Chemosensors

2820 KiB

Open AccessArticle

Electrochemical Immunosensor for Detection of IgY in Food and Food Supplements

by Chiara Gaetani, Emmanuele Ambrosi, Paolo Ugo and Ligia M. Moretto

Chemosensors 2017, 5(1), 10; https://doi.org/10.3390/chemosensors5010010 - 2 Mar 2017

Cited by 14 | Viewed by 5917

Immunoglobulin Y is a water-soluble protein present in high concentration in hen serum and egg yolk. IgY has applications in many fields, e.g., from food stuff to the mass production of antibodies. In this work, we have implemented an electrochemical immunosensor for IgY [...] Read more.

Immunoglobulin Y is a water-soluble protein present in high concentration in hen serum and egg yolk. IgY has applications in many fields, e.g., from food stuff to the mass production of antibodies. In this work, we have implemented an electrochemical immunosensor for IgY based on templated nanoelectrodes ensembles. IgY is captured by the templating polycarbonate and reacted with anti-IgY labeled with horseradish peroxidase. In the presence of H₂O₂ and methylene blue as the redox mediator, an electrocatalytic current is generated which scales with IgY concentration in the sample. After optimizing the extracting procedure, the immunosensor was applied for analysis of fresh eggs and food integrators. The data obtained with the biosensor were validated by SDS-PAGE and Western blot measurements. Full article

(This article belongs to the Special Issue Electrochemical Immunosensors and Aptasensors)

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2776 KiB

Open AccessArticle

Electrochemical Study of Trametes Versicolor Laccase Compatibility to Different Polyphenolic Substrates

by Milan Sýs, Radovan Metelka, Arbër Frangu, Karel Vytřas and Tahir Arbneshi

Chemosensors 2017, 5(1), 9; https://doi.org/10.3390/chemosensors5010009 - 26 Feb 2017

Cited by 19 | Viewed by 7477

Abstract

The aim of this electrochemical study was to ascertain which position of hydroxy groups on a benzene ring provides electroactive products after enzymatic oxidation by laccase originating from the Trametes versicolor mushroom, exhibiting intense redox signals that are exploitable for their amperometric determination. [...] Read more.

The aim of this electrochemical study was to ascertain which position of hydroxy groups on a benzene ring provides electroactive products after enzymatic oxidation by laccase originating from the Trametes versicolor mushroom, exhibiting intense redox signals that are exploitable for their amperometric determination. The electrochemical properties of phenol together with all isomers of benzenediol and cresol at the bare carbon paste electrode (CPE) and CPE modified with enzyme laccase (CPE/Laccase) were investigated using cyclic voltammetry at various scan rates. Comparison of resulting redox signals and their differences confirmed the suitability of classes of polyphenolic compounds as substrates for Trametes versicolor laccase and their potential use as suitable biological components in the development of amperometric enzyme biosensors for the determination of such species. The feasibility of the proposed approach was verified by electrochemical assays of the enzymatic oxidation of polyphenolic analogues of simple phenols, e.g., gentisic acid, caffeic acid, resveratrol, and others. Full article

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5835 KiB

Open AccessReview

Electrochemical Affinity Biosensors in Food Safety

by Susana Campuzano, Paloma Yáez-Sedeño and José Manuel Pingarrón

Chemosensors 2017, 5(1), 8; https://doi.org/10.3390/chemosensors5010008 - 20 Feb 2017

Cited by 43 | Viewed by 10612

Abstract

Safety and quality are key issues of today’s food industry. Since the food chain is becoming more and more complex, powerful analytical methods are required to verify the performance of food safety and quality systems. Indeed, such methods require high sensitivity, selectivity, ability [...] Read more.

