Electrochemical and surface analytical techniques applied to microbiologically influenced corrosion investigation

AbstractSuitable application of techniques for detection and monitoring of microbiologically influenced corrosion (MIC) is crucial for understanding the mechanisms of the interactions and for selecting inhibition and control approaches. This paper presents a review of the application of electrochemical and surface analytical techniques in studying the MIC process of metals and their alloys. Conventional electrochemical techniques, such as corrosion potential (Ecorr), redox potential, dual-cell technique, polarization curves, electrochemical impedance spectroscopy (EIS), electrochemical noise (EN) analysis, and microelectrode techniques, are discussed, with examples of their use in various MIC studies. Electrochemical quartz crystal microbalance, which is newly used in MIC study, is also discussed. Microscopic techniques [scanning electron microscopy (SEM), environmental SEM (ESEM), atomic force microscopy (AFM), confocal laser microscopy (CLM), confocal laser scanning microscopy (CLSM), confocal Raman microscopy] and spectroscopic analytical methods [Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS)] are also highlighted. This review highlights the heterogeneous characteristics of microbial consortia and use of special techniques to study their probable effects on the metal substrata. The aim of this review is to motivate using a combination of new procedures for research and practical measurement and calculation of the impact of MIC and biofilms on metals and their alloys.

Download Full-text

Study of the Corrosion Process of AZ91D Magnesium Alloy during the First Hours of Immersion in 3.5 wt.% NaCl Solution

International Journal of Corrosion ◽

10.1155/2018/8785154 ◽

2018 ◽

Vol 2018 ◽

pp. 1-20 ◽

Cited By ~ 2

Author(s):

Vanessa Mandarano Pinela ◽

Leandro Antônio de Oliveira ◽

Mara Cristina Lopes de Oliveira ◽

Renato Altobelli Antunes

Keyword(s):

Magnesium Alloy ◽

Photoelectron Spectroscopy ◽

Laser Scanning ◽

Electrochemical Impedance ◽

Corrosion Process ◽

Laser Scanning Microscopy ◽

Confocal Laser ◽

Nacl Solution ◽

X Ray ◽

Az91d Magnesium Alloy

The AZ91D magnesium alloy was immersed in 3.5 wt.% NaCl solution at room temperature for times ranging from 1 minute up to 72 hours. The aim was to investigate the evolution of the corrosion process using confocal laser scanning microscopy (CLSM), electrochemical impedance spectroscopy, and X-ray photoelectron spectroscopy. The microstructure of the as-received alloy was initially characterized by optical microscopy and scanning electron microscopy (SEM). The crystalline phases were identified by X-ray diffractometry. The main phases were primary-α, eutectic-α, and β (Mg17Al12). Vickers microhardness markings were made on the surface of one etched sample to facilitate the identification of the same region at each different immersion time, thus enabling the observation of the corrosion process evolution. Corrosion initiates at the grain boundaries of the eutectic microconstituent and, then, propagates through primary α-grains. The β-phase was less severely attacked.

Download Full-text

Confocal and SEM imaging to demonstrate food pathogen- biofilm biocontrol by pyocyanin from Pseudomonas aeruginosa BTRY1

International Journal of Bioassays ◽

10.21746/ijbio.2017.01.007 ◽

2016 ◽

Vol 6 (01) ◽

pp. 5218

Author(s):

Laxmi Mohandas ◽

Anju T. R. ◽

Sarita G. Bhat*

Keyword(s):

Pseudomonas Aeruginosa ◽

Biofilm Formation ◽

Laser Scanning ◽

Laser Scanning Microscopy ◽

Confocal Laser ◽

Antibiofilm Activity ◽

Opportunistic Pathogens ◽

Redox Active ◽

Sem Imaging ◽

The Impact

An assortment of redox-active phenazine compounds like pyocyanin with their characteristic blue-green colour are synthesized by Pseudomonas aeruginosa, Gram-negative opportunistic pathogens, which are also considered one of the most commercially valuable microorganisms. In this study, pyocyanin from Pseudomonas aeruginosa BTRY1 from food sample was assessed for its antibiofilm activity by micro titer plate assay against strong biofilm producers belonging to the genera Bacillus, Staphylococcus, Brevibacterium and Micrococcus. Pyocyanin inhibited biofilm activity in very minute concentrations. This was also confirmed by Scanning Electron Microscopy (SEM) and Confocal Laser Scanning Microscopy (CLSM). Both SEM and CLSM helped to visualize the biocontrol of biofilm formation by eight pathogens. The imaging and quantification by CLSM also established the impact of pyocyanin on biofilm-biocontrol mainly in the food industry.

