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Tasić N, Konjević I, Lobato A, Metarapi D, Finšgar M, Oliveira FM, Sofer Z, Gusmão R, Zhang X, Hočevar SB. Study of V 2CT x-MXene Based Immunosensor for Sensitive Label-Free Impedimetric Detection of SARS-CoV-2 Spike Protein. ACS APPLIED MATERIALS & INTERFACES 2024. [PMID: 38814245 DOI: 10.1021/acsami.4c04567] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2024]
Abstract
Rapid and reliable immunosensing is undoubtedly one of the priorities in the efficient management and combat against a pandemic, as society has experienced with the SARS-CoV-2 outbreak; simple and cost-effective sensing strategies are at the forefront of these efforts. In this regard, 2D-layered MXenes hold great potential for electrochemical biosensing due to their attractive physicochemical properties. Herein, we present a V2CTx MXene-based sensing layer as an integral part of a label-free immunosensor for sensitive and selective detection of the SARS-CoV-2 spike protein. The sensor was fabricated on a supporting screen-printed carbon electrode using Nafion as an immobilizing agent for MXene and glutaraldehyde, the latter enabling effective binding of protein A for further site-oriented immobilization of anti-SARS-CoV-2 antibodies. A thorough structural analysis of the sensor architecture was carried out, and several key parameters affecting the fabrication and analytical performance of the immunosensor were investigated and optimized. The immunosensor showed excellent electroanalytical performance in combination with an impedimetric approach and exhibited a low detection limit of only 45 fM SARS-CoV-2 spike protein. Its practical applicability was successfully demonstrated by measuring the spike protein in a spiked artificial nasopharyngeal fluid sample.
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Affiliation(s)
- Nikola Tasić
- Department of Analytical Chemistry, National Institute of Chemistry, Hajdrihova ulica 19, 1000 Ljubljana, Slovenia
| | - Ivan Konjević
- Department of Analytical Chemistry, National Institute of Chemistry, Hajdrihova ulica 19, 1000 Ljubljana, Slovenia
- Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, 1000 Ljubljana, Slovenia
| | - Alnilan Lobato
- Department of Analytical Chemistry, National Institute of Chemistry, Hajdrihova ulica 19, 1000 Ljubljana, Slovenia
- International Postgraduate School Jožef Štefan, Jamova 39, 1000 Ljubljana, Slovenia
| | - Dino Metarapi
- Department of Analytical Chemistry, National Institute of Chemistry, Hajdrihova ulica 19, 1000 Ljubljana, Slovenia
| | - Matjaž Finšgar
- Faculty of Chemistry and Chemical Engineering, University of Maribor, Smetanova ulica 17, 2000 Maribor, Slovenia
| | - Filipa M Oliveira
- Department of Inorganic Chemistry, University of Chemistry and Technology Prague, Technická 5, 166 28 Praha 6-Dejvice, Czech Republic
| | - Zděnek Sofer
- Department of Inorganic Chemistry, University of Chemistry and Technology Prague, Technická 5, 166 28 Praha 6-Dejvice, Czech Republic
| | - Rui Gusmão
- Department of Inorganic Chemistry, University of Chemistry and Technology Prague, Technická 5, 166 28 Praha 6-Dejvice, Czech Republic
| | - Xueji Zhang
- School of Biomedical Engineering, Shenzhen University Health Science Center, 3688 Nanhai Road, Nanshan District, Shenzhen 518054, Guangdong P.R. China
| | - Samo B Hočevar
- Department of Analytical Chemistry, National Institute of Chemistry, Hajdrihova ulica 19, 1000 Ljubljana, Slovenia
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van Breda SV, van der Merwe CF, Robbertse H, Apostolides Z. Immunohistochemical localization of caffeine in young Camellia sinensis (L.) O. Kuntze (tea) leaves. PLANTA 2013; 237:849-858. [PMID: 23143222 DOI: 10.1007/s00425-012-1804-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2012] [Accepted: 10/30/2012] [Indexed: 06/01/2023]
Abstract
The anatomical localization of caffeine within young Camellia sinensis leaves was investigated using immunohistochemical methods and confocal scanning laser microscopy. Preliminary fixation experiments were conducted with young C. sinensis leaves to determine which fixation procedure retained caffeine the best as determined by high-performance liquid chromatography analysis. High pressure freezing, freeze substitution, and embedding in resin was deemed the best protocol as it retained most of the caffeine and allowed for the samples to be sectioned with ease. Immunohistochemical localization with primary anti-caffeine antibodies and conjugated secondary antibodies on leaf sections proved at the tissue level that caffeine was localized and accumulated within vascular bundles, mainly the precursor phloem. With the use of a pressure bomb, xylem sap was collected using a micro syringe. The xylem sap was analyzed by thin-layer chromatography and the presence of caffeine was determined. We hypothesize that caffeine is synthesized in the chloroplasts of photosynthetic cells and transported to vascular bundles where it acts as a chemical defense against various pathogens and predators. Complex formation of caffeine with chlorogenic acid is also discussed as this may also help explain caffeine's localization.
