Special Issue "Nanomaterials Based Optical Biosensors"

A special issue of Biosensors (ISSN 2079-6374).

Deadline for manuscript submissions: closed (30 September 2017).

Special Issue Editor

Prof. Dr. Guozhen Liu
Website
Guest Editor
Graduate School of Biomedical Engineering, UNSW Sydney, Australia
Interests: biosensors; point-of-care diagnostics; microfluidic-paper-based analytical devices µPADs); intelligent nanoparticles; medical devices
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Special Issue Information

Dear Colleagues,

Optical biosensing platforms, based on absorbance, photoluminescence, fluorescence, and SPR, as the next generation of sensing devices, have attracted a great deal of attention, especially in biomedical science. They have advantages in high precision and label-free concepts. Biosensing platforms require traducers with advances for the effective signal transformation of a biological interaction into a physical signal. Nanomaterials have demonstrated tremendous potential to be integrated with optical biosensors, due to their extremely small sizes, special optical properties, high specific surface, and versatile surface chemistry, allowing intimate interactions with an enhanced amount of capture molecules for analytes. With the aid of nanotechnology, optical biosensors are superior in sensitivity. In addition to the enhanced sensing performances, in terms of sensitivity and detection limits down to single molecules detection, the specific properties of nanomaterials also offer alternatives to classic transduction methods by modification of a spectrum of receptors. Furthermore, the combination of different nanomaterials in the same sensing interface, each with its characteristics, to further enhance the performances of optical biosensors, is a well-accepted strategy.

This Special Issue of Biosensors, “Nanomaterial based Optical Biosensors” aims to collect a compilation of articles that prominently demonstrate the continuous efforts in developing advanced nanomaterial-based optical sensing technologies for various bioanalytes. It focuses on the synthesis, properties, and prospective optical biosensing applications of nanomaterials. The topics cover a wide range of research fields, including nanomaterials, optical biosensors, and nanofabrication in the forms of reviews, communications, and academic articles.

Dr. Guozhen Liu
Guest Editor

Manuscript Submission Information

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Published Papers (6 papers)

