bluuebunny/crossref_metadata_2025 huggingface dataset:
Insights into the Kinetics of Electrostatic Denaturation of Surface-Bound DNA
Authors: Taylor Jeffrey K , Raghu Gayatri , West Ryan M
Published: May 2020

Electrostatic denaturation of double-stranded DNA (dsDNA), i.e. electrochemical melting, can be used to interrogate duplex stability, allowing discrimination of dsDNA based on the presence of mismatches, deletions, and other mutations (1). More recently, electrochemical melting has allowed examination of DNA-small molecule interactions, e.g. DNA-cisplatin adducts (2). Denaturation of dsDNA in self-assembled monolayers (SAMs) occurs when a sufficiently negative potential is applied to the DNA-modified working electrode, presumably due to strong electrostatic repulsion of the phosphate background in the presence of the high electric field in the electrical double-layer (109 V/m). In our work, we use a purely electrochemical approach for monitoring the electric field-induced melting of dsDNA SAMs. Application of moderate negative potentials (-500 mV vs. Ag/AgCl) is sufficient to melt DNA without substantial thiol reduction (1). Here we present the dependence of electrochemical melting on the temperature of the buffer and the frequency of applied potential in an effort to better understand the complex interplay of DNA stability, backbone charge screening, and double-layer structure. Previous studies have shown that electrochemical melting depends on temperature in the range 10 – 18 °C while no effect of temperature was found above this 18 °C (3). Here, we explore the temperature dependence in more detail to better understand how temperature effects the electric field effects. In particular, we examine the kinetics of the melting process at different temperatures. Additionally, the formation of the high electric fields necessary for melting depends on the screening of electrode charge by counterions from solution. Rant et al. reported that the responsiveness of the immobilized DNA is directly related to the formation of the electrical double-layer (4). By applying fast potentials pulses to melt the DNA, we determine the frequency at which the rate of melting drastically decreases due to insufficient time for the strong field to develop. Together, the temperature and frequency dependence of electrochemical melting shines new light on the role of electrical fields on DNA stability.

References

1. S. Mahajan, J. Richardson, T. Brown and P. N. Bartlett, Journal of the American Chemical Society, 130, 15589 (2008).

2. E. Madrigal, G. Raghu, J. Taylor and R. M. West, Cross-linking of DNA Monolayers by Cisplatin Examined Using Electrochemical Melting Analysis, The Journal of Electroanalytical Chemistry, Submitted (2019).

3. E. Papadopoulou, M. Meneghello, P. Marafini, R. P. Johnson, T. Brown and P. N. Bartlett, Bioelectrochemistry, 106, 353 (2015).

4. C. Sendner, Y. W. Kim, U. Rant, K. Arinaga, M. Tornow and R. Netz, physica status solidi (a), 203, 3476 (2006).
Functional Hydrogels for Electrical Stimulation and Detection of Cells Growth
Authors: Chiang Tze-Ting , Huang Bo-Han , Hsieh Yi-Chieh , Wu Pu-Wei
Published: May 2020

Chitosan is considered to be a natural polymer for promising applications in drug delivery, wound dressing/healing, biocompatible coating, and tissue engineering. Since the chitosan is known for bio-compatibility, non-toxicity, anti-bacterial ability, and low cost, there has been increasing interest to leverage the unique characteristics of chitosan to fabricate bio-composites for specific bio-medical purposes. In this work, we demonstrate a facile synthetic approach to fabricate composite hydrogels consisting of chitosan, poly(3,4-ethylenedioxythiophene (PEDOT), and iridium oxide (IrO2) nanoparticles. Our synthesis step entails a potentiostatic mode that enables electrophoresis and water electrolysis simultaneously to produce free-standing conductive hydrogels with high porosity. Materials characterization of the as-synthesized composite hydrogels confirm reasonable electric conductivity and impressive anti-bacterial performance. In addition, structural and compositional analysis such as SEM, EDX, XPS, and Raman spectroscopy are conducted. From in-vitro tests of fibroblast cells, we observe that the application of electrical signals accelerates the growth rate, and the resulting current responses are contingent on the magnitude of cell proliferation. Our composite hydrogels combine both electrical stimulation and detection functionality, desirable attributes for potential use in wound healing application.
(Plenary) Wearable Sensors for Monitoring Chemical Markers: Beyond Steps and Vitals
Authors: Wang Joseph
Published: May 2020

