| 1. |
- Helgadóttir, Saga Huld, 1991, et al.
(författare)
-
Vitamin C Pretreatment Enhances the Antibacterial Effect of Cold Atmospheric Plasma
- 2017
-
Ingår i: Frontiers in cellular and infection microbiology. - : Frontiers Media SA. - 2235-2988. ; 7:FEB
-
Tidskriftsartikel (refereegranskat)abstract
- Bacterial biofilms are three-dimensional structures containing bacterial cells enveloped in a protective polymeric matrix, which renders them highly resistant to antibiotics and the human immune system. Therefore, the capacity to make biofilms is considered as a major virulence factor for pathogenic bacteria. Cold Atmospheric Plasma (CAP) is known to be quite efficient in eradicating planktonic bacteria, but its effectiveness against biofilms has not been thoroughly investigated. The goal of this study was to evaluate the effect of exposure of CAP against mature biofilm for different time intervals and to evaluate the effect of combined treatment with vitamin C. We demonstrate that CAP is not very effective against 48 h mature bacterial biofilms of several common opportunistic pathogens: Staphylococcus epidermidis, Escherichia coli, and Pseudomonas aeruginosa. However, if bacterial biofilms are pre-treated with vitamin C for 15 min before exposure to CAP, a significantly stronger bactericidal effect can be obtained. Vitamin C pretreatment enhances the bactericidal effect of cold plasma by reducing the viability from 10 to 2% in E. coli biofilm, 50 to 11% in P. aeruginosa, and 61 to 18% in S. epidermidis biofilm. Since it is not feasible to use extended CAP treatments in medical practice, we argue that the pre-treatment of infectious lesions with vitamin C prior to CAP exposure can be a viable route for efficient eradication of bacterial biofilms in many different applications.
|
|
| 2. |
- Mokkapati, Venkata Raghavendra Subrahmanya Sar, 1981, et al.
(författare)
-
Bacterial response to graphene oxide and reduced graphene oxide integrated in agar plates
- 2018
-
Ingår i: Royal Society Open Science. - : The Royal Society. - 2054-5703. ; 5:11
-
Tidskriftsartikel (refereegranskat)abstract
- There are contradictory reports in the literature regarding the anti-bacterial activity of graphene, graphene oxide (GO) and reduced graphene oxide (rGO). This controversy is mostly due to variations in key parameters of the reported experiments, like: type of substrate, form of graphene, number of layers, type of solvent and most importantly, type of bacteria. Here, we present experimental data related to bacterial response to GO and rGO integrated in solid agar-based nutrient plates-a standard set-up for bacterial growth that is widely used by microbiologists. Bacillus subtilis and Pseudomonas aeruginosa strains were used for testing bacterial growth. We observed that plate-integrated rGO showed strong anti-bacterial activity against both bacterial species. By contrast, plate-integrated GO was harmless to both bacteria. These results reinforce the notion that the response of bacteria depends critically on the type of graphene material used and can vary dramatically from one bacterial strain to another, depending on bacterial physiology.
|
|
| 3. |
- Pandit, Santosh, 1987, et al.
(författare)
-
Combination of Cold Atmospheric Plasma and Vitamin C Effectively Disrupts Bacterial Biofilms
- 2017
-
Ingår i: Clinical microbiology. - : OMICS Publishing Group. - 2327-5073. ; 6:3
-
Tidskriftsartikel (refereegranskat)abstract
- Cold atmospheric plasma (CAP) is increasingly used in medical applications for eradication of bacterial and tumor cells. CAP treatment devices, known as plasma jet pens, produce reactive oxygen and nitrogen species at atmospheric pressure and room temperature. The produced reactive species are concentrated in a small and precisely defined area, allowing for high precision medical treatments. CAP has been demonstrated as very effective against planktonic bacterial cells. Unfortunately, bacterial cells in biofilms are typically aggregated and protected by dense exopolymeric matrix, synthesized and secreted by the bacterial community. The main limitation in using CAP against bacterial biofilms is the thick protective matrix of extracellular polymers that shields bacterial cells within this complex architecture. CAP has also been shown to effectively eradicate tumor cells, but the main current limitation is the susceptibility of the surrounding healthy tissues to higher doses. We have recently demonstrated that vitamin C, a natural food supplement, can be used to destabilize bacterial biofilms and render them more susceptible to the CAP killing treatment. Here we discuss the possible impact that a pre-treatment with vitamin C could have on CAP applications in medicine. Specifically, we argue that vitamin C could enhance the effectiveness of CAP treatments against both the bacterial biofilms and some selected tumors.
|
|
| 4. |
- Pandit, Santosh, 1987, et al.
