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Special Issue "Advances in Optical Biosensors"

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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 (15 November 2014)

Special Issue Editors

Guest Editor
Prof. Dr. M. Selim Ünlü (Website)

Department of Electrical and Computer Engineering, Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA
Fax: +1 617 353 5929
Interests: bionanotechnology; molecular diagnostics; optical biosensors; label-free detection; immunosensors; protein and DNA microarrays; single particle detection; virus detection; biochips; biomolecular recognition; immobilization techniques; fluorescence
Guest Editor
Dr. Ayca Yalcin Ozkumur

Electrical and Electronics Engineering Department, Bahcesehir University, Istanbul 34353, Turkey
Phone: +90 212 381 0878
Fax: +90 212 381 0020
Interests: molecular diagnostics; label-free optical detection; real-time measurements; protein and DNA microarrays; single particle sensing; immobilization techniques; fluorescence; high-throughput single-cell analysis; immunoassays

Special Issue Information

Dear Colleagues,

The field of optical biosensors continues to grow rapidly with advancements in engineering, material science, computer science, chemistry, physics, biology, and medicine. The applications are broad and diverse; uses range from ones concerning fundamental biological research to diagnostics in resource-limited settings, from environmental monitoring to uses in defense and security, and from agricultural uses to applications in personalized medicine.

This Special Issue aims to bring together recent advancements concerning the research and development of optical biosensors in a wide variety of disciplines. We aim to publish a special issue that will be of interest to a broad group of readers from academia, industry, and government.

We seek papers that address a wide range of novel, optical biosensing techniques, as well as the emerging applications of such techniques. Potential topics include, but are not limited to, novel materials and techniques for optical biosensing, point-of-care and lab-on-a-chip devices, surface functionalization methodologies, single-molecule detection, intracellular sensing, and applications in genomics, proteomics, medical diagnostics, drug delivery, health care, food analysis, environmental monitoring, defense, and security. We invite authors to submit original research papers relating to optical biosensors.

Prof. Dr. M. Selim Ünlü
Dr. Ayca Yalcin Ozkumur
Guest Editor

Submission

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are refereed through a peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Sensors is an international peer-reviewed Open Access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs).


Keywords

  • optical biosensors
  • immunosensors
  • lab-on-a-chip
  • point-of-care
  • nanobiosensors
  • resonant sensors
  • waveguide sensors
  • DNA chips, nucleic acid sensors
  • protein chips
  • microarray
  • fluorescence
  • label-free
  • real-time monitoring
  • high-throughput
  • multiplexed detection

Published Papers (18 papers)