Safety and quality are key issues of today’s food industry. Since the food chain is becoming more and more complex, powerful analytical methods are required to verify the performance of food safety and quality systems. Indeed, such methods require high sensitivity, selectivity, ability for rapid implementation and capability of automatic screening. Electroanalytical chemistry has, for decades, played a relevant role in food safety and quality assessment, taking more and more significance over time in the solution of analytical problems. At present, the implementation of electrochemical methods in the food is evident. This is in a large part due to the relevant results obtained by combining the attractive advantages of electrochemical transduction strategies (in terms of relatively simple hardware, versatility, interface with automatic logging and feasibility of application outside the laboratory environment) with those from biosensors technology. Important examples of enzyme electrochemical biosensors are those dedicated to the determination of glucose, alcohol or cholesterol are important examples. In addition, other types of different electrochemical biosensing approaches have emerged strongly in the last years. Among these, the strategies involving affinity interactions have been shown to possess a large number of applications. Therefore, electrochemical immunosensors and DNA-based biosensors have been widely used to determine major and minor components in foodstuffs, providing sufficient data to evaluate food freshness, the quality of raw materials, or the origin of samples, as well as to determine a variety of compounds at trace levels related to food safety such as micotoxins, allergens, drugs residues or pathogen microorganisms. This review discusses some critical examples of the latest advances in this area, pointing out relevant methodologies related to the measurement techniques, including the use of nanostructured electrodes and strategies for signal amplification. Full article

(This article belongs to the Special Issue Biosensors Applications in Food Safety)

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3277 KiB

Open AccessReview

Gravimetric Viral Diagnostics: QCM Based Biosensors for Early Detection of Viruses

by Adeel Afzal, Adnan Mujahid, Romana Schirhagl, Sadia Zafar Bajwa, Usman Latif and Saima Feroz

Chemosensors 2017, 5(1), 7; https://doi.org/10.3390/chemosensors5010007 - 13 Feb 2017

Cited by 117 | Viewed by 15952

Abstract

Viruses are pathogenic microorganisms that can inhabit and replicate in human bodies causing a number of widespread infectious diseases such as influenza, gastroenteritis, hepatitis, meningitis, pneumonia, acquired immune deficiency syndrome (AIDS) etc. A majority of these viral diseases are contagious and can spread [...] Read more.

Viruses are pathogenic microorganisms that can inhabit and replicate in human bodies causing a number of widespread infectious diseases such as influenza, gastroenteritis, hepatitis, meningitis, pneumonia, acquired immune deficiency syndrome (AIDS) etc. A majority of these viral diseases are contagious and can spread from infected to healthy human beings. The most important step in the treatment of these contagious diseases and to prevent their unwanted spread is to timely detect the disease-causing viruses. Gravimetric viral diagnostics based on quartz crystal microbalance (QCM) transducers and natural or synthetic receptors are miniaturized sensing platforms that can selectively recognize and quantify harmful virus species. Herein, a review of the label-free QCM virus sensors for clinical diagnostics and point of care (POC) applications is presented with major emphasis on the nature and performance of different receptors ranging from the natural or synthetic antibodies to selective macromolecular materials such as DNA and aptamers. A performance comparison of different receptors is provided and their limitations are discussed. Full article

(This article belongs to the Special Issue Molecularly Imprinted Polymers—Robust Artificial Receptor Materials for Chemical Sensing)

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2339 KiB

Open AccessArticle

Hierarchical Self-Assembly of Amino Acid Derivatives into Enzyme-Responsive Luminescent Gel

by Yibao Li, Yu Peng, Wei Liu, Yulan Fan, Yongquan Wu, Xun Li and Xiaolin Fan

Chemosensors 2017, 5(1), 6; https://doi.org/10.3390/chemosensors5010006 - 7 Feb 2017

Cited by 6 | Viewed by 4911

Abstract

In this study, a novel three-component hydrogel has been designed and fabricated via hierarchical self-assembly by amino acid derivative (NPPD), riboflavin (RF) and α-cyclodextrin (α-CD). These molecules were aggregated to form some fibrous structures based on hydrogen bond and π–π stacking. The results [...] Read more.

In this study, a novel three-component hydrogel has been designed and fabricated via hierarchical self-assembly by amino acid derivative (NPPD), riboflavin (RF) and α-cyclodextrin (α-CD). These molecules were aggregated to form some fibrous structures based on hydrogen bond and π–π stacking. The results show that the hydrogel has a specific response to α-amylase and the fluorescence disappears once hydrolyzed. Therefore, this multi-component hydrogel has potential application in the field of drug delivery. Full article

(This article belongs to the Special Issue Bioinspired Chemical Sensing)

