| 1. |
- Andersson, Tilde, et al.
(författare)
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Common skin bacteria protect their host from oxidative stress through secreted antioxidant RoxP
- 2019
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Cutibacterium acnes is an abundant skin commensal with several proposed mutualistic functions. A protein with strong antioxidant activity was recently identified from the C. acnes secretome. This protein, termed RoxP, facilitated aerobic bacterial growth in vitro and ex vivo. As reducing events naturally occurred outside of the bacterial cell, it was further hypothesized that RoxP could also serve to modulate redox status of human skin. The biological function of RoxP was here assessed in vitro and in vivo, through oxidatively stressed cell cultures and through protein quantification from skin affected by oxidative disease (actinic keratosis and basal cell carcinoma), respectively. 16S rDNA amplicon deep sequencing and single locus sequence typing was used to correlate bacterial prevalence to cutaneous RoxP abundances. We show that RoxP positively influence the viability of monocytes and keratinocytes exposed to oxidative stress, and that a congruent concentration decline of RoxP can be observed in skin affected by oxidative disease. Basal cell carcinoma was moreover associated with microbial dysbiosis, characterized by reduced C. acnes prevalence. C. acnes's secretion of RoxP, an exogenous but naturally occurring antioxidant on human skin, is likely to positively influence the human host. Results furthermore attest to its prospective usability as a biopharmaceutical.
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| 2. |
- Andersson, Tilde, et al.
(författare)
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Development of a Molecular Imprinting-Based Surface Plasmon Resonance Biosensor for Rapid and Sensitive Detection of Staphylococcus aureus Alpha Hemolysin From Human Serum
- 2020
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Ingår i: Frontiers in cellular and infection microbiology. - : Frontiers Media SA. - 2235-2988. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Stapylococcus aureus is a common infectious agent in e.g. sepsis, associated with both high mortality rates and severe long-term effects. The cytolytic protein α-hemolysin has repeatedly been shown to enhance the virulence of S. aureus. Combined with an unhindered spread of multi drug-resistant strains, this has triggered research into novel anti virulence (i.e. anti α-hemolysin) drugs. Their functionality will depend on our ability to identify infections that might be alleviated by such. We therefore saw a need for detection methods that could identify individuals suffering from S. aureus infections where α-hemolysin was a major determinant. Molecular imprinted polymers were subsequently prepared on gold coated sensor chips. Used in combination with a surface plasmon resonance biosensor, α-hemolysin could therethrough be quantified from septic blood samples (n = 9), without pre-culturing of the infectious agent. The biosensor recognized α-hemolysin with high affinity (KD = 2.75 x 10-7 M) and demonstrated a statistically significant difference (p < 0.0001) between the α-hemolysin response and potential sample contaminants. The detection scheme proved equally good, or better, when compared to antibody-based detection methods. This novel detection scheme constitutes a more rapid, economical, and user-friendly alternative to many methods currently in use. Heightening both reproducibility and sensitivity, molecular imprinting in combination with surface plasmon resonance (SPR)-technology could be a versatile new tool in clinical- and research-settings alike.
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| 3. |
- Bergdahl, Gizem Ertürk, et al.
(författare)
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Bisphosphonate Ligand Mediated Ultrasensitive Capacitive Protein Sensor : Complementary Match of Supramolecular and Dynamic Chemistry
- 2019
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Ingår i: New Journal of Chemistry. - : Royal Society of Chemistry. - 1144-0546 .- 1369-9261. ; 43:2, s. 847-852
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Tidskriftsartikel (refereegranskat)abstract
- Modern healthcare demands rapid and accurate detection of proteins/enzymes at the ultratrace level. Herein we present a molecularly imprinted capacitive sensor for Trypsin, developed by microcontact imprinting. High affinity and selectivity was achieved by doping the prepolymerization mixture with a stoichiometric amount of methacrylamide-based bisphosphonate (BP) monomer. Taking advantage of the strong interaction of bisphosphonate with lysine/arginine residues on the surface of Trypsin, we have constructed a powerful polymeric sensor. The BP based sensor has the ability to recognize trypsin over other arginine-rich proteins, even in high ionic strength buffers with a sub-picomolar detection limit (pM). We believe that the combination of supramolecular chemistry, molecular imprinting and advanced instrumentation has a potential for future drug development and diagnostics that extends beyond biomolecular recognition.
