based antimicrobial susceptibility testing (AST) method, which is affected by antibacterial agents via mechanisms offending all Gram-negative bacteria, regardless of their autotrophic or heterotrophic metabolic pathways [49].…”

Section: Bactericidal Activity Of Copper and Silvermentioning

confidence: 99%

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Optimization of Antibacterial Properties of “Hybrid” Metal-Sputtered Superhydrophobic Surfaces

et al. 2019

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Bacterial attachment and colonization to hygiene sensitive surfaces, both public and nosocomial, as well as in food industry areas, poses a serious problem to human healthcare. Several infection incidents are reported, while bacterial resistance to antibiotics is increasing. Recently, novel techniques for the design of antibacterial surfaces to limit bacterial spreading have emerged, including bifunctional antibacterial surfaces with antifouling and bactericidal action. In this context, we have recently developed smart, universal, metal-sputtered superhydrophobic surfaces, demonstrating both bacterial repulsion and killing efficacy. Herein, we present the optimization process that led to the realization of these “hybrid” antibacterial surfaces. To this end, two bactericidal agents, silver and copper, were tested for their efficiency against Gram-negative bacteria, with copper showing a stronger bactericidal action. In addition, between two low surface energy coatings, the fluorinated-alkyl self-assembled chlorosilane layer from perfluorinated octyltrichlorosilane (pFOTS) solution and the fluorocarbon layer from octafluorocyclobutane (C4F8) plasma were both approved for their anti-adhesive properties after immersion in bacterial solution. However, the latter was found to be more efficient when engrafted with the bactericidal agent in shielding its killing performance. Furthermore, the thickness of the plasma-deposited fluorocarbon layer was optimized, in order to simultaneously retain both the superhydrophobicity of the surface and its long-term bactericidal activity.

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Covalently Modified Kevlar Fabric Incorporating Graphene Oxide with Enhanced Antibacterial Properties and Preserved Strength

Canton‐Vitoria,

Heliopoulos,

Boukos

et al. 2023

Chemistry A European J

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This work describes a multi‐step modification process for the covalent transformation of Kevlar fabric en route to the incorporation of graphene oxide (GO) nanosheets. Spectroscopic, thermal and microscopy imaging techniques have been employed to follow step‐by‐step the modification of Kevlar and the formation of the corresponding Kevlar‐GO hybrid fabric. The level of Kevlar's functionalization can be controlled with the nitration time, the first reaction in the multi‐sequence organic transformations, for obtaining the hybrid fabric with a content of GO up to 30 %. Most importantly, the covalent post‐modification of Kevlar does not occur in the expense of the other excellent mechanical properties of the fabric. Under optimal conditions, the Kevlar‐GO hybrid fabric shows a 20 % enhancement of the ultimate strength. Notably, when the Kevlar‐GO hybrid fabric was exposed to cyanobacterial Synechococcus the bacteria growth was fully inhibited. Overall, the covalently modified fabric demonstrated significant antibacterial behavior, excellent strength and stability under common processes. Due to its simplicity, the methodology presented in this work not only promises to result in a standard procedure to functionalize the mer units of Kevlar with a variety of chemicals and nanomaterials but it can be also extended for the modification and hybridization of other fabrics.

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An in situ antimicrobial susceptibility testing method based on in vivo measurements of chlorophyll α fluorescence

Cited by 10 publications

References 19 publications

Is There a Threshold in the Antibacterial Action of Superhydrophobic Surfaces?

Is There a Threshold in the Antibacterial Action of Superhydrophobic Surfaces?

Optimization of Antibacterial Properties of “Hybrid” Metal-Sputtered Superhydrophobic Surfaces

Covalently Modified Kevlar Fabric Incorporating Graphene Oxide with Enhanced Antibacterial Properties and Preserved Strength

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