Download Full-text

Investigation of Spin Coating Cerium-Doped Hydroxyapatite Thin Films with Antifungal Properties

Coatings ◽

10.3390/coatings11040464 ◽

2021 ◽

Vol 11 (4) ◽

pp. 464

Author(s):

Simona Liliana Iconaru ◽

Mihai Valentin Predoi ◽

Patrick Chapon ◽

Sofia Gaiaschi ◽

Krzysztof Rokosz ◽

...

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

Photoelectron Spectroscopy ◽

Spin Coating ◽

Laser Scanning ◽

Laser Scanning Microscopy ◽

Confocal Laser ◽

X Ray ◽

Antifungal Properties ◽

Scanning Electron

In this study, the cerium-doped hydroxyapatite (Ca10−xCex(PO4)6(OH)2 with xCe = 0.1, 10Ce-HAp) coatings obtained by the spin coating method were presented for the first time. The stability of the 10Ce-HAp suspension particles used in the preparation of coatings was evaluated by ultrasonic studies, transmission electron microscopy (TEM), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The surface morphology of the 10Ce-HAp coating was studied by SEM and atomic force microscopy (AFM) techniques. The obtained 10Ce-HAp coatings were uniform and without cracks or unevenness. Glow discharge optical emission spectroscopy (GDOES) and X-ray photoelectron spectroscopy (XPS) were used for the investigation of fine chemical depth profiling. The antifungal properties of the HAp and 10Ce-HAp suspensions and coatings were assessed using Candida albicans ATCC 10231 (C. albicans) fungal strain. The quantitative antifungal assays demonstrated that both 10Ce-HAp suspensions and coatings exhibited strong antifungal properties and that they successfully inhibited the development and adherence of C. albicans fungal cells for all the tested time intervals. The scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) visualization of the C. albicans fungal cells adherence to the 10Ce-HAp surface also demonstrated their strong inhibitory effects. In addition, the qualitative assays also suggested that the 10Ce-HAp coatings successfully stopped the biofilm formation.

Download Full-text

The effect of the dispersion of microfibrillated cellulose on the mechanical properties of melt-compounded polypropylene–polyethylene copolymer

Cellulose ◽

10.1007/s10570-019-02756-8 ◽

2019 ◽

Vol 26 (18) ◽

pp. 9645-9659 ◽

Cited By ~ 9

Author(s):

Caterina Palange ◽

Marcus A. Johns ◽

David J. Scurr ◽

Jonathan S. Phipps ◽

Stephen J. Eichhorn

Keyword(s):

Tannic Acid ◽

Laser Scanning ◽

Secondary Ion Mass Spectrometry ◽

High Surface ◽

Microfibrillated Cellulose ◽

Laser Scanning Microscopy ◽

Confocal Laser ◽

Cellulose Content ◽

Reinforced Composites ◽

The Impact

Abstract Microfibrillated cellulose (MFC) is a highly expanded, high surface area networked form of cellulose-based reinforcement. Due to the poor compatibility of cellulose with most common apolar thermoplastic matrices, the production of cellulose-reinforced composites in industry is currently limited to polar materials. In this study, a facile water-based chemistry, based on the reaction of MFC with tannic acid and subsequent functionalisation with an alkyl amine, is used to render the surface of the MFC fibrils hydrophobic and enhance the dispersion of the cellulose-based filler into an apolar thermoplastic matrix. The level of dispersion of the compatibilized MFC reinforced composites was evaluated using Time of Flight Secondary Ion Mass Spectrometry and multi-channel Spectral Confocal Laser Scanning Microscopy. The agglomeration of cellulosic filler within the composites was reduced by functionalising the surface of the MFC fibrils with tannic acid and octadecylamine. The resulting composites exhibited an increase in modulus at a high cellulose content. Despite the dispersion of a large portion of the functionalised filler, the presence of some remaining aggregates affected the impact properties of the composites produced.

