Biosensors

2704 KiB

Open AccessArticle

Sensing of Salivary Glucose Using Nano-Structured Biosensors

by Yunqing Du, Wenjun Zhang and Ming L. Wang

Biosensors 2016, 6(1), 10; https://doi.org/10.3390/bios6010010 - 17 Mar 2016

Cited by 49 | Viewed by 17560

The anxiety and pain associated with frequent finger pricking has always been troublesome for diabetics measuring blood glucose (BG) in their daily lives. For this reason, a reliable glucose monitoring system that allows noninvasive measurements is highly desirable. Our main objective is to [...] Read more.

The anxiety and pain associated with frequent finger pricking has always been troublesome for diabetics measuring blood glucose (BG) in their daily lives. For this reason, a reliable glucose monitoring system that allows noninvasive measurements is highly desirable. Our main objective is to develop a biosensor that can detect low-level glucose in saliva (physiological range 0.5–20 mg/dL). Salivary glucose (SG) sensors were built using a layer-by-layer self-assembly of single-walled carbon nanotubes, chitosan, gold nanoparticles, and glucose oxidase onto a screen-printed platinum electrode. An electrochemical method was utilized for the quantitative detection of glucose in both buffer solution and saliva samples. A standard spectrophotometric technique was used as a reference method to validate the glucose content of each sample. The disposable glucose sensors have a detection limit of 0.41 mg/dL, a sensitivity of 0.24 μA·s·dL·mg⁻¹, a linear range of 0.5–20 mg/dL in buffer solution, and a response time of 30 s. A study of 10 healthy subjects was conducted, and SG levels between 1.1 to 10.1 mg/dL were successfully detected. The results revealed that the noninvasive SG monitoring could be an alternative for diabetes self-management at home. This paper is not intended to replace regular BG tests, but to study SG itself as an indicator for the quality of diabetes care. It can potentially help patients control and monitor their health conditions, enabling them to comply with prescribed treatments for diabetes. Full article

(This article belongs to the Special Issue Advances in Lab-on-Chip Devices)

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2007 KiB

Open AccessArticle

Multi-Wire Tri-Gate Silicon Nanowires Reaching Milli-pH Unit Resolution in One Micron Square Footprint

by Enrico Accastelli, Paolo Scarbolo, Thomas Ernst, Pierpaolo Palestri, Luca Selmi and Carlotta Guiducci

Biosensors 2016, 6(1), 9; https://doi.org/10.3390/bios6010009 - 15 Mar 2016

Cited by 23 | Viewed by 8022

Abstract

The signal-to-noise ratio of planar ISFET pH sensors deteriorates when reducing the area occupied by the device, thus hampering the scalability of on-chip analytical systems which detect the DNA polymerase through pH measurements. Top-down nano-sized tri-gate transistors, such as silicon nanowires, are designed [...] Read more.

The signal-to-noise ratio of planar ISFET pH sensors deteriorates when reducing the area occupied by the device, thus hampering the scalability of on-chip analytical systems which detect the DNA polymerase through pH measurements. Top-down nano-sized tri-gate transistors, such as silicon nanowires, are designed for high performance solid-state circuits thanks to their superior properties of voltage-to-current transduction, which can be advantageously exploited for pH sensing. A systematic study is carried out on rectangular-shaped nanowires developed in a complementary metal-oxide-semiconductor (CMOS)-compatible technology, showing that reducing the width of the devices below a few hundreds of nanometers leads to higher charge sensitivity. Moreover, devices composed of several wires in parallel further increase the exposed surface per unit footprint area, thus maximizing the signal-to-noise ratio. This technology allows a sub milli-pH unit resolution with a sensor footprint of about 1 µm², exceeding the performance of previously reported studies on silicon nanowires by two orders of magnitude. Full article

(This article belongs to the Special Issue Field-Effect Transistor Biosensors)

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4470 KiB

Open AccessArticle

Aryl Diazonium Chemistry for the Surface Functionalization of Glassy Biosensors

by Wei Zheng, Remko Van den Hurk, Yong Cao, Rongbing Du, Xuejun Sun, Yiyu Wang, Mark T. McDermott and Stephane Evoy

Biosensors 2016, 6(1), 8; https://doi.org/10.3390/bios6010008 - 14 Mar 2016

Cited by 11 | Viewed by 8395

Abstract

Nanostring resonator and fiber-optics-based biosensors are of interest as they offer high sensitivity, real-time measurements and the ability to integrate with electronics. However, these devices are somewhat impaired by issues related to surface modification. Both nanostring resonators and photonic sensors employ glassy materials, [...] Read more.

