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Special Issue "Bioassays"

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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 (1 August 2012)

Special Issue Editor

Guest Editor
Prof. Dr. Bertold Hock

Chair of Proteomics and Bioanalytics, Technische Universitaet Muenchen, Alte Akademie 6, D-85354 Freising, Germany
Website | E-Mail
Fax: +49 8161 232030
Interests: immunochemical analysis; immunoassays; bioassays; receptor assays; monoclonal and recombinant antibodies; bioresponse-linked instrumental analysis

Special Issue Information

Dear Colleagues,

Bioanalysis studies biological responses in order to gain information on toxicological or pharmacological impacts caused by chemical or physical effects on living systems. A prominent example dates back to the nineteenth century when the Finnish scientist William Nylander related the disappearance of lichen populations in Paris to the influence of coal-burning furnaces. In this case lichens were used as bioindicators—as it has been discovered later on—for SO2 in the air. Another historic example is the life-saving practice of coal miners when they took canary birds to their mines. These birds are extremely sensitive to carbon monoxide and therefore signal by their death the immediate threat to humans. In this case biotests with whole organisms were performed.

Modern bioanalytical tools have experienced a remarkable development during the past. Today they offer a broad spectrum of options, which are mainly exploited in environmental analysis, toxicology and pharmacology.The emergence of new fields, particularly genomics, proteomics and systems biology, as well as the appearance of advanced techniques such as genetic engineering to create reporter organisms have given bioanalysis a new dimension. This does not mean that established classical test, being used for decades, are obsolete. On the contrary, tests with whole organisms experience a remarkable revival. They benefit from progress in standardization and enable improved validity and reliability. However, tests at the cellular and biomolecular level, often coupled to sensing devices ("biosensors"), and tests with reporter organisms, mostly microorganisms, may eventually prevail as a consequence of current trends. The reasons are higher reproducibility and precision, combined with lower costs. The whole spectrum of tests - independent of the biological material - falls under the term bioassays.

An intriguing problem, most frequently encountered in environmental science, stems from the question whether and to which extent suborganismic bioassays are relevant to the entire organism. Suborganismic tests as well as tests with reporter organisms clearly cover only a small spectrum of possible bioeffects. To get around this problem, multifunctional tests in a possibly miniaturized format of test arrays can be constructed. A skillful combination of subcellular tests representing major classes of bioresponses are expected to solve the dilemma outlined above.

An alternative is the analysis of the transcriptome and proteome. Changes in gene expression and protein expression patterns in model organisms (or cell cultures) can be related to molecular targets for chemical or even physical stresses and the involved signal transduction pathways. It may even be possible to obtain hints for the cause for the observed changes. The scope of this approach is clearly limited to single species or populations. But eventually it may also include entire ecosystems, which are particularly subject to injuries with far reaching impacts on mankind.

Yet bioanalysis is not able to provide information on the chemical or physical nature of the observed impact. It yields information on biological activity expressed in toxicological or pharmacological equivalents. In contrast, chemical analysis delivers information on the composition of samples of interest. In this way, structure and concentration of pollutants can be determined. In principle it is possible to combine both approaches by bioresponse-linked instrumental analysis. Here biomolecular components such as receptors or enzymes serve as targets for bioactive substances. This means that classical binding assays providing information on toxicological or pharmacological equivalents can be combined with the structural analysis of the bound ligands.

This outlook underlines the enormous potential of bioanalytical tools. This special issue of "Bioassays" is devoted to the entire spectrum of bioanalysis. It ranges from pharmacological and toxicological tests for drug development and pharmaceutical products, medical applications such as immunogenicity testing to environmental analysis. Validation and standardization are important aspects of this venture.