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Research

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Open AccessArticle
Encapsulation-Stabilized, Europium Containing Nanoparticle as a Probe for Time-Resolved luminescence Detection of Cardiac Troponin I
Biosensors 2017, 7(4), 48; https://doi.org/10.3390/bios7040048 - 18 Oct 2017
Cited by 7
Abstract
The use of a robust optical signaling probe with a high signal-to-noise ratio is important in the development of immunoassays. Lanthanide chelates are a promising material for this purpose, which provide time-resolved luminescence (TRL) due to their large Stokes shift and long luminescence [...] Read more.
The use of a robust optical signaling probe with a high signal-to-noise ratio is important in the development of immunoassays. Lanthanide chelates are a promising material for this purpose, which provide time-resolved luminescence (TRL) due to their large Stokes shift and long luminescence lifetime. From this, they have attracted considerable interest in the in vitro diagnostics field. However, the direct use of lanthanide chelates is limited because their luminescent signal can be easily affected by various quenchers. To overcome this drawback, strategies that rely on the entrapment of lanthanide chelates inside nanoparticles, thereby enabling the protection of the lanthanide chelate from water, have been reported. However, the poor stability of the lanthanide-entrapped nanoparticles results in a significant fluctuation in TRL signal intensity, and this still remains a challenging issue. To address this, we have developed a Lanthanide chelate-Encapsulated Silica Nano Particle (LESNP) as a new immunosensing probe. In this approach, the lanthanide chelate is covalently crosslinked within the silane monomer during the silica nanoparticle formation. The resulting LESNP is physically stable and retains TRL properties of the parent lanthanide chelate. Using the probe, a highly sensitive, sandwich-based TRL immunoassay for the cardiac troponin I was conducted, exhibiting a limit of detection of 48 pg/mL. On the basis of the features of the LESNP such as TRL signaling capability, stability, and the ease of biofunctionalization, we expect that the LESNP can be widely applied in the development of TRL-based immunosensing. Full article
(This article belongs to the Special Issue Nanomaterials Based Optical Biosensors)
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Open AccessArticle
Electrospun Chitosan-Gelatin Biopolymer Composite Nanofibers for Horseradish Peroxidase Immobilization in a Hydrogen Peroxide Biosensor
Biosensors 2017, 7(4), 47; https://doi.org/10.3390/bios7040047 - 15 Oct 2017
Cited by 8
Abstract
A biosensor based on chitosan-gelatin composite biopolymers nanofibers is found to be effective for the immobilization of horseradish peroxidase to detect hydrogen peroxide. The biopolymer nanofibers were fabricated by an electrospining technique. Upon optimization of synthesis parameters, biopolymers nanofibers, an average of 80 [...] Read more.
A biosensor based on chitosan-gelatin composite biopolymers nanofibers is found to be effective for the immobilization of horseradish peroxidase to detect hydrogen peroxide. The biopolymer nanofibers were fabricated by an electrospining technique. Upon optimization of synthesis parameters, biopolymers nanofibers, an average of 80 nm in diameter, were obtained and were then modified on the working electrode surface. The effects of the concentration of enzyme, pH, and concentration of the buffer and the working potential on the current response of the nanofibers-modified electrode toward hydrogen peroxide were optimized to obtain the maximal current response. The results found that horseradish peroxidase immobilization on chitosan-gelatin composite biopolymer nanofibers had advantages of fast response, excellent reproducibility, high stability, and showed a linear response to hydrogen peroxide in the concentration range from 0.1 to 1.7 mM with a detection limit of 0.05 mM and exhibited high sensitivity of 44 µA∙mM−1∙cm−2. The developed system was evaluated for analysis of disinfectant samples and showed good agreement between the results obtained by the titration method without significant differences at the 0.05 significance level. The proposed strategy based on chitosan-gelatin composite biopolymer nanofibers for the immobilization of enzymes can be extended for the development of other enzyme-based biosensors. Full article
(This article belongs to the Special Issue Nanomaterials Based Optical Biosensors)
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Open AccessArticle
A Rationally Designed Reversible ‘Turn-Off’ Sensor for Glutathione
Biosensors 2017, 7(3), 36; https://doi.org/10.3390/bios7030036 - 06 Sep 2017
Cited by 4
Abstract
γ-Glutamyl-cysteinyl-glycine (GSH) plays a critical role in maintaining redox homeostasis in biological systems and a decrease in its cellular levels is associated with diseases. Existing fluorescence-based chemosensors for GSH acts as irreversible reaction-based probes that exhibit a maximum fluorescence (‘turn-on’) once the reaction [...] Read more.
γ-Glutamyl-cysteinyl-glycine (GSH) plays a critical role in maintaining redox homeostasis in biological systems and a decrease in its cellular levels is associated with diseases. Existing fluorescence-based chemosensors for GSH acts as irreversible reaction-based probes that exhibit a maximum fluorescence (‘turn-on’) once the reaction is complete, regardless of the actual concentration of GSH. A reversible, reaction-based ‘turn-off’ probe (1) is reported here to sense the decreasing levels of GSH, a situation known to occur at the onset of various diseases. The more fluorescent merocyanine (MC) isomer of 1 exists in aqueous solution and this reacts with GSH to induce formation of the ring-closed spiropyran (SP) isomer, with a measurable decrease in absorbance and fluorescence (‘turn-off’). Sensor 1 has good aqueous solubility and shows an excellent selectivity for GSH over other biologically relevant metal ions and aminothiol analytes. The sensor permeates HEK 293 cells and an increase in fluorescence is observed on adding buthionine sulfoximine, an inhibitor of GSH synthesis. Full article
(This article belongs to the Special Issue Nanomaterials Based Optical Biosensors)
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Open AccessArticle
An Affordable Microsphere-Based Device for Visual Assessment of Water Quality
Biosensors 2017, 7(3), 31; https://doi.org/10.3390/bios7030031 - 05 Aug 2017
Cited by 1
Abstract
This work developed a prototype of an affordable, long-term water quality detection device that provides a visual readout upon detecting bacterial contamination. This device prototype consists of: (1) enzyme-releasing microspheres that lyse bacteria present in a sample, (2) microspheres that release probes that [...] Read more.
This work developed a prototype of an affordable, long-term water quality detection device that provides a visual readout upon detecting bacterial contamination. This device prototype consists of: (1) enzyme-releasing microspheres that lyse bacteria present in a sample, (2) microspheres that release probes that bind the DNA of the lysed bacteria, and (3) a detector region consisting of gold nanoparticles. The probes bind bacterial DNA, forming complexes. These complexes induce aggregation of the gold nanoparticles located in the detector region. The nanoparticle aggregation process causes a red to blue color change, providing a visual indicator of contamination being detected. Our group fabricated and characterized microspheres made of poly (ε-caprolactone) that released lysozyme (an enzyme that degrades bacterial cell walls) and hairpin DNA probes that bind to regions of the Escherichia coli genome over a 28-day time course. The released lysozyme retained its ability to lyse bacteria. We then showed that combining these components with gold nanoparticles followed by exposure to an E. coli-contaminated water sample (concentrations tested—106 and 108 cells/mL) resulted in a dramatic red to blue color change. Overall, this device represents a novel low-cost system for long term detection of bacteria in a water supply and other applications. Full article
(This article belongs to the Special Issue Nanomaterials Based Optical Biosensors)
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Open AccessArticle
Lipid Bilayer Membrane in a Silicon Based Micron Sized Cavity Accessed by Atomic Force Microscopy and Electrochemical Impedance Spectroscopy
Biosensors 2017, 7(3), 26; https://doi.org/10.3390/bios7030026 - 05 Jul 2017
Cited by 9
Abstract
Supported lipid bilayers (SLBs) are widely used in biophysical research to probe the functionality of biological membranes and to provide diagnoses in high throughput drug screening. Formation of SLBs at below phase transition temperature (Tm) has applications in nano-medicine research where [...] Read more.
Supported lipid bilayers (SLBs) are widely used in biophysical research to probe the functionality of biological membranes and to provide diagnoses in high throughput drug screening. Formation of SLBs at below phase transition temperature (Tm) has applications in nano-medicine research where low temperature profiles are required. Herein, we report the successful production of SLBs at above—as well as below—the Tm of the lipids in an anisotropically etched, silicon-based micro-cavity. The Si-based cavity walls exhibit controlled temperature which assist in the quick and stable formation of lipid bilayer membranes. Fusion of large unilamellar vesicles was monitored in real time in an aqueous environment inside the Si cavity using atomic force microscopy (AFM), and the lateral organization of the lipid molecules was characterized until the formation of the SLBs. The stability of SLBs produced was also characterized by recording the electrical resistance and the capacitance using electrochemical impedance spectroscopy (EIS). Analysis was done in the frequency regime of 10−2–105 Hz at a signal voltage of 100 mV and giga-ohm sealed impedance was obtained continuously over four days. Finally, the cantilever tip in AFM was utilized to estimate the bilayer thickness and to calculate the rupture force at the interface of the tip and the SLB. We anticipate that a silicon-based, micron-sized cavity has the potential to produce highly-stable SLBs below their Tm. The membranes inside the Si cavity could last for several days and allow robust characterization using AFM or EIS. This could be an excellent platform for nanomedicine experiments that require low operating temperatures. Full article
(This article belongs to the Special Issue Nanomaterials Based Optical Biosensors)
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Review