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Research

Jump to: Review

Open AccessArticle An Optical Biosensor from Green Fluorescent Escherichia coli for the Evaluation of Single and Combined Heavy Metal Toxicities
Sensors 2015, 15(6), 12668-12681; doi:10.3390/s150612668
Received: 28 January 2015 / Accepted: 31 March 2015 / Published: 28 May 2015
Cited by 2 | PDF Full-text (906 KB) | HTML Full-text | XML Full-text
Abstract
A fluorescence-based fiber optic toxicity biosensor based on genetically modified Escherichia coli (E. coli) with green fluorescent protein (GFP) was developed for the evaluation of the toxicity of several hazardous heavy metal ions. The toxic metals include Cu(II), Cd(II), Pb(II), [...] Read more.
A fluorescence-based fiber optic toxicity biosensor based on genetically modified Escherichia coli (E. coli) with green fluorescent protein (GFP) was developed for the evaluation of the toxicity of several hazardous heavy metal ions. The toxic metals include Cu(II), Cd(II), Pb(II), Zn(II), Cr(VI), Co(II), Ni(II), Ag(I) and Fe(III). The optimum fluorescence excitation and emission wavelengths of the optical biosensor were 400 ± 2 nm and 485 ± 2 nm, respectively. Based on the toxicity observed under optimal conditions, the detection limits of Cu(II), Cd(II), Pb(II), Zn(II), Cr(VI), Co(II), Ni(II), Ag(I) and Fe(III) that can be detected using the toxicity biosensor were at 0.04, 0.32, 0.46, 2.80, 100, 250, 400, 720 and 2600 μg/L, respectively. The repeatability and reproducibility of the proposed biosensor were 3.5%–4.8% RSD (relative standard deviation) and 3.6%–5.1% RSD (n = 8), respectively. The biosensor response was stable for at least five weeks, and demonstrated higher sensitivity towards metal toxicity evaluation when compared to a conventional Microtox assay. Full article
(This article belongs to the Special Issue Advances in Optical Biosensors)
Open AccessArticle Stand-Off Biodetection with Free-Space Coupled Asymmetric Microsphere Cavities
Sensors 2015, 15(4), 8968-8980; doi:10.3390/s150408968
Received: 21 November 2014 / Revised: 9 April 2015 / Accepted: 10 April 2015 / Published: 16 April 2015
Cited by 9 | PDF Full-text (2063 KB) | HTML Full-text | XML Full-text
Abstract
Asymmetric microsphere resonant cavities (ARCs) allow for free-space coupling to high quality (Q) whispering gallery modes (WGMs) while exhibiting highly directional light emission, enabling WGM resonance measurements in the far-field. These remarkable characteristics make “stand-off” biodetection in which no coupling device is [...] Read more.
Asymmetric microsphere resonant cavities (ARCs) allow for free-space coupling to high quality (Q) whispering gallery modes (WGMs) while exhibiting highly directional light emission, enabling WGM resonance measurements in the far-field. These remarkable characteristics make “stand-off” biodetection in which no coupling device is required in near-field contact with the resonator possible. Here we show asymmetric microsphere resonators fabricated from optical fibers which support dynamical tunneling to excite high-Q WGMs, and demonstrate free-space coupling to modes in an aqueous environment. We characterize the directional emission by fluorescence imaging, demonstrate coupled mode effects due to free space coupling by dynamical tunneling, and detect adsorption kinetics of a protein in aqueous solution. Based on our approach, new, more robust WGM biodetection schemes involving microfluidics and in-vivo measurements can be designed. Full article
(This article belongs to the Special Issue Advances in Optical Biosensors)