Download Full-text

Influence of the Electrolyte Composition on the Corrosion Behavior of Anodized AZ31B Magnesium Alloy

Materials Science Forum ◽

10.4028/www.scientific.net/msf.1012.424 ◽

2020 ◽

Vol 1012 ◽

pp. 424-429

Author(s):

Leandro Antonio de Oliveira ◽

Renato Altobelli Antunes

Keyword(s):

Magnesium Alloy ◽

Laser Scanning ◽

Electrochemical Impedance ◽

Electrolyte Composition ◽

Laser Scanning Microscopy ◽

Confocal Laser ◽

Mixed Solution ◽

Protective Properties ◽

Az31b Magnesium Alloy ◽

Substrate Dissolution

Investigations have been performed to study the effects of the electrolyte composition on the properties of anodized films grown on AZ31B magnesium alloy. The corrosion protection ability of the oxide layers was explored by using potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy. Film morphology was examined by scanning electron microscopy and confocal laser scanning microscopy. In spite of its higher roughness average, the film formed in the silicate and hydroxide mixed solution enhanced the protective properties of the anodized layer, thus reducing the substrate dissolution rate.

Download Full-text

Surface Analysis, Microstructural Characterization and Local Corrosion Processes in Decarburized SAE 9254 Spring Steel

CORROSION ◽

10.5006/3234 ◽

2019 ◽

Vol 75 (12) ◽

pp. 1474-1486

Author(s):

Jéssica Cristina Costa de Castro Santana ◽

Rejane Maria Pereira da Silva ◽

Renato Altobelli Antunes ◽

Sydney Ferreira Santos

Keyword(s):

Surface Chemistry ◽

Photoelectron Spectroscopy ◽

Electrochemical Impedance ◽

Microstructural Characterization ◽

Spring Steel ◽

Laser Scanning Microscopy ◽

Local Corrosion ◽

Confocal Laser ◽

X Ray ◽

Decarburized Layer

The aim of the present work was to study the surface chemistry, microstructure, and local corrosion processes at the decarburized layer of the SAE 9254 automotive spring steel. The samples were austenitized at 850°C and 900°C, and oil quenched. The microstructure was investigated using confocal laser scanning microscopy and scanning electron microscopy. The surface chemistry was analyzed by x-ray photoelectron spectroscopy. Electrochemical impedance spectroscopy and potentiodynamic polarization were used to assess the global corrosion behavior of the decarburized samples. Scanning electrochemical microscopy was used to evaluate the influence of decarburization on the local corrosion activity. Microstructural characterization and x-ray photoelectron spectroscopy analysis indicate a dependence of the local electrochemical processes with the steel microconstituents and Si oxides in the decarburized layer.

Download Full-text

Characterisation of electrochemical immunosensor for detection of viable not-culturable forms of Legionellla pneumophila in water samples

Chemical Papers ◽

10.1515/chempap-2015-0170 ◽

2015 ◽

Vol 69 (11) ◽

Cited By ~ 7

Author(s):

Dejla Sboui ◽

Mina Souiri ◽

Stephanie Reynaud ◽

Sabine Palle ◽

Manel Ben Ismail ◽

...

Keyword(s):

Legionella Pneumophila ◽

Indium Tin Oxide ◽

Membrane Filtration ◽

Laser Scanning ◽

Electrochemical Impedance ◽

Limit Of Detection ◽

Angle Measurement ◽

Electrochemical Immunosensor ◽

Laser Scanning Microscopy ◽

Confocal Laser

AbstractLegionella pneumophila may cause a fatal pneumonia in humans known as Legionnaires’ disease (LD). The strategies of L. pneumophila to adapt to and resist stressful environmental conditions include the ability to enter into a VBNC (viable but not culturable) state. The detection of L. pneumophila in environmental samples benefits from the use of standardised methods: for detection and enumeration following membrane filtration (AFNOR T90-431, ISO 11731) and detection and quantification by polymerase chain reaction PCR (AFNOR T90-471, ISO 12869). Culture is hampered by its inability to detect VBNC forms and PCR is unable to discriminate between live and dead bacteria. The present immunosensor was obtained by the immobilisation of a monoclonal anti-L. pneumophila antibody (MAb) on an indium-tin oxide (ITO) electrode by the self-assembled monolayers (SAMs) method using an aminosilane. The immunosensor was characterised by wettability (contact angle measurement), atomic force microscopy (AFM), confocal laser scanning microscopy (CLSM), and electrochemical impedance spectroscopy (EIS). A limit of detection of 10 bacteria per mL was observed on artificial samples.

