Imaging surface plasmon resonance for multiplex microassay sensing of mycotoxins

A prototype imaging surface plasmon resonance-based multiplex microimmunoassay for mycotoxins is described. A microarray of mycotoxin–protein conjugates was fabricated using a continuous flow microspotter device. A competitive inhibition immunoassay format was developed for the simultaneous detection of deoxynivalenol (DON) and zearalenone (ZEN), using a single sensor chip. Initial in-house validation showed limits of detection of 21 and 17 ng/mL for DON and 16 and 10 ng/mL for ZEN in extracts, which corresponds to 84 and 68 µg/kg for DON and 64 and 40 µg/kg for ZEN in maize and wheat samples, respectively. Finally, the results were critically compared with data obtained from liquid chromatography-mass spectrometry confirmatory analysis method and found to be in good agreement. The described multiplex immunoassay for the rapid screening of several mycotoxins meets European Union regulatory limits and represents a robust platform for mycotoxin analysis in food and feed sample

Fv antibodies to aflatoxin B1 derived from a pre-immunized antibody phage display library system

The production and characterization of recombinant antibodies to aflatoxin B[SUB1] (AFB[SUB1]), a potent mycotoxin and carcinogen is described. The antibody fragments produced were then applied for use in a surface plasmon resonance-based biosensor (BIAcore), which measures biomolecular interactions in 'real-time'. Single chain Fv (scFv) antibodies were generated to aflatoxin B1 from an established phage display system, which incorporated a range of different plasmids for efficient scFv expression. The scFv's were used in the development of a competitive ELISA, and also for the development of surface plasmon resonance (SPR)-based inhibition immunoassays. They were found to be suitable for the detection of AFB[SUB1], in this format, with the assays being sensitive and reproducible

Glyconanoparticles for colorimetric bioassays

Carbohydrate molecules are involved in many of the cellular processes that are important for life. By combining the specific analyte targeting of carbohydrates with the multivalent structure and change of solution colour as a consequence of plasmonic interactions with the aggregation of metal nanoparticles, glyconanoparticles have been used extensively for the development of bioanalytical assays. The noble metals used to create the nanocore, the methodologies used to assemble the carbohydrates on the nanoparticle surface, the carbohydrate chosen for each specific target, the length of the tether that separates the carbohydrate from the nanocore and the density of carbohydrates on the surface all impact on the structural formation of metal based glyconanoparticles. This tutorial review highlights these key components, which directly impact on the selectivity and sensitivity of the developed bioassay, for the colorimetric detection of lectins, toxins and viruses

Methods for nanoparticle labeling of ricin and effect on toxicity

The unique optical properties associated with nanostructured materials that support the excitation of surface plasmons offer many new opportunities for the enhanced optical investigation of biological materials that pose a security threat. In particular, ricin is considered a significant bioterrorism risk due to its high toxicity combined with its ready availability as a byproduct in castor oil production. Therefore, the development of optical techniques capable of rapid on-site toxin detection with high molecular specificity and sensitivity continues to be of significant importance. Furthermore, understanding of the ricin cell entry and intracellular pathways remains poor due to a lack of suitable bioanalytical techniques. Initial work aimed at simultaneously tackling both these issues is described where different approaches for the nanoparticle labeling of ricin are investigated along with changes in ricin toxicity associated with the labeling process

Present and future of surface-enhanced Raman scattering

The discovery of the enhancement of Raman scattering by molecules adsorbed on nanostructured metal surfaces is a landmark in the history of spectroscopic and analytical techniques. Significant experimental and theoretical effort has been directed toward understanding the surface-enhanced Raman scattering (SERS) effect and demonstrating its potential in various types of ultrasensitive sensing applications in a wide variety of fields. In the 45 years since its discovery, SERS has blossomed into a rich area of research and technology, but additional efforts are still needed before it can be routinely used analytically and in commercial products. In this Review, prominent authors from around the world joined together to summarize the state of the art in understanding and using SERS and to predict what can be expected in the near future in terms of research, applications, and technological development. This Review is dedicated to SERS pioneer and our coauthor, the late Prof. Richard Van Duyne, whom we lost during the preparation of this article

Bioaffinity detection of pathogens on surfaces

The demand for improved technologies capable of rapidly detecting pathogens with high sensitivity and selectivity in complex environments continues to be a significant challenge that helps drive the development of new analytical techniques. Surface-based detection platforms are particularly attractive as multiple bioaffinity interactions between different targets and corresponding probe molecules can be monitored simultaneously in a single measurement. Furthermore, the possibilities for developing new signal transduction mechanisms alongside novel signal amplification strategies aremuchmore varied. In this article, we describe some of the latest advances in the use of surface bioaffinity detection of pathogens. Three major sections will be discussed: (i) a brief overview on the choice of probe molecules such as antibodies, proteins and aptamers specific to pathogens and surface attachment chemistries to immobilize those probes onto various substrates, (ii) highlighting examples among the current generation of surface biosensors, and (iii) exploring emerging technologies that are highly promising and likely to form the basis of the next generation of pathogenic sensors

