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Special Issue "Immunosensors 2014"

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A special issue of Sensors (ISSN 1424-8220). This special issue belongs to the section "Biosensors".

Deadline for manuscript submissions: closed (31 March 2015)

Special Issue Editors

Guest Editor
Dr. Jo V. Rushworth (Website)

LIGHT Laboratories, School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
Interests: biosensors; impedance; biochemistry; synthetic bioreceptors; Alzheimer’s disease; amyloid-beta
Guest Editor
Prof. Dr. Paul A. Millner (Website)

Professor of Bionanotechnology and Head of School, LIGHT Laboratories, School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
Interests: bionanotechnology; biosensors; electrochemistry; impedance; photo-remediation; nanoparticles; nanofibres.

Special Issue Information

Dear Colleagues,

Antibodies are employed as bioreceptors in a wide range of biosensing devices, including electrochemical, optical and mechanical sensors, as well as immunoassays and ELISAs. Antibodies facilitate highly specific and sensitive analyte detection by virtue of the high-affinity antibody-antigen interaction. Immunosensors utilize antibodies, or fragments of antibodies, to transduce analyte binding into a measurable signal based on several methods, including generation of (i) an optical signal from a colored product or fluorescent signal, (ii) an electrochemical signal or (iii) a mechanical readout. Immunosensors have been developed for various applications, including medical diagnostics, environmental monitoring and public health and safety applications. These technologies allow for portable, rapid and cost-effective analyte detection and monitoring, which can be performed in the field without the need for specialist users or costly lab equipment.

Recently, efforts are focussed on several areas in order to improve immunosensor performance and to encourage commercialisation of laboratory-based technologies. These include bioreceptor orientation and antibody engineering, transducer surface nano-modification, device miniaturisation and integration with microfluidic platforms. Furthermore, label-free immunosensors present the advantages of reduced costs and ease of operation without the need for sample pre-treatment.

We are delighted to invite you to submit both original research papers and review articles relating to the application of antibodies, or their derivatives, to biosensing devices.

Dr. Jo V. Rushworth
Prof. Dr. Paul A. Millner
Guest Editors

Submission

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are refereed through a peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Sensors is an international peer-reviewed Open Access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs).


Keywords

  • immunosensor
  • antibody
  • half-antibody
  • bioreceptor immobilisation/orientation
  • transducer nano-modification
  • label-free
  • electrochemistry
  • optical biosensing
  • quartz crystal microbalance (QCM)
  • surface plasmon resonance (SPR)
  • point-of-care

Published Papers (14 papers)