Wearable sensors have received a major recent attention owing to their considerable promise for monitoring the wearer’s health and wellness. The medical interest for wearable systems arises from the need for monitoring patients over long periods of time. These devices have the potential to continuously collect vital health information from a person’s body and provide this information to them or their healthcare provider in a timely fashion. Unlike early efforts aimed at monitoring mobility and vital signs, our recent efforts aim at filling the gaps by providing continuous biochemical information. The new chemical sensing wearable platforms provide new avenues to continuously and non-invasively monitor individuals and can thus tender crucial real-time information regarding a wearer’s health. This presentation will discuss recent developments in the field of wearable electrochemical sensors integrated directly on the epidermis or within the mouth for various non-invasive biomedical monitoring applications [1-3]. Particular attention will be given to non-invasive monitoring of metabolites and electrolytes using flexible amperometric and potentiometric sensors, respectively, along with related materials, energy and integration considerations. Microneedle sensor arrays for multiplexed ISF monitoring will also be discussed also with wearable energy harvesters aimed to power these devices. The preparation and characterization of such wearable electrochemical sensors will be described, along with their current status and future prospects and challenges.

REFERENCES [1] "Wearable Chemical Sensors: Present Challenges and Future Prospects" A. J. Bandodkar, I. Jeerapan, J. Wang, ACS Sensors,
2016, 1, 464.

[2] A. J. Bandodkar and J. Wang, “Non-invasive wearable electrochemical sensors: a review”, Trends Biotechnol.,
2014, 32, 363.

[3] “Wearable biosensors for healthcare monitoring”, J. Kim, A. S. Campbell, B. Esteban-Fernández de Ávila, and J. Wang, Nature Biotechnology, 2019, 37, 389.
Raman Sensor Design for Point of Care Medical and Environmental Analysis
Authors: Charron Benjamin , Masson Jean-Francois
Published: May 2020

Due to its ability to directly probe water containing samples as well as yielding specific signal, Raman spectroscopy is rapidly expanding to various fields. The great potential of this technique has also drawn a lot of attention on the different ways by which Raman signal can be enhanced, notably by plasmonic nanostructures. Plasmonic materials enhance Raman by generating an enhanced oscillating field. The strength of that field has a great impact on the intensity of the Raman signal obtained from analysis with these materials. This field can be optimized by various methods shown before like an optimized nanostructure, addition of a stronger plasmonic metal, or alternating layers of metal and dielectric. We report here the result of a study of a newly designed plasmonic sensor combining multiple of these previously mentioned optimizations. This sensor is designed to be used for point of care analysis of street drugs on Canadian supervised consumption or overdose prevention sites and for analysis of microalgaes secretions in the ocean. Street drugs are to be analysed in order to detect contaminants and dangerous component. A user warned about a dangerous compound in its drugs is more likely to reduce his dose or even avoid taking the drug at all, effectively preventing unfortunate consequences. On the other hand, algaes play an important role in the marine ecosystem. Their life cycles and the bio-molecules they produce correlate with the environment in which they grow. Being able to detect, identify and quantify these secretions in real time directly in the ocean would allow us to use them as sensors for global warming. As an example, the melting of the icecaps would locally dilute the nutrients which in turn would change the way the algaes survive and their secretions. The resulting sensor must therefor offer strong Raman signal and good stability, be easy to use and produce, and be cheap to produce.

To tackle these multiple challenges, we have developed a sensor produced directly on a stressed polymer sheet available in arts and craft stores. The sheets are covered with layers of metal and nanostructures before being heated in an oven. The heat causes the polymer to shrink, effectively wrinkling the metal sheets on its surface. This type of surface has first been studied with various thicknesses of silver and gold. The best surface was then studied with additional structures on its surface in order to create both a stronger and a more homogeneous surface.

