Next Issue
Previous Issue

Table of Contents

Biosensors, Volume 2, Issue 1 (March 2012), Pages 1-113

  • Issues are regarded as officially published after their release is announced to the table of contents alert mailing list.
  • You may sign up for e-mail alerts to receive table of contents of newly released issues.
  • PDF is the official format for papers published in both, html and pdf forms. To view the papers in pdf format, click on the "PDF Full-text" link, and use the free Adobe Readerexternal link to open them.
View options order results:
result details:
Displaying articles 1-8
Export citation of selected articles as:

Research

Jump to: Review

Open AccessArticle Electrochemical Biosensor for Rapid and Sensitive Detection of Magnetically Extracted Bacterial Pathogens
Biosensors 2012, 2(1), 15-31; doi:10.3390/bios2010015
Received: 16 December 2011 / Revised: 4 January 2012 / Accepted: 16 January 2012 / Published: 17 January 2012
Cited by 24 | PDF Full-text (607 KB) | HTML Full-text | XML Full-text
Abstract
Biological defense and security applications demand rapid, sensitive detection of bacterial pathogens. This work presents a novel qualitative electrochemical detection technique which is applied to two representative bacterial pathogens, Bacillus cereus (as a surrogate for B. anthracis) and Escherichia coli O157:H7, resulting [...] Read more.
Biological defense and security applications demand rapid, sensitive detection of bacterial pathogens. This work presents a novel qualitative electrochemical detection technique which is applied to two representative bacterial pathogens, Bacillus cereus (as a surrogate for B. anthracis) and Escherichia coli O157:H7, resulting in detection limits of 40 CFU/mL and 6 CFU/mL, respectively, from pure culture. Cyclic voltammetry is combined with immunomagnetic separation in a rapid method requiring approximately 1 h for presumptive positive/negative results. An immunofunctionalized magnetic/polyaniline core/shell nano-particle (c/sNP) is employed to extract target cells from the sample solution and magnetically position them on a screen-printed carbon electrode (SPCE) sensor. The presence of target cells significantly inhibits current flow between the electrically active c/sNPs and SPCE. This method has the potential to be adapted for a wide variety of target organisms and sample matrices, and to become a fully portable system for routine monitoring or emergency detection of bacterial pathogens. Full article
Open AccessArticle Development of Chemiluminescent Lateral Flow Assay for the Detection of Nucleic Acids
Biosensors 2012, 2(1), 32-42; doi:10.3390/bios2010032
Received: 8 December 2011 / Revised: 6 January 2012 / Accepted: 16 January 2012 / Published: 18 January 2012
Cited by 9 | PDF Full-text (739 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Rapid, sensitive detection methods are of utmost importance for the identification of pathogens related to health and safety. Herein we report the development of a nucleic acid sequence-based lateral flow assay which achieves a low limit of detection using chemiluminescence. On-membrane enzymatic [...] Read more.
Rapid, sensitive detection methods are of utmost importance for the identification of pathogens related to health and safety. Herein we report the development of a nucleic acid sequence-based lateral flow assay which achieves a low limit of detection using chemiluminescence. On-membrane enzymatic signal amplification is used to reduce the limit of detection to the sub-femtomol level. To demonstrate this assay, we detected synthetic nucleic acid sequences representative of Trypanosoma mRNA, the causative agent for African sleeping sickness, with relevance in human and animal health in sub-Saharan Africa. The intensity of the chemiluminescent signal was evaluated by using a charge-coupled device as well as a microtiter plate reader. We demonstrated that our lateral flow chemiluminescent assay has a very low limit of detection and is easy to use. The limit of detection was determined to be 0.5 fmols of nucleic acid target. Full article
Open AccessArticle Linking Single Domain Antibodies that Recognize Different Epitopes on the Same Target
Biosensors 2012, 2(1), 43-56; doi:10.3390/bios2010043
Received: 13 December 2011 / Revised: 13 January 2012 / Accepted: 29 January 2012 / Published: 1 February 2012
Cited by 6 | PDF Full-text (642 KB) | HTML Full-text | XML Full-text
Abstract
Single domain antibodies (sdAb) are the recombinantly expressed variable regions from the heavy-chain-only antibodies found in camelids and sharks. SdAb are able to bind antigens with high affinity, and most are capable of refolding after heat or chemical denaturation to bind antigen [...] Read more.
Single domain antibodies (sdAb) are the recombinantly expressed variable regions from the heavy-chain-only antibodies found in camelids and sharks. SdAb are able to bind antigens with high affinity, and most are capable of refolding after heat or chemical denaturation to bind antigen again. Starting with our previously isolated ricin binding sdAb determined to bind to four non-overlapping epitopes, we constructed a series of sdAb pairs, which were genetically linked through peptides of different length. We designed the series so that the sdAb are linked in both orientations with respect to the joining peptide. We confirmed that each of the sdAb in the constructs was able to bind to the ricin target, and have evidence that they are both binding ricin simultaneously. Through this work we determined that the order of genetically linked sdAb seems more important than the linker length. The genetically linked sdAb allowed for improved ricin detection with better limits of detection than the best anti-ricin monoclonal we evaluated, however they were not able to refold as well as unlinked component sdAb. Full article
Open AccessArticle Fabrication of Biocompatible, Vibrational Magnetoelastic Materials for Controlling Cellular Adhesion
Biosensors 2012, 2(1), 57-69; doi:10.3390/bios2010057
Received: 6 January 2012 / Revised: 8 February 2012 / Accepted: 10 February 2012 / Published: 13 February 2012
Cited by 8 | PDF Full-text (665 KB) | HTML Full-text | XML Full-text
Abstract
This paper describes the functionalization of magnetoelastic (ME) materials with Parylene-C coating to improve the surface reactivity to cellular response. Previous study has demonstrated that vibrating ME materials were capable of modulating cellular adhesion when activated by an externally applied AC magnetic [...] Read more.
