scholarly journals Graphene-based biosensors

2018 ◽  
Vol 8 (3) ◽  
pp. 20160132 ◽  
Author(s):  
Sabine Szunerits ◽  
Rabah Boukherroub
Keyword(s):  
Biological Samples ◽  
Early Stage ◽  
Point Of Care ◽  
High Surface ◽  
Volume Ratio ◽  
Wide Range ◽  
The Status ◽  
Delays In Diagnosis ◽  
Short Time ◽  
Sensor Interfaces

Reliable data obtained from analysis of DNA, proteins, bacteria and other disease-related molecules or organisms in biological samples have become a fundamental and crucial part of human health diagnostics and therapy. The development of non-invasive tests that are rapid, sensitive, specific and simple would allow patient discomfort to be prevented, delays in diagnosis to be avoided and the status of a disease to be followed up. Bioanalysis is thus a progressive discipline for which the future holds many exciting opportunities. The use of biosensors for the early diagnosis of diseases has become widely accepted as a point-of-care diagnosis with appropriate specificity in a short time. To allow a reliable diagnosis of a disease at an early stage, highly sensitive biosensors are required as the corresponding biomarkers are generally expressed at very low concentrations. In the past 50 years, various biosensors have been researched and developed encompassing a wide range of applications. This contrasts the limited number of commercially available biosensors. When it comes to sensing of biomarkers with the required picomolar (pM) sensitivity for real-time sensing of biological samples, only a handful of sensing systems have been proposed, and these are often rather complex and costly. Lately, graphene-based materials have been considered as superior over other nanomaterials for the development of sensitive biosensors. The advantages of graphene-based sensor interfaces are numerous, including enhanced surface loading of the desired ligand due to the high surface-to-volume ratio, excellent conductivity and a small band gap that is beneficial for sensitive electrical and electrochemical read-outs, as well as tunable optical properties for optical read-outs such as fluorescence and plasmonics. In this paper, we review the advances made in recent years on graphene-based biosensors in the field of medical diagnosis.

A Comprehensive Review: Development of Biosensors Based on Graphene-Mesoporous Combined Materials

2019 ◽  
pp. 24-33 ◽  
Author(s):  
Kamrun Nahar Fatema ◽  
Won-Chun Oh
Keyword(s):  
Early Stage ◽  
Point Of Care ◽  
High Surface ◽  
Volume Ratio ◽  
Ordered Mesoporous Materials ◽  
Wide Range ◽  
The Status ◽  
Delays In Diagnosis ◽  
Short Time ◽  
Sensor Interfaces

Reliable data obtained from analysis of DNA, proteins, bacteria and other disease-related molecules or organisms in biological samples have become a fundamental and crucial part of human health diagnostics and therapy. After a brief summary of the implication of template based ordered mesoporous materials in electrochemical science, the various types of inorganic and organic-inorganic hybrid mesostructured used to date in electroanalysis and the corresponding electrode configurations are described. The development of non-invasive tests that are rapid, sensitive, specific and simple would allow patient discomfort to be prevented, delays in diagnosis to be avoided and the status of a disease to be followed up. The use of biosensors for the early diagnosis of diseases has become widely accepted as a point-of-care diagnosis with appropriate specificity in a short time. To allow a reliable diagnosis of a disease at an early stage, highly sensitive biosensors are required as the corresponding biomarkers are generally expressed at very low concentrations. In past 50 years, various biosensors have been researched and developed encompassing a wide range of applications. This contrasts the limited number of commercially available biosensors. Lately, graphene-based materials have been considered as superior over other nanomaterials for the development of sensitive biosensors. The advantages of graphenebased sensor interfaces are numerous, including enhanced surface loading of desired ligand due to the high surface-to-volume ratio, excellent conductivity and a small band gap that is beneficial for sensitive electrical and electrochemical read-outs, as well as tunable optical properties for optical read-outs such as fluorescence and plasmonics. In this paper, we review the advances made in recent years on graphenebased biosensors in the field of medical diagnosis.

scholarly journals Contagion Management at the Méditerranée Infection University Hospital Institute

2021 ◽  
Vol 10 (12) ◽  
pp. 2627
Author(s):  
Pierre-Edouard Fournier ◽  
Sophie Edouard ◽  
Nathalie Wurtz ◽  
Justine Raclot ◽  
Marion Bechet ◽  
...  
Keyword(s):  
Infectious Disease ◽  
Early Diagnosis ◽  
Personal Protective Equipment ◽  
Early Stage ◽  
Point Of Care ◽  
University Hospital ◽  
Protective Equipment ◽  
Monitoring Point ◽  
Epidemiological Monitoring ◽  
Wide Range