Prof. Dr. Bertold Hock
Guest Editor

Keywords

  • bioanalyis
  • biomonitoring
  • biosensors
  • biotests
  • cell-based assays
  • toxicity testing

Published Papers (15 papers)

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Research

Jump to: Review

Open AccessArticle Electrochemical Genotoxicity Assay Based on a SOS/umu Test Using Hydrodynamic Voltammetry in a Droplet
Sensors 2012, 12(12), 17414-17432; doi:10.3390/s121217414
Received: 17 September 2012 / Revised: 10 December 2012 / Accepted: 12 December 2012 / Published: 14 December 2012
Cited by 3 | PDF Full-text (612 KB) | HTML Full-text | XML Full-text
Abstract
The SOS/umu genotoxicity assay evaluates the primary DNA damage caused by chemicals from the β-galactosidase activity of S. typhimurium. One of the weaknesses of the common umu test system based on spectrophotometric detection is that it is unable to measure samples
[...] Read more.
The SOS/umu genotoxicity assay evaluates the primary DNA damage caused by chemicals from the β-galactosidase activity of S. typhimurium. One of the weaknesses of the common umu test system based on spectrophotometric detection is that it is unable to measure samples containing a high concentration of colored dissolved organic matters, sediment, and suspended solids. However, umu tests with electrochemical detection techniques prove to be a better strategy because it causes less interference, enables the analysis of turbid samples and allows detection even in small volumes without loss of sensitivity. Based on this understanding, we aim to develop a new umu test system with hydrodynamic chronoamperometry using a rotating disk electrode (RDE) in a microliter droplet. PAPG when used as a substrate is not electroactive at the potential at which PAP is oxidized to p-quinone imine (PQI), so the current response of chronoamperometry resulting from the oxidation of PAP to PQI is directly proportional to the enzymatic activity of S. typhimurium. This was achieved by performing genotoxicity tests for 2-(2-furyl)-3-(5-nitro-2-furyl)-acrylamide (AF-2) and 2-aminoanthracene (2-AA) as model genotoxic compounds. The results obtained in this study indicated that the signal detection in the genotoxicity assay based on hydrodynamic voltammetry was less influenced by the presence of colored components and sediment particles in the samples when compared to the usual colorimetric signal detection. The influence caused by the presence of humic acids (HAs) and artificial sediment on the genotoxic property of selected model compounds such as 4-nitroquinoline-N-oxide (4-NQO), 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX), 1,8-dinitropyrene (1,8-DNP) and 1-nitropyrene (1-NP) were also investigated. The results showed that the genotoxicity of 1-NP and MX changed in the presence of 10 mg∙L–1 HAs. The genotoxicity of tested chemicals with a high hydrophobicity such as 1,8-DNP and 1-NP were decreased substantially with the presence of 1 g∙L–1 sediment. This was not observed in the case of genotoxins with a low log Kow value. Full article
(This article belongs to the Special Issue Bioassays)
Open AccessArticle Effects of Cry1Ab Transgenic Maize on Lifecycle and Biomarker Responses of the Earthworm, Eisenia Andrei
Sensors 2012, 12(12), 17155-17167; doi:10.3390/s121217155
Received: 16 September 2012 / Revised: 14 November 2012 / Accepted: 30 November 2012 / Published: 12 December 2012
Cited by 4 | PDF Full-text (276 KB) | HTML Full-text | XML Full-text
Abstract
A 28-day study was conducted to determine the effects of the Bacillus thuringiensis Cry1Ab toxin on the earthworm Eisenia andrei. Previously, investigations have been limited to life-cycle level effects of this protein on earthworms, and mostly on E. fetida. In this
[...] Read more.
A 28-day study was conducted to determine the effects of the Bacillus thuringiensis Cry1Ab toxin on the earthworm Eisenia andrei. Previously, investigations have been limited to life-cycle level effects of this protein on earthworms, and mostly on E. fetida. In this study several endpoints were compared which included biomass changes, cocoon production, hatching success, a cellular metal-stress biomarker (Neutral Red Retention Time; NRRT) and potential genotoxic effects in terms of Randomly Amplified Polymorphic DNA sequences (RAPDs). NRRT results indicated no differences between treatments (p > 0.36), and NRRT remained the same for both treatments at different times during the experiment (p = 0.18). Likewise, no significant differences were found for cocoon production (p = 0.32) or hatching success (p = 0.29). Conversely, biomass data indicated a significant difference between the control treatment and the Bt treatment from the second week onwards (p < 0.001), with the Bt treatment losing significantly more weight than the isoline treatment. Possible confounding factors were identified that might have affected the differences in weight loss between groups. From the RAPD profiles no conclusive data were obtained that could link observed genetic variation to exposure of E. andrei to Cry1Ab proteins produced by Bt maize. Full article
