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Functionalised surfaces for bacterial discrimination
Linköping University, Faculty of Science & Engineering. Linköping University, Department of Physics, Chemistry and Biology.
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Bacterial detection and identification is a critical step in many arenas, including food and water safety, clinical diagnostics, bioprocess control and biosecurity. Social hygiene has a direct correlation with the strict control of microorganisms in these fields. The worldwide cases of bacterial infectious disease is assessed to be 1-2 billion annually, and these have a massive negative effect on the global economy. Although many precise techniques are currently available, a huge mortality and morbidity related to bacterial infection disease continues to be reported annually due to misdiagnosis or delay in diagnosis. Increasing efficiency and reliability of pathogen detection methods will potentially improve social health and protect society against pathogenic diseases.

The development of culture media for selective isolation and differentiation of bacteria started in the late 19th century. Immunological assays and then genotyping techniques were developed in 20th century, in addition to many less commonly used techniques for bacterial detection. Each of the currently used methods has its advantages and weaknesses in terms of speed, cost and accuracy. Much effort has recently been devoted to developing biosensors for bacterial detection for simpler and more rapid use.

This thesis is focused on functionalised surfaces for the development of biosensors for bacterial discrimination and detection, and is divided in three subsections. First, we explored a new approach for bacterial discrimination based on pattern recognition. Traditional culturing methods discriminate bacteria based on their metabolic activity pattern. Taking inspiration from the extensive body of work that reports the use of electronic-noses to differentiate bacteria based on the volatiles patterns they produce, we explored the possibility of bacteria differentiation based on adhesion patterns. By altering the electropolymerisation conditions, the physicalchemical surface properties of polypyrrole (PPy) can be tuned to fabricate a range of dissimilar surfaces. The adhesion of different bacteria on a series of polymers was measured. Data analysis of the adhesion patterns proved that bacteria can be discriminated by examining their adhesion to dissimilar surfaces. Next, we developed a new functionalisation of PPy by doping PPy with 4-N-Pentylphenylboronic Acid and investigated the modulation of bacteria binding to those surfaces. In this second section, a new electropolymerisation technique for whole-cell imprinting was developed based on different functional monomers. 3-Aminophenyl boronic acid was shown to be a good monomer to produce whole-cell imprinted polymers (CIP) with high affinity for bacterial cells with improved releasing ability. Finally, in the third section aptamers, which are promising synthetic recognition elements, were explored for bacterial detection testing. A specific aptamer was used to fabricate of a prototype of label-free aptasensor for bacterial detection. Also, the SELEX process was used to produce a pool of aptamers, or “polyclonal” aptamers, which targeted a group of bacteria species. Using polyclonal aptamers as a recognition element enables biosensors to enhance their resolution to detect broader types of bacterial species using a single serological-like test.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2016. , p. 55
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1770
Keywords [sv]
Biosensorer, Bakterier, Mönsterigenkänning
National Category
Bio Materials
Identifiers
URN: urn:nbn:se:liu:diva-160803ISBN: 9789176857519 (print)OAI: oai:DiVA.org:liu-160803DiVA, id: diva2:1359319
Public defence
2016-06-17, Nobel, B-huset, Campus Valla, Linköping, 10:15 (English)
Opponent
Supervisors
Available from: 2019-10-09 Created: 2019-10-09 Last updated: 2019-10-09Bibliographically approved
List of papers
1. Tuning the surface properties of polypyrrole films for modulating bacterial adhesion.
Open this publication in new window or tab >>Tuning the surface properties of polypyrrole films for modulating bacterial adhesion.
2016 (English)In: Macromolecular Chemistry and Physics, ISSN 1022-1352, E-ISSN 1521-3935, Vol. 217, no 10, p. 1128-1135Article in journal (Refereed) Published
Abstract [en]

Tuning the physical–chemical properties of polypyrrole (PPy) opens up potentially exciting new applications, especially in the area of bacterial adhesion. Polypyrrole is electrochemically synthesized under various conditions and the physical properties of the films and their effects on bacterial adhesion are characterized. Five types of dopants—chloride (Cl), perchlorate (ClO4), p-toluene-sulfonate (ToS), dodecylbenzene sulfonate (DBS), and poly sodium styrene sulfonate (PSS)—are used to fabricate PPy films at two different constant potentials (0.500 and 0.850 V) with and without Fe3+. Their thickness, roughness, and wettability are measured. The adhesion tendency of Escherichia coli, as a model bacterium, to the four polymers is studied. E. coli shows greater adhesion tendency to the hydrophobic, rough surface of PPy-DBS, and less adhesion tendency to the smooth and hydrophilic surface of PPy-PSS. The results facilitate the choice of appropriate electropolymerization conditions to modulate bacterial adhesion.

