Sensors

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9047 KiB

Open AccessArticle

Highly Sensitive Bacteria Quantification Using Immunomagnetic Separation and Electrochemical Detection of Guanine-Labeled Secondary Beads

by Harikrishnan Jayamohan, Bruce K. Gale, Bj Minson, Christopher J. Lambert, Neil Gordon and Himanshu J. Sant

Sensors 2015, 15(5), 12034-12052; https://doi.org/10.3390/s150512034 - 22 May 2015

Cited by 46 | Viewed by 10646

Abstract

In this paper, we report the ultra-sensitive indirect electrochemical detection of E. coli O157:H7 using antibody functionalized primary (magnetic) beads for capture and polyguanine (polyG) oligonucleotide functionalized secondary (polystyrene) beads as an electrochemical tag. Vacuum filtration in combination with E. coli O157:H7 specific [...] Read more.

In this paper, we report the ultra-sensitive indirect electrochemical detection of E. coli O157:H7 using antibody functionalized primary (magnetic) beads for capture and polyguanine (polyG) oligonucleotide functionalized secondary (polystyrene) beads as an electrochemical tag. Vacuum filtration in combination with E. coli O157:H7 specific antibody modified magnetic beads were used for extraction of E. coli O157:H7 from 100 mL samples. The magnetic bead conjugated E. coli O157:H7 cells were then attached to polyG functionalized secondary beads to form a sandwich complex (magnetic bead/E. coli secondary bead). While the use of magnetic beads for immuno-based capture is well characterized, the use of oligonucleotide functionalized secondary beads helps combine amplification and potential multiplexing into the system. The antibody functionalized secondary beads can be easily modified with a different antibody to detect other pathogens from the same sample and enable potential multiplexing. The polyGs on the secondary beads enable signal amplification up to 10$^{8}$ guanine tags per secondary bead ($7.5\times10^{6}$ biotin-FITC per secondary bead, 20 guanines per oligonucleotide) bound to the target (E. coli). A single-stranded DNA probe functionalized reduced graphene oxide modified glassy carbon electrode was used to bind the polyGs on the secondary beads. Fluorescent imaging was performed to confirm the hybridization of the complex to the electrode surface. Differential pulse voltammetry (DPV) was used to quantify the amount of polyG involved in the hybridization event with tris(2,2'-bipyridine)ruthenium(II) (Ru(bpy)$_{3}^{2+}$) as the mediator. The amount of polyG signal can be correlated to the amount of E. coli O157:H7 in the sample. The method was able to detect concentrations of E. coli O157:H7 down to 3 CFU/100 mL, which is 67 times lower than the most sensitive technique reported in literature. The signal to noise ratio for this work was 3. We also demonstrate the use of the protocol for detection of E. coli O157:H7 seeded in waste water effluent samples. Full article

(This article belongs to the Special Issue Biosensors for Pathogen Detection)

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2450 KiB

Open AccessArticle

Sensor Node for Remote Monitoring of Waterborne Disease-Causing Bacteria

by Kyukwang Kim and Hyun Myung

Sensors 2015, 15(5), 10569-10579; https://doi.org/10.3390/s150510569 - 5 May 2015

Cited by 27 | Viewed by 10475

Abstract

A sensor node for sampling water and checking for the presence of harmful bacteria such as E. coli in water sources was developed in this research. A chromogenic enzyme substrate assay method was used to easily detect coliform bacteria by monitoring the color [...] Read more.

A sensor node for sampling water and checking for the presence of harmful bacteria such as E. coli in water sources was developed in this research. A chromogenic enzyme substrate assay method was used to easily detect coliform bacteria by monitoring the color change of the sampled water mixed with a reagent. Live webcam image streaming to the web browser of the end user with a Wi-Fi connected sensor node shows the water color changes in real time. The liquid can be manipulated on the web-based user interface, and also can be observed by webcam feeds. Image streaming and web console servers run on an embedded processor with an expansion board. The UART channel of the expansion board is connected to an external Arduino board and a motor driver to control self-priming water pumps to sample the water, mix the reagent, and remove the water sample after the test is completed. The sensor node can repeat water testing until the test reagent is depleted. The authors anticipate that the use of the sensor node developed in this research can decrease the cost and required labor for testing samples in a factory environment and checking the water quality of local water sources in developing countries. Full article