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Affiliation(s)
- Shane V van Breda
- Department of Biochemistry, University of Pretoria, Lynnwood Road, Hatfield, Pretoria, 0002, Gauteng, South Africa.
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Wu F, Saleem MA, Kampik NB, Satchwell TJ, Williamson RC, Blattner SM, Ni L, Toth T, White G, Young MT, Parker MD, Alper SL, Wagner CA, Toye AM. Anion exchanger 1 interacts with nephrin in podocytes. J Am Soc Nephrol 2010; 21:1456-67. [PMID: 20576809 DOI: 10.1681/asn.2009090921] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
The central role of the multifunctional protein nephrin within the macromolecular complex forming the glomerular slit diaphragm is well established, but the mechanisms linking the slit diaphragm to the cytoskeleton and to the signaling pathways involved in maintaining the integrity of the glomerular filter remain incompletely understood. Here, we report that nephrin interacts with the bicarbonate/chloride transporter kidney anion exchanger 1 (kAE1), detected by yeast two-hybrid assay and confirmed by immunoprecipitation and co-localization studies. We confirmed low-level glomerular expression of kAE1 in human and mouse kidneys by immunoblotting and immunofluorescence microscopy. We observed less kAE1 in human glomeruli homozygous for the NPHS1(FinMaj) nephrin mutation, whereas kAE1 expression remained unchanged in the collecting duct. We could not detect endogenous kAE1 expression in NPHS1(FinMaj) podocytes in primary culture, but heterologous re-introduction of wild-type nephrin into these podocytes rescued kAE1 expression. In kidneys of Ae1(-/-) mice, nephrin abundance was normal but its distribution was altered along with the reported kAE1-binding protein integrin-linked kinase (ILK). Ae1(-/-) mice had increased albuminuria with glomerular enlargement, mesangial expansion, mesangiosclerosis, and expansion of the glomerular basement membrane. Glomeruli with ILK-deficient podocytes also demonstrated altered AE1 and nephrin expression, further supporting the functional interdependence of these proteins. These data suggest that the podocyte protein kAE1 interacts with nephrin and ILK to maintain the structure and function of the glomerular basement membrane.
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Affiliation(s)
- Fiona Wu
- Department of Clinical Sciences, South Bristol, UK
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Priester JH, Horst AM, Van de Werfhorst LC, Saleta JL, Mertes LAK, Holden PA. Enhanced visualization of microbial biofilms by staining and environmental scanning electron microscopy. J Microbiol Methods 2006; 68:577-87. [PMID: 17196692 DOI: 10.1016/j.mimet.2006.10.018] [Citation(s) in RCA: 128] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2006] [Accepted: 10/28/2006] [Indexed: 11/29/2022]
Abstract
Bacterial biofilms, i.e. surface-associated cells covered in hydrated extracellular polymeric substances (EPS), are often studied with high-resolution electron microscopy (EM). However, conventional desiccation and high vacuum EM protocols collapse EPS matrices which, in turn, deform biofilm appearances. Alternatively, wet-mode environmental scanning electron microscopy (ESEM) is performed under a moderate vacuum and without biofilm drying. If completely untreated, however, EPS is not electron dense and thus is not resolved well in ESEM. Therefore, this study was towards adapting several conventional SEM staining protocols for improved resolution of biofilms and EPS using ESEM. Three different biofilm types were used: 1) Pseudomonas aeruginosa unsaturated biofilms cultured on membranes, 2) P. aeruginosa cultured in moist sand, and 3) mixed community biofilms cultured on substrates in an estuary. Working with the first specimen type, a staining protocol using ruthenium red, glutaraldehyde, osmium tetroxide and lysine was optimized for best topographic resolution. A quantitative image analysis tool that maps relief, newly adopted here for studying biofilms, was used to compare micrographs. When the optimized staining and ESEM protocols were applied to moist sand cultures and aquatic biofilms, the smoothening effect that bacterial biofilms have on rough sand, and the roughening that aquatic biofilms impart on initially smooth coupons, were each quantifiable. This study thus provides transferable staining and ESEM imaging protocols suitable for a wide range of biofilms, plus a novel tool for quantifying biofilm image data.
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Affiliation(s)
- John H Priester
- Donald Bren School of Environmental Science and Management, University of California, Santa Barbara, CA 93106-5131, USA
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Doughty M, Bergmanson J, Blocker Y. Impact of glutaraldehyde versus glutaraldehyde-formaldehyde fixative on cell organization in fish corneal epithelium. Tissue Cell 1995; 27:701-12. [DOI: 10.1016/s0040-8166(05)80025-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/1995] [Accepted: 07/24/1995] [Indexed: 11/29/2022]
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