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Farkas E, Tarr R, Gerecsei T, Saftics A, Kovács KD, Stercz B, Domokos J, Peter B, Kurunczi S, Szekacs I, Bonyár A, Bányai A, Fürjes P, Ruszkai-Szaniszló S, Varga M, Szabó B, Ostorházi E, Szabó D, Horvath R. Development and In-Depth Characterization of Bacteria Repellent and Bacteria Adhesive Antibody-Coated Surfaces Using Optical Waveguide Biosensing. BIOSENSORS 2022; 12:bios12020056. [PMID: 35200317 PMCID: PMC8869200 DOI: 10.3390/bios12020056] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2021] [Revised: 01/07/2022] [Accepted: 01/13/2022] [Indexed: 05/10/2023]
Abstract
Bacteria repellent surfaces and antibody-based coatings for bacterial assays have shown a growing demand in the field of biosensors, and have crucial importance in the design of biomedical devices. However, in-depth investigations and comparisons of possible solutions are still missing. The optical waveguide lightmode spectroscopy (OWLS) technique offers label-free, non-invasive, in situ characterization of protein and bacterial adsorption. Moreover, it has excellent flexibility for testing various surface coatings. Here, we describe an OWLS-based method supporting the development of bacteria repellent surfaces and characterize the layer structures and affinities of different antibody-based coatings for bacterial assays. In order to test nonspecific binding blocking agents against bacteria, OWLS chips were coated with bovine serum albumin (BSA), I-block, PAcrAM-g-(PMOXA, NH2, Si), (PAcrAM-P) and PLL-g-PEG (PP) (with different coating temperatures), and subsequent Escherichia coli adhesion was monitored. We found that the best performing blocking agents could inhibit bacterial adhesion from samples with bacteria concentrations of up to 107 cells/mL. Various immobilization methods were applied to graft a wide range of selected antibodies onto the biosensor's surface. Simple physisorption, Mix&Go (AnteoBind) (MG) films, covalently immobilized protein A and avidin-biotin based surface chemistries were all fabricated and tested. The surface adsorbed mass densities of deposited antibodies were determined, and the biosensor;s kinetic data were evaluated to divine the possible orientations of the bacteria-capturing antibodies and determine the rate constants and footprints of the binding events. The development of affinity layers was supported by enzyme-linked immunosorbent assay (ELISA) measurements in order to test the bacteria binding capabilities of the antibodies. The best performance in the biosensor measurements was achieved by employing a polyclonal antibody in combination with protein A-based immobilization and PAcrAM-P blocking of nonspecific binding. Using this setting, a surface sensitivity of 70 cells/mm2 was demonstrated.
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Affiliation(s)
- Eniko Farkas
- Centre for Energy Research, Nanobiosensorics Laboratory, Institute of Technical Physics and Materials Science, 1121 Budapest, Hungary; (E.F.); (R.T.); (T.G.); (A.S.); (K.D.K.); (B.P.); (S.K.); (I.S.)
| | - Robert Tarr
- Centre for Energy Research, Nanobiosensorics Laboratory, Institute of Technical Physics and Materials Science, 1121 Budapest, Hungary; (E.F.); (R.T.); (T.G.); (A.S.); (K.D.K.); (B.P.); (S.K.); (I.S.)
- Department of Electronics Technology, Faculty of Electrical Engineering and Informatics, Budapest University of Technology and Economics, 1111 Budapest, Hungary;
| | - Tamás Gerecsei
- Centre for Energy Research, Nanobiosensorics Laboratory, Institute of Technical Physics and Materials Science, 1121 Budapest, Hungary; (E.F.); (R.T.); (T.G.); (A.S.); (K.D.K.); (B.P.); (S.K.); (I.S.)
- Department of Biological Physics, Eötvös Loránd University, 1117 Budapest, Hungary
| | - Andras Saftics
- Centre for Energy Research, Nanobiosensorics Laboratory, Institute of Technical Physics and Materials Science, 1121 Budapest, Hungary; (E.F.); (R.T.); (T.G.); (A.S.); (K.D.K.); (B.P.); (S.K.); (I.S.)
| | - Kinga Dóra Kovács
- Centre for Energy Research, Nanobiosensorics Laboratory, Institute of Technical Physics and Materials Science, 1121 Budapest, Hungary; (E.F.); (R.T.); (T.G.); (A.S.); (K.D.K.); (B.P.); (S.K.); (I.S.)