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Research

Open AccessArticle A Highly Sensitive Porous Silicon (P-Si)-Based Human Kallikrein 2 (hK2) Immunoassay Platform toward Accurate Diagnosis of Prostate Cancer
Sensors 2015, 15(5), 11972-11987; doi:10.3390/s150511972
Received: 19 February 2015 / Accepted: 14 May 2015 / Published: 22 May 2015
Cited by 4 | PDF Full-text (2462 KB) | HTML Full-text | XML Full-text
Abstract
Levels of total human kallikrein 2 (hK2), a protein involved the pathology of prostate cancer (PCa), could be used as a biomarker to aid in the diagnosis of this disease. In this study, we report on a porous silicon antibody immunoassay platform [...] Read more.
Levels of total human kallikrein 2 (hK2), a protein involved the pathology of prostate cancer (PCa), could be used as a biomarker to aid in the diagnosis of this disease. In this study, we report on a porous silicon antibody immunoassay platform for the detection of serum levels of total hK2. The surface of porous silicon has a 3-dimensional macro- and nanoporous structure, which offers a large binding capacity for capturing probe molecules. The tailored pore size of the porous silicon also allows efficient immobilization of antibodies by surface adsorption, and does not require chemical immobilization. Monoclonal hK2 capture antibody (6B7) was dispensed onto P-Si chip using a piezoelectric dispenser. In total 13 × 13 arrays (169 spots) were spotted on the chip with its single spot volume of 300 pL. For an optimization of capture antibody condition, we firstly performed an immunoassay of the P-Si microarray under a titration series of hK2 in pure buffer (PBS) at three different antibody densities (75, 100 and 145 µg/mL). The best performance of the microarray platform was seen at 100 µg/mL of the capture antibody concentration (LOD was 100 fg/mL). The platform then was subsequently evaluated for a titration series of serum-spiked hK2 samples. The developed platform utilizes only 15 µL of serum per test and the total assay time is about 3 h, including immobilization of the capture antibody. The detection limit of the hK2 assay was 100 fg/mL in PBS buffer and 1 pg/mL in serum with a dynamic range of 106 (10−4 to 102 ng/mL). Full article
(This article belongs to the Special Issue Immunosensors 2014)
Open AccessArticle A New Surface Plasmon Resonance Immunosensor for Triazine Pesticide Determination in Bovine Milk: A Comparison with Conventional Amperometric and Screen-Printed Immunodevices
Sensors 2015, 15(5), 10255-10270; doi:10.3390/s150510255
Received: 17 February 2015 / Revised: 3 April 2015 / Accepted: 27 April 2015 / Published: 30 April 2015
Cited by 3 | PDF Full-text (1268 KB) | HTML Full-text | XML Full-text
Abstract
A detailed comparison was made of the analytical features of a new Surface Plasmon Resonance (SPR) immunodevice for triazine pesticide determination with those of two other amperometric (conventional and screen-printed) immunosensors and the advantages and disadvantages of the SPR method were thoroughly [...] Read more.
A detailed comparison was made of the analytical features of a new Surface Plasmon Resonance (SPR) immunodevice for triazine pesticide determination with those of two other amperometric (conventional and screen-printed) immunosensors and the advantages and disadvantages of the SPR method were thoroughly investigated. For conventional amperometric and screen-printed devices, “competitive” assays were used; conversely, the SPR transduction technique allowed a “direct” measurement format to be used. As far as the main analytical data are concerned, the SPR method does not seem to offer substantial advantages. Nevertheless the measurement time is much shorter and the measurement itself much easier to perform. Lastly several applications and recovery tests were carried out on bovine milk samples, before and after spiking, to check for triazine pesticides in the samples, obtaining satisfactory results. Full article
(This article belongs to the Special Issue Immunosensors 2014)
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Open AccessArticle Sensitive, Fast, and Specific Immunoassays for Methyltestosterone Detection
Sensors 2015, 15(5), 10059-10073; doi:10.3390/s150510059
Received: 27 January 2015 / Revised: 21 March 2015 / Accepted: 27 April 2015 / Published: 29 April 2015
Cited by 3 | PDF Full-text (1372 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