(This article belongs to the Special Issue Bioassays)
Open AccessArticle Immunoanalysis Methods for the Detection of Dioxins and Related Chemicals
Sensors 2012, 12(12), 16710-16731; doi:10.3390/s121216710
Received: 19 September 2012 / Revised: 24 October 2012 / Accepted: 2 November 2012 / Published: 5 December 2012
Cited by 3 | PDF Full-text (330 KB) | HTML Full-text | XML Full-text
Abstract
With the development of biotechnology, approaches based on antibodies, such as enzyme-linked immunosorbent assay (ELISA), active aryl hydrocarbon immunoassay (Ah-I) and other multi-analyte immunoassays, have been utilized as alternatives to the conventional techniques based on gas chromatography and mass spectroscopy for the analysis
[...] Read more.
With the development of biotechnology, approaches based on antibodies, such as enzyme-linked immunosorbent assay (ELISA), active aryl hydrocarbon immunoassay (Ah-I) and other multi-analyte immunoassays, have been utilized as alternatives to the conventional techniques based on gas chromatography and mass spectroscopy for the analysis of dioxin and dioxin-like compounds in environmental and biological samples. These screening methods have been verified as rapid, simple and cost-effective. This paper provides an overview on the development and application of antibody-based approaches, such as ELISA, Ah-I, and multi-analyte immunoassays, covering the sample extraction and cleanup, antigen design, antibody preparation and immunoanalysis. However, in order to meet the requirements for on-site fast detection and relative quantification of dioxins in the environment, further optimization is needed to make these immuno-analytical methods more sensitive and easy to use. Full article
(This article belongs to the Special Issue Bioassays)
Open AccessArticle A DO- and pH-Based Early Warning System of Nitrification Inhibition for Biological Nitrogen Removal Processes
Sensors 2012, 12(12), 16334-16352; doi:10.3390/s121216334
Received: 10 August 2012 / Revised: 29 October 2012 / Accepted: 5 November 2012 / Published: 26 November 2012
Cited by 5 | PDF Full-text (1474 KB) | HTML Full-text | XML Full-text
Abstract
In Korea, more than 80% of municipal wastewater treatment plants (WWTPs) with capacities of 500 m3·d−1 or more are capable of removing nitrogen from wastewater through biological nitrification and denitrification processes. Normally, these biological processes show excellent performance, but if
[...] Read more.
In Korea, more than 80% of municipal wastewater treatment plants (WWTPs) with capacities of 500 m3·d−1 or more are capable of removing nitrogen from wastewater through biological nitrification and denitrification processes. Normally, these biological processes show excellent performance, but if a toxic chemical is present in the influent to a WWTP, the biological processes (especially, the nitrification process) may be affected and fail to function normally; nitrifying bacteria are known very vulnerable to toxic substances. Then, the toxic compound as well as the nitrogen in wastewater may be discharged into a receiving water body without any proper treatment. Moreover, it may take significant time for the process to return back its normal state. In this study, a DO- and pH-based strategy to identify potential nitrification inhibition was developed to detect early the inflow of toxic compounds to a biological nitrogen removal process. This strategy utilizes significant changes observed in the oxygen uptake rate and the pH profiles of the mixed liquor when the activity of nitrifying bacteria is inhibited. Using the strategy, the toxicity from test wastewater with 2.5 mg·L−1 Hg2+, 0.5 mg·L−1 allythiourea, or 0.25 mg·L−1 chloroform could be successfully detected. Full article
(This article belongs to the Special Issue Bioassays)
Open AccessArticle Development of Immunoassay Based on Monoclonal Antibody Reacted with the Neonicotinoid Insecticides Clothianidin and Dinotefuran
Sensors 2012, 12(11), 15858-15872; doi:10.3390/s121115858