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Open AccessArticle Portable and Reusable Optofluidics-Based Biosensing Platform for Ultrasensitive Detection of Sulfadimidine in Dairy Products
Sensors 2015, 15(4), 8302-8313; doi:10.3390/s150408302
Received: 3 February 2015 / Revised: 1 April 2015 / Accepted: 3 April 2015 / Published: 9 April 2015
PDF Full-text (1045 KB) | HTML Full-text | XML Full-text
Abstract
Sulfadimidine (SM2) is a highly toxic and ubiquitous pollutant which requires rapid, sensitive and portable detection method for environmental and food monitoring. Herein, the use for the detection of SM2 of a portable optofluidics-based biosensing platform, which was used [...] Read more.
Sulfadimidine (SM2) is a highly toxic and ubiquitous pollutant which requires rapid, sensitive and portable detection method for environmental and food monitoring. Herein, the use for the detection of SM2 of a portable optofluidics-based biosensing platform, which was used for the accurate detection of bisphenol A, atrazine and melamine, is reported for the first time. The proposed compact biosensing system combines the advantages of an evanescent wave immunosensor and microfluidic technology. Through the indirect competitive immunoassay, the detection limit of the proposed optofluidics-based biosensing platform for SM2 reaches 0.05 μg·L−1 at the concentration of Cy5.5-labeled antibody of 0.1 μg·mL−1. Linearity is obtained over a dynamic range from 0.17 μg·L−1 to 10.73 μg·L−1. The surface of the fiber probe can be regenerated more than 300 times by means of 0.5% sodium dodecyl sulfate solution (pH = 1.9) washes without losing sensitivity. This method, featuring high sensitivity, portability and acceptable reproducibility shows potential in the detection of SM2 in real milk and other dairy products. Full article
(This article belongs to the Special Issue Advances in Optical Biosensors)
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Open AccessArticle Label-Free, Single Molecule Resonant Cavity Detection: A Double-Blind Experimental Study
Sensors 2015, 15(3), 6324-6341; doi:10.3390/s150306324
Received: 11 November 2014 / Revised: 27 February 2015 / Accepted: 5 March 2015 / Published: 16 March 2015
PDF Full-text (1870 KB) | HTML Full-text | XML Full-text
Abstract
Optical resonant cavity sensors are gaining increasing interest as a potential diagnostic method for a range of applications, including medical prognostics and environmental monitoring. However, the majority of detection demonstrations to date have involved identifying a “known” analyte, and the more rigorous [...] Read more.
Optical resonant cavity sensors are gaining increasing interest as a potential diagnostic method for a range of applications, including medical prognostics and environmental monitoring. However, the majority of detection demonstrations to date have involved identifying a “known” analyte, and the more rigorous double-blind experiment, in which the experimenter must identify unknown solutions, has yet to be performed. This scenario is more representative of a real-world situation. Therefore, before these devices can truly transition, it is necessary to demonstrate this level of robustness. By combining a recently developed surface chemistry with integrated silica optical sensors, we have performed a double-blind experiment to identify four unknown solutions. The four unknown solutions represented a subset or complete set of four known solutions; as such, there were 256 possible combinations. Based on the single molecule detection signal, we correctly identified all solutions. In addition, as part of this work, we developed noise reduction algorithms. Full article
(This article belongs to the Special Issue Advances in Optical Biosensors)
Figures