An indirect competitive enzyme-linked immunosorbent assay (icELISA) and an immunochromatographic strip assay using a highly specific monoclonal antibody, were developed to detect methyltestosterone (MT) residues in animal feed. The optimized icELISA had a half-inhibition concentration value of 0.26 ng/mL and a limit [...] Read more.
An indirect competitive enzyme-linked immunosorbent assay (icELISA) and an immunochromatographic strip assay using a highly specific monoclonal antibody, were developed to detect methyltestosterone (MT) residues in animal feed. The optimized icELISA had a half-inhibition concentration value of 0.26 ng/mL and a limit of detection value of 0.045 ng/mL. There was no cross-reactivity with eight analogues, revealing high specificity for MT. Based on icELISA results, the recovery rate of MT in animal feed was 82.4%–100.6%. The results were in accordance with those obtained by gas chromatography-mass spectrometry. The developed immunochromatographic strip assay, as the first report for MT detection, had a visual cut-off value of 1 ng/mL in PBS, 2.5 ng/g in fish feed, and 2.5 ng/g in pig feed. Therefore, these immunoassays are useful and fast tools for MT residue detection in animal feed. Full article
(This article belongs to the Special Issue Immunosensors 2014)
Open AccessArticle Development of an Immunochromatographic Strip for Rapid Detection of Pantoea stewartii subsp. stewartii
Sensors 2015, 15(2), 4291-4301; doi:10.3390/s150204291
Received: 12 December 2014 / Revised: 4 January 2015 / Accepted: 3 February 2015 / Published: 12 February 2015
Cited by 8 | PDF Full-text (413 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
A rapid, simple, sensitive, and specific immunochromatographic test strip was developed for the detection of Pantoea stewartii subsp. stewartii (Pss) in corn seed which was soaked overnight and then centrifuged for precipitate re-dissolved as samples. A pair of sensitive monoclonal antibodies for [...] Read more.
A rapid, simple, sensitive, and specific immunochromatographic test strip was developed for the detection of Pantoea stewartii subsp. stewartii (Pss) in corn seed which was soaked overnight and then centrifuged for precipitate re-dissolved as samples. A pair of sensitive monoclonal antibodies for the immunochromatographic test strip was generated by mice immunization and cell fusion. Under optimized conditions, the lower detection limit of the strips for Pss was 1 × 105 cfu/mL both in 0.01 M phosphate buffer solution and corn seed samples, with no cross-reactivity with other common plant pathogens. The developed strip is useful and rapid for the detection of Pss in corn seed samples. Full article
(This article belongs to the Special Issue Immunosensors 2014)
Open AccessArticle Nano-Magnetic Immunosensor Based on Staphylococcus Protein A and the Amplification Effect of HRP-Conjugated Phage Antibody
Sensors 2015, 15(2), 3896-3910; doi:10.3390/s150203896
Received: 26 November 2014 / Accepted: 2 February 2015 / Published: 9 February 2015
Cited by 3 | PDF Full-text (2228 KB) | HTML Full-text | XML Full-text
Abstract
In this research, super-paramagnetic Fe3O4 nanoparticles (magnetic particles) were coated with Staphylococcus protein A (SPA) and coupled with polyclonal antibody (pcAb) to construct magnetic capturing probes, and HRP-conjugated phage antibody was then used as specific detecting probe to design [...] Read more.
In this research, super-paramagnetic Fe3O4 nanoparticles (magnetic particles) were coated with Staphylococcus protein A (SPA) and coupled with polyclonal antibody (pcAb) to construct magnetic capturing probes, and HRP-conjugated phage antibody was then used as specific detecting probe to design a labeled immunosensor for trace detection of Staphylococcus aureus enterotoxin B (SEB). The linear detection range of the sensor was 0.008~125 µg/L, the regression equation was Y = 0.487X + 1.2 (R = 0.996, N = 15, p < 0.0001), the limit of detection (LOD) was 0.008 µg/L, and the limit of quantification (LOQ) was 0.008 µg/L. HRP-conjugated phage antibody, SPA and magnetic particles can enhance the sensitivity 4-fold, 3-fold and 2.6-fold higher, respectively. Compared with conventional double-antibody sandwich ELISA, the detection sensitivity of the sensor was 31-fold higher resulting from the integrated amplifying effect. The immunosensor integrates the unique advantages of SPA-oriented antibody as magnetic capturing probe, HRP-conjugated phage antibody as detecting probe, magnetic separation immunoassay technique, and several other advanced techniques, so it achieves high sensitivity, specificity and interference-resistance. It is proven to be well suited for analysis of trace SEB in various environmental samples with high recovery rate and reproducibility. Full article