Received: 12 October 2012 / Revised: 12 November 2012 / Accepted: 13 November 2012 / Published: 15 November 2012
Cited by 11 | PDF Full-text (284 KB) | HTML Full-text | XML Full-text
Abstract
Enzyme-linked immunosorbent assay (ELISA) based on a monoclonal antibody (MoAb) was developed for the neonicotinoid insecticide clothianidin. A new clothianidin hapten (3-[5-(3-methyl-2-nitroguanidinomethyl)-1,3-thiazol-2-ylthio] propionic acid) was synthesized and conjugated to keyhole limpet hemocyanin, and was used for monoclonal antibody preparation. The resulting MoAb CTN-16A3-13
[...] Read more.
Enzyme-linked immunosorbent assay (ELISA) based on a monoclonal antibody (MoAb) was developed for the neonicotinoid insecticide clothianidin. A new clothianidin hapten (3-[5-(3-methyl-2-nitroguanidinomethyl)-1,3-thiazol-2-ylthio] propionic acid) was synthesized and conjugated to keyhole limpet hemocyanin, and was used for monoclonal antibody preparation. The resulting MoAb CTN-16A3-13 was characterized by a direct competitive ELISA (dc-ELISA). The 50% of inhibition concentration value with clothianidin was 4.4 ng/mL, and the working range was 1.5–15 ng/mL. The antibody showed high cross-reactivity (64%) to dinotefuran among the structurally related neonicotinoid insecticides. The recovery examinations of clothianidin for cucumber, tomato and apple showed highly agreement with the spiked concentrations; the recovery rate was between 104% and 124% and the coefficient of variation value was between 1.8% and 15%. Although the recovery rate of the dc-ELISA was slightly higher than that of HPLC analysis, the difference was small enough to accept the dc-ELISA as a useful method for residue analysis of clothianidin in garden crops. Full article
(This article belongs to the Special Issue Bioassays)
Open AccessArticle A Novel CD105 Determination System Based on an Ultrasensitive Bioelectrochemical Strategy with Pt Nanoparticles
Sensors 2012, 12(10), 13471-13479; doi:10.3390/s121013471
Received: 8 August 2012 / Revised: 7 September 2012 / Accepted: 20 September 2012 / Published: 8 October 2012
Cited by 3 | PDF Full-text (670 KB) | HTML Full-text | XML Full-text
Abstract
CD105 is a well-known tumor metastasis marker and useful for early monitoring of metastasis and cancer relapse. It is important to generate rapid, reliable and precise analytical information regarding CD105 levels. To establish a simple, selective and sensitive detection method, we prepared an
[...] Read more.
CD105 is a well-known tumor metastasis marker and useful for early monitoring of metastasis and cancer relapse. It is important to generate rapid, reliable and precise analytical information regarding CD105 levels. To establish a simple, selective and sensitive detection method, we prepared an immunosensor with novel bioconjugates based on Pt nanoparticles, thionin acetate and antibodies. The proposed immunosensor displayed a broader linear response to CD105, with a working range of 1.3 to 200.0 ng/mL and a detection limit of 0.9 ng/mL under optimal conditions. Moreover, the studied immunosensor exhibited high sensitivity, fast analysis and adequate stability. The proposed methodology could readily be extended to other clinical- or environment-related biospecies. Full article
(This article belongs to the Special Issue Bioassays)
Open AccessCommunication Development of a Plastic-Based Microfluidic Immunosensor Chip for Detection of H1N1 Influenza
Sensors 2012, 12(8), 10810-10819; doi:10.3390/s120810810
Received: 4 July 2012 / Revised: 26 July 2012 / Accepted: 31 July 2012 / Published: 6 August 2012
Cited by 6 | PDF Full-text (824 KB) | HTML Full-text | XML Full-text
Abstract
Lab-on-a-chip can provide convenient and accurate diagnosis tools. In this paper, a plastic-based microfluidic immunosensor chip for the diagnosis of swine flu (H1N1) was developed by immobilizing hemagglutinin antigen on a gold surface using a genetically engineered polypeptide. A fluorescent dye-labeled antibody (Ab)
[...] Read more.
Lab-on-a-chip can provide convenient and accurate diagnosis tools. In this paper, a plastic-based microfluidic immunosensor chip for the diagnosis of swine flu (H1N1) was developed by immobilizing hemagglutinin antigen on a gold surface using a genetically engineered polypeptide. A fluorescent dye-labeled antibody (Ab) was used for quantifying the concentration of Ab in the immunosensor chip using a fluorescent technique. For increasing the detection efficiency and reducing the errors, three chambers and three microchannels were designed in one microfluidic chip. This protocol could be applied to the diagnosis of other infectious diseases in a microfluidic device. Full article