- Department of Biological Physics, Eötvös Loránd University, 1117 Budapest, Hungary
| | - Balazs Stercz
- Institute of Medical Microbiology, Semmelweis University, 1089 Budapest, Hungary; (B.S.); (J.D.); (E.O.); (D.S.)
| | - Judit Domokos
- Institute of Medical Microbiology, Semmelweis University, 1089 Budapest, Hungary; (B.S.); (J.D.); (E.O.); (D.S.)
| | - Beatrix Peter
- Centre for Energy Research, Nanobiosensorics Laboratory, Institute of Technical Physics and Materials Science, 1121 Budapest, Hungary; (E.F.); (R.T.); (T.G.); (A.S.); (K.D.K.); (B.P.); (S.K.); (I.S.)
| | - Sandor Kurunczi
- Centre for Energy Research, Nanobiosensorics Laboratory, Institute of Technical Physics and Materials Science, 1121 Budapest, Hungary; (E.F.); (R.T.); (T.G.); (A.S.); (K.D.K.); (B.P.); (S.K.); (I.S.)
| | - Inna Szekacs
- Centre for Energy Research, Nanobiosensorics Laboratory, Institute of Technical Physics and Materials Science, 1121 Budapest, Hungary; (E.F.); (R.T.); (T.G.); (A.S.); (K.D.K.); (B.P.); (S.K.); (I.S.)
| | - Attila Bonyár
- Department of Electronics Technology, Faculty of Electrical Engineering and Informatics, Budapest University of Technology and Economics, 1111 Budapest, Hungary;
| | - Anita Bányai
- Centre for Energy Research, Microsystems Lab, Institute of Technical Physics and Materials Science, 1121 Budapest, Hungary; (A.B.); (P.F.)
| | - Péter Fürjes
- Centre for Energy Research, Microsystems Lab, Institute of Technical Physics and Materials Science, 1121 Budapest, Hungary; (A.B.); (P.F.)
| | | | - Máté Varga
- 77 Elektronika Ltd., 1116 Budapest, Hungary; (S.R.-S.); (M.V.); (B.S.)
| | - Barnabás Szabó
- 77 Elektronika Ltd., 1116 Budapest, Hungary; (S.R.-S.); (M.V.); (B.S.)
| | - Eszter Ostorházi
- Institute of Medical Microbiology, Semmelweis University, 1089 Budapest, Hungary; (B.S.); (J.D.); (E.O.); (D.S.)
| | - Dóra Szabó
- Institute of Medical Microbiology, Semmelweis University, 1089 Budapest, Hungary; (B.S.); (J.D.); (E.O.); (D.S.)
| | - Robert Horvath
- Centre for Energy Research, Nanobiosensorics Laboratory, Institute of Technical Physics and Materials Science, 1121 Budapest, Hungary; (E.F.); (R.T.); (T.G.); (A.S.); (K.D.K.); (B.P.); (S.K.); (I.S.)
- Correspondence:
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Catalyst-free “click” functionalization of polymer brushes preserves antifouling properties enabling detection in blood plasma. Anal Chim Acta 2017; 971:78-87. [DOI: 10.1016/j.aca.2017.03.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2016] [Revised: 01/26/2017] [Accepted: 03/01/2017] [Indexed: 11/22/2022]
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3
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Last Advances in Silicon-Based Optical Biosensors. SENSORS 2016; 16:285. [PMID: 26927105 PMCID: PMC4813860 DOI: 10.3390/s16030285] [Citation(s) in RCA: 134] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Revised: 01/25/2016] [Accepted: 02/18/2016] [Indexed: 12/11/2022]
Abstract
We review the most important achievements published in the last five years in the field of silicon-based optical biosensors. We focus specially on label-free optical biosensors and their implementation into lab-on-a-chip platforms, with an emphasis on developments demonstrating the capability of the devices for real bioanalytical applications. We report on novel transducers and materials, improvements of existing transducers, new and improved biofunctionalization procedures as well as the prospects for near future commercialization of these technologies.