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| 4. |
- Bergdahl, Gizem Ertürk, et al.
(författare)
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Capacitive Saccharide Sensor Based on Immobilized Phenylboronic Acid with Diol Specificity
- 2019
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Ingår i: Applied Biochemistry and Biotechnology. - : Springer Science and Business Media LLC. - 0273-2289 .- 1559-0291. ; 188:1, s. 124-137
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Tidskriftsartikel (refereegranskat)abstract
- A capacitive sensor for saccharide detection is described in this study. The detection is based on selective interaction between diols and aminophenylboronic acid (APBA) immobilized on a gold electrode. Glucose, fructose, and dextran (MW: 40 kDa) were tested with the system over wide concentration ranges (1.0 x 10−8 M - 1.0 x 10−3 M for glucose, 1.0 x 10−8 M - 1.0 x 10−2 M for fructose and 1.0 x 10−10 M - 1.0 x 10−5 M for dextran). The limits of detection (LODs) were 0.8 nM for glucose, 0.6 nM for fructose, and 13 pM for dextran. These data were comparable to the others reported previously. In order to demonstrate glycoprotein detection with the same sensor, human immunoglobulin G (IgG) as well as horseradish peroxidase were used as model analytes. The sensor responded to IgG in the concentration range of 1.0 x 10−13 M - 1.0 x 10−7 M with a LOD value of 16 fM. The performance of the assay of peroxidase was compared to a spectrophotometric assay by determining the enzymatic activity of a captured analyte. The results showed that the method might be useful for label-free, fast, and sensitive detection of saccharides as well as glycoproteins over a wide concentration range.
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| 5. |
- Bergdahl, Gizem Ertürk, et al.
(författare)
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Capacitive Sensor to Monitor Enzyme Activity by Following Degradation of Macromolecules in Real Time
- 2019
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Ingår i: Applied Biochemistry and Biotechnology. - : Springer Science and Business Media LLC. - 0273-2289 .- 1559-0291. ; 189, s. 374-383
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Tidskriftsartikel (refereegranskat)abstract
- A capacitive sensor was developed to analyze the presence and enzymatic activity of a model protease from standard solutions by following the degradation of the substrate in real time. The enzyme was chosen based on its specific digestion of the hinge region of immunoglobulin G (IgG). Real-time enzyme activity was monitored by measuring the change in capacitance (∆C) based on the release of IgG fragments after enzymatic digestion by the enzyme. The results indicated that the developed capacitive system might be used successfully for label-free and real-time monitoring of enzymatic activity of different enzymes in a sensitive, rapid, and inexpensive manner in biotechnological, environmental, and clinical applications.
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| 6. |
- Canfarotta, Francesco, et al.
(författare)
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A Novel Capacitive Sensor Based on Molecularly Imprinted Nanoparticles as Recognition Elements
- 2018
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Ingår i: Biosensors and Bioelectronics. - : Elsevier BV. - 0956-5663. ; , s. 108-114
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Tidskriftsartikel (refereegranskat)abstract
- Molecularly Imprinted Polymers (MIPs) are synthetic receptors capable of selective binding to their target (template) molecules and, hence, are used as recognition elements in assays and sensors as a replacement for relatively unstable enzymes and antibodies. Herein, we describe a manufacturing-friendly protocol for integration of MIP nanoparticles (nanoMIPs) with a (label-free) capacitive sensor. The nanoMIPs were produced by solid-phase synthesis for two templates with different sizes and properties, including a small molecule tetrahydrocannabinol (THC) and a protein (trypsin). NanoMIPs were deposited on the surface of the sensor and the change in capacitance (ΔC) upon binding of the target was measured. The significant improvement in the selectivity and limit of detection (one order of magnitude compared to previously used MIP microparticles) can be attributed to their increased surface-to-volume ratio and higher specificity of the nanoMIPs produced by the solid-phase method. The methodology described is also compatible with common sensor fabrication approaches, as opposed to methods involving in situ MIP polymerisation. The proposed sensor shows high selectivity, fast sensor response (45 min including injection, regeneration and re-equilibration with running buffer), and straightforward data analysis, which makes it viable for label-free monitoring in real-time. The set of targets assessed in this manuscript shows the general applicability of the biosensor platform.