This paper describes the functionalization of magnetoelastic (ME) materials with Parylene-C coating to improve the surface reactivity to cellular response. Previous study has demonstrated that vibrating ME materials were capable of modulating cellular adhesion when activated by an externally applied AC magnetic field. However, since ME materials are not inherently biocompatible, surface modifications are needed for their implementation in biological settings. Here, the long-term stability of the ME material in an aqueous and biological environment is achieved by chemical-vapor deposition of a conformal Parylene-C layer, and further functionalized by methods of oxygen plasma etching and protein adsorption. In vitro cytotoxicity measurement and characterization of the vibrational behavior of the ME materials showed that Parylene-C coatings of 10 µm or greater could prevent hydrolytic degradation without sacrificing the vibrational behavior of the ME material. This work allows for long-term durability and functionality of ME materials in an aqueous and biological environment and makes the potential use of this technology in monitoring and modulating cellular behavior at the surface of implantable devices feasible. Full article
Open AccessArticle Poly(lactic acid)/Carbon Nanotube Fibers as Novel Platforms for Glucose Biosensors
Biosensors 2012, 2(1), 70-82; doi:10.3390/bios2010070
Received: 16 January 2012 / Revised: 11 February 2012 / Accepted: 24 February 2012 / Published: 27 February 2012
Cited by 11 | PDF Full-text (293 KB) | HTML Full-text | XML Full-text
Abstract
The focus of this paper is the development and investigation of properties of new nanostructured architecture for biosensors applications. Highly porous nanocomposite fibers were developed for use as active materials in biosensors. The nanocomposites comprised poly(lactic acid)(PLA)/multi-walled carbon nanotube (MWCNT) fibers obtained [...] Read more.
The focus of this paper is the development and investigation of properties of new nanostructured architecture for biosensors applications. Highly porous nanocomposite fibers were developed for use as active materials in biosensors. The nanocomposites comprised poly(lactic acid)(PLA)/multi-walled carbon nanotube (MWCNT) fibers obtained via solution-blow spinning onto indium tin oxide (ITO) electrodes. The electrocatalytic properties of nanocomposite-modified ITO electrodes were investigated toward hydrogen peroxide (H2O2) detection. We investigated the effect of carbon nanotube concentration and the time deposition of fibers on the sensors properties, viz., sensitivity and limit of detection. Cyclic voltammetry experiments revealed that the nanocomposite-modified electrodes displayed enhanced activity in the electrochemical reduction of H2O2, which offers a number of attractive features to be explored in development of an amperometric biosensor. Glucose oxidase (GOD) was further immobilized by drop coating on an optimized ITO electrode covered by poly(lactic acid)/carbon nanotube nanofibrous mats. The optimum biosensor response was linear up to 800 mM of glucose with a sensitivity of 358 nA·mM−1 and a Michaelis-Menten constant (KM) of 4.3 mM. These results demonstrate that the solution blow spun nanocomposite fibers have great potential for application as amperometric biosensors due to their high surface to volume ratio, high porosity and permeability of the substrate. The latter features may significantly enhance the field of glucose biosensors. Full article
(This article belongs to the Special Issue Electrochemical Based Biosensors)
Open AccessArticle In-Field Implementation of a Recombinant Factor C Assay for the Detection of Lipopolysaccharide as a Biomarker of Extant Life within Glacial Environments
Biosensors 2012, 2(1), 83-100; doi:10.3390/bios2010083
Received: 6 February 2012 / Revised: 29 February 2012 / Accepted: 6 March 2012 / Published: 9 March 2012
Cited by 3 | PDF Full-text (828 KB) | HTML Full-text | XML Full-text
Abstract
The discovery over the past two decades of viable microbial communities within glaciers has promoted interest in the role of glaciers and ice sheets (the cryosphere) as contributors to subglacial erosion, global biodiversity, and in regulating global biogeochemical cycles. In situ or [...] Read more.
The discovery over the past two decades of viable microbial communities within glaciers has promoted interest in the role of glaciers and ice sheets (the cryosphere) as contributors to subglacial erosion, global biodiversity, and in regulating global biogeochemical cycles. In situ or in-field detection and characterisation of microbial communities is becoming recognised as an important approach to improve our understanding of such communities. Within this context we demonstrate, for the first time, the ability to detect Gram-negative bacteria in glacial field-environments (including subglacial environments) via the detection of lipopolysaccharide (LPS); an important component of Gram-negative bacterial cell walls. In-field measurements were performed using the recently commercialised PyroGene® recombinant Factor C (rFC) endotoxin detection system and used in conjunction with a handheld fluorometer to measure the fluorescent endpoint of the assay. Twenty-seven glacial samples were collected from the surface, bed and terminus of a low-biomass Arctic valley glacier (Engabreen, Northern Norway), and were analysed in a field laboratory using the rFC assay. Sixteen of these samples returned positive LPS detection. This work demonstrates that LPS detection via rFC assay is a viable in-field method and is expected to be a useful proxy for microbial cell concentrations in low biomass environments. Full article
Open AccessArticle Enzyme-Gelatin Electrochemical Biosensors: Scaling Down
Biosensors 2012, 2(1), 101-113; doi:10.3390/bios2010101
Received: 1 February 2012 / Revised: 3 March 2012 / Accepted: 14 March 2012 / Published: 15 March 2012
Cited by 5 | PDF Full-text (1025 KB) | HTML Full-text | XML Full-text
Abstract
In this article we investigate the possibility of scaling down enzyme-gelatin modified electrodes by spin coating the enzyme-gelatin layer. Special attention is given to the electrochemical behavior of the selected enzymes inside the gelatin matrix. A glassy carbon electrode was used as [...] Read more.
In this article we investigate the possibility of scaling down enzyme-gelatin modified electrodes by spin coating the enzyme-gelatin layer. Special attention is given to the electrochemical behavior of the selected enzymes inside the gelatin matrix. A glassy carbon electrode was used as a substrate to immobilize, in the first instance, horse heart cytochrome c (HHC) in a gelatin matrix. Both a drop dried and a spin coated layer was prepared. On scaling down, a transition from diffusion controlled reactions towards adsorption controlled reactions is observed. Compared to a drop dried electrode, a spin coated electrode showed a more stable electrochemical behavior. Next to HHC, we also incorporated catalase in a spin coated gelatin matrix immobilized on a glassy carbon electrode. By spincoating, highly uniform sub micrometer layers of biocompatible matrices can be constructed. A full electrochemical study and characterization of the modified surfaces has been carried out. It was clear that in the case of catalase, gluteraldehyde addition was needed to prevent leaking of the catalase from the gelatin matrix. Full article
(This article belongs to the Special Issue Electrochemical Based Biosensors)