(This article belongs to the Special Issue Bioassays)
Open AccessArticle Investigating the Quantitative Structure-Activity Relationships for Antibody Recognition of Two Immunoassays for Polycyclic Aromatic Hydrocarbons by Multiple Regression Methods
Sensors 2012, 12(7), 9363-9374; doi:10.3390/s120709363
Received: 2 May 2012 / Revised: 12 June 2012 / Accepted: 25 June 2012 / Published: 9 July 2012
PDF Full-text (254 KB) | HTML Full-text | XML Full-text
Abstract
Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous contaminants found in the environment. Immunoassays represent useful analytical methods to complement traditional analytical procedures for PAHs. Cross-reactivity (CR) is a very useful character to evaluate the extent of cross-reaction of a cross-reactant in immunoreactions and immunoassays.
[...] Read more.
Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous contaminants found in the environment. Immunoassays represent useful analytical methods to complement traditional analytical procedures for PAHs. Cross-reactivity (CR) is a very useful character to evaluate the extent of cross-reaction of a cross-reactant in immunoreactions and immunoassays. The quantitative relationships between the molecular properties and the CR of PAHs were established by stepwise multiple linear regression, principal component regression and partial least square regression, using the data of two commercial enzyme-linked immunosorbent assay (ELISA) kits. The objective is to find the most important molecular properties that affect the CR, and predict the CR by multiple regression methods. The results show that the physicochemical, electronic and topological properties of the PAH molecules have an integrated effect on the CR properties for the two ELISAs, among which molar solubility (Sm) and valence molecular connectivity index (3χv) are the most important factors. The obtained regression equations for RisC kit are all statistically significant (p < 0.005) and show satisfactory ability for predicting CR values, while equations for RaPID kit are all not significant (p > 0.05) and not suitable for predicting. It is probably because that the RisC immunoassay employs a monoclonal antibody, while the RaPID kit is based on polyclonal antibody. Considering the important effect of solubility on the CR values, cross-reaction potential (CRP) is calculated and used as a complement of CR for evaluation of cross-reactions in immunoassays. Only the compounds with both high CR and high CRP can cause intense cross-reactions in immunoassays. Full article
(This article belongs to the Special Issue Bioassays)
Open AccessArticle TNF as Biomarker for Rapid Quantification of Active Staphylococcus Enterotoxin A in Food
Sensors 2012, 12(5), 5978-5985; doi:10.3390/s120505978
Received: 3 March 2012 / Revised: 19 April 2012 / Accepted: 3 May 2012 / Published: 10 May 2012
Cited by 3 | PDF Full-text (212 KB) | HTML Full-text | XML Full-text
Abstract
Staphylococcus aureus is a major bacterial pathogen which causes clinical infections and food poisoning. This bacterium produces a group of twenty-one enterotoxins (SEs). These enterotoxins have two separate but related biological activities. They cause gastroenteritis and function as superantigens that activate large numbers
[...] Read more.
Staphylococcus aureus is a major bacterial pathogen which causes clinical infections and food poisoning. This bacterium produces a group of twenty-one enterotoxins (SEs). These enterotoxins have two separate but related biological activities. They cause gastroenteritis and function as superantigens that activate large numbers of T cells. The current method for detection of enterotoxins activity is an in vivo monkey or kitten bioassay; however, this method is not practical to test on a large number of samples. Several immunological assays have been developed however, but these assays cannot distinguish between active toxin which causes food poisoning and inactive toxin, which can bind antibody, but shows no toxicity. The current study demonstrates that short term ex vivo exposure of primary naïve CD4+ T-cells or splenocytes to SEA induces differential expression and secretion of tumor necrosis factor (TNF) protein. We used immunomagnetic beads coated with anti-SEA antibody to specifically isolate SEA from food. After the eluted toxin was added to the cells SEA biological activity was measured by quantifying TNF protein expression or secretion. Full article