Nanostring resonator and fiber-optics-based biosensors are of interest as they offer high sensitivity, real-time measurements and the ability to integrate with electronics. However, these devices are somewhat impaired by issues related to surface modification. Both nanostring resonators and photonic sensors employ glassy materials, which are incompatible with electrochemistry. A surface chemistry approach providing strong and stable adhesion to glassy surfaces is thus required. In this work, a diazonium salt induced aryl film grafting process is employed to modify a novel SiCN glassy material. Sandwich rabbit IgG binding assays are performed on the diazonium treated SiCN surfaces. Fluorescently labelled anti-rabbit IgG and anti-rabbit IgG conjugated gold nanoparticles were used as markers to demonstrate the absorption of anti-rabbit IgG and therefore verify the successful grafting of the aryl film. The results of the experiments support the effectiveness of diazonium chemistry for the surface functionalization of SiCN surfaces. This method is applicable to other types of glassy materials and potentially can be expanded to various nanomechanical and optical biosensors. Full article

(This article belongs to the Special Issue Micro- and Nano-Bio-Interfaces)

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2979 KiB

Open AccessReview

Comparison of Electrochemical Immunosensors and Aptasensors for Detection of Small Organic Molecules in Environment, Food Safety, Clinical and Public Security

by Benoit Piro, Shihui Shi, Steeve Reisberg, Vincent Noël and Guillaume Anquetin

Biosensors 2016, 6(1), 7; https://doi.org/10.3390/bios6010007 - 29 Feb 2016

Cited by 49 | Viewed by 11295

Abstract

We review here the most frequently reported targets among the electrochemical immunosensors and aptasensors: antibiotics, bisphenol A, cocaine, ochratoxin A and estradiol. In each case, the immobilization procedures are described as well as the transduction schemes and the limits of detection. It is [...] Read more.

We review here the most frequently reported targets among the electrochemical immunosensors and aptasensors: antibiotics, bisphenol A, cocaine, ochratoxin A and estradiol. In each case, the immobilization procedures are described as well as the transduction schemes and the limits of detection. It is shown that limits of detections are generally two to three orders of magnitude lower for immunosensors than for aptasensors, due to the highest affinities of antibodies. No significant progresses have been made to improve these affinities, but transduction schemes were improved instead, which lead to a regular improvement of the limit of detections corresponding to ca. five orders of magnitude over these last 10 years. These progresses depend on the target, however. Full article

(This article belongs to the Special Issue Affinity Sensors)

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1782 KiB

Open AccessArticle

Protein-Flavonoid Interaction Studies by a Taylor Dispersion Surface Plasmon Resonance (SPR) Technique: A Novel Method to Assess Biomolecular Interactions

by Preejith P. Vachali, Binxing Li, Brian M. Besch and Paul S. Bernstein

Biosensors 2016, 6(1), 6; https://doi.org/10.3390/bios6010006 - 25 Feb 2016

Cited by 16 | Viewed by 8604

Abstract

Flavonoids are common polyphenolic compounds widely distributed in fruits and vegetables. These pigments have important pharmacological relevance because emerging research suggests possible anti-cancer and anti-inflammatory properties as well other beneficial health effects. These compounds are relatively hydrophobic molecules, suggesting the role of blood [...] Read more.