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| 7. |
- Chowdhury, Sounak, et al.
(författare)
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Streptococcus pyogenes Forms Serotype- and Local Environment-Dependent Interspecies Protein Complexes
- 2021
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Ingår i: mSystems. - 2379-5077. ; 6:5, s. 1-19
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Tidskriftsartikel (refereegranskat)abstract
- Streptococcus pyogenes is known to cause both mucosal and systemic infections in humans. In this study, we used a combination of quantitative and structural mass spectrometry techniques to determine the composition and structure of the interaction network formed between human plasma proteins and the surfaces of different S. pyogenes serotypes. Quantitative network analysis revealed that S. pyogenes forms serotype-specific interaction networks that are highly dependent on the domain arrangement of the surface-attached M protein. Subsequent structural mass spectrometry analysis and computational modeling of one of the M proteins, M28, revealed that the network structure changes across different host microenvironments. We report that M28 binds secretory IgA via two separate binding sites with high affinity in saliva. During vascular leakage mimicked by increasing plasma concentrations in saliva, the binding of secretory IgA was replaced by the binding of monomeric IgA and C4b-binding protein (C4BP). This indicates that an upsurge of C4BP in the local microenvironment due to damage to the mucosal membrane drives the binding of C4BP and monomeric IgA to M28. These results suggest that S. pyogenes has evolved to form microenvironment-dependent host-pathogen protein complexes to combat human immune surveillance during both mucosal and systemic infections. IMPORTANCE Streptococcus pyogenes (group A Streptococcus [GAS]), is a human-specific Gram-positive bacterium. Each year, the bacterium affects 700 million people globally, leading to 160,000 deaths. The clinical manifestations of S. pyogenes are diverse, ranging from mild and common infections like tonsillitis and impetigo to life-threatening systemic conditions such as sepsis and necrotizing fasciitis. S. pyogenes expresses multiple virulence factors on its surface to localize and initiate infections in humans. Among all these expressed virulence factors, the M protein is the most important antigen. In this study, we perform an in-depth characterization of the human protein interactions formed around one of the foremost human pathogens. This strategy allowed us to decipher the protein interaction networks around different S. pyogenes strains on a global scale and to compare and visualize how such interactions are mediated by M proteins.
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| 8. |
- Ertürk Bergdahl, Gizem, et al.
(författare)
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In Vivo Detection and Absolute Quantification of a Secreted Bacterial Factor from Skin Using Molecularly Imprinted Polymers in a Surface Plasmon Resonance Biosensor for Improved Diagnostic Abilities
- 2019
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Ingår i: ACS Sensors. - : American Chemical Society (ACS). - 2379-3694. ; 4:3, s. 717-725
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Tidskriftsartikel (refereegranskat)abstract
- In this study, a surface plasmon resonance (SPR) biosensor was developed for the detection and quantification of a secreted bacterial factor (RoxP) from skin. A molecular imprinting method was used for the preparation of sensor chips and five different monomer-cross-linker compositions were evaluated for sensitivity, selectivity, affinity, and kinetic measurements. The most promising molecularly imprinted polymer (MIP) was characterized by using scanning electron microscopy, atomic force microscopy, and cyclic voltammetry. Limit of detection (LOD) value was calculated as 0.23 nM with an affinity constant of 3.3 × 10-9 M for the promising MIP. Besides being highly sensitive, the developed system was also very selective for the template protein RoxP, proven by the calculated selectivity coefficients. Finally, absolute concentrations of RoxP in several skin swabs were analyzed by using the developed MIP-SPR biosensor and compared to a competitive ELISA. Consequently, the developed system offers a very efficient tool for the detection and quantification of RoxP as an early indicator for some oxidative skin diseases especially when they are present in low-abundance levels (e.g., skin samples).