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Makarona E, Petrou P, Kakabakos S, Misiakos K, Raptis I. Point-of-Need bioanalytics based on planar optical interferometry. Biotechnol Adv 2016; 34:209-33. [PMID: 26876018 DOI: 10.1016/j.biotechadv.2016.02.005] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Revised: 02/09/2016] [Accepted: 02/09/2016] [Indexed: 02/02/2023]
Abstract
This review brings about a comprehensive presentation of the research on interferometric transducers, which have emerged as extremely promising candidates for viable, truly-marketable solutions for PoN applications due to the attested performance that has reached down to 10(-8) in term of effective refractive index changes. The review explores the operation of the various interferometric architectures along with their design, fabrication, and analytical performance aspects. The issues of biosensor functionalization and immobilization of receptors are also addressed. As a conclusion, the comparison among them is attempted in order to delve into and acknowledge their current limitations, and define the future trends.
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Affiliation(s)
- E Makarona
- Optical Biosensors Lab, Institute of Nanoscience and Nanotechnology, NCSR "Demokritos", 15310 Athens, Greece
| | - P Petrou
- Immunoassay/Immunosensors Lab, Institute of Nuclear & Radiological Sciences & Technology, Energy & Safety, NCSR "Demokritos", 15310 Athens, Greece
| | - S Kakabakos
- Immunoassay/Immunosensors Lab, Institute of Nuclear & Radiological Sciences & Technology, Energy & Safety, NCSR "Demokritos", 15310 Athens, Greece
| | - K Misiakos
- Optical Biosensors Lab, Institute of Nanoscience and Nanotechnology, NCSR "Demokritos", 15310 Athens, Greece
| | - I Raptis
- Optical Biosensors Lab, Institute of Nanoscience and Nanotechnology, NCSR "Demokritos", 15310 Athens, Greece.
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Functionalizable low-fouling coatings for label-free biosensing in complex biological media: advances and applications. Anal Bioanal Chem 2015; 407:3927-53. [DOI: 10.1007/s00216-015-8606-5] [Citation(s) in RCA: 99] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Revised: 02/20/2015] [Accepted: 02/27/2015] [Indexed: 12/31/2022]
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Integrated planar optical waveguide interferometer biosensors: A comparative review. Biosens Bioelectron 2014; 58:287-307. [DOI: 10.1016/j.bios.2014.02.049] [Citation(s) in RCA: 215] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Revised: 02/10/2014] [Accepted: 02/11/2014] [Indexed: 02/04/2023]
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Qi ZM, Zhao S, Chen F, Liu R, Xia S. Performance investigation of an integrated Young interferometer sensor using a novel prism-chamber assembly. OPTICS EXPRESS 2010; 18:7421-7426. [PMID: 20389765 DOI: 10.1364/oe.18.007421] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
A novel prism-chamber assembly was prepared for application in optical waveguide based chemical and biological sensors, making the sensor easily and reproducibly operate. By using the prism-chamber assembly, the performance of a composite waveguide based integrated Young interferometer sensor was investigated. The temporal interference pattern detected with a single-slit photodetector heavily relies on the slit width, and regular high-contrast patterns can be obtained under the condition that the slit width is smaller than the spatial periodicity of the sensor. Increasing the temperature of water in the chamber leads to a quasi-linear variation in the phase difference with Deltaphi/DeltaT approximately -9.1 degrees/degrees C. Significant dependence of the sensor's sensitivity on the polarization state of the guided mode was also observed. The sensor is stable and reliable, capable of real-time detection of very slow bioreactions at the interface.
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Affiliation(s)
- Zhi-mei Qi
- State Key Laboratory of Transducer Technology, Institute of Electronics, Chinese Academy of Sciences, No. 19 Beisihuan West Road, Beijing, 100190, China.