(This article belongs to the Special Issue Bioassays)
Open AccessArticle A Bioanalytical Platform for Simultaneous Detection and Quantification of Biological Toxins
Sensors 2012, 12(2), 2324-2339; doi:10.3390/s120202324
Received: 10 January 2012 / Revised: 9 February 2012 / Accepted: 20 February 2012 / Published: 21 February 2012
Cited by 20 | PDF Full-text (548 KB) | HTML Full-text | XML Full-text
Abstract
Prevalent incidents support the notion that toxins, produced by bacteria, fungi, plants or animals are increasingly responsible for food poisoning or intoxication. Owing to their high toxicity some toxins are also regarded as potential biological warfare agents. Accordingly, control, detection and neutralization of
[...] Read more.
Prevalent incidents support the notion that toxins, produced by bacteria, fungi, plants or animals are increasingly responsible for food poisoning or intoxication. Owing to their high toxicity some toxins are also regarded as potential biological warfare agents. Accordingly, control, detection and neutralization of toxic substances are a considerable economic burden to food safety, health care and military biodefense. The present contribution describes a new versatile instrument and related procedures for array-based simultaneous detection of bacterial and plant toxins using a bioanalytical platform which combines the specificity of covalently immobilized capture probes with a dedicated instrumentation and immuno-based microarray analytics. The bioanalytical platform consists of a microstructured polymer slide serving both as support of printed arrays and as incubation chamber. The platform further includes an easy-to-operate instrument for simultaneous slide processing at selectable assay temperature. Cy5 coupled streptavidin is used as unifying fluorescent tracer. Fluorescence image analysis and signal quantitation allow determination of the toxin’s identity and concentration. The system’s performance has been investigated by immunological detection of Botulinum Neurotoxin type A (BoNT/A), Staphylococcal enterotoxin B (SEB), and the plant toxin ricin. Toxins were detectable at levels as low as 0.5–1 ng·mL−1 in buffer or in raw milk. Full article
(This article belongs to the Special Issue Bioassays)
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Open AccessArticle Label Free Inhibitor Screening of Hepatitis C Virus (HCV) NS5B Viral Protein Using RNA Oligonucleotide
Sensors 2011, 11(7), 6685-6696; doi:10.3390/s110706685
Received: 11 May 2011 / Revised: 22 June 2011 / Accepted: 27 June 2011 / Published: 27 June 2011
Cited by 4 | PDF Full-text (421 KB) | HTML Full-text | XML Full-text
Abstract
Globally, over 170 million people (ca. 3% of the World’s population) are infected with the hepatitis C virus (HCV), which can cause serious liver diseases such as chronic hepatitis, evolving into subsequent health problems. Driven by the need to detect the presence of
[...] Read more.
Globally, over 170 million people (ca. 3% of the World’s population) are infected with the hepatitis C virus (HCV), which can cause serious liver diseases such as chronic hepatitis, evolving into subsequent health problems. Driven by the need to detect the presence of HCV, as an essential factor in diagnostic medicine, the monitoring of viral protein has been of great interest in developing simple and reliable HCV detection methods. Despite considerable advances in viral protein detection as an HCV disease marker, the current enzyme linked immunosorbent assay (ELISA) based detection methods using antibody treatment have several drawbacks. To overcome this bottleneck, an RNA aptamer become to be emerged as an antibody substitute in the application of biosensor for detection of viral protein. In this study, we demonstrated a streptavidin-biotin conjugation method, namely, the RNA aptamer sensor system that can quantify viral protein with detection level of 700 pg mL−1 using a biotinylated RNA oligonucleotide on an Octet optical biosensor. Also, we showed this method can be used to screen inhibitors of viral protein rapidly and simply on a biotinylated RNA oligonucleotide biosensor. Among the inhibitors screened, (−)-Epigallocatechin gallate showed high binding inhibition effect on HCV NS5B viral protein. The proposed method can be considered a real-time monitoring method for inhibitor screening of HCV viral protein and is expected to be applicable to other types of diseases. Full article
(This article belongs to the Special Issue Bioassays)