The Méditerranée Infection University Hospital Institute (IHU) is located in a recent building, which includes experts on a wide range of infectious disease. The IHU strategy is to develop innovative tools, including epidemiological monitoring, point-of-care laboratories, and the ability to mass screen the population. In this study, we review the strategy and guidelines proposed by the IHU and its application to the COVID-19 pandemic and summarise the various challenges it raises. Early diagnosis enables contagious patients to be isolated and treatment to be initiated at an early stage to reduce the microbial load and contagiousness. In the context of the COVID-19 pandemic, we had to deal with a shortage of personal protective equipment and reagents and a massive influx of patients. Between 27 January 2020 and 5 January 2021, 434,925 nasopharyngeal samples were tested for the presence of SARS-CoV-2. Of them, 12,055 patients with COVID-19 were followed up in our out-patient clinic, and 1888 patients were hospitalised in the Institute. By constantly adapting our strategy to the ongoing situation, the IHU has succeeded in expanding and upgrading its equipment and improving circuits and flows to better manage infected patients.

scholarly journals A Review on Biosensors and Recent Development of Nanostructured Materials-Enabled Biosensors

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1109
Author(s):  
Varnakavi. Naresh ◽  
Nohyun Lee
Keyword(s):  
High Surface ◽  
Three Dimensional ◽  
Biological Response ◽  
Volume Ratio ◽  
Recent Decade ◽  
Disease Diagnosis ◽  
Electrical Signal ◽  
Detection Sensitivity ◽  
Wide Range ◽  
Color Tunability

A biosensor is an integrated receptor-transducer device, which can convert a biological response into an electrical signal. The design and development of biosensors have taken a center stage for researchers or scientists in the recent decade owing to the wide range of biosensor applications, such as health care and disease diagnosis, environmental monitoring, water and food quality monitoring, and drug delivery. The main challenges involved in the biosensor progress are (i) the efficient capturing of biorecognition signals and the transformation of these signals into electrochemical, electrical, optical, gravimetric, or acoustic signals (transduction process), (ii) enhancing transducer performance i.e., increasing sensitivity, shorter response time, reproducibility, and low detection limits even to detect individual molecules, and (iii) miniaturization of the biosensing devices using micro-and nano-fabrication technologies. Those challenges can be met through the integration of sensing technology with nanomaterials, which range from zero- to three-dimensional, possessing a high surface-to-volume ratio, good conductivities, shock-bearing abilities, and color tunability. Nanomaterials (NMs) employed in the fabrication and nanobiosensors include nanoparticles (NPs) (high stability and high carrier capacity), nanowires (NWs) and nanorods (NRs) (capable of high detection sensitivity), carbon nanotubes (CNTs) (large surface area, high electrical and thermal conductivity), and quantum dots (QDs) (color tunability). Furthermore, these nanomaterials can themselves act as transduction elements. This review summarizes the evolution of biosensors, the types of biosensors based on their receptors, transducers, and modern approaches employed in biosensors using nanomaterials such as NPs (e.g., noble metal NPs and metal oxide NPs), NWs, NRs, CNTs, QDs, and dendrimers and their recent advancement in biosensing technology with the expansion of nanotechnology.

scholarly journals Continuous tuning of the plasmon resonance frequency of porous gold nanoparticles by mixed oxide layers

2020 ◽  
Vol 27 (6) ◽  
pp. 1583-1588
Author(s):  
Laura Juhász ◽  
Bence Parditka ◽  
Péter Petrik ◽  
Csaba Cserháti ◽  
Zoltán Erdélyi
Keyword(s):  
Gold Nanoparticles ◽  
Resonance Frequency ◽  
Mixed Oxide ◽  
High Surface ◽  
Volume Ratio ◽  
Mixture Ratio ◽  
Optical Extinction ◽  
Oxide Layers ◽  
Porous Gold ◽  
Wide Range

Abstract Porous gold nanoparticles (PGNs) are very popular due to their high surface/volume ratio, moreover they have stronger plasmonic properties than their solid counterparts. These properties make the porous gold nanoparticles very useful for lots of applications, for instance chemical sensors, cancer therapy applications. For applications, however, it is indispensable that the resonance frequency (RF) of a plasmonic structure to be tuneable. In this work we show that the RF can be set in a wide range as desired by coating the PGNs by mixed oxide layers. By changing the composition of the coating layer, that is the mixture ratio, the RF can be shifted practically continuously in a wide range determined by the refractive index of the used oxides. As a demonstration, PGNs were coated with mixed alumina-titania oxide layers (5–7 nm) using plasma-enhanced atomic layer deposition method. The oxide layer, beside as a tuning tool, also stabilises the structure of the PGNs when are exposed to elevated temperature. This is shown by the influence of the temperature (from $$350\, ^{\circ }\hbox {C}$$ 350 ∘ C up to $$900\, ^{\circ }\hbox {C}$$ 900 ∘ C ) on the morphology, and as a consequence the optical extinction spectra, of the oxide coated PGNs.