(This article belongs to the Special Issue Immunosensors 2014)
Open AccessArticle Application on Gold Nanoparticles-Dotted 4-Nitrophenylazo Graphene in a Label-Free Impedimetric Deoxynivalenol Immunosensor
Sensors 2015, 15(2), 3854-3871; doi:10.3390/s150203854
Received: 22 October 2014 / Revised: 17 November 2014 / Accepted: 7 December 2014 / Published: 6 February 2015
Cited by 7 | PDF Full-text (2169 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, we report a new concept to construct a label-free electrochemical inhibition-based immunosensor for the detection of the mycotoxin deoxynivalenol (DON) in cereal samples. The electrochemical impedance spectroscopy of tris(bipyridine) ruthenium (II) chloride was used as a marker enhanced with [...] Read more.
In this paper, we report a new concept to construct a label-free electrochemical inhibition-based immunosensor for the detection of the mycotoxin deoxynivalenol (DON) in cereal samples. The electrochemical impedance spectroscopy of tris(bipyridine) ruthenium (II) chloride was used as a marker enhanced with gold nanoparticles-dotted 4-nitrophenylazo functionalized graphene (AuNp/G/PhNO2) nanocatalyst mediated in Nafion on a glassy carbon electrode. Under the optimized conditions, the formation of immunocomplexes inhibited electron flow and increased the charge transfer resistance of the sensing interface linearly. The change in impedance was proportional to DON concentrations in the range of 6–30 ng/mL with a sensitivity and detection limit of 32.14 ΩL/ng and 0.3 µg/mL, respectively, which compares favorably with the ELISA result. The proposed sensor had a stability of 80.3%, good precision and selectivity in DON standard solution containing different interfering agents, indicating promising application prospect for this strategy in designing impedimetric, electrochemiluminescent, voltammetric or amperometric sensors. Full article
(This article belongs to the Special Issue Immunosensors 2014)
Open AccessArticle A Fumonisins Immunosensor Based on Polyanilino-Carbon Nanotubes Doped with Palladium Telluride Quantum Dots
Sensors 2015, 15(1), 529-546; doi:10.3390/s150100529
Received: 17 October 2014 / Accepted: 22 December 2014 / Published: 30 December 2014
Cited by 2 | PDF Full-text (813 KB) | HTML Full-text | XML Full-text
Abstract
An impedimetric immunosensor for fumonisins was developed based on poly(2,5-dimethoxyaniline)-multi-wall carbon nanotubes doped with palladium telluride quantum dots onto a glassy carbon surface. The composite was assembled by a layer-by-layer method to form a multilayer film of quantum dots (QDs) and poly(2,5-dimethoxyaniline)-multi-wall [...] Read more.
An impedimetric immunosensor for fumonisins was developed based on poly(2,5-dimethoxyaniline)-multi-wall carbon nanotubes doped with palladium telluride quantum dots onto a glassy carbon surface. The composite was assembled by a layer-by-layer method to form a multilayer film of quantum dots (QDs) and poly(2,5-dimethoxyaniline)-multi-wall carbon nanotubes (PDMA-MWCNT). Preparation of the electrochemical immunosensor for fumonisins involved drop-coating of fumonisins antibody onto the composite modified glassy carbon electrode. The electrochemical impedance spectroscopy response of the FB1 immunosensor (GCE/PT-PDMA-MWCNT/anti-Fms-BSA) gave a linear range of 7 to 49 ng L−1 and the corresponding sensitivity and detection limits were 0.0162 kΩ L ng−1 and 0.46 pg L−1, respectively, hence the limit of detection of the GCE/PT-PDMA-MWCNT immunosensor for fumonisins in corn certified material was calculated to be 0.014 and 0.011 ppm for FB1, and FB2 and FB3, respectively. These results are lower than those obtained by ELISA, a provisional maximum tolerable daily intake (PMTDI) for fumonisins (the sum of FB1, FB2, and FB3) established by the Joint FAO/WHO expert committee on food additives and contaminants of 2 μg kg−1 and the maximum level recommended by the U.S. Food and Drug Administration (FDA) for protection of human consumption (2–4 mg L−1). Full article
(This article belongs to the Special Issue Immunosensors 2014)
Open AccessArticle Rapid Detection of Chloramphenicol Residues in Aquatic Products Using Colloidal Gold Immunochromatographic Assay
Sensors 2014, 14(11), 21872-21888; doi:10.3390/s141121872
Received: 30 July 2014 / Revised: 15 September 2014 / Accepted: 4 November 2014 / Published: 18 November 2014
Cited by 2 | PDF Full-text (2757 KB) | HTML Full-text | XML Full-text