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2562 KiB

Open AccessArticle

Selectivity and Efficiency of Conductive Molecularly Imprinted Polymer (c-MIP) Based on 5-Phenyl-Dipyrromethane and 5-Phenol-Dipyrromethane for Quorum Sensing Precursors Detection

by Sabina Susmel and Clara Comuzzi

Chemosensors 2017, 5(1), 5; https://doi.org/10.3390/chemosensors5010005 - 4 Feb 2017

Cited by 6 | Viewed by 6175

Abstract

Functional polymers that selectively recognize target compounds are developed by imprinting polymerization. In the present paper, two different dipyrromethanes, 5-phenol-dipyrromethane (5-pOH-DP) and 5-phenyl-dipyrromethane (5-ph-DP), are synthetized and investigated to develop conductive molecularly imprinted polymer (cMIP) sensors. As target molecules, two homoserine lactone derivatives [...] Read more.

Functional polymers that selectively recognize target compounds are developed by imprinting polymerization. In the present paper, two different dipyrromethanes, 5-phenol-dipyrromethane (5-pOH-DP) and 5-phenyl-dipyrromethane (5-ph-DP), are synthetized and investigated to develop conductive molecularly imprinted polymer (cMIP) sensors. As target molecules, two homoserine lactone derivatives were templated by an electrochemically driven polymerization process. Acyl-homoserine lactones (AHLs), also called homoserine lactones (HS), are a class of signaling molecules involved in bacterial quorum sensing (QS), which is a strategy of coordination among bacteria mediated by population density. The preparation of cMIP from 5-pOH-DP and 5-ph-DP in the presence of acetyl-homoserine lactone (Acetyl-HS) or carboxybenzyl-homoserine lactone (Cbz-HS) was performed by cyclic voltammetry (CV). The cMIP selectivity and sensitivity were assessed by microgravimetry (QCM). Both series of measurements were performed with the aid of an Electrochemical Quartz Crystal Microbalance (EQCM/QCM). The experimental evidences are discussed with respect to NMR measurements that were conducted to gain insight into the interactions established between monomers and templates. The NMR data interpretation offers preliminary information about the most probable positions involved in interaction development for both molecules and highlights the role of the hydration shell. The QCM-cMIP sensor was able to detect the analyte in the linear range from 10⁻⁸ mol·L⁻¹ to 10⁻⁶ mol·L⁻¹ and a limit of detection (LOD) of 22.3 ng (3σ of the blank signal) were evaluated. QCM rebinding tests demonstrated that cMIP selectivity was driven by the pendant group of dipyrromethane, which was also confirmed by the NMR data. Full article

(This article belongs to the Special Issue Molecularly Imprinted Polymers—Robust Artificial Receptor Materials for Chemical Sensing)

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4874 KiB

Open AccessArticle

Investigation of the Influence of the As-Grown ZnO Nanorods and Applied Potentials on an Electrochemical Sensor for In-Vitro Glucose Monitoring

by Mohammed Marie and Omar Manasreh

Chemosensors 2017, 5(1), 4; https://doi.org/10.3390/chemosensors5010004 - 26 Jan 2017

Cited by 3 | Viewed by 5528

Abstract

The influence of the as-grown zinc oxide nanorods (ZnO NRs) on the fabricated electrochemical sensor for in vitro glucose monitoring were investigated. A direct growth of ZnO NRs was performed on the Si/SiO₂/Au electrode, using hydrothermal and sol-gel techniques at low [...] Read more.

The influence of the as-grown zinc oxide nanorods (ZnO NRs) on the fabricated electrochemical sensor for in vitro glucose monitoring were investigated. A direct growth of ZnO NRs was performed on the Si/SiO₂/Au electrode, using hydrothermal and sol-gel techniques at low temperatures. The structure, consisting of a Si/SiO₂/Au/GO_x/Nafion membrane, was considered as a baseline, and it was tested under several applied potential 0.1–0.8 V. The immobilized working electrode, with GO_x and a nafion membrane, was characterized amperometrically using a source meter Keithely 2410, and an electrochemical impedance Gamry potentiostat. The sensor exhibited the following: a high sensitivity of ~0.468 mA/cm² mM, a low detection limit in the order of 166.6 µM, and a fast and sharp response time of around 2 s. The highest sensitivity and the lowest limit of detection were obtained at 0.4 volt, after the growth of ZnO NRs. The highest net sensitivity was obtained after subtracting the sensitivity of the baseline, and it was in the order of 0.315 mA/cm²·mM. The device was tested with a range of glucose concentrations from 1–10 mM, showing a linear line from 3–8 mM, and the device was saturated after exceeding high concentrations of glucose. Such devices can be used for in vitro glucose monitoring, since glucose changes can be accurately detected. Full article