Keeping the targeted analytes in mind, the sensors’ potential was evaluated both with 633 nm and 785 nm laser. Ability to choose the wavelength is important as a lower laser wavelength offers a stronger Raman intensity, but a higher wavelength limits fluorescence of the analyte or solution. Sensors were also tested both in air and in water, and compared with other Raman sensors.
(Invited) Plasmonic and Surface Plasmon Electrochemiluminescence Sensors for Detecting Biomarkers and Drugs
Authors: Masson Jean-Francois , Polo Federico
Published: May 2020

In this presentation, a series of different plasmonic sensors for the detection of cancer biomarkers, cancer therapeutic drugs and the response of patients to oncological biological drugs will be presented. The plasmonic sensors are based on a portable 4-channel SPR instrument and surface chemistry developed to present fouling of the sensors in crude serum or plasma. Sensors for detecting methotrexate and for the immune response induced by asparaginase in leukemia treatments directly in sera of patients during ongoing therapies will be presented. Our work towards the detection of HER-2 positive breast cancers will also be presented, with a comparison of commercial and point of care SPR instruments. Our initial work on the development of a SPR-electrochemiluminescence instrument will be presented. We recently revealed that performing SPR and electrochemiluminescence on a single instrument provides unprecedented information about the interfacial processes occurring on the electrode. In addition, studying the energy transfer between the ECL and the plasmon revealed that the optically excited plasmon reduced the ECL intensity in the far-field by about 40% due to a lower plasmon mediated luminescence process. Hence, the combination of SPR and ECL is highly advantageous to study electrochemical processes.
(Invited) Microfluidics-Enabled Sensing for Making in Vitro Diagnostics Miniaturized, Portable and Even Wearable
Authors: Jiang Xingyu
Published: May 2020

Microfluidics represent a collection of technologies for the precise manipulation of minute amount of fluids. We demonstrate that microfluidics can dramatically improve the efficiency of diagnostic analysis, such as immunoassays (for proteins and small molecules), amplification of nucleic acids, and analysis of cells. Driven by miniaturization and surface chemistry, microscale-chips allow high throughput analysis of these biological entities for improvement of outcome in quality of diagnosis, such that many diseases can treated early or prevented. Miniaturization allow diagnostics to become de-centralized such that many types of assays can be done in point-of-care settings, instead of in centralized laboratories. These point-of-care applications allow many of these assays to become more like the blood sugar tests, which are increasingly done at home. A future idea is to further miniaturize these devices such that they can be wearable. A challenge in making these electrical devices wearable is the inherent hardness of all components in electrical devices. An avenue in which microfluidics can help with this area is to make wearable electronics possible by confining liquid metals into polymeric composite (MPC)-based microfluidics to make printed circuitry completely flexible such that essentially any device can become soft and wearable. The superior biocompatibility of these MPC may have applications in many areas.
(Invited) Wearable Sweat Sensors for Personalized Health Monitoring
Authors: Gao Wei
Published: May 2020

The rising research interest in personalized and precision medicine promises to revolutionize traditional medical practices. This presents a tremendous opportunity for developing wearable devices toward predictive analytics and treatment. In this talk, I will introduce fully-integrated flexible biosensors for multiplexed in-situ perspiration analysis, which can selectively and accurately measure a wide spectrum of sweat analytes (e.g., metabolites, electrolytes, heavy metals, drugs, and other small molecules). This platform allows us to gain real-time insight into the sweat secretion and gland physiology. I will also demonstrate an integrated wearable sweat extraction and sensing system which can be programmed to induce sweat on demand with various secretion profiles. To demonstrate the clinical value of our wearable sweat sensing platform, human subject studies were performed toward fitness monitoring, physiological monitoring, disease diagnosis and drug monitoring. These wearable and flexible devices open the door to a wide range of personalized monitoring and diagnostic applications.
WITHDRAWN: Differential Multiplexed Signalling Strategy Enables Ultrasensitive Photoelectrochemical DNA Detection Via Direct Electron Transfer between Plasmonic and Semiconductive Nanoparticles
Authors: Victorious Amanda Pansy , Saha Sudip Kumar , Soleymani Leyla
Published: May 2020

This abstract has been withdrawn at the request of the authors.
Battery-Powered Distance-Based Electrochemical Sensor
Authors: Chow Kwok-Fan , Wijesinghe Sachintha
Published: May 2020