Place, publisher, year, edition, pages
John Wiley & Sons, 2016
Keywords
Biopolymer surface, modulating bacterial adhesion, polymer thickness, polypyrrole roughness, wettability
National Category
Polymer Technologies
Identifiers
urn:nbn:se:liu:diva-128197 (URN)10.1002/macp.201500445 (DOI)000380018100004 ()
Note

Funding agencies:  Iranian Ministry of Science, Research and Technology; Linkoping University; Swedish Research Council [VR-2014-3079]

Available from: 2016-05-20 Created: 2016-05-20 Last updated: 2019-10-09
2. Tunable conjugated polymers for bacterial differentiation
Open this publication in new window or tab >>Tunable conjugated polymers for bacterial differentiation
2016 (English)In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 222, p. 839-848Article in journal (Refereed) Published
Abstract [en]

A novel rapid method for bacterial differentiation is explored based on the specific adhesion pattern of bacterial strains to tunable polymer surfaces. Different types of counter ions were used to electrochemically fabricate dissimilar polypyrrole (PPy) films with diverse physicochemical properties such as hydrophobicity, thickness and roughness. These were then modulated into three different oxidation states in each case. The dissimilar sets of conducting polymers were exposed to five different bacterial strains, Deinococcus proteolyticus, Serratia marcescens, Pseudomonas fluorescens, Alcaligenes faecalis and Staphylococcus epidermidis. By analysis of the fluorescent microscope images, the number of bacterial cells adhered to each surface were evaluated. Generally, the number of cells of a particular bacterial strain that adhered varied when exposed to dissimilar polymer surfaces, due to the effects of the surface properties of the polymer on bacterial attachment. Similarly, the number of cells that adhered varied with different bacterial strains exposed to the same surface, reflecting the different surface properties of the bacteria. Principal component analysis showed that each strain of bacteria had its own specific adhesion pattern. Hence, they could be discriminated by this simple, label-free method based on tunable polymer arrays combined with pattern recognition. (C) 2015 Elsevier B.V. All rights reserved.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE SA, 2016
Keywords
Conducting polymer; Polypyrrole; Rapid microbial detection; Bacterial adhesion; Pattern recognition; Principal component analysis (PCA)
National Category
Polymer Chemistry Textile, Rubber and Polymeric Materials
Identifiers
urn:nbn:se:liu:diva-122780 (URN)10.1016/j.snb.2015.09.033 (DOI)000363815800109 ()
Note

Funding Agencies|Iranian Ministry of Science, Research and Technology; Linkoping University; Swedish Research Council [VR-2014-3079]

Available from: 2015-11-23 Created: 2015-11-23 Last updated: 2019-10-09
3. Doping Polypyrrole Films with 4-N-Pentylphenylboronic Acid to Enhance Affinity towards Bacteria and Dopamine
Open this publication in new window or tab >>Doping Polypyrrole Films with 4-N-Pentylphenylboronic Acid to Enhance Affinity towards Bacteria and Dopamine
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2016 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, no 11, article id e0166548Article in journal (Refereed) Published
Abstract [en]

Here we demonstrate the use of a functional dopant as a fast and simple way to tune the chemical affinity and selectivity of polypyrrole films. More specifically, a boronic-functionalised dopant, 4-N-Pentylphenylboronic Acid (PBA), was used to provide to polypyrrole films with enhanced affinity towards diols. In order to prove the proposed concept, two model systems were explored: (i) the capture and the electrochemical detection of dopamine and (ii) the adhesion of bacteria onto surfaces. The chemisensor, based on overoxidised polypyrrole boronic doped film, was shown to have the ability to capture and retain dopamine, thus improving its detection; furthermore the chemisensor showed better sensitivity in comparison with overoxidised perchlorate doped films. The adhesion of bacteria, Deinococcus proteolyticus, Escherichia coli, Streptococcus pneumoniae and Klebsiella pneumoniae, onto the boric doped polypyrrole film was also tested. The presence of the boronic group in the polypyrrole film was shown to favour the adhesion of sugar-rich bacterial cells when compared with a control film (Dodecyl benzenesulfonate (DBS) doped film) with similar morphological and physical properties. The presented single step synthesis approach is simple and fast, does not require the development and synthesis of functional monomers, and can be easily expanded to the electrochemical, and possibly chemical, fabrication of novel functional surfaces and interfaces with inherent pre-defined sensing and chemical properties.