(författare)
-
Low Concentrations of Vitamin C Reduce the Synthesis of Extracellular Polymers and Destabilize Bacterial Biofilms
- 2017
-
Ingår i: Frontiers in Microbiology. - : Frontiers Media SA. - 1664-302X. ; 8
-
Tidskriftsartikel (refereegranskat)abstract
- Extracellular polymeric substances (EPS) produced by bacteria form a matrix supporting the complex three-dimensional architecture of biofilms. This EPS matrix is primarily composed of polysaccharides, proteins and extracellular DNA. In addition to supporting the community structure, the EPS matrix protects bacterial biofilms from the environment. Specifically, it shields the bacterial cells inside the biofilm, by preventing antimicrobial agents from getting in contact with them, thereby reducing their killing effect. New strategies for disrupting the formation of the EPS matrix can therefore lead to a more efficient use of existing antimicrobials. Here we examined the mechanism of the known effect of vitamin C (sodium ascorbate) on enhancing the activity of various antibacterial agents. Our quantitative proteomics analysis shows that non-lethal concentrations of vitamin C inhibit bacterial quorum sensing and other regulatory mechanisms underpinning biofilm development. As a result, the EPS biosynthesis in reduced, and especially the polysaccharide component of the matrix is depleted. Once the EPS content is reduced beyond a critical point, bacterial cells get fully exposed to the medium. At this stage, the cells are more susceptible to killing, either by vitamin C-induced oxidative stress as reported here, or by other antimicrobials or treatments.
|
|
| 5. |
- Pandit, Santosh, 1987, et al.
(författare)
-
Vertically Aligned Graphene Coating is Bactericidal and Prevents the Formation of Bacterial Biofilms
- 2018
-
Ingår i: Advanced Materials Interfaces. - : Wiley. - 2196-7350. ; 5:7
-
Tidskriftsartikel (refereegranskat)abstract
- The key first step in developing bacterial infections related to implants and medical devices is the attachment of planktonic bacterial cells, and subsequent formation of biofilms. Herein, it is reported that graphene, a 2D carbon-based material, can be effectively used to prevent bacterial attachment. The key parameter for this effect is the orientation of graphene with respect to the coated surface. Chemical vapor deposition (CVD) graphene, deposited horizontally on the surface, exhibits no antibacterial effect. By contrast, an array of graphene flakes grown perpendicularly to the surface by a plasma-enhanced CVD (PECVD) process prevent biofilm formation. Electron microscopy reveals that the exposed edges of vertically aligned graphene flakes penetrate the bacterial membrane and drain the cytosolic content. Bacteria are not able to develop resistance to this killing mechanism during multiple exposures. By keeping the height of the vertical graphene coating between 60 and 100 nm, the coating is able to effectively kill bacteria, while being completely harmless to mammalian cells.
|
|
| 6. |
- Wang, Nan, 1988, et al.
(författare)
-
Efficient surface modification of carbon nanotubes for fabricating high performance CNT based hybrid nanostructures
- 2017
-
Ingår i: Carbon. - : Elsevier BV. - 0008-6223. ; 111, s. 402-410
-
Tidskriftsartikel (refereegranskat)abstract
- Carbon nanotubes (CNTs) were chemically modified to achieve strong binding strength with the attached functional components as well as good dispersability and nanoparticle size-uniformity. An efficient multi-oxidation process was developed to create porous out layer with many nanoscale defects on the surface of CNTs for metallic nanoparticle close attachment and bond sufficient oxygen-containing groups, which assisted the dispersion of CNTs in the aqueous solution. The surface modified CNTs have advantages of strong binding capability, large surface area, high mechanical strength and good dispersability, which show great potential as building blocks for hybrid nanomaterials. Monodispersed silver nano particles with an average size of 3 nm were formed from inside the created nanoscale defects on the surface of CNTs without any obvious agglomerations. The fabricated hybrid exhibited much enhanced anti-bacterial performance compared to commercial silver nanoparticles due to the combined antibacterial effects of CNTs and silver nanoparticles. With these superior properties, the developed surface modification process could be widely used for improving the performances of many CNT based hybrid nanomaterials in diverse applications.
|
|