In this presentation, we report a battery-powered distance-based electrochemical sensor that can be operated without the need for laboratory-based instruments. This sensing platform can effectively convert an electrochemical current from a sensing reaction to a visual signal that is identifiable as the length of the silver band electrode (Ag BE). As presently configured, the electrochemical sensing reaction occurs when the working electrode triggers the electro-oxidation of the Ag on the Ag BE, which causes the Ag BE to shorten due to oxidation. The key advantage of this new sensor is that it can be operated using a two-electrode system, which allows this sensing platform to operate using only two AA batteries as the power source. We suggest this approach as a conceptual pathway that can lead to instrument-free distance-based electrochemical sensor design.
Graphene Oxide Modified Electrode for DNA Amperometric Detection Using Microfluidic Electrophoresis Chip
Authors: Kim Hyo Eun , Schuck Ariadna , Kim Yong-Sang
Published: May 2020

The amperometric technique of capillary electrophoresis (CE) is an electrochemical detection method with various advantages that is suitable for biosensors. The amperometric detection system can be easily integrated with the CE system without the need for complicated additional equipment for optical detection. For this reason, the size of the sensor can be reduced to micro-scale, also reducing the cost of the fabrication process, enabling this system to be used in point-of-care applications [1]. The optical method depends on the detection of the fluorescence intensity of the target sample. However, amperometric detection omits the pretreatment process of the sample, such as purification extraction of samples and fluorescent staining for detection [2]. These features allow the device system to be miniaturized and having a rapid response for applications like lab-on-a-chip [3]. Modified Au electrodes integrated with PDMS based microfluidic channels were proposed as an on-chip amperometric detection of CE for DNA sensors. The graphene oxide (GO)-modified Au electrodes were fabricated via photolithography process and drop-casting deposition. First, the deposited Au electrodes were patterned with positive photoresist (PR) using the photolithography method. Next, the graphene oxide was deposited 5 layers on the bare Au using drop-casting technique. Finally, the PR was dissolved by acetone and the unwanted GO was lifted-off. The surface characterization of this the GO-modified Au electrodes is shown in Fig. 1(a) by microscopy image. It was observed that the GO was deposited on Au electrodes following the desired pattern. This treatment amplifies the current signal of amperometric detection of the CE microchip. The performance of the CE amperometric detection device has been demonstrated by sensing an amplicon lambda phage DNA. Then, 1 µL of amplified lambda phage DNA (1 ng/µL) using the conventional polymerase chain reaction (PCR) with a 30-cycle reaction was used as target sample. Figure 1(b) shows the current peak of amperometric detection before (1.9 µA) and after (6.6 µA) GO-modified on the Au electrodes which amplified the sensitivity more than 3.5 times before electrode modification. The emphasized detection of lambda phage DNA using modified electrodes gives a further possibility of biomedical applications through our developed microchip.

References

1. D. E. Scott, S. D. Willis, S. Gabbert, D. Johnson, E. Naylor, E. M. Janle, J. E. Krichevsky, C. E. Lunte and S. M. Lunte, Analyst, 2015, 140, 3820–3829.

2. N.-C. Chen, C.-H. Chen, M.-K. Chen, L.-S. Jang, M.-H. Wang, Sens. Actuators B Chem. 2014, 190, 570–577.

3. K. Ha, G. S. Joo, S. K. Jha, Y.-S. Kim, Microelectr. Eng. 2009, 86, 1407–1410.

Figure 1
Performance and DRT Analysis of Surface Decorated Spinel-Oxide Electrodes for Mixed-Potential Type Ammonia Gas Sensor
Authors: Bhardwaj Aman , Kumar Aniket , Bae Hohan , Song Sun-Ju
Published: May 2020

The solid-electrolyte based electrochemical gas sensors appeared as the most promising sensing technology for the in-situ quantification of exhaust pollutants. At present, high sensitivity and selectivity supplemented by suitable long-term stability is the bottleneck challenge for these technologies to commercialize. In present work, highly sensitive and ammonia (NH3) selective mixed-potential gas sensors were developed using surface decorated CuFe2O4(CFO) spinel oxide electrodes. The CFO–NiO composite SE delivered a maximum response of −62 mV to 80 ppm ammonia, supported by a sensitivity of -70 mV/dec. at 650 ℃. By a thorough analysis of response behavior and I–V characteristics, the sensing mechanism was found to be based upon the mixed-potential model complying to the reaction-rate limited Butler–Volmer NH3 oxidation kinetics. Finally, the DRT analysis of impedance spectra confirmed that the overall polarization resistance was invariable of the mass-transport processes and solely governed by the extent of interfacial redox reactions proceeding at the triple-phase boundaries (TPB), determining the electrode potential of the sensor. Moreover, the high sensitivity, selectivity, and excellent stability without a degradation over five months, validated the suitability of these sensors to be a potential candidate for in-situ ammonia quantifications in industrial and automotive applications.
Synthesis and Electrochemical Application of MxFe3-XO4 (M=Cu,Co) for the Detection and Removal of Metal Pollutants
Authors: Mohammed Soumhi
Published: May 2020