Place, publisher, year, edition, pages
PUBLIC LIBRARY SCIENCE, 2016
National Category
Other Chemistry Topics
Identifiers
urn:nbn:se:liu:diva-133388 (URN)10.1371/journal.pone.0166548 (DOI)000388886000017 ()27875555 (PubMedID)
Note

Funding Agencies|Ministry of Science Research and Technology of Iran; Linkoping University; Swedish Research Council [VR-2014-3079]; Erasmus exchange program of the European Commission

Available from: 2016-12-27 Created: 2016-12-22 Last updated: 2019-10-09
4. Electrochemical bacterial detection using poly(3-aminophenylboronic acid)-based imprinted polymer.
Open this publication in new window or tab >>Electrochemical bacterial detection using poly(3-aminophenylboronic acid)-based imprinted polymer.
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2017 (English)In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 93, p. 87-93Article in journal (Refereed) Published
Abstract [en]

Biosensors can deliver the rapid bacterial detection that is needed in many fields including food safety, clinical diagnostics, biosafety and biosecurity. Whole-cell imprinted polymers have the potential to be applied as recognition elements in biosensors for selective bacterial detection. In this paper, we report on the use of 3-aminophenylboronic acid (3-APBA) for the electrochemical fabrication of a cell-imprinted polymer (CIP). The use of a monomer bearing a boronic acid group, with its ability to specifically interact with cis-diol, allowed the formation of a polymeric network presenting both morphological and chemical recognition abilities. A particularly beneficial feature of the proposed approach is the reversibility of the cis-diol-boronic group complex, which facilitates easy release of the captured bacterial cells and subsequent regeneration of the CIP. Staphylococcus epidermidis was used as the model target bacteria for the CIP and electrochemical impedance spectroscopy (EIS) was explored for the label-free detection of the target bacteria. The modified electrodes showed a linear response over the range of 103–107 cfu/mL. A selectivity study also showed that the CIP could discriminate its target from non-target bacteria having similar shape. The CIPs had high affinity and specificity for bacterial detection and provided a switchable interface for easy removal of bacterial cell.

Place, publisher, year, edition, pages
Elsevier, 2017
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-133647 (URN)10.1016/j.bios.2016.09.088 (DOI)000399259000013 ()27751788 (PubMedID)
Note

Funding agencies: Ministry of Science Research and Technology of Iran [MSRT 89100094]; Linkoping University [1259 00 0200]; Swedish Research Council [VR-2014-3079]

Available from: 2017-01-05 Created: 2017-01-05 Last updated: 2019-10-09
5. Diazonium-based impedimetric aptasensor for the rapid label-free detection of Salmonella typhimurium in food sample
Open this publication in new window or tab >>Diazonium-based impedimetric aptasensor for the rapid label-free detection of Salmonella typhimurium in food sample
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2016 (English)In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 80, p. 566-573Article in journal (Refereed) Published
Abstract [en]

Fast and accurate detection of microorganisms is of key importance in clinical analysis and in food and water quality monitoring. Salmonella typhimurium is responsible for about a third of all cases of food borne diseases and consequently, its fast detection is of great importance for ensuring the safety of foodstuffs. We report the development of a label-free impedimetric aptamer-based biosensor for S. typhimurium detection. The aptamer biosensor was fabricated by grafting a diazonium-supporting layer onto screen printed carbon electrodes (SPEs), via electrochemical or chemical approaches, followed by chemical immobilisation of aminated-aptamer. FTIR-ATR, contact angle and electrochemical measurements were used to monitor the fabrication process. Results showed that electrochemical immobilisation of the diazonium-grafting layer allowed the formation of a denser aptamer layer, which resulted in higher sensitivity. The developed aptamer-biosensor responded linearly, on a logarithm scale, over the concentration range 1 x 10(1) to 1 x 10(8) CFU mL(-1), with a limit of quantification (LOQ) of 1 x 10(1) CFU mL(-1) and a limit of detection (LOD) of 6 CFU mL(-1). Selectivity studies showed that the aptamer biosensor could discriminate S. typhimurium from 6 other model bacteria strains. Finally, recovery studies demonstrated its suitability for the detection of S. typhimurium in spiked (1 x 10(2), 1 x 10(4) and 1 x 10(6) CFU mL(-1)) apple juice samples. (C) 2016 Elsevier B.V. All rights reserved.

Place, publisher, year, edition, pages
ELSEVIER ADVANCED TECHNOLOGY, 2016
Keywords
Diazonium grafting; Aptamer; S. typhimurium; Label-free detection; Electrochemical impedance spectroscopy; Food analysis
National Category
Biological Sciences
Identifiers
urn:nbn:se:liu:diva-127249 (URN)10.1016/j.bios.2016.02.024 (DOI)000372558500079 ()26894987 (PubMedID)
Note

Funding Agencies|Vetenskapsradet (Pathoscreen project; Swedish Research Link) [D0675001]; Ministry of Science Research and Technology of Iran

Available from: 2016-04-20 Created: 2016-04-19 Last updated: 2019-10-09Bibliographically approved

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