Review

Jump to: Research

Open AccessReview Effect-Based Tools for Monitoring and Predicting the Ecotoxicological Effects of Chemicals in the Aquatic Environment
Sensors 2012, 12(9), 12741-12771; doi:10.3390/s120912741
Received: 31 July 2012 / Revised: 28 August 2012 / Accepted: 30 August 2012 / Published: 18 September 2012
Cited by 43 | PDF Full-text (886 KB) | HTML Full-text | XML Full-text
Abstract
Ecotoxicology faces the challenge of assessing and predicting the effects of an increasing number of chemical stressors on aquatic species and ecosystems. Herein we review currently applied tools in ecological risk assessment, combining information on exposure with expected biological effects or environmental water
[...] Read more.
Ecotoxicology faces the challenge of assessing and predicting the effects of an increasing number of chemical stressors on aquatic species and ecosystems. Herein we review currently applied tools in ecological risk assessment, combining information on exposure with expected biological effects or environmental water quality standards; currently applied effect-based tools are presented based on whether exposure occurs in a controlled laboratory environment or in the field. With increasing ecological relevance the reproducibility, specificity and thus suitability for standardisation of methods tends to diminish. We discuss the use of biomarkers in ecotoxicology including ecotoxicogenomics-based endpoints, which are becoming increasingly important for the detection of sublethal effects. Carefully selected sets of biomarkers allow an assessment of exposure to and effects of toxic chemicals, as well as the health status of organisms and, when combined with chemical analysis, identification of toxicant(s). The promising concept of “adverse outcome pathways (AOP)” links mechanistic responses on the cellular level with whole organism, population, community and potentially ecosystem effects and services. For most toxic mechanisms, however, practical application of AOPs will require more information and the identification of key links between responses, as well as key indicators, at different levels of biological organization, ecosystem functioning and ecosystem services. Full article
(This article belongs to the Special Issue Bioassays)
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Open AccessReview Multiple Applications of Alamar Blue as an Indicator of Metabolic Function and Cellular Health in Cell Viability Bioassays
Sensors 2012, 12(9), 12347-12360; doi:10.3390/s120912347
Received: 10 July 2012 / Revised: 21 August 2012 / Accepted: 31 August 2012 / Published: 10 September 2012
Cited by 90 | PDF Full-text (220 KB) | HTML Full-text | XML Full-text
Abstract
Accurate prediction of the adverse effects of test compounds on living systems, detection of toxic thresholds, and expansion of experimental data sets to include multiple toxicity end-point analysis are required for any robust screening regime. Alamar Blue is an important redox indicator that
[...] Read more.
Accurate prediction of the adverse effects of test compounds on living systems, detection of toxic thresholds, and expansion of experimental data sets to include multiple toxicity end-point analysis are required for any robust screening regime. Alamar Blue is an important redox indicator that is used to evaluate metabolic function and cellular health. The Alamar Blue bioassay has been utilized over the past 50 years to assess cell viability and cytotoxicity in a range of biological and environmental systems and in a number of cell types including bacteria, yeast, fungi, protozoa and cultured mammalian and piscine cells. It offers several advantages over other metabolic indicators and other cytotoxicity assays. However, as with any bioassay, suitability must be determined for each application and cell model. This review seeks to highlight many of the important considerations involved in assay use and design in addition to the potential pitfalls. Full article
(This article belongs to the Special Issue Bioassays)
Open AccessReview A Unifying Review of Bioassay-Guided Fractionation, Effect-Directed Analysis and Related Techniques
Sensors 2012, 12(7), 9181-9209; doi:10.3390/s120709181
Received: 16 May 2012 / Revised: 26 June 2012 / Accepted: 2 July 2012 / Published: 4 July 2012