Over the last two decades, nanomaterials (metallic nanoparticles, carbonaceous nanostructures) have triggered great interest thanks to their specific physic-chemical properties. The improvements they have made in the field of electro-analysis are numerous. Thus, a wide range of physic-chemical technologies based on the use of inorganic materials for the detection and removal of water pollutants has become a promising voice. In this context, we were interested in the design of electrodes modified by nanomaterials of the spinel type CxFe3-xO4 for the detection and quantification of metallic micro pollutants in water. The phases of the spinel system were synthesized by the sol-gel method, and physic-chemical characterization was performed by ATD-TG, DRX and MEB. The methods used for the electrochemical test are cyclic voltammetry (CV), square wave voltammetry (SWV) and impedance spectroscopy (EIS).

The results of the physic-chemical analysis of the oxides showed that the phase is obtained at a calcination temperature of 600°C, and the electrochemical tests of the elaborate electrode revealed a very high sensitivity to ions (Mn2+, cd2+, pb2+, Hg2+).

Keywords:
nanoparticles, spinals, metal pollutants, modified electrode, electrochemical tests.
Preparation of Nanopore-Containing Metal Oxide Particles and Their Gas Sensing Characteristics
Authors: Akamatsu Takafumi , Itoh Toshio , Masuda Yoshitake
Published: May 2020

We reported the successful formation of nanopores within core-shell type metal oxide particles using the shell layer as a template. Using the polyol method, core-shell type metal oxide particles such as cerium oxide, zinc oxide, and cobalt oxide with primary particles of ~10 nm and secondary particle sizes between 20 and 300 nm were prepared, where the polymer shells comprised 10-20 wt% of the total mass. These particles were easily dispersed in water and organic solvents without the use of dispersants. In addition, the core-shell type metal oxide particles were composed of an agglomeration of several tens of nanometer-sized core-shell primary particles, with sintering at 400 °C generating the desired nanopore-containing metal oxide particles. It was reported that in the SnO2 gas sensor for H2S sensing, nanopore manipulation in the sensor response layer leads to an increased response and selectivity toward H2S compared to the smaller and more reactive hydrogen gas. We therefore expected that an increase in the specific surface area of sensing films through the formation of nanopores in the secondary particles could result in additional reaction sites to lead to a higher gas responsiveness. Indeed, this was assumed to account for the high selectivities of high specific surface area cobalt nanofiber and nanosheet gas sensors toward acetone gas and ethanol gas. In this work, metal oxide particles with nanopores were prepared by a polyol method and sintering. The gas sensor characteristics of the particles with nanopores were compared with those of the particles without nanopores, and the effectiveness of 3D-nanostructure for gas sensing was also examined.

Figure. Schematic representation of the strategy used to prepare the 3D nanostructure of metal oxide particles with nanopores.

Figure 1
Hydrothermal Growth of Molybdenum Disulfide Composited with Electrodeposited Gold and Its Photoelectrochemical Properties
Authors: Jalali Mahsa , Siavash Moakhar Roozbeh , Abdelfattah Tamer , Filine Elizabeth , Mahshid Sahar Sadat , Mahshid Sara
Published: May 2020