(This article belongs to the Special Issue Biosensors for Pathogen Detection)

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1204 KiB

Open AccessArticle

Comparison of Whole-Cell SELEX Methods for the Identification of Staphylococcus Aureus-Specific DNA Aptamers

by Jihea Moon, Giyoung Kim, Saet Byeol Park, Jongguk Lim and Changyeun Mo

Sensors 2015, 15(4), 8884-8897; https://doi.org/10.3390/s150408884 - 15 Apr 2015

Cited by 68 | Viewed by 10443

Abstract

Whole-cell Systemic Evolution of Ligands by Exponential enrichment (SELEX) is the process by which aptamers specific to target cells are developed. Aptamers selected by whole-cell SELEX have high affinity and specificity for bacterial surface molecules and live bacterial targets. To identify DNA aptamers [...] Read more.

Whole-cell Systemic Evolution of Ligands by Exponential enrichment (SELEX) is the process by which aptamers specific to target cells are developed. Aptamers selected by whole-cell SELEX have high affinity and specificity for bacterial surface molecules and live bacterial targets. To identify DNA aptamers specific to Staphylococcus aureus, we applied our rapid whole-cell SELEX method to a single-stranded ssDNA library. To improve the specificity and selectivity of the aptamers, we designed, selected, and developed two categories of aptamers that were selected by two kinds of whole-cell SELEX, by mixing and combining FACS analysis and a counter-SELEX process. Using this approach, we have developed a biosensor system that employs a high affinity aptamer for detection of target bacteria. FAM-labeled aptamer sequences with high binding to S. aureus, as determined by fluorescence spectroscopic analysis, were identified, and aptamer A14, selected by the basic whole-cell SELEX using a once-off FACS analysis, and which had a high binding affinity and specificity, was chosen. The binding assay was evaluated using FACS analysis. Our study demonstrated the development of a set of whole-cell SELEX derived aptamers specific to S. aureus; this approach can be used in the identification of other bacteria. Full article

(This article belongs to the Special Issue Biosensors for Pathogen Detection)

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2081 KiB

Open AccessCommunication

Rapid Detection of Ebola Virus with a Reagent-Free, Point-of-Care Biosensor

by Justin T. Baca, Virginia Severns, Debbie Lovato, Darren W. Branch and Richard S. Larson

Sensors 2015, 15(4), 8605-8614; https://doi.org/10.3390/s150408605 - 14 Apr 2015

Cited by 52 | Viewed by 10675

Abstract

Surface acoustic wave (SAW) sensors can rapidly detect Ebola antigens at the point-of-care without the need for added reagents, sample processing, or specialized personnel. This preliminary study demonstrates SAW biosensor detection of the Ebola virus in a concentration-dependent manner. The detection limit with [...] Read more.

Surface acoustic wave (SAW) sensors can rapidly detect Ebola antigens at the point-of-care without the need for added reagents, sample processing, or specialized personnel. This preliminary study demonstrates SAW biosensor detection of the Ebola virus in a concentration-dependent manner. The detection limit with this methodology is below the average level of viremia detected on the first day of symptoms by PCR. We observe a log-linear sensor response for highly fragmented Ebola viral particles, with a detection limit corresponding to 1.9 × 10⁴ PFU/mL prior to virus inactivation. We predict greatly improved sensitivity for intact, infectious Ebola virus. This point-of-care methodology has the potential to detect Ebola viremia prior to symptom onset, greatly enabling infection control and rapid treatment. This biosensor platform is powered by disposable AA batteries and can be rapidly adapted to detect other emerging diseases in austere conditions. Full article

(This article belongs to the Special Issue Biosensors for Pathogen Detection)

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Graphical abstract

2067 KiB

Open AccessArticle

A Portable Automatic Endpoint Detection System for Amplicons of Loop Mediated Isothermal Amplification on Microfluidic Compact Disk Platform

by Shah Mukim Uddin, Fatimah Ibrahim, Abkar Ahmed Sayad, Aung Thiha, Koh Xiu Pei, Mas S. Mohktar, Uda Hashim, Jongman Cho and Kwai Lin Thong

Sensors 2015, 15(3), 5376-5389; https://doi.org/10.3390/s150305376 - 5 Mar 2015

Cited by 32 | Viewed by 10718

Abstract

In recent years, many improvements have been made in foodborne pathogen detection methods to reduce the impact of food contamination. Several rapid methods have been developed with biosensor devices to improve the way of performing pathogen detection. This paper presents an automated endpoint [...] Read more.