Surface plasmon resonance biosensing: Approaches for screening and characterising antibodies for food diagnostics

Research in biosensing approaches as alternative techniques for food diagnostics for the detection of chemical contaminants and foodborne pathogens has increased over the last twenty years. The key component of such tests is the biorecognition element whereby polyclonal or monoclonal antibodies still dominate the market. Traditionally the screening of sera or cell culture media for the selection of polyclonal or monoclonal candidate antibodies respectively has been performed by enzyme immunoassays. For niche toxin compounds, enzyme immunoassays can be expensive and/or prohibitive methodologies for antibody production due to limitations in toxin supply for conjugate production. Automated, self-regenerating, chip-based biosensors proven in food diagnostics may be utilised as rapid screening tools for antibody candidate selection. This work describes the use of both single channel and multi-channel surface plasmon resonance (SPR) biosensors for the selection and characterisation of antibodies, and their evaluation in shellfish tissue as standard techniques for the detection of domoic acid, as a model toxin compound. The key advantages in the use of these biosensor techniques for screening hybridomas in monoclonal antibody production were the real time observation of molecular interaction and rapid turnaround time in analysis compared to enzyme immunoassays. The multichannel prototype instrument was superior with 96 analyses completed in 2 h compared to 12 h for the single channel and over 24 h for the ELISA immunoassay. Antibodies of high sensitivity, IC(50)'s ranging from 4.8 to 6.9 ng/mL for monoclonal and 2.3–6.0 ng/mL for polyclonal, for the detection of domoic acid in a 1 min analysis time were selected. Although there is a progression for biosensor technology towards low cost, multiplexed portable diagnostics for the food industry, there remains a place for laboratory-based SPR instrumentation for antibody development for food diagnostics as shown herein

Developments in nanoparticles for use in biosensors to assess food safety and quality

The following will provide an overview on how advances in nanoparticle technology have contributed towards developing biosensors to screen for safety and quality markers associated with foods. The novel properties of nanoparticles will be described and how such characteristics have been exploited in sensor design will be provided. All the biosensor formats were initially developed for the health care sector to meet the demand for point-of-care diagnostics. As a consequence, research has been directed towards miniaturization thereby reducing the sample volume to nanolitres. However, the needs of the food sector are very different which may ultimately limit commercial application of nanoparticle based nanosensors. © 2014 Elsevier Ltd

Multicomponent Analysis by Surface Plasmon Resonance-based Immunosensor for Control of Food Hygiene

博士(学術)京都女子大

Plasmonic Metasurfaces for Specific SERS Detection of Shiga Toxins

open14siThe authors gratefully acknowledge the support for this work from MIUR funding the project "Design and development of environmental sensors for the research of microbiological and chemical contaminants hazardous to health (H2OSafety)" (POC01_00109) in the framework of Fund for Development and Cohesion (FSC) Proof of Concept projectsThe interest in the development of nanoscale plasmonic technologies has dramatically increased in recent years. The photonic properties of plasmonic nanopatterns can be controlled and tuned via their size, shape, or the arrangement of their constituents. In this work, we propose a 2D hybrid metallic polymeric nanostructure based on the octupolar framework with enhanced sensing property. We analyze its plasmonic features both numerically and experimentally, demonstrating the higher values of their relevant figures of merit: we estimated a surface-enhanced Raman spectroscopy (SERS) enhancement factor of 9 × 107 and a SPR bulk sensitivity of 430 nm/RIU. In addition, our nanostructure exhibits a dual resonance in the visible and near-infrared region, enabling our system toward multispectral plasmonic analysis. Finally, we illustrate our design engineering strategy as enabled by electron beam lithography by the outstanding performance of a SERS-based biosensor that targets the Shiga toxin 2a, a clinically relevant bacterial toxin. To the best of our knowledge, this is the first time that a SERS fingerprint of this toxin has been evidenced.openRippa M.; Sagnelli D.; Vestri A.; Marchesano V.; Munari B.; Carnicelli D.; Varrone E.; Brigotti M.; Tozzoli R.; Montalbano M.; Morabito S.; Zhou J.; Zyss J.; Petti L.Rippa M.; Sagnelli D.; Vestri A.; Marchesano V.; Munari B.; Carnicelli D.; Varrone E.; Brigotti M.; Tozzoli R.; Montalbano M.; Morabito S.; Zhou J.; Zyss J.; Petti L