Abstract
A colloidal gold immunochromatographic assay (GICA) was developed for rapid detection of chloramphenicol (CAP) residues in aquatic products. A nitrocellulose (NC) membrane was used as the carrier, and the polyclonal CAP antibody was used as the marker protein. The average diameter of [...] Read more.
A colloidal gold immunochromatographic assay (GICA) was developed for rapid detection of chloramphenicol (CAP) residues in aquatic products. A nitrocellulose (NC) membrane was used as the carrier, and the polyclonal CAP antibody was used as the marker protein. The average diameter of as-prepared colloidal gold nanoparticles (AuNPs) was about 20 nm. The optimal pH value of colloidal gold solutions and the amount of the antibody of CAP were 8.0 and 7.2 μg/mL, respectively. The CAP antibody was immobilized onto the conjugate pad after purification. The CAP conjugate and goat anti-rabbit IgG (secondary antibody) were coated onto the NC membrane. Next, the non-specific sites were blocked with 1% bovine serum albumin. The minimum detectable concentration of CAP in standard solution is 0.5 ng/mL, with good reproducibility. For the real samples from crucian carps injected with a single-dose of CAP in the dorsal muscles, the minimum detectable concentration of CAP residues was 0.5 µg/kg. The chromatographic analysis time was less than 10 min, and the strip had a long storage lifetime of more than 90 days at different temperatures. The strips provide a means for rapid detection of CAP residues in aquatic products. Full article
(This article belongs to the Special Issue Immunosensors 2014)
Open AccessArticle Heterogeneous Electrochemical Immunoassay of Hippuric Acid on the Electrodeposited Organic Films
Sensors 2014, 14(10), 18886-18897; doi:10.3390/s141018886
Received: 24 July 2014 / Revised: 5 September 2014 / Accepted: 25 September 2014 / Published: 13 October 2014
Cited by 3 | PDF Full-text (1177 KB) | HTML Full-text | XML Full-text
Abstract
By directly coordinating hippuric acid (HA) to the ferrate (Fe) as an electron transfer mediator, we synthesized a Fe-HA complex, which shows a good electrochemical signal and thus enables the electrochemical immunoanalysis for HA. We electrodeposited organic films containing imidazole groups on [...] Read more.
By directly coordinating hippuric acid (HA) to the ferrate (Fe) as an electron transfer mediator, we synthesized a Fe-HA complex, which shows a good electrochemical signal and thus enables the electrochemical immunoanalysis for HA. We electrodeposited organic films containing imidazole groups on the electrode surface and then bonded Ni ion (positive charge) to induce immobilization of Fe-HA (negative charge) through the electrostatic interaction. The heterogeneous competitive immunoassay system relies on the interaction between immobilized Fe-HA antigen conjugate and free HA antigen to its antibody (anti-HA). The electric signal becomes weaker due to the hindered electron transfer reaction when a large-sized HA antibody is bound onto the Fe-HA. However, in the presence of HA, the electric signal increases because free HA competitively reacts with the HA antibody prior to actual reaction and thus prevents the HA antibody from interacting with Fe-HA at the electrode surface. This competition reaction enabled an electrochemical quantitative analysis of HA concentration with a detection limit of 0.5 μg mL−1, and thus allowed us to develop a simple and rapid electrochemical immunosensor. Full article
(This article belongs to the Special Issue Immunosensors 2014)
Open AccessArticle Love Wave Immunosensor for the Detection of Carbaryl Pesticide
Sensors 2014, 14(9), 16434-16453; doi:10.3390/s140916434
Received: 24 June 2014 / Revised: 11 August 2014 / Accepted: 21 August 2014 / Published: 3 September 2014
Cited by 2 | PDF Full-text (2311 KB) | HTML Full-text | XML Full-text
Abstract
A Love Wave (LW) immunosensor was developed for the detection of carbaryl pesticide. The experimental setup consisted on: a compact electronic characterization circuit based on phase and amplitude detection at constant frequency; an automated flow injection system; a thermal control unit; a [...] Read more.