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Nagel T, Ehrentreich-Förster E, Bier FF. Label-free serodiagnosis on a grating coupler. Methods Mol Biol 2009; 503:189-200. [PMID: 19151942 DOI: 10.1007/978-1-60327-567-5_10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The unique feature of the label-free measurement techniques for screening specific binding molecules against a certain ligand is that knowledge about the analyte is not required. Due to the direct monitoring of the binding event, no further detection step, e.g., by a fluorescently labeled antibody, is necessary. This technique enables not only the analysis of binding properties, but also applications in serodiagnosis and in primary screening in drug discovery. Especially when complex biological solutions such as blood serum are used as sample fluids, the minimization of unspecific attachment is the crucial point of the assay. In this chapter, the basic handling of the grating coupler as an example of a label-free transducer is described, together with a simple protocol to minimize unspecific attachment when measuring undiluted blood serum.
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Affiliation(s)
- Thomas Nagel
- Department of Molecular Bioanalytics & Bioelectronics, Fraunhofer Institute for Biomedical Engineering, Branch Potsdam-Golm, Potsdam, Germany
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9
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Towards biosensors based on conducting polymer nanowires. Anal Bioanal Chem 2008; 393:1225-31. [PMID: 19115054 DOI: 10.1007/s00216-008-2556-0] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2008] [Revised: 11/26/2008] [Accepted: 11/28/2008] [Indexed: 10/21/2022]
Abstract
We report the electrochemical deposition of poly(pyrrolepropylic acid) nanowires, their covalent modification with antibodies and their conversion into potential functional sensor devices. The nanowires and the devices were characterised by optical microscopy, fluorescence microscopy, electron microscopy and electrical measurements. Fluorescence images, current-voltage (I-V) profiles and real-time sensing measurements demonstrated a rapid and highly sensitive and selective detection of human serum albumin (HSA), a substance that has been used to diagnose incipient renal disease. The detection is based on the selective binding of HSA onto anti-HSA that is covalently attached to the nanowires. The binding changes the electrical properties of the nanowires thus enabling the real-time detection. Whilst the utility of the research was demonstrated for protein binding/detection, the technology could easily be designed for the detection of other analytes by the modification of polymer nanowires with other analyte-specific molecules/biomolecules. Therefore, the technology has the potential to positively impact broad analytical applications in the biomedical, environmental and other sectors.
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Houska M, Brynda E, Solovyev A, Broučková A, Křížová P, Vaníčková M, Dyr JE. Hemocompatible albumin‐heparin coatings prepared by the layer‐by‐layer technique. The effect of layer ordering on thrombin inhibition and platelet adhesion. J Biomed Mater Res A 2008; 86:769-78. [DOI: 10.1002/jbm.a.31663] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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11
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Evanescent field Sensors Based on Tantalum Pentoxide Waveguides - A Review. SENSORS 2008; 8:711-738. [PMID: 27879731 PMCID: PMC3927514 DOI: 10.3390/s8020711] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/05/2007] [Accepted: 01/29/2008] [Indexed: 12/13/2022]
Abstract
Evanescent field sensors based on waveguide surfaces play an important rolewhere high sensitivity is required. Particularly tantalum pentoxide (Ta₂O₅) is a suitablematerial for thin-film waveguides due to its high refractive index and low attenuation.Many label-free biosensor systems such as grating couplers and interferometric sensors aswell as fluorescence-based systems benefit from this waveguide material leading toextremely high sensitivity. Some biosensor systems based on Ta₂O₅ waveguides alreadytook the step into commercialization. This report reviews the various detection systems interms of limit of detection, the applications, and the suitable surface chemistry.