Open AccessArticle Role of Edge Inclination in an Optical Microdisk Resonator for Label-Free Sensing
Sensors 2015, 15(3), 4796-4809; doi:10.3390/s150304796
Received: 11 January 2015 / Revised: 10 February 2015 / Accepted: 13 February 2015 / Published: 26 February 2015
Cited by 4 | PDF Full-text (1814 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, we report on the measurement and modeling of enhanced optical refractometric sensors based on whispering gallery modes. The devices under test are optical microresonators made of silicon nitride on silicon oxide, which differ in their sidewall inclination angle. In [...] Read more.
In this paper, we report on the measurement and modeling of enhanced optical refractometric sensors based on whispering gallery modes. The devices under test are optical microresonators made of silicon nitride on silicon oxide, which differ in their sidewall inclination angle. In our approach, these microresonators are vertically coupled to a buried waveguide with the aim of creating integrated and cost-effective devices. Device modeling shows that the optimization of the device is a delicate balance of the resonance quality factor and evanescent field overlap with the surrounding environment to analyze. By numerical simulations, we show that the microdisk thickness is critical to yield a high figure of merit for the sensor and that edge inclination should be kept as high as possible. We also show that bulk-sensing figures of merit as high as 1600 RIU-1 (refractive index unit) are feasible. Full article
(This article belongs to the Special Issue Advances in Optical Biosensors)
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Open AccessArticle Ionizing Radiation Detectors Based on Ge-Doped Optical Fibers Inserted in Resonant Cavities
Sensors 2015, 15(2), 4242-4252; doi:10.3390/s150204242
Received: 7 November 2014 / Revised: 9 December 2014 / Accepted: 5 February 2015 / Published: 12 February 2015
PDF Full-text (1219 KB) | HTML Full-text | XML Full-text
Abstract
The measurement of ionizing radiation (IR) is a crucial issue in different areas of interest, from environmental safety and industrial monitoring to aerospace and medicine. Optical fiber sensors have recently proven good candidates as radiation dosimeters. Here we investigate the effect of [...] Read more.
The measurement of ionizing radiation (IR) is a crucial issue in different areas of interest, from environmental safety and industrial monitoring to aerospace and medicine. Optical fiber sensors have recently proven good candidates as radiation dosimeters. Here we investigate the effect of IR on germanosilicate optical fibers. A piece of Ge-doped fiber enclosed between two fiber Bragg gratings (FBGs) is irradiated with gamma radiation generated by a 6 MV medical linear accelerator. With respect to other FBG-based IR dosimeters, here the sensor is only the bare fiber without any special internal structure. A near infrared laser is frequency locked to the cavity modes for high resolution measurement of radiation induced effects on the fiber optical parameters. In particular, we observe a variation of the fiber thermo-optic response with the radiation dose delivered, as expected from the interaction with Ge defect centers, and demonstrate a detection limit of 360 mGy. This method can have an impact in those contexts where low radiation doses have to be measured both in small volumes or over large areas, such as radiation therapy and radiation protection, while bare optical fibers are cheap and disposable. Full article
(This article belongs to the Special Issue Advances in Optical Biosensors)
Open AccessCommunication Amplification of the Signal Intensity of Fluorescence-Based Fiber-Optic Biosensors Using a Fabry-Perot Resonator Structure
Sensors 2015, 15(2), 3565-3574; doi:10.3390/s150203565
Received: 13 November 2014 / Revised: 19 January 2015 / Accepted: 29 January 2015 / Published: 4 February 2015
Cited by 1 | PDF Full-text (928 KB) | HTML Full-text | XML Full-text
Abstract
Fluorescent biosensors have been widely used in biomedical applications. To amplify the intensity of fluorescence signals, this study developed a novel structure for an evanescent wave fiber-optic biosensor by using a Fabry-Perot resonator structure. An excitation light was coupled into the optical [...] Read more.