In recent years, many improvements have been made in foodborne pathogen detection methods to reduce the impact of food contamination. Several rapid methods have been developed with biosensor devices to improve the way of performing pathogen detection. This paper presents an automated endpoint detection system for amplicons generated by loop mediated isothermal amplification (LAMP) on a microfluidic compact disk platform. The developed detection system utilizes a monochromatic ultraviolet (UV) emitter for excitation of fluorescent labeled LAMP amplicons and a color sensor to detect the emitted florescence from target. Then it processes the sensor output and displays the detection results on liquid crystal display (LCD). The sensitivity test has been performed with detection limit up to 2.5 × 10⁻³ ng/µL with different DNA concentrations of Salmonella bacteria. This system allows a rapid and automatic endpoint detection which could lead to the development of a point-of-care diagnosis device for foodborne pathogens detection in a resource-limited environment. Full article

(This article belongs to the Special Issue Biosensors for Pathogen Detection)

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Graphical abstract

1145 KiB

Open AccessArticle

Rapid and Efficient Estimation of Pea Resistance to the Soil-Borne Pathogen Fusarium oxysporum by Infrared Imaging

by Nicolas Rispail and Diego Rubiales

Sensors 2015, 15(2), 3988-4000; https://doi.org/10.3390/s150203988 - 9 Feb 2015

Cited by 17 | Viewed by 6132

Abstract

Fusarium wilts are widespread diseases affecting most agricultural crops. In absence of efficient alternatives, sowing resistant cultivars is the preferred approach to control this disease. However, actual resistance sources are often overcome by new pathogenic races, forcing breeders to continuously search for novel [...] Read more.

Fusarium wilts are widespread diseases affecting most agricultural crops. In absence of efficient alternatives, sowing resistant cultivars is the preferred approach to control this disease. However, actual resistance sources are often overcome by new pathogenic races, forcing breeders to continuously search for novel resistance sources. Selection of resistant accessions, mainly based on the evaluation of symptoms at timely intervals, is highly time-consuming. Thus, we tested the potential of an infra-red imaging system in plant breeding to speed up this process. For this, we monitored the changes in surface leaf temperature upon infection by F. oxysporum f. sp. pisi in several pea accessions with contrasting response to Fusarium wilt under a controlled environment. Using a portable infra-red imaging system we detected a significant temperature increase of at least 0.5 °C after 10 days post-inoculation in the susceptible accessions, while the resistant accession temperature remained at control level. The increase in leaf temperature at 10 days post-inoculation was positively correlated with the AUDPC calculated over a 30 days period. Thus, this approach allowed the early discrimination between resistant and susceptible accessions. As such, applying infra-red imaging system in breeding for Fusarium wilt resistance would contribute to considerably shorten the process of selection of novel resistant sources. Full article

(This article belongs to the Special Issue Biosensors for Pathogen Detection)

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2121 KiB

Open AccessArticle

A Novel Ultrasensitive ECL Sensor for DNA Detection Based on Nicking Endonuclease-Assisted Target Recycling Amplification, Rolling Circle Amplification and Hemin/G-Quadruplex

by Fukang Luo, Guimin Xiang, Xiaoyun Pu, Juanchun Yu, Ming Chen and Guohui Chen

Sensors 2015, 15(2), 2629-2643; https://doi.org/10.3390/s150202629 - 26 Jan 2015

Cited by 11 | Viewed by 7513

Abstract

In this study, we describe a novel universal and highly sensitive strategy for the electrochemiluminescent (ECL) detection of sequence specific DNA at the aM level based on Nt.BbvCI (a nicking endonuclease)-assisted target recycling amplification (TRA), rolling circle amplification (RCA) and hemin/G-quadruplex. The target [...] Read more.