Recently, molybdenum disulfide (MoS2) has received remarkably attention due to its excellent optical and electrical properties. Notably, the narrow bandgap of transition metal dichalcogenide (TMDC) MoS2 makes it a promising candidate for photoelectrochemical (PEC) applications. Direct growth of MoS2 via hydrothermal synthesize offers improved electrical conductivity between the MoS2 and the substrate, which allows for better application and electrical signal readings as a result of elevated electron transfer routs compared with drop-casted MoS2. Here, we studied the effect of hydrothermal growth time of MoS2 nanosheets on the morphology evolution as well as the PEC sensing properties. The time evolution studies conducted in the range of 2-10 hours. We used surface characterization method such as field emission scanning electron microscopy and analytical techniques such as chronoamperometry, cyclic voltammetry and electrochemical impedance spectroscopy to study the morphology evolution and PEC sensing properties. Our results revealed that the direct growth of MoS2 not only enhances the sensor signal but also encourages nanocomposites of MoS2 with gold- a key to simultaneouse amplification of the optical and electrical properties. Effect of applied bias potential in the range of 0.45-0.85 V vs. Ag/AgCl on photocurrent response was also investigated. We further used 3D COMSOL simulation to assess the effect of gold thickness on the electric field intensity of the sensing MoS2/Au electrodes. Eventually, we studied sensitive and selective detection of glucose as an important molecule in the human body. Our developed MoS2/Au composite demonstrated a very low limit of detection (1.3 nM) and excellent sensitivity for non-enzymatic PEC sensing of glucose. Moreover, the selectivity of the fabricated sensor were examined by monitoring the photocurrent responses towards different interfering agents under illumination.
Ultra-High-Sensitive Detection Using Pulse-Heating of MEMS-Type Oxide Semiconductor Gas Sensor: (1) Detection of Toluene in Ppt Level
Authors: Shimanoe Kengo , Suematsu Koichi , Watanabe Ken
Published: May 2020

Ultra-High-Sensitive gas detection in ppt level has been proposed by using pulse-heating of MEMS-device based on SnO2. My group reported three important factors, receptor, transducer functions and utility factor, for gas sensor material designs and their integration in 2003 (1) and 2006 (2), respectively. In 2014, based on the integration of the above factors, the gas sensor using Pd-SnO2 clusters prepared by hydrothermal treatment could successfully detect toluene in ppb level (3). To enhance the sensor response more, we investigated the combination of utility factor and pulse-heating of MEMS. In 2018, we reported that such sensor responded to toluene in 0.1 ppb (4). To enhance the sensor response, we paid attention to oxygen adsorption species and the amounts. In the case of Pd-SnO2, oxygen adsorbed as mainly O2- on the surface, but the amounts become smaller with decreasing in temperature. To overcome such oxygen adsorption state, we investigated the preheating and waiting-time before pulse-heating for measurement. Finally, the gas response was found to increase as shown in Fig. 1. It is found that the sensor response depends on the waiting-time between pre-heating and measure-heating. In the presentation, I will show the details of UHS (Ultra-High Sensitive) gas sensor.

References

(1) N. Yamazoe, G. Sakai, K. Shimanoe, Catalysis Surveys from Asia, 7(1), 63-75 (2003).

(2) K. Shimanoe, N. Yamazoe, Proc. The 4th AIST International Workshop on Chemical Sensors, pp. 43-51 (2006).

(3) K. Suematsu, Y. Shin, Z. Hua, K. Yoshida, M. Yuasa, T. Kida, K. Shimanoe, ACS Appl. Mater., 6, 5319−5326 (2014).

(4) K. Suematsu, W. Harano, T. Oyama, Y. Shin, K. Watanabe, K. Shimanoe, Anal. Chem., 90(19), 11219-11223 (2018).

Figure 1
Autonomous Silicate Electrochemical Sensor in Seawater
Authors: Chen Legrand Dancheng , David Arnaud , Barus Carole
Published: May 2020

Long term monitoring of dissolved inorganic nutrient concentrations such as silicate is the key to improve our understanding of biogeochemical cycles in the ocean. Electrochemical methods are proposed to measure in situ silicate concentration as they allow developing miniaturized, reagentless sensor. We report here on the development and the optimization of the in situ version of our silicate sensor.

Silicate is a non-electroactive specie and its determination is performed by measuring its corresponding silicomolybdic complex formed in situ at acidic pH after the oxidation of a molybdenum electrode while the counter electrode is isolated behind a Nafion® membrane [1].

The mechanical design of the sensor has been adapted from the laboratory prototype containing two connected cells: one to form the complexe and one for its detection on a gold electrode (Φ=2mm) by cyclic voltammetry. All the electrochemical and chemical parameters, such as the Mo oxidation, the complexation time, the silicomolybdic complex detection as well as the complex transfer from one cell to the other and the cleaning protocol have been optimized to detect the smallest silicate concentration possible with the shortest time. Reproducible calibrations performed with this sensor provided linear regressions between 1.63 µmol L-1 and 140 µmol L-1 and a limit of quantification of 1.63 µmol L-1. Repeatability is achieved over 53 tests on the same silicate concentration with less than 4% variation. The study of temperature effect revealed no influence on the electrochemical signal between 7° and 21°C.