Fluorescent biosensors have been widely used in biomedical applications. To amplify the intensity of fluorescence signals, this study developed a novel structure for an evanescent wave fiber-optic biosensor by using a Fabry-Perot resonator structure. An excitation light was coupled into the optical fiber through a laser-drilled hole on the proximal end of the resonator. After entering the resonator, the excitation light was reflected back and forth inside the resonator, thereby amplifying the intensity of the light in the fiber. Subsequently, the light was used to excite the fluorescent molecules in the reactive region of the sensor. The experimental results showed that the biosensor signal was amplified eight-fold when the resonator reflector was formed using a 92% reflective coating. Furthermore, in a simulation, the biosensor signal could be amplified 20-fold by using a 99% reflector. Full article
(This article belongs to the Special Issue Advances in Optical Biosensors)
Open AccessArticle Optical Microsystem for Analysis of Diffuse Reflectance and Fluorescence Signals Applied to Early Gastrointestinal Cancer Detection
Sensors 2015, 15(2), 3138-3153; doi:10.3390/s150203138
Received: 17 September 2014 / Accepted: 23 January 2015 / Published: 30 January 2015
Cited by 1 | PDF Full-text (1232 KB) | HTML Full-text | XML Full-text
Abstract
The detection of cancer at its earliest stage is crucial in order to increase the probability of a successful treatment. Optical techniques, specifically diffuse reflectance and fluorescence, may considerably improve the ability to detect pre-cancerous lesions. These techniques have high sensitivity to [...] Read more.
The detection of cancer at its earliest stage is crucial in order to increase the probability of a successful treatment. Optical techniques, specifically diffuse reflectance and fluorescence, may considerably improve the ability to detect pre-cancerous lesions. These techniques have high sensitivity to some biomarkers present on the tissues, providing morphological and biochemical information of normal and diseased tissue. The development of a chip sized spectroscopy microsystem, based on these techniques, will greatly improve the early diagnosis of gastrointestinal cancers. The main innovation is the detection of the spectroscopic signals using only few, but representative, spectral bands allowing for miniaturization. This paper presents the mathematical models, its validation and analysis for retrieving data of the measured spectroscopic signals. These models were applied to a set of phantoms clearly representative of gastrointestinal tissues, leading to a more accurate diagnostic by a pathologist. Moreover, it was demonstrated that the models can use the reconstructed spectroscopic signals based only on its extraction on those specific spectral bands. As a result, the viability of the spectroscopy microsystem implementation was proved. Full article
(This article belongs to the Special Issue Advances in Optical Biosensors)
Open AccessArticle A Fiber-Tip Label-Free Biological Sensing Platform: A Practical Approach toward In-Vivo Sensing
Sensors 2015, 15(1), 1168-1181; doi:10.3390/s150101168
Received: 2 October 2014 / Accepted: 31 December 2014 / Published: 9 January 2015
Cited by 8 | PDF Full-text (2599 KB) | HTML Full-text | XML Full-text
Abstract
The platform presented here was devised to address the unmet need for real time label-free in vivo sensing by bringing together a refractive index transduction mechanism based on Whispering Gallery Modes (WGM) in dye doped microspheres and Microstructured Optical Fibers. In addition [...] Read more.
The platform presented here was devised to address the unmet need for real time label-free in vivo sensing by bringing together a refractive index transduction mechanism based on Whispering Gallery Modes (WGM) in dye doped microspheres and Microstructured Optical Fibers. In addition to providing remote excitation and collection of the WGM signal, the fiber provides significant practical advantages such as an easy manipulation of the microresonator and the use of this sensor in a dip sensing architecture, alleviating the need for a complex microfluidic interface. Here, we present the first demonstration of the use of this approach for biological sensing and evaluate its limitation in a sensing configuration deprived of liquid flow which is most likely to occur in an in vivo setting. We also demonstrate the ability of this sensing platform to be operated above its lasing threshold, enabling enhanced device performance. Full article
(This article belongs to the Special Issue Advances in Optical Biosensors)
Open AccessArticle Accelerated Detection of Viral Particles by Combining AC Electric Field Effects and Micro-Raman Spectroscopy
Sensors 2015, 15(1), 1047-1059; doi:10.3390/s150101047
Received: 4 September 2014 / Accepted: 30 December 2014 / Published: 8 January 2015
Cited by 1 | PDF Full-text (1302 KB) | HTML Full-text | XML Full-text
Abstract