Download Full-text

Mosaic-CLSM Assessment of Bacterial Spatial Distribution in Cosmetic Matrices According to Matrix Viscosity and Bacterial Hydrophobicity

Cosmetics ◽

10.3390/cosmetics7020032 ◽

2020 ◽

Vol 7 (2) ◽

pp. 32

Author(s):

Samia Almoughrabie ◽

Chrisse Ngari ◽

Romain Briandet ◽

Valérie Poulet ◽

Florence Dubois-Brissonnet

Keyword(s):

Spatial Distribution ◽

Laser Scanning ◽

Rapid Assessment ◽

Challenge Test ◽

Surface Hydrophobicity ◽

Laser Scanning Microscopy ◽

Confocal Laser ◽

Bacterial Surface ◽

Bacterial Hydrophobicity ◽

The Impact

The reliability of the challenge test depends, among other parameters, on the spatial distribution of microorganisms in the matrix. The present study aims to quickly identify factors that are susceptible to impair a uniform distribution of inoculated bacteria in cosmetic matrices in this context. We used mosaic confocal laser scanning microscopy (M-CLSM) to obtain rapid assessment of the impact of the composition and viscosity of cosmetic matrices on S. aureus spatial distribution. Several models of cosmetic matrices were formulated with different concentrations of two thickeners and were inoculated with three S. aureus strains having different levels of hydrophobicity. The spatial distribution of S. aureus in each matrix was evaluated according to the frequency distribution of the fluorescence values of at least 1350 CLSM images. We showed that, whatever the thickener used, an increasingly concentration of thickener results in increasingly bacterial clustered distribution. Moreover, higher bacterial hydrophobicity also resulted in a more clustered spatial distribution. In conclusion, CLSM-based method allows a rapid characterization of bacterial spatial distribution in complex emulsified systems. Both matrix viscosity and bacterial surface hydrophobicity affect the bacterial spatial distribution which can have an impact on the reliability of bacterial enumeration during challenge test.

Download Full-text

Finding the comfort zone: Online-monitoring of electroactive bacteria colonising electrode surfaces with different chemical properties

10.5194/biofilms9-46 ◽

2020 ◽

Author(s):

Hanna Frühauf ◽

Markus Stöckl ◽

Dirk Holtmann

Keyword(s):

Electrochemical Impedance Spectroscopy ◽

Impedance Spectroscopy ◽

Confocal Laser Scanning Microscopy ◽

Electrode Surface ◽

Biofilm Formation ◽

Laser Scanning ◽

Electrochemical Impedance ◽

Flow Cell ◽

Laser Scanning Microscopy ◽

Confocal Laser

Mechanisms of electron transfer vary greatly within the diverse group of electroactive microorganisms and so does the need to attach to the electrode surface, e.g. by forming a biofilm. Electrochemical impedance spectroscopy (EIS) and confocal laser scanning microscopy (CLSM) are well established methods to monitor cell attachment to an electrode surface and have therefore been combined in a flow cell as a screening system. The flow cell, equipped with a transparent indium tin oxide working electrode (ITO WE), allows monitoring of attachment processes in real time with minimal needs for additional biofilm preparation. In preliminary experiments the flow cell was successfully used as microbial fuel cell (MFC) with a potential of +0.4 V vs. Ag/AgCl using Shewanella oneidensis as electroactive model organism. [1] Commonly, graphite-based electrode materials are used in bioelectrochemical systems due to their low costs and high conductivity. However, the hydrophobic and negatively charged surface is not yet optimal for microbial attachment. There are numerous attempts on electrode surface engineering in order to overcome this problem. In the majority of studies the biofilm analysis and evaluation of the attachment takes place at the end of the experiment, neglecting the impacts of the chemical surface properties and initial electrode conditioning during the very beginning of biofilm formation. To investigate initial attachment and biofilm formation in real-time, the transparent ITO-electrode is coated with polyelectrolytes differing in hydrophobicity and polarity to evaluate their effects on the initial surface colonisation by different electroactive microorganisms. Combining CLSM and EIS, both, surface coverage and electrochemical interaction of electrode-associated bacteria can be assessed. With this we aim to understand and ease initial steps of biofilm formation to improve efficiency of bioelectrochemical applications, e.g. with regards to start-up time. &#160; [1] St&#246;ckl, M., Schlegel, C., Sydow, A., Holtmann, D., Ulber, R., & Mangold, K. M. (2016). Membrane separated flow cell for parallelized electrochemical impedance spectroscopy and confocal laser scanning microscopy to characterize electro-active microorganisms.&#160;Electrochimica Acta,&#160;220, 444-452.

Download Full-text