A Love Wave (LW) immunosensor was developed for the detection of carbaryl pesticide. The experimental setup consisted on: a compact electronic characterization circuit based on phase and amplitude detection at constant frequency; an automated flow injection system; a thermal control unit; a custom-made flow-through cell; and Quartz /SiO2 LW sensors with a 40 μm wavelength and 120 MHz center frequency. The carbaryl detection was based on a competitive immunoassay format using LIB-CNH45 monoclonal antibody (MAb). Bovine Serum Albumin-CNH (BSA-CNH) carbaryl hapten-conjugate was covalently immobilized, via mercaptohexadecanoic acid self-assembled monolayer (SAM), onto the gold sensing area of the LW sensors. This immobilization allowed the reusability of the sensor for at least 70 assays without significant signal losses. The LW immunosensor showed a limit of detection (LOD) of 0.09 μg/L, a sensitivity of 0.31 μg/L and a linear working range of 0.14–1.63 μg/L. In comparison to other carbaryl immunosensors, the LW immunosensor achieved a high sensitivity and a low LOD. These features turn the LW immunosensor into a promising tool for applications that demand a high resolution, such as for the detection of pesticides in drinking water at European regulatory levels. Full article
(This article belongs to the Special Issue Immunosensors 2014)
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Open AccessArticle Electrochemical Detection of Fluoroquinolone Antibiotics in Milk Using a Magneto Immunosensor
Sensors 2014, 14(9), 15965-15980; doi:10.3390/s140915965
Received: 24 May 2014 / Revised: 4 August 2014 / Accepted: 25 August 2014 / Published: 28 August 2014
Cited by 3 | PDF Full-text (1323 KB) | HTML Full-text | XML Full-text
Abstract
An amperometric magneto-immunosensor (AMIS) for the detection of residues of fluoroquinolone antibiotics in milk samples is described for the first time. The immunosensor presented combines magnetic beads biomodified with an antibody with a broad recognition profile of fluoroquinolones, a haptenized enzyme and [...] Read more.
An amperometric magneto-immunosensor (AMIS) for the detection of residues of fluoroquinolone antibiotics in milk samples is described for the first time. The immunosensor presented combines magnetic beads biomodified with an antibody with a broad recognition profile of fluoroquinolones, a haptenized enzyme and a magnetic graphite–epoxy composite (m-GEC) electrode. After the immunochemical reaction with specific enzyme tracer, the antibody biomodified magnetic beads are easily captured by an electrode made of graphite-epoxy composite containing a magnet, which also acts as transducer for the electrochemical detection. In spite of the complexity of milk, the use of magnetic beads allows elimination of potential interferences caused by the matrix components; hence the AMIS could perform quantitative measurements, directly in these samples, without any additional sample cleanup or extraction step. The immunosensor is able to detect up to seven different fluoroquinolones far below the MRLs defined by the UE for milk; for example ciprofloxacin is detected directly in milk with an IC50 of 0.74 µg/L and a LOD of 0.009 µg/L. This strategy offers great promise for rapid, simple, cost-effective, and on-site analysis fluoroquinolones in complex samples. Full article
(This article belongs to the Special Issue Immunosensors 2014)
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Open AccessArticle An Immunosensor Based on Antibody Binding Fragments Attached to Gold Nanoparticles for the Detection of Peptides Derived from Avian Influenza Hemagglutinin H5
Sensors 2014, 14(9), 15714-15728; doi:10.3390/s140915714
Received: 19 May 2014 / Revised: 10 July 2014 / Accepted: 11 August 2014 / Published: 25 August 2014
Cited by 6 | PDF Full-text (864 KB) | HTML Full-text | XML Full-text
Abstract
This paper concerns the development of an immunosensor for detection of peptides derived from avian influenza hemagglutinin H5. Its preparation consists of successive gold electrode modification steps: (i) modification with 1,6-hexanedithiol and gold colloidal nanoparticles; (ii) immobilization of antibody-binding fragments (Fab’) of [...] Read more.
This paper concerns the development of an immunosensor for detection of peptides derived from avian influenza hemagglutinin H5. Its preparation consists of successive gold electrode modification steps: (i) modification with 1,6-hexanedithiol and gold colloidal nanoparticles; (ii) immobilization of antibody-binding fragments (Fab’) of anti-hemagglutinin H5 monoclonal antibodies Mab 6-9-1 via S-Au covalent bonds; and (iii) covering the remaining free space on the electrode surfaces with bovine serum albumin. The interactions between Fab’ fragments and hemagglutinin (HA) variants have been explored with electrochemical impedance spectroscopy (EIS) in the presence of [Fe(CN)6]3−/4− as an electroactive marker. The immunosensor was able to recognize three different His-tagged variants of recombinant hemagglutinin from H5N1 viruses: H1 subunit (17–340 residues) of A/swan/Poland/305-135V08/2006, the long HA (17–530 residues) A/Bar-headed Goose/Qinghai/12/2005 and H1 subunit (1–345 residues) of A/Vietnam/1194/2004. The strongest response has been observed for the long variant with detection limit of 2.2 pg/mL and dynamic range from 4.0 to 20.0 pg/mL. Full article