scholarly journals Flash C-H Chlorination of Ethylene Carbonate Using a New Photoflow Setup

2021 ◽  
Author(s):  
Takayoshi Kasakado ◽  
Takahide Fukuyama ◽  
Tomohiro Nakagawa ◽  
Shinji Taguchi ◽  
Ilhyong Ryu
Keyword(s):  
Ethylene Carbonate ◽  
High Surface ◽  
Volume Ratio ◽  
Contaminated Water ◽  
Radical Initiation ◽  
Flow Channels ◽  
Chlorine Gas ◽  
Biphasic Reaction ◽  
Short Time ◽  
Direct Use

We report flash C-H chlorination of ethylene carbonate, which gives chloroethylene carbonate, a precursor to ethylene carbonate.  A novel photoflow setup designed for a gas-liquid biphasic reaction turned out to be useful for the direct use of chlorine gas in flow.  The setup employed sloped channels so as to make the liquid phase thinner, ensuring high surface to volume ratio.  When ethylene carbonate was introduced to the reactor, the residence time was measured to be 15 or 30 sec, depending on the slope of the reactor to be 15 or 5 °C, respectively.  Such short time exposition sufficed the photo C-H chlorination.  The partial irradiation of the flow channels sufficed for the C-H chlorination, which is consistent with the requirement of photoirradiation for the purpose of radical initiation. We also found that the contaminated water negatively influenced the performance of C-H chlorination.  The 100% selectivity for single chlorination required the low conversion of ethylene carbonate such as 9%, which was controlled by limited introduction of chlorine gas.  At a higher conversion of ethylene carbonate such as 63%, the selectivity for mono-chlorinated ethylene carbonate over di-chlorinated ethylene carbonate was 86%.  We found that the contaminated water negatively influenced the performance of the C-H chlorination.

scholarly journals Revisiting the configurationality issue in Old Icelandic

2021 ◽  
Author(s):  
Hannah Booth
Keyword(s):  
Word Order ◽  
Early Stage ◽  
Functional Grammar ◽  
Old Icelandic ◽  
Modern Language ◽  
Lexical Functional Grammar ◽  
Wide Range ◽  
The Status ◽  
Corpus Data

The status of Old Icelandic with respect to (argument) configurationality was subject to debate in the early 1990s (e.g. Faarlund 1990; Rögnvaldsson 1995) and remains unresolved. Since this work, further research on a wide range of languages has enhanced our understanding of configurationality, in particular within Lexical Functional Grammar (e.g. Austin & Bresnan 1996; Nordlinger 1998) and syntactically annotated Old Icelandic data are now available (Wallenberg et al. 2011). It is thus fitting to revisit the matter. In this paper, I show that allowing for argument configurationality as a gradient property, and also taking into account discourse configurationality (Kiss 1995) as a further gradient property, can neatly account for word order patterns in this early stage of Icelandic. Specifically, I show that corpus data supports part of the original claim in Faarlund (1990), that Old Icelandic lacks a VP-constituent, thus being somewhat less argument-configurational than the modern language. Furthermore, the observed word order patterns indicate a designated topic position in the postfinite domain, thus reflecting some degree of discourse configurationality at this early stage of the language.

One-dimensional inorganic semiconductor nanostructures: A new carrier for nanosensors

2010 ◽  
Vol 82 (11) ◽  
pp. 2185-2198 ◽  
Author(s):  
Xiaosheng Fang ◽  
Linfeng Hu ◽  
Changhui Ye ◽  
Lide Zhang
Keyword(s):  
High Performance ◽  
High Surface ◽  
Volume Ratio ◽  
Semiconductor Nanostructures ◽  
One Dimensional ◽  
Semiconductor Nanostructure ◽  
Research Activities ◽  
Wide Range ◽  
Inorganic Semiconductor ◽  
Art Research

One-dimensional (1D) inorganic semiconductor nanostructures have witnessed an explosion of interest over the last decade because of advances in their controlled synthesis and unique property and potential applications. A wide range of gases, chemicals, biomedical nanosensors, and photodetectors have been assembled using 1D inorganic semiconductor nanostructures. The high-performance characteristics of these nanosensors are particularly attributable to the inorganic semiconducting nanostructure high surface-to-volume ratio (SVR) and its rationally designed surface. In this review, we provide a brief summary of the state-of-the-art research activities in the field of 1D inorganic semiconductor nanostructure-based nanosensors. Some perspectives and the outlook for future developments in this area are presented.

scholarly journals Applications of electrospun nanofibers in the biomedical field