Cited by 28 | PDF Full-text (548 KB) | HTML Full-text | XML Full-text
Abstract
The success of modern methods in analytical chemistry sometimes obscures the problem that the ever increasing amount of analytical data does not necessarily give more insight of practical relevance. As alternative approaches, toxicity- and bioactivity-based assays can deliver valuable information about biological effects
[...] Read more.
The success of modern methods in analytical chemistry sometimes obscures the problem that the ever increasing amount of analytical data does not necessarily give more insight of practical relevance. As alternative approaches, toxicity- and bioactivity-based assays can deliver valuable information about biological effects of complex materials in humans, other species or even ecosystems. However, the observed effects often cannot be clearly assigned to specific chemical compounds. In these cases, the establishment of an unambiguous cause-effect relationship is not possible. Effect-directed analysis tries to interconnect instrumental analytical techniques with a biological/biochemical entity, which identifies or isolates substances of biological relevance. Successful application has been demonstrated in many fields, either as proof-of-principle studies or even for complex samples. This review discusses the different approaches, advantages and limitations and finally shows some practical examples. The broad emergence of effect-directed analytical concepts might lead to a true paradigm shift in analytical chemistry, away from ever growing lists of chemical compounds. The connection of biological effects with the identification and quantification of molecular entities leads to relevant answers to many real life questions. Full article
(This article belongs to the Special Issue Bioassays)
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Open AccessReview Protein Reporter Bioassay Systems for the Phenotypic Screening of Candidate Drugs: A Mouse Platform for Anti-Aging Drug Screening
Sensors 2012, 12(2), 1648-1656; doi:10.3390/s120201648
Received: 12 December 2011 / Revised: 18 January 2012 / Accepted: 2 February 2012 / Published: 7 February 2012
Cited by 6 | PDF Full-text (168 KB) | HTML Full-text | XML Full-text
Abstract
Recent drug discovery efforts have utilized high throughput screening (HTS) of large chemical libraries to identify compounds that modify the activity of discrete molecular targets. The molecular target approach to drug screening is widely used in the pharmaceutical and biotechnology industries, because of
[...] Read more.
Recent drug discovery efforts have utilized high throughput screening (HTS) of large chemical libraries to identify compounds that modify the activity of discrete molecular targets. The molecular target approach to drug screening is widely used in the pharmaceutical and biotechnology industries, because of the amount of knowledge now available regarding protein structure that has been obtained by computer simulation. The molecular target approach requires that the structure of target molecules, and an understanding of their physiological functions, is known. This approach to drug discovery may, however, limit the identification of novel drugs. As an alternative, the phenotypic- or pathway-screening approach to drug discovery is gaining popularity, particularly in the academic sector. This approach not only provides the opportunity to identify promising drug candidates, but also enables novel information regarding biological pathways to be unveiled. Reporter assays are a powerful tool for the phenotypic screening of compound libraries. Of the various reporter genes that can be used in such assays, those encoding secreted proteins enable the screening of hit molecules in both living cells and animals. Cell- and animal-based screens enable simultaneous evaluation of drug metabolism or toxicity with biological activity. Therefore, drug candidates identified in these screens may have increased biological efficacy and a lower risk of side effects in humans. In this article, we review the reporter bioassay systems available for phenotypic drug discovery. Full article
(This article belongs to the Special Issue Bioassays)

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