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12
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Sperling C, Houska M, Brynda E, Streller U, Werner C. In vitro hemocompatibility of albumin-heparin multilayer coatings on polyethersulfone prepared by the layer-by-layer technique. J Biomed Mater Res A 2006; 76:681-9. [PMID: 16302224 DOI: 10.1002/jbm.a.30519] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Polyethersulfone foils (PES)--a unique material for blood purification membranes--were coated with a multilayer assembly of heparin (unfractionated or high anticoagulant activity fraction heparin) and albumin (albumin-heparin coatings), or with a multilayer of albumin (albumin coating), using the layer-by-layer technique. The coatings combine advantages of albumin (reduction of nonspecific interactions) and heparin (specific interactions with blood coagulation proteins). The differences between the two heparins, while significant for their biological activity, had only a minor effect on the multilayer assembly with albumin monitored in situ by reflection infrared spectroscopy (FTIR MIRS). Uncoated as well as modified PES surfaces were evaluated using an in vitro assay with freshly drawn, slightly heparinized (1.5 IU heparin/mL) human whole blood. The blood was circulated with a roller pump over the sample surfaces in shear flow across rectangular slit channels ( app. 6 mL/min and 120 s(-1)) for 1.5 h at 37 degrees C. All coatings effectively reduced platelet adhesion and activation according to the PF4 release. The activation of coagulation evaluated as TAT generation was significantly lowered for the coating composed of albumin and high activity heparin. A further beneficial effect of the heparin containing coatings was reduced complement activation as determined by different complement fragments.
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Affiliation(s)
- Claudia Sperling
- Department of Biocompatible Materials, Leibniz Institute of Polymer Research Dresden and The Max Bergmann Center of Biomaterials Dresden, Hohe Str. 6, 01069 Dresden, Germany.
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Sepúlveda B, Río JSD, Moreno M, Blanco FJ, Mayora K, Domínguez C, Lechuga LM. Optical biosensor microsystems based on the integration of highly sensitive Mach–Zehnder interferometer devices. ACTA ACUST UNITED AC 2006. [DOI: 10.1088/1464-4258/8/7/s41] [Citation(s) in RCA: 140] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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14
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Brynda E, Pacherník J, Houska M, Pientka Z, Dvorák P. Surface immobilized protein multilayers for cell seeding. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2005; 21:7877-83. [PMID: 16089395 DOI: 10.1021/la046846o] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Multilayer assemblies containing various cell-adhesive proteins such as gelatin, collagen IV, and laminin or polycations polylysine and poly(ethyleneimine) were immobilized on the polystyrene surface using the layer-by-layer technique based on hydrophobic and electrostatic interactions between oppositely charged macromolecules. The formation and stability of the assemblies and the adsorption of proteins from a serum containing cell-cultivation media onto their surfaces were observed in real time by Fourier transform infrared multiple internal reflection spectroscopy. The adhesion and growth of mouse embryonic stem cells line D3 were tested in polystyrene culture dishes coated with the assemblies. The cells were seeded in complete serum-containing media or in serum-free media and in the presence (non-differentiated) and/or absence (differentiated) of leukemia inhibitory factor. Proteins from serum-containing cell-cultivation media adsorbed rapidly onto positively charged surfaces. The cells grew best on surfaces coated with gelatin and collagen IV assemblies. There were no significant differences in the growth of the non-differentiated and differentiated cells in complete serum-containing media. When seeded in serum-free media, non-differentiated cells grew better than the differentiated ones. Particularly, polycation surfaces treated with glutaraldehyde promoted the growth of the non-differentiated cells and hindered the growth of the differentiated cells. The layer-by-layer deposition appears to be a practicable technique by which scaffolds for tissue engineering can be coated with biomolecular assemblies tailored to specific cells and applications.