SURG Journal ◽  
2012 ◽  
Vol 5 (2) ◽  
pp. 63-73 ◽  
Author(s):  
Nishath Khan
Keyword(s):  
High Surface ◽  
High Surface Area ◽  
Volume Ratio ◽  
Electrospun Nanofibers ◽  
Ease Of Use ◽  
The Past ◽  
Wide Range ◽  
Novel Method ◽  
Biomedical Field ◽  
Highly Porous

Electrospinning is a technology that has been widely used as a novel method for the generation of nano scale fibres. Electrospun fibres are used in a wide range of applications from electronics to textile. The viability and popularity of this technology can be evidenced by its ease of use and the simplicity of the science behind building the electrospinning machine. The generated fibres have a high surface area- to- volume ratio, the fibrous mats are highly porous and display excellent mechanical properties when compared to other materials of the same scale. In the past decade, this technology has taken off with the use of biocompatible and biodegradable polymers. This review is a summary of the different ways in which electrospinning can be used in the biomedical field. This article analyzes the recent advances of this technology in tissue engineering, drug delivery and in enzyme immobilisation, which once again showcases the versatility of the electrospinning procedure.

scholarly journals Novel Indicator to Ascertain the Status and Trend of COVID-19 Spread: Modeling Study (Preprint)

2020 ◽  
Author(s):  
Takashi Nakano ◽  
Yoichi Ikeda
Keyword(s):  
Early Stage ◽  
Logarithmic Derivative ◽  
Current Status ◽  
Difference Approximation ◽  
Time Interval ◽  
Cumulative Number ◽  
Infected People ◽  
Linear Decrease ◽  
Wide Range ◽  
The Status

BACKGROUND In the fight against the pandemic of COVID-19, it is important to ascertain the status and trend of the infection spread quickly and accurately. OBJECTIVE The purpose of our study is to formulate a new and simple indicator that represents the COVID-19 spread rate by using publicly available data. METHODS The new indicator <i>K</i> is a backward difference approximation of the logarithmic derivative of the cumulative number of cases with a time interval of 7 days. It is calculated as a ratio of the number of newly confirmed cases in a week to the total number of cases. RESULTS The analysis of the current status of COVID-19 spreading over countries showed an approximate linear decrease in the time evolution of the <i>K</i> value. The slope of the linear decrease differed from country to country. In addition, it was steeper for East and Southeast Asian countries than for European countries. The regional difference in the slope seems to reflect both social and immunological circumstances for each country. CONCLUSIONS The approximate linear decrease of the <i>K</i> value indicates that the COVID-19 spread does not grow exponentially but starts to attenuate from the early stage. The <i>K</i> trajectory in a wide range was successfully reproduced by a phenomenological model with the constant attenuation assumption, indicating that the total number of the infected people follows the Gompertz curve. Focusing on the change in the value of <i>K</i> will help to improve and refine epidemiological models of COVID-19.

scholarly journals Immobilization of Protein A on Monodisperse Magnetic Nanoparticles for Biomedical Applications

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Bui Trung Thanh ◽  
Nguyen Van Sau ◽  
Heongkyu Ju ◽  
Mohammed J. K. Bashir ◽  
Hieng Kiat Jun ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Magnetic Nanoparticles ◽  
Biomedical Applications ◽  
Point Of Care ◽  
High Surface ◽  
Protein A ◽  
Volume Ratio ◽  
Controlled Drug Release ◽  
Disease Diagnosis

We presented synthesis and physical characterization of iron oxide magnetic nanoparticles (Fe3O4) for biomedical applications in the size range of 10-30 nm. Magnetic nanoparticles were synthesized by the coprecipitation method, and the particles’ size was controlled by two different injection methods of sodium hydroxide (NaOH). The synthesized magnetic nanoparticles were then modified by using series of linkers including tetraethyl orthosilicate (TEOS), 3-aminopropyltriethoxysilane (APTES), and glutaraldehyde (GA) to generate the structure of Fe3O4/SiO2/NH2/CHO, which can be used for immobilization of protein A. Additionally, we used transmission electron microscopy (TEM), X-ray powder diffraction (XRD), vibrating-sample magnetometry (VSM), and Fourier-transform infrared spectroscopy (FTIR), for characterization of properties and structure of the nanoparticles. An immobilization of protein A on magnetic nanoparticles was studied with a UV-Vis spectrum (UV-Vis) and fluorescence electron microscopy and Bradford method. Results showed that an XRD spectrum with a peak at (311) corresponded to the standard peak of magnetic nanoparticles. In addition, the magnetic nanoparticles with d≥30 nm have higher saturation magnetizations in comparison with the smaller ones with d≤10 nm. However, the smaller magnetic nanoparticles offered higher efficiency for binding of protein A, due to the high surface/volume ratio. These particles with functional groups on their surface are promising candidates for biomedical applications, e.g., drug delivery, controlled drug release, or disease diagnosis in point-of-care test.

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