A detection method that combines electric field-assisted virus capture on antibody-decorated surfaces with the “fingerprinting” capabilities of micro-Raman spectroscopy is demonstrated for the case of M13 virus in water. The proof-of-principle surface mapping of model bioparticles (protein coated polystyrene spheres) captured by [...] Read more.
A detection method that combines electric field-assisted virus capture on antibody-decorated surfaces with the “fingerprinting” capabilities of micro-Raman spectroscopy is demonstrated for the case of M13 virus in water. The proof-of-principle surface mapping of model bioparticles (protein coated polystyrene spheres) captured by an AC electric field between planar microelectrodes is presented with a methodology for analyzing the resulting spectra by comparing relative peak intensities. The same principle is applied to dielectrophoretically captured M13 phage particles whose presence is indirectly confirmed with micro-Raman spectroscopy using NeutrAvidin-Cy3 as a labeling molecule. It is concluded that the combination of electrokinetically driven virus sampling and micro-Raman based signal transduction provides a promising approach for time-efficient and in situ detection of viruses. Full article
(This article belongs to the Special Issue Advances in Optical Biosensors)
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Open AccessArticle Microencapsulated Aliivibrio fischeri in Alginate Microspheres for Monitoring Heavy Metal Toxicity in Environmental Waters
Sensors 2014, 14(12), 23248-23268; doi:10.3390/s141223248
Received: 23 September 2014 / Revised: 13 November 2014 / Accepted: 24 November 2014 / Published: 5 December 2014
Cited by 3 | PDF Full-text (846 KB) | HTML Full-text | XML Full-text
Abstract
In this article a luminescence fiber optic biosensor for the microdetection of heavy metal toxicity in waters based on the marine bacterium Aliivibrio fischeri (A. fischeri) encapsulated in alginate microspheres is described. Cu(II), Cd(II), Pb(II), Zn(II), Cr(VI), Co(II), Ni(II), Ag(I) [...] Read more.
In this article a luminescence fiber optic biosensor for the microdetection of heavy metal toxicity in waters based on the marine bacterium Aliivibrio fischeri (A. fischeri) encapsulated in alginate microspheres is described. Cu(II), Cd(II), Pb(II), Zn(II), Cr(VI), Co(II), Ni(II), Ag(I) and Fe(II) were selected as sample toxic heavy metal ions for evaluation of the performance of this toxicity microbiosensor. The loss of bioluminescence response from immobilized A. fischeri bacterial cells corresponds to changes in the toxicity levels. The inhibition of the luminescent biosensor response collected at excitation and emission wavelengths of 287 ± 2 nm and 487 ± 2 nm, respectively, was found to be reproducible and repeatable within the relative standard deviation (RSD) range of 2.4–5.7% (n = 8). The toxicity biosensor based on alginate micropsheres exhibited a lower limit of detection (LOD) for Cu(II) (6.40 μg/L), Cd(II) (1.56 μg/L), Pb(II) (47 μg/L), Ag(I) (18 μg/L) than Zn(II) (320 μg/L), Cr(VI) (1,000 μg/L), Co(II) (1700 μg/L), Ni(II) (2800 μg/L), and Fe(III) (3100 μg/L). Such LOD values are lower when compared with other previous reported whole cell toxicity biosensors using agar gel, agarose gel and cellulose membrane biomatrices used for the immobilization of bacterial cells. The A. fischeri bacteria microencapsulated in alginate biopolymer could maintain their metabolic activity for a prolonged period of up to six weeks without any noticeable changes in the bioluminescence response. The bioluminescent biosensor could also be used for the determination of antagonistic toxicity levels for toxicant mixtures. A comparison of the results obtained by atomic absorption spectroscopy (AAS) and using the proposed luminescent A. fischeri-based biosensor suggests that the optical toxicity biosensor can be used for quantitative microdetermination of heavy metal toxicity in environmental water samples. Full article
(This article belongs to the Special Issue Advances in Optical Biosensors)
Open AccessArticle Real-Time, Label-Free Detection of Biomolecular Interactions in Sandwich Assays by the Oblique-Incidence Reflectivity Difference Technique
Sensors 2014, 14(12), 23307-23320; doi:10.3390/s141223307
Received: 21 October 2014 / Revised: 20 November 2014 / Accepted: 25 November 2014 / Published: 5 December 2014
PDF Full-text (2326 KB) | HTML Full-text | XML Full-text
Abstract
One of the most important goals in proteomics is to detect the real-time kinetics of diverse biomolecular interactions. Fluorescence, which requires extrinsic tags, is a commonly and widely used method because of its high convenience and sensitivity. However, in order to maintain [...] Read more.