In this study, we describe a novel universal and highly sensitive strategy for the electrochemiluminescent (ECL) detection of sequence specific DNA at the aM level based on Nt.BbvCI (a nicking endonuclease)-assisted target recycling amplification (TRA), rolling circle amplification (RCA) and hemin/G-quadruplex. The target DNAs can hybridize with self-assembled capture probes and assistant probes to form “Y” junction structures on the electrode surface, thus triggering the execution of a TRA reaction with the aid of Nt.BbvCI. Then, the RCA reaction and the addition of hemin result in the production of numerous hemin/G-quadruplex, which consume the dissolved oxygen in the detection buffer and result in a significant ECL quenching effect toward the O₂/S₂O₈²⁻ system. The proposed strategy combines the amplification ability of TRA, RCA and the inherent high sensitivity of the ECL technique, thus enabling low aM (3.8 aM) detection for sequence-specific DNA and a wide linear range from 10.0 aM to 1.0 pM. At the same time, this novel strategy shows high selectivity against single-base mismatch sequences, which makes our novel universal and highly sensitive method a powerful addition to specific DNA sequence detection. Full article

(This article belongs to the Special Issue Biosensors for Pathogen Detection)

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842 KiB

Open AccessArticle

Comparison between a Conductometric Biosensor and ELISA in the Evaluation of Johne’s Disease

by Chika Okafor, Daniel Grooms, Evangelyn Alocilja and Steven Bolin

Sensors 2014, 14(10), 19128-19137; https://doi.org/10.3390/s141019128 - 15 Oct 2014

Cited by 14 | Viewed by 6004

Abstract

Johne’s disease (JD), caused by Mycobacterium avium subspecies paratuberculosis (MAP), is an important gastrointestinal disease of cattle worldwide because of the economic losses encountered in JD-affected herds. These losses include reduction in milk yield in cows, premature culling and reduced carcass weight of [...] Read more.

Johne’s disease (JD), caused by Mycobacterium avium subspecies paratuberculosis (MAP), is an important gastrointestinal disease of cattle worldwide because of the economic losses encountered in JD-affected herds. These losses include reduction in milk yield in cows, premature culling and reduced carcass weight of culled diseased animals. In the U.S. dairy industry, economic losses from reduced productivity associated with JD are estimated to cost between $200 and $250 million annually. The development of non-laboratory-based assays would support more frequent testing of animals for JD and could improve its control. Conductometric biosensors combine immunomigration technology with electronic signal detection and have been adapted for the detection of IgG antibody against MAP. In the present study, a capture membrane with limited variability in the immunomigration channel and an optimal concentration of the secondary anti-bovine antibody used in a previously developed conductometric biosensor were compared with a commercially available antibody detection ELISA in their evaluation of JD, using samples of serum from cattle whose JD status where unknown. There was a moderate strength of agreement (kappa = 0.41) between the two assays. Findings from this preliminary study support the continued development of conductometric biosensors for use in the diagnosis of JD. Full article

(This article belongs to the Special Issue Biosensors for Pathogen Detection)

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Review

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1916 KiB

Open AccessReview

A Review of Membrane-Based Biosensors for Pathogen Detection

by Remko Van den Hurk and Stephane Evoy

Sensors 2015, 15(6), 14045-14078; https://doi.org/10.3390/s150614045 - 15 Jun 2015

Cited by 56 | Viewed by 16216

Abstract

Biosensors are of increasing interest for the detection of bacterial pathogens in many applications such as human, animal and plant health, as well as food and water safety. Membranes and membrane-like structures have been integral part of several pathogen detection platforms. Such structures [...] Read more.

Biosensors are of increasing interest for the detection of bacterial pathogens in many applications such as human, animal and plant health, as well as food and water safety. Membranes and membrane-like structures have been integral part of several pathogen detection platforms. Such structures may serve as simple mechanical support, function as a part of the transduction mechanism, may be used to filter out or concentrate pathogens, and may be engineered to specifically house active proteins. This review focuses on membrane materials, their associated biosensing applications, chemical linking procedures, and transduction mechanisms. The sensitivity of membrane biosensors is discussed, and the state of the field is evaluated and summarized. Full article

(This article belongs to the Special Issue Biosensors for Pathogen Detection)

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14079 KiB

Open AccessReview

Modulated Raman Spectroscopy for Enhanced Cancer Diagnosis at the Cellular Level

by Anna Chiara De Luca, Kishan Dholakia and Michael Mazilu

Sensors 2015, 15(6), 13680-13704; https://doi.org/10.3390/s150613680 - 11 Jun 2015

Cited by 49 | Viewed by 13426

Abstract

Raman spectroscopy is emerging as a promising and novel biophotonics tool for non-invasive, real-time diagnosis of tissue and cell abnormalities. However, the presence of a strong fluorescence background is a key issue that can detract from the use of Raman spectroscopy in routine [...] Read more.