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Affiliation(s)
- Eduard Brynda
- Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovskenho nam. 2, 162 06 Prague 6, Czech Republic
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15
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Determination of lactoferrin in bovine milk, colostrum and infant formulas by optical biosensor analysis. Int Dairy J 2005. [DOI: 10.1016/j.idairyj.2004.09.003] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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16
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Andreescu D, Andreescu S, Sadik OA. Chapter 7 New materials for biosensors, biochips and molecular bioelectronics. BIOSENSORS AND MODERN BIOSPECIFIC ANALYTICAL TECHNIQUES 2005. [DOI: 10.1016/s0166-526x(05)44007-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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17
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Lechuga LM. Chapter 5 Optical biosensors. BIOSENSORS AND MODERN BIOSPECIFIC ANALYTICAL TECHNIQUES 2005. [DOI: 10.1016/s0166-526x(05)44005-2] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
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Houska M, Brynda E, Bohatá K. The effect of polyelectrolyte chain length on layer-by-layer protein/polyelectrolyte assembly--an experimental study. J Colloid Interface Sci 2004; 273:140-7. [PMID: 15051443 DOI: 10.1016/j.jcis.2003.12.056] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2003] [Accepted: 12/19/2003] [Indexed: 11/25/2022]
Abstract
The effect of polyelectrolyte chain length on the formation of multilayered assemblies of alternating globular proteins and linear polyanions prepared by the layer-by-layer electrostatic adsorption technique was investigated. The systems studied were albumin/sodium poly(styrenesulfonate), immunoglobulin G/sodium poly(styrenesulfonate), albumin/sodium dextran sulfate, and albumin/heparin. The formation of assemblies was followed using FTIR multiple internal reflection spectroscopy. While the amount of polyelectrolyte adsorbed on the first (primary) protein layer did not depend on its molecular weight, the effect of polyelectrolyte chain length was clearly observed in the following steps of alternating adsorption. Some short-chain polyanion molecules were removed from the surface when a next protein layer was adsorbed from solution. The short polyanion chains were not able to make a sufficient number of ion pairs for stable interaction with additional protein molecules and left the surface as soluble protein/polyanion complexes. The most pronounced effect could be seen with sodium poly(styrenesulfonate) of Mw up to ca. 2 x 10(4), but a detectable effect could be traced even up to Mw ca. 8 x 10(4). Such a pronounced effect, however, was not observed with dextran sulfate. The effect of molecular weight of heparin was clearly observed but all heparins tested, regardless of their molecular weight, effectively assembled with albumin to form multilayer.
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Affiliation(s)
- Milan Houska
- Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, 16206 Prague 6, Czech Republic.
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Indyk HE, Filonzi EL. Direct optical biosensor analysis of folate-binding protein in milk. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2004; 52:3253-3258. [PMID: 15161178 DOI: 10.1021/jf030651p] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
An automated, rapid, sensitive, and label-free biosensor-based assay for folate-binding protein (FBP) in bovine milk utilizing surface plasmon resonance optical detection is described. The active concentration of FBP is estimated from its specific interaction with a pteroyl-l-glutamic (folic) acid derivative immobilized on the sensor surface in a direct binding assay format. Milk, colostrum, and milk powders are prepared for analysis by dilution into buffer. Analysis conditions, including ligand immobilization, flow rate, contact time, and regeneration, have been defined, and nonspecific binding considerations were evaluated. Performance parameters include a working range for FBP in buffer of 0-200 ng/mL, a method detection limit of 0.13 microg/mL in fluid milk, overall instrument response RSD(R) of 0.64%, a mean interassay RSD(R) of 7.3% for skim milk powder, and surface stability over ca. 200 samples. The technique was applied to the measurement of active FBP content of consumer milks, the heat classification of skim milk powders manufactured under a wide range of thermal processing protocols, and change during early bovine lactation.
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Affiliation(s)
- Harvey E Indyk
- Fonterra, PO Box 7, Waitoa, New Zealand, and Biacore International Limited, Box Hill, Melbourne, Victoria 3128, Australia.
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Keren S, Horowitz M. Distributed three-dimensional fiber Bragg grating refractometer for biochemical sensing. OPTICS LETTERS 2003; 28:2037-2039. [PMID: 14587807 DOI: 10.1364/ol.28.002037] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We demonstrate a three-dimensional (3-D) distributed refractometer that measures refractive index in a small volume. The sensor is based on an evanescent-wave fiber Bragg grating that is interrogated by low-coherence spectral interferometry. The measurement can be performed on a short time scale without the need for a mechanical scan. The new sensor was used to simultaneously measure glucose concentration in several droplets along a single sensor and to interrogate the time-dependent evaporation process of a water droplet. The new measurement technique might enable novel 3-D distributed sensors to be developed and multiple discrete measurements to be made in a small volume.
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Affiliation(s)
- S Keren
- Department of Electrical Engineering, Technion--Israel Institute of Technology, Haifa 32000, Israel
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