Flavonoids are common polyphenolic compounds widely distributed in fruits and vegetables. These pigments have important pharmacological relevance because emerging research suggests possible anti-cancer and anti-inflammatory properties as well other beneficial health effects. These compounds are relatively hydrophobic molecules, suggesting the role of blood transport proteins in their delivery to tissues. In this study, we assess the binding interactions of four flavonoids (kaempferol, luteolin, quercetin, and resveratrol) with human serum albumin (HSA), the most abundant protein in the blood, and with glutathione S-transferase pi isoform-1 (GSTP1), an enzyme with well-characterized hydrophobic binding sites that plays an important role in detoxification of xenobiotics with reduced glutathione, using a novel Taylor dispersion surface plasmon resonance (SPR) technique. For the first time, HSA sites revealed a high-affinity binding site for flavonoid interactions. Out of the four flavonoids that we examined, quercetin and kaempferol showed the strongest equilibrium binding affinities (K_D) of 63 ± 0.03 nM and 37 ± 0.07 nM, respectively. GSTP1 displayed lower affinities in the micromolar range towards all of the flavonoids tested. The interactions of flavonoids with HSA and GSTP1 were studied successfully using this novel SPR assay method. The new method is compatible with both kinetic and equilibrium analyses. Full article

(This article belongs to the Special Issue Affinity Sensors)

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243 KiB

Open AccessReview

Developing Biosensors in Developing Countries: South Africa as a Case Study

by Ronen Fogel and Janice Limson

Biosensors 2016, 6(1), 5; https://doi.org/10.3390/bios6010005 - 2 Feb 2016

Cited by 31 | Viewed by 10848

Abstract

A mini-review of the reported biosensor research occurring in South Africa evidences a strong emphasis on electrochemical sensor research, guided by the opportunities this transduction platform holds for low-cost and robust sensing of numerous targets. Many of the reported publications centre on fundamental [...] Read more.

A mini-review of the reported biosensor research occurring in South Africa evidences a strong emphasis on electrochemical sensor research, guided by the opportunities this transduction platform holds for low-cost and robust sensing of numerous targets. Many of the reported publications centre on fundamental research into the signal transduction method, using model biorecognition elements, in line with international trends. Other research in this field is spread across several areas including: the application of nanotechnology; the identification and validation of biomarkers; development and testing of biorecognition agents (antibodies and aptamers) and design of electro-catalysts, most notably metallophthalocyanine. Biosensor targets commonly featured were pesticides and metals. Areas of regional import to sub-Saharan Africa, such as HIV/AIDs and tuberculosis diagnosis, are also apparent in a review of the available literature. Irrespective of the targets, the challenge to the effective deployment of such sensors remains shaped by social and economic realities such that the requirements thereof are for low-cost and universally easy to operate devices for field settings. While it is difficult to disentangle the intertwined roles of national policy, grant funding availability and, certainly, of global trends in shaping areas of emphasis in research, most notable is the strong role that nanotechnology, and to a certain extent biotechnology, plays in research regarding biosensor construction. Stronger emphasis on collaboration between scientists in theoretical modelling, nanomaterials application and or relevant stakeholders in the specific field (e.g., food or health monitoring) and researchers in biosensor design may help evolve focused research efforts towards development and deployment of low-cost biosensors. Full article

(This article belongs to the Special Issue Low-Cost Biosensors for Developing Countries)

2631 KiB

Open AccessArticle

Variation in Gas and Volatile Compound Emissions from Human Urine as It Ages, Measured by an Electronic Nose

by Siavash Esfahani, Nidhi M. Sagar, Ioannis Kyrou, Ella Mozdiak, Nicola O’Connell, Chuka Nwokolo, Karna D. Bardhan, Ramesh P. Arasaradnam and James A. Covington

Biosensors 2016, 6(1), 4; https://doi.org/10.3390/bios6010004 - 25 Jan 2016

Cited by 33 | Viewed by 6778

Abstract

The medical profession is becoming ever more interested in the use of gas-phase biomarkers for disease identification and monitoring. This is due in part to its rapid analysis time and low test cost, which makes it attractive for many different clinical arenas. One [...] Read more.