Review

Jump to: Research

Open AccessReview Graphene and Other Nanomaterial-Based Electrochemical Aptasensors
Biosensors 2012, 2(1), 1-14; doi:10.3390/bios2010001
Received: 21 November 2011 / Revised: 22 December 2011 / Accepted: 12 January 2012 / Published: 13 January 2012
Cited by 25 | PDF Full-text (291 KB) | HTML Full-text | XML Full-text
Abstract
Electrochemical aptasensors, which are based on the specificity of aptamer-target recognition, with electrochemical transduction for analytical purposes have received particular attention due to their high sensitivity and selectivity, simple instrumentation, as well as low production cost. Aptamers are functional nucleic acids with [...] Read more.
Electrochemical aptasensors, which are based on the specificity of aptamer-target recognition, with electrochemical transduction for analytical purposes have received particular attention due to their high sensitivity and selectivity, simple instrumentation, as well as low production cost. Aptamers are functional nucleic acids with specific and high affinity to their targets, similar to antibodies. However, they are completely selected in vitro in contrast to antibodies. Due to their stability, easy chemical modifications and proneness to nanostructured device construction, aptamer-based sensors have been incorporated in a variety of applications including electrochemical sensing devices. In recent years, the performance of aptasensors has been augmented by incorporating novel nanomaterials in the preparation of better electrochemical sensors. In this review, we summarize the recent trends in the use of nanomaterials for developing electrochemical aptasensors. Full article
Figures

Journal Contact

MDPI AG
Biosensors Editorial Office
St. Alban-Anlage 66, 4052 Basel, Switzerland
biosensors@mdpi.com
Tel. +41 61 683 77 34
Fax: +41 61 302 89 18
Editorial Board
Contact Details Submit to Biosensors
Back to Top