(This article belongs to the Special Issue Immunosensors 2014)
Open AccessArticle Strategy for Making a Superior Quenchbody to Proteins: Effect of the Fluorophore Position
Sensors 2014, 14(7), 13285-13297; doi:10.3390/s140713285
Received: 27 May 2014 / Revised: 3 July 2014 / Accepted: 16 July 2014 / Published: 23 July 2014
Cited by 3 | PDF Full-text (3562 KB) | HTML Full-text | XML Full-text
Abstract
Antibody-based sensors have made outstanding contributions to the fields of molecular biology and biotechnology. Our group recently developed a novel powerful fluorescent immunosensor strategy named Quenchbody (Q-body), which has been applied to the detection of a range of antigens in a rapid, [...] Read more.
Antibody-based sensors have made outstanding contributions to the fields of molecular biology and biotechnology. Our group recently developed a novel powerful fluorescent immunosensor strategy named Quenchbody (Q-body), which has been applied to the detection of a range of antigens in a rapid, simple, and sensitive manner. However, there were some Q-bodies whose fluorescence response was limited, especially for detecting protein antigens. With the aim of improving this issue, here we made twelve types of Q-bodies incorporated with different number and position of TAMRA fluorophore in the single chain Fv of HyHEL-10, an anti-hen egg lysozyme antibody, as a model. By measuring the fluorescence intensity and its antigen dependency, it was revealed that VL-VH type Q-bodies labeled at a non-CDR loop region of the VL shows the highest fluorescence response. This position locates close to the quenching Trp35 in VL, while it is far from Trp residues in the bound antigen. This result clearly suggests the importance of dye position to maximize the fluorescence quenching and antigen-dependent de-quenching. The discovery may open a way to make many other Q-bodies with superior response. Full article
(This article belongs to the Special Issue Immunosensors 2014)
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Open AccessArticle A New Surface Plasmon Resonance-Based Immunoassay for Rapid, Reproducible and Sensitive Quantification of Pentraxin-3 in Human Plasma
Sensors 2014, 14(6), 10864-10875; doi:10.3390/s140610864
Received: 24 April 2014 / Revised: 31 May 2014 / Accepted: 11 June 2014 / Published: 19 June 2014
Cited by 3 | PDF Full-text (530 KB) | HTML Full-text | XML Full-text
Abstract
A new immunoassay based on surface plasmon resonance (SPR) for the rapid, reproducible and sensitive determination of pentraxin-3 (PTX3) levels in human plasma has been developed and characterized. The method involves a 3-min flow of plasma over a sensor chip pre-coated with [...] Read more.
A new immunoassay based on surface plasmon resonance (SPR) for the rapid, reproducible and sensitive determination of pentraxin-3 (PTX3) levels in human plasma has been developed and characterized. The method involves a 3-min flow of plasma over a sensor chip pre-coated with a monoclonal anti-PTX3 antibody (MNB4), followed by a 3-min flow of a polyclonal anti-PTX3 antibody (pAb), required for specific recognition of captured PTX3. The SPR signal generated with this secondary antibody linearly correlates with the plasma PTX3 concentration, in the range of 5–1500 ng/mL, with a lowest limit of detection of 5 ng/mL. The PTX3 concentrations determined with the SPR-based immunoassay in the plasma of 21 patients with sepsis, ranging 15–1600 ng/mL, were superimposable to those found in a classic ELISA immunoassay. Since the PTX3 concentration in the plasma of healthy subjects is <2 ng/mL, but markedly rises in certain medical conditions, the method is useful to quantify pathological levels of this important biomarker, with important diagnostic applications. In comparison with the classic ELISA, the SPR-based approach is much faster (30 min versus 4–5 h) and could be exploited for the development of new cost-effective SPR devices for point-of-care diagnosis. Full article
(This article belongs to the Special Issue Immunosensors 2014)
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