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| 9. |
- Ertürk, Gizem, et al.
(författare)
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A sensitive and real-time assay of trypsin by using molecular imprinting-based capacitive biosensor
- 2016
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Ingår i: Biosensors and Bioelectronics. - : Elsevier BV. - 0956-5663. ; 86, s. 557-565
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Tidskriftsartikel (refereegranskat)abstract
- Use of a highly sensitive, selective capacitive biosensor is reported for label-free, real-time, easy and rapid detection of trypsin by using the microcontact imprinting method. Real-time trypsin detection was performed with trypsin-imprinted (trypsin-MIP) capacitive electrodes using standard trypsin solutions in the concentration range of 1.0×10−13–1.0×10−7 M with a detection limit of 3.0×10−13 M. Selectivity and cross-reactivity of the system were tested by using competing proteins including chymotrypsin (chy), bovine serum albumin (BSA), lysozyme (lyz) and cytochrome c (cyt c) in singular and competitive manner and the selectivity of the system was determined with the selectivity coefficients of approximately 705.1, 6.5, 6.4 and 5.1 for chy, BSA, lyz and cyt c, respectively. The trypsin-MIP capacitive electrode was used for ~80 assays during 2 months and retained its binding property during all that time with a decrease of approximately 2.3% in the signal amplitude. In the last step, trypsin activity was measured by using Nα-Benzoyl-D, L-arginine 4-nitroanilide hydrochloride (BAPNA) as the substrate with spectrophotometer at 410 nm. The trypsin activity was measured as 9 mU/mL by spectrophotometer while the amount of captured enzyme calculated from the capacitive system was 7.9 mU/mL which shows the correlation between two methods. From the comparison it is obvious that the new method is an attractive alternative for assaying trypsin and the developed capacitive system might be used successfully to monitor label-free, real-time enzymatic activity of different proteases in a sensitive, rapid, cost-effective manner for different applications.
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| 10. |
- Ertürk, Gizem, et al.
(författare)
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Bacteriophages as biorecognition elements in capacitive biosensors : Phage and host bacteria detection
- 2018
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Ingår i: Sensors and Actuators B: Chemical. - : Elsevier BV. - 0925-4005. ; 258, s. 535-543
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Tidskriftsartikel (refereegranskat)abstract
- Herein, we introduced a molecular imprinting based capacitive biosensor for real-time and highly sensitive bacteriophage detection. The sensing mechanism was based on the binding of target phage into the specific cavities on the electrode surface which resulted in a measurable change in the total capacitance of the system. Phage detection was investigated in the concentration range of 1.0 × 101–1.0 × 105 plaque forming units (pfu)/mL and the limit of detection (LOD) was measured as 10 pfu/mL which shows the high sensitivity of the system compared to results reported for previous studies. The system also allowed the detection of phages in river water samples which is very important for the usability of the system as in-field analysis for different applications e.g. investigating the contamination of drinking water via wastewater or reservoir water in the future. Recently, due to their high specificity towards their host bacteria, being cost-effective and also stable in harsh environments, bacteriophages have been used as biorecognition elements in many studies. Due to this reason, the applicability of the phage imprinted biosensor was also investigated for host bacteria detection. E. coli detection has been performed in the concentration range of 1.0 × 102–1.0 × 107 colony forming units (cfu)/mL with a LOD value of 100 cfu/mL. This system offers direct, real-time, very sensitive and rapid detection of bacteriophage and its host bacteria.
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