The very first time series of silicate concentration was obtained after a successful deployment of our silicate sensor at 55 meters depth on a mooring off Coquimbo, Chili in 2017 [2].

More recently, two synchronized silicate sensors have been deployed in May 2019 off-shore Easter Island (Rapa Nui) at 100 meters depth in the Pacific Ocean. Several seawater samples were also collected at the same depth of sensor deployment to analyse the silicate concentration by colorimetric measurement in order to inter-compare the results obtained by the sensors and make corrections of any drift.

Also, one silicate electrochemical sensor has been deployed in Thau pond (Mediterranean Sea), France at 1.5 meters depth during 19 days (July 2019). Water samplings were carried out at the same depth, twice a day (one in the morning and one in the afternoon) during the week and will be analysed by colorimetric measurement at the Marine Station in order to inter-compare the results obtained with silicate sensors.

The sensors were measuring silicate concentration every 45 minutes. All the results obtained during these deployments will be presented and discussed.

[1] Lacombe et al., Talanta 77 (2008) 744-750.

[2] Barus/Chen Legrand et al., Frontier in Marine Science (2018) 5, 60
Nanomaterial-Based Electrochemical Sensor for the Monitoring of Sodium Metabisulfite
Authors: Durairaj Sharmila , Sidhureddy Boopathi , Manikandan Venkatesh , Wang Qi , Chen Aicheng
Published: May 2020

Deoxynivalenol (DON) is a mycotoxin, which is produced by the Fusarium genus and widely found in cereal grains such as wheat and corn. Swine are sensitive to DON; even a small amount (1 ppm) can make swine sick (e.g., upset stomach, vomit, less feed intake). Sodium metabisulfite (SMBS) is a promising feed additive in swine farming to overcome the issues caused by DON. Currently, high performance liquid chromatography, mass spectroscopy, UV-Visible spectroscopy and infrared spectroscopy are used for the quantification of SMBS. However, all these techniques are expensive and time-consuming; they cannot be used in field analysis. Here, we report on an advanced electrochemical sensor based on fluorinated reduced graphene oxide modified with gold nanoparticles (Au/F-rGO) for rapid detection and monitoring of SMBS. Scanning electron microscopy and energy dispersive X-ray spectroscopy were employed to characterize the morphology and the composition of the fabricated Au/F-rGO electrode. Cyclic voltammetry, linear sweep voltammetry and differential pulse voltammetry were used to investigate the electrochemical performance of the Au/F-rGO sensor. Our study has shown that the optimized Au/F-rGO electrode exhibits a wide linear range of responses, a low limit of detection, high sensitivity and high stability for the SMBS detection. The sensor has been further tested with different digestive fluids (e.g., stimulated salivary fluid, stimulated intestinal fluid and stimulated gastric fluid), showing high selectivity and promising practical applications.
Inkjet-Printed Cpw Fed Wideband Bowtie Slot Antenna on PET Substrate for Flexible Iot Applications
Authors: Riheen Manjurul Ahsan , Nguyen Tuan Thanh , Saha Tonmoy Kumar , Karacolak Tutku , Sekhar Praveen K.
Published: May 2020

A bowtie shaped slot antenna with a new design is realized on a flexible and low-cost polyethylene terephthalate (PET). The slotted bowtie design is implemented with asymmetric flare angle with metal strip underneath each slot of the antenna. The designed free space antenna is fabricated using inkjet printing and tested. The measurements showed good agreement with the simulations. The fabricated antenna operates over 2.1– 4.35 GHz frequency range (69.77% fractional bandwidth) and exhibits omnidirectional radiation pattern with a peak gain of 6.3 dBi at 4.35 GHz. The bending test of the fabricated device reveals good flexibility on a curved surface without significant antenna performance degradation. The antenna is simple in structure and easy to retune to achieve the desired radiation characteristics. The tunability is validated by simulating another version of the parent antenna (free space antenna) for drywall mounting applications. The compact size, higher bandwidth, omnidirectional pattern with a higher peak gain and flexible properties