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Open AccessReview
Fluorescent and Colorimetric Electrospun Nanofibers for Heavy-Metal Sensing
Biosensors 2017, 7(4), 61; https://doi.org/10.3390/bios7040061 - 15 Dec 2017
Cited by 16
Abstract
The accumulation of heavy metals in the human body and/or in the environment can be highly deleterious for mankind, and currently, considerable efforts have been made to develop reliable and sensitive techniques for their detection. Among the detection methods, chemical sensors appear as [...] Read more.
The accumulation of heavy metals in the human body and/or in the environment can be highly deleterious for mankind, and currently, considerable efforts have been made to develop reliable and sensitive techniques for their detection. Among the detection methods, chemical sensors appear as a promising technology, with emphasis on systems employing optically active nanofibers. Such nanofibers can be obtained by the electrospinning technique, and further functionalized with optically active chromophores such as dyes, conjugated polymers, carbon-based nanomaterials and nanoparticles, in order to produce fluorescent and colorimetric nanofibers. In this review we survey recent investigations reporting the use of optically active electrospun nanofibers in sensors aiming at the specific detection of heavy metals using colorimetry and fluorescence methods. The examples given in this review article provide sufficient evidence of the potential of optically electrospun nanofibers as a valid approach to fabricate highly selective and sensitive optical sensors for fast and low-cost detection of heavy metals. Full article
(This article belongs to the Special Issue Nanomaterials Based Optical Biosensors)
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