(This article belongs to the Special Issue Advanced in Glucose Biosensing)

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280 KiB

Open AccessEditorial

Acknowledgement to Reviewers of Chemosensors in 2016

by Chemosensors Editorial Office

Chemosensors 2017, 5(1), 3; https://doi.org/10.3390/chemosensors5010003 - 12 Jan 2017

Viewed by 3177

Abstract

The editors of Chemosensors would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2016.[...] Full article

2304 KiB

Open AccessArticle

Nitrate Ion Selective Electrode Based on Ion Imprinted Poly(N-methylpyrrole)

by Ellen M. Bomar, George S. Owens and George M. Murray

Chemosensors 2017, 5(1), 2; https://doi.org/10.3390/chemosensors5010002 - 4 Jan 2017

Cited by 26 | Viewed by 8814

Abstract

A poly(N-methylpyrrole) based ion selective electrode (ISE) has been prepared by electro-polymerization of N-methylpyrrole using potassium nitrate as the supporting electrolyte. Electrochemical and chemical variables were used to optimize the potentiometric response of the electrodes and to maximize the selectivity [...] Read more.

A poly(N-methylpyrrole) based ion selective electrode (ISE) has been prepared by electro-polymerization of N-methylpyrrole using potassium nitrate as the supporting electrolyte. Electrochemical and chemical variables were used to optimize the potentiometric response of the electrodes and to maximize the selectivity for nitrate over potential interferences. The selectivity, longevity and stability of the ion-imprinted polymer give this electrode advantages over traditional nitrate ISEs. The best prototype electrode exhibits a linear potential response to nitrate ion within the concentration range of 5.0 × 10⁻⁶ to 0.1 M nitrate with a near Nernstian slope of −56.3 mV per decade (R² = 0.9998) and a strong preference for the nitrate ion over other anions. The selectivity coefficients of the electrode were evaluated by the fixed interference method. The use of N-methylpyrrole has advantages over pyrrole in terms of selectivity and pH insensitivity. Full article

(This article belongs to the Special Issue Molecularly Imprinted Polymers—Robust Artificial Receptor Materials for Chemical Sensing)

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2112 KiB

Open AccessReview

Recent Advances in Electrochemical-Based Sensing Platforms for Aflatoxins Detection

by Atul Sharma, Kotagiri Yugender Goud, Akhtar Hayat, Sunil Bhand and Jean Louis Marty

Chemosensors 2017, 5(1), 1; https://doi.org/10.3390/chemosensors5010001 - 26 Dec 2016

Cited by 38 | Viewed by 8283

Abstract

Mycotoxin are small (MW ~700 Da), toxic secondary metabolites produced by fungal species that readily colonize crops and contaminate them at both pre- and post-harvesting. Among all, aflatoxins (AFs) are mycotoxins of major significance due to their presence in common food commodities and [...] Read more.

Mycotoxin are small (MW ~700 Da), toxic secondary metabolites produced by fungal species that readily colonize crops and contaminate them at both pre- and post-harvesting. Among all, aflatoxins (AFs) are mycotoxins of major significance due to their presence in common food commodities and the potential threat to human health worldwide. Based on the severity of illness and increased incidences of AFs poisoning, a broad range of conventional and analytical detection techniques that could be useful and practical have already been reported. However, due to the variety of structural analogous of these toxins, it is impossible to use one common technique for their analysis. Numerous recent research efforts have been directed to explore alternative detection technologies. Recently, immunosensors and aptasensors have gained promising potential in the area of sample preparation and detection systems. These sensors offer the advantages of disposability, portability, miniaturization, and on-site analysis. In a typical design of an aptasensor, an aptamer (ssDNA or RNA) is used as a bio-recognition element either integrated within or in intimate association with the transducer surface. This review paper is focused on the recent advances in electrochemical immuno- and aptasensing platforms for detection of AFs in real samples. Full article

(This article belongs to the Special Issue Electrochemical Immunosensors and Aptasensors)

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