One of the most important goals in proteomics is to detect the real-time kinetics of diverse biomolecular interactions. Fluorescence, which requires extrinsic tags, is a commonly and widely used method because of its high convenience and sensitivity. However, in order to maintain the conformational and functional integrality of biomolecules, label-free detection methods are highly under demand. We have developed the oblique-incidence reflectivity difference (OI-RD) technique for label-free, kinetic measurements of protein-biomolecule interactions. Incorporating the total internal refection geometry into the OI-RD technique, we are able to detect as low as 0.1% of a protein monolayer, and this sensitivity is comparable with other label-free techniques such as surface plasmon resonance (SPR). The unique advantage of OI-RD over SPR is no need for dielectric layers. Moreover, using a photodiode array as the detector enables multi-channel detection and also eliminates the over-time signal drift. In this paper, we demonstrate the applicability and feasibility of the OI-RD technique by measuring the kinetics of protein-protein and protein-small molecule interactions in sandwich assays. Full article
(This article belongs to the Special Issue Advances in Optical Biosensors)
Open AccessArticle A Coumarin-Based Fluorescent Probe as a Central Nervous System Disease Biomarker
Sensors 2014, 14(11), 21140-21150; doi:10.3390/s141121140
Received: 17 September 2014 / Revised: 18 October 2014 / Accepted: 29 October 2014 / Published: 10 November 2014
Cited by 1 | PDF Full-text (341 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Homocysteine and methylmalonic acid are important biomarkers for diseases associated with an impaired central nervous system (CNS). A new chemoassay utilizing coumarin-based fluorescent probe 1 to detect the levels of homocysteine is successfully implemented using Parkinson’s disease (PD) patients’ blood serum. In [...] Read more.
Homocysteine and methylmalonic acid are important biomarkers for diseases associated with an impaired central nervous system (CNS). A new chemoassay utilizing coumarin-based fluorescent probe 1 to detect the levels of homocysteine is successfully implemented using Parkinson’s disease (PD) patients’ blood serum. In addition, a rapid identification of homocysteine and methylmalonic acid levels in blood serum of PD patients was also performed using the liquid chromatography-mass spectrometry (LC-MS). The results obtained from both analyses were in agreement. The new chemoassay utilizing coumarin-based fluorescent probe 1 offers a cost- and time-effective method to identify the biomarkers in CNS patients. Full article
(This article belongs to the Special Issue Advances in Optical Biosensors)
Open AccessArticle Modeling and Analysis of a Microresonating Biosensor for Detection of Salmonella Bacteria in Human Blood
Sensors 2014, 14(7), 12885-12899; doi:10.3390/s140712885
Received: 8 May 2014 / Revised: 10 June 2014 / Accepted: 19 June 2014 / Published: 18 July 2014
Cited by 3 | PDF Full-text (1893 KB) | HTML Full-text | XML Full-text
Abstract
A new photonics biosensor configuration comprising a Double-side Ring Add-drop Filter microring resonator (DR-ADF) made from SiO2-TiO2 material is proposed for the detection of Salmonella bacteria (SB) in blood. The scattering matrix method using inductive calculation is used to [...] Read more.
A new photonics biosensor configuration comprising a Double-side Ring Add-drop Filter microring resonator (DR-ADF) made from SiO2-TiO2 material is proposed for the detection of Salmonella bacteria (SB) in blood. The scattering matrix method using inductive calculation is used to determine the output signal’s intensities in the blood with and without presence of Salmonella. The change in refractive index due to the reaction of Salmonella bacteria with its applied antibody on the flagellin layer loaded on the sensing and detecting microresonator causes the increase in through and dropper port’s intensities of the output signal which leads to the detection of SB in blood. A shift in the output signal wavelength is observed with resolution of 0.01 nm. The change in intensity and shift in wavelength is analyzed with respect to the change in the refractive index which contributes toward achieving an ultra-high sensitivity of 95,500 nm/RIU which is almost two orders higher than that of reported from single ring sensors and the limit of detection is in the order of 1 × 10−8 RIU. In applications, such a system can be employed for a high sensitive and fast detection of bacteria. Full article
(This article belongs to the Special Issue Advances in Optical Biosensors)