Raman spectroscopy is emerging as a promising and novel biophotonics tool for non-invasive, real-time diagnosis of tissue and cell abnormalities. However, the presence of a strong fluorescence background is a key issue that can detract from the use of Raman spectroscopy in routine clinical care. The review summarizes the state-of-the-art methods to remove the fluorescence background and explores recent achievements to address this issue obtained with modulated Raman spectroscopy. This innovative approach can be used to extract the Raman spectral component from the fluorescence background and improve the quality of the Raman signal. We describe the potential of modulated Raman spectroscopy as a rapid, inexpensive and accurate clinical tool to detect the presence of bladder cancer cells. Finally, in a broader context, we show how this approach can greatly enhance the sensitivity of integrated Raman spectroscopy and microfluidic systems, opening new prospects for portable higher throughput Raman cell sorting. Full article

(This article belongs to the Special Issue Biosensors for Pathogen Detection)

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2380 KiB

Open AccessReview

Development of a HIV-1 Virus Detection System Based on Nanotechnology

by Jin-Ho Lee, Byung-Keun Oh and Jeong-Woo Choi

Sensors 2015, 15(5), 9915-9927; https://doi.org/10.3390/s150509915 - 27 Apr 2015

Cited by 20 | Viewed by 8395

Abstract

Development of a sensitive and selective detection system for pathogenic viral agents is essential for medical healthcare from diagnostics to therapeutics. However, conventional detection systems are time consuming, resource-intensive and tedious to perform. Hence, the demand for sensitive and selective detection system for [...] Read more.

Development of a sensitive and selective detection system for pathogenic viral agents is essential for medical healthcare from diagnostics to therapeutics. However, conventional detection systems are time consuming, resource-intensive and tedious to perform. Hence, the demand for sensitive and selective detection system for virus are highly increasing. To attain this aim, different aspects and techniques have been applied to develop virus sensor with improved sensitivity and selectivity. Here, among those aspects and techniques, this article reviews HIV virus particle detection systems incorporated with nanotechnology to enhance the sensitivity. This review mainly focused on four different detection system including vertically configured electrical detection based on scanning tunneling microscopy (STM), electrochemical detection based on direct electron transfer in virus, optical detection system based on localized surface plasmon resonance (LSPR) and surface enhanced Raman spectroscopy (SERS) using plasmonic nanoparticle. Full article

(This article belongs to the Special Issue Biosensors for Pathogen Detection)

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1480 KiB

Open AccessBrief Report

Non-Invasive Optical Sensor Based Approaches for Monitoring Virus Culture to Minimize BSL3 Laboratory Entry

by Viswanath Ragupathy, Mohan Kumar Hayuri Giri Setty, Yordan Kostov, Xudong Ge, Shaunak Uplekar, Indira Hewlett and Govind Rao

Sensors 2015, 15(7), 14864-14870; https://doi.org/10.3390/s150714864 - 24 Jun 2015

Cited by 1 | Viewed by 5004

Abstract

High titers of infectious viruses for vaccine and diagnostic reference panel development are made by infecting susceptible mammalian cells. Laboratory procedures are strictly performed in a Bio-Safety Level-3 (BSL3) laboratory and each entry and exit involves the use of disposable Personnel Protective Equipment [...] Read more.

High titers of infectious viruses for vaccine and diagnostic reference panel development are made by infecting susceptible mammalian cells. Laboratory procedures are strictly performed in a Bio-Safety Level-3 (BSL3) laboratory and each entry and exit involves the use of disposable Personnel Protective Equipment (PPE) to observe cell culture conditions. Routine PPE use involves significant recurring costs. Alternative non-invasive optical sensor based approaches to remotely monitor cell culture may provide a promising and cost effective approach to monitor infectious virus cultures resulting in lower disruption and costs. We report here the monitoring of high titer cultures of Human Immunodeficiency Virus-1 (HIV-1) and Herpes Simplex Virus-2 (HSV-2) remotely with the use of optical oxygen sensors aseptically placed inside the cell culture vessel. The replacement of culture media for cell and virus propagation and virus load monitoring was effectively performed using this fluorescent sensor and resulted in half the number of visits to the BSL3 lab (five versus ten). Full article

(This article belongs to the Special Issue Biosensors for Pathogen Detection)

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