The medical profession is becoming ever more interested in the use of gas-phase biomarkers for disease identification and monitoring. This is due in part to its rapid analysis time and low test cost, which makes it attractive for many different clinical arenas. One technology that is showing promise for analyzing these gas-phase biomarkers is the electronic nose—an instrument designed to replicate the biological olfactory system. Of the possible biological media available to “sniff”, urine is becoming ever more important as it is easy to collect and to store for batch testing. However, this raises the question of sample storage shelf-life, even at −80 °C. Here we investigated the effect of storage time (years) on stability and reproducibility of total gas/vapour emissions from urine samples. Urine samples from 87 patients with Type 2 Diabetes Mellitus were collected over a four-year period and stored at −80 °C. These samples were then analyzed using FAIMS (field-asymmetric ion mobility spectrometry—a type of electronic nose). It was discovered that gas emissions (concentration and diversity) reduced over time. However, there was less variation in the initial nine months of storage with greater uniformity and stability of concentrations together with tighter clustering of the total number of chemicals released. This suggests that nine months could be considered a general guide to a sample shelf-life. Full article

(This article belongs to the Special Issue Biosensors in Environmental Studies)

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166 KiB

Open AccessEditorial

Acknowledgement to Reviewers of Biosensors in 2015

by Biosensors Editorial Office

Biosensors 2016, 6(1), 3; https://doi.org/10.3390/bios6010003 - 22 Jan 2016

Viewed by 4150

Abstract

The editors of Biosensors would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2015. [...] Full article

2577 KiB

Open AccessArticle

Cancer-Cells on Chip for Label-Free Detection of Secreted Molecules

by Ophélie I. Berthuy, Loïc J. Blum and Christophe A. Marquette

Biosensors 2016, 6(1), 2; https://doi.org/10.3390/bios6010002 - 15 Jan 2016

Cited by 15 | Viewed by 7737

Abstract

In the present report, we are making the proof of concept of cell small populations (from 1 to 100 cells) spotting, culture and secretion detection on a gold surface. In order to keep the cells in a hydrated environment during the robotized micropipetting [...] Read more.

In the present report, we are making the proof of concept of cell small populations (from 1 to 100 cells) spotting, culture and secretion detection on a gold surface. In order to keep the cells in a hydrated environment during the robotized micropipetting and to address different cell lines on a single chip, a biocompatible alginate polymer was used. This approach enables the encapsulation of the cell in a very small volume (30 nL), directly on the substrate and permits a precise control of the number of cells in each alginate bead. After 24 h of culture, the adherent cells are ready for surface plasmon resonance imaging (SPRi) experimentation. To enable the detection of secreted proteins, various antibodies are immobilized in an organized manner on a SPRi sensor and permitted the multiplex detection of different proteins secreted by the different cultured cell lines. Evidence of the real-time detection will be presented for Prostate Specific Antigen (PSA) and β-2-microglobulin (B2M) secreted by prostate cancer cells following induction by dihydrotestosterone (DHT). Different kinetics for the two secreted proteins were then demonstrated and precisely determined using the chip. Full article

(This article belongs to the Special Issue Cell and Organ on Chip: Challenges and Advances)

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2310 KiB

Open AccessArticle

Asymmetric Mach–Zehnder Interferometer Based Biosensors for Aflatoxin M1 Detection

by Tatevik Chalyan, Romain Guider, Laura Pasquardini, Manuela Zanetti, Floris Falke, Erik Schreuder, Rene G. Heideman, Cecilia Pederzolli and Lorenzo Pavesi

Biosensors 2016, 6(1), 1; https://doi.org/10.3390/bios6010001 - 6 Jan 2016

Cited by 55 | Viewed by 10084

Abstract

In this work, we present a study of Aflatoxin M1 detection by photonic biosensors based on Si₃N₄ Asymmetric Mach–Zehnder Interferometer (aMZI) functionalized with antibodies fragments (Fab′). We measured a best volumetric sensitivity of 10⁴ rad/RIU, leading to a Limit [...] Read more.

In this work, we present a study of Aflatoxin M1 detection by photonic biosensors based on Si₃N₄ Asymmetric Mach–Zehnder Interferometer (aMZI) functionalized with antibodies fragments (Fab′). We measured a best volumetric sensitivity of 10⁴ rad/RIU, leading to a Limit of Detection below 5 × 10⁻⁷ RIU. On sensors functionalized with Fab′, we performed specific and non-specific sensing measurements at various toxin concentrations. Reproducibility of the measurements and re-usability of the sensor were also investigated. Full article

(This article belongs to the Special Issue Optical Sensors for Biomedical Applications)

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Biosensors, Volume 6, Issue 1 (March 2016) – 10 articles

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