Review

Jump to: Research

Open AccessReview Enhanced Vibrational Spectroscopies as Tools for Small Molecule Biosensing
Sensors 2015, 15(9), 21239-21264; doi:10.3390/s150921239
Received: 15 March 2015 / Revised: 6 August 2015 / Accepted: 10 August 2015 / Published: 28 August 2015
Cited by 2 | PDF Full-text (2621 KB) | HTML Full-text | XML Full-text
Abstract
In this short summary we summarize some of the latest developments in vibrational spectroscopic tools applied for the sensing of (small) molecules and biomolecules in a label-free mode of operation. We first introduce various concepts for the enhancement of InfraRed spectroscopic techniques, [...] Read more.
In this short summary we summarize some of the latest developments in vibrational spectroscopic tools applied for the sensing of (small) molecules and biomolecules in a label-free mode of operation. We first introduce various concepts for the enhancement of InfraRed spectroscopic techniques, including the principles of Attenuated Total Reflection InfraRed (ATR-IR), (phase-modulated) InfraRed Reflection Absorption Spectroscopy (IRRAS/PM-IRRAS), and Surface Enhanced Infrared Reflection Absorption Spectroscopy (SEIRAS). Particular attention is put on the use of novel nanostructured substrates that allow for the excitation of propagating and localized surface plasmon modes aimed at operating additional enhancement mechanisms. This is then be complemented by the description of the latest development in Surface- and Tip-Enhanced Raman Spectroscopies, again with an emphasis on the detection of small molecules or bioanalytes. Full article
(This article belongs to the Special Issue Advances in Optical Biosensors)
Open AccessReview Interferometric Reflectance Imaging Sensor (IRIS)—A Platform Technology for Multiplexed Diagnostics and Digital Detection
Sensors 2015, 15(7), 17649-17665; doi:10.3390/s150717649
Received: 8 April 2015 / Revised: 30 June 2015 / Accepted: 14 July 2015 / Published: 20 July 2015
Cited by 3 | PDF Full-text (3300 KB) | HTML Full-text | XML Full-text
Abstract
Over the last decade, the growing need in disease diagnostics has stimulated rapid development of new technologies with unprecedented capabilities. Recent emerging infectious diseases and epidemics have revealed the shortcomings of existing diagnostics tools, and the necessity for further improvements. Optical biosensors [...] Read more.
Over the last decade, the growing need in disease diagnostics has stimulated rapid development of new technologies with unprecedented capabilities. Recent emerging infectious diseases and epidemics have revealed the shortcomings of existing diagnostics tools, and the necessity for further improvements. Optical biosensors can lay the foundations for future generation diagnostics by providing means to detect biomarkers in a highly sensitive, specific, quantitative and multiplexed fashion. Here, we review an optical sensing technology, Interferometric Reflectance Imaging Sensor (IRIS), and the relevant features of this multifunctional platform for quantitative, label-free and dynamic detection. We discuss two distinct modalities for IRIS: (i) low-magnification (ensemble biomolecular mass measurements) and (ii) high-magnification (digital detection of individual nanoparticles) along with their applications, including label-free detection of multiplexed protein chips, measurement of single nucleotide polymorphism, quantification of transcription factor DNA binding, and high sensitivity digital sensing and characterization of nanoparticles and viruses. Full article
(This article belongs to the Special Issue Advances in Optical Biosensors)
Open AccessReview Optical Nano Antennas: State of the Art, Scope and Challenges as a Biosensor Along with Human Exposure to Nano-Toxicology
Sensors 2015, 15(4), 8787-8831; doi:10.3390/s150408787
Received: 18 November 2014 / Revised: 19 January 2015 / Accepted: 2 February 2015 / Published: 15 April 2015
Cited by 2 | PDF Full-text (2014 KB) | HTML Full-text | XML Full-text
Abstract
The concept of optical antennas in physical optics is still evolving. Like the antennas used in the radio frequency (RF) regime, the aspiration of optical antennas is to localize the free propagating radiation energy, and vice versa. For this purpose, optical [...] Read more.
The concept of optical antennas in physical optics is still evolving. Like the antennas used in the radio frequency (RF) regime, the aspiration of optical antennas is to localize the free propagating radiation energy, and vice versa. For this purpose, optical antennas utilize the distinctive properties of metal nanostructures, which are strong plasmonic coupling elements at the optical regime. The concept of optical antennas is being advanced technologically and they are projected to be substitute devices for detection in the millimeter, infrared, and visible regimes. At present, their potential benefits in light detection, which include polarization dependency, tunability, and quick response times have been successfully demonstrated. Optical antennas also can be seen as directionally responsive elements for point detectors. This review provides an overview of the historical background of the topic, along with the basic concepts and parameters of optical antennas. One of the major parts of this review covers the use of optical antennas in biosensing, presenting biosensing applications with a broad description using different types of data. We have also mentioned the basic challenges in the path of the universal use of optical biosensors, where we have also discussed some legal matters. Full article
(This article belongs to the Special Issue Advances in Optical Biosensors)
Open AccessReview Algal Biomass Analysis by Laser-Based Analytical Techniques—A Review
Sensors 2014, 14(9), 17725-17752; doi:10.3390/s140917725
Received: 28 April 2014 / Revised: 5 September 2014 / Accepted: 11 September 2014 / Published: 23 September 2014
Cited by 11 | PDF Full-text (1720 KB) | HTML Full-text | XML Full-text
Abstract
Algal biomass that is represented mainly by commercially grown algal strains has recently found many potential applications in various fields of interest. Its utilization has been found advantageous in the fields of bioremediation, biofuel production and the food industry. This paper reviews [...] Read more.
Algal biomass that is represented mainly by commercially grown algal strains has recently found many potential applications in various fields of interest. Its utilization has been found advantageous in the fields of bioremediation, biofuel production and the food industry. This paper reviews recent developments in the analysis of algal biomass with the main focus on the Laser-Induced Breakdown Spectroscopy, Raman spectroscopy, and partly Laser-Ablation Inductively Coupled Plasma techniques. The advantages of the selected laser-based analytical techniques are revealed and their fields of use are discussed in detail. Full article
(This article belongs to the Special Issue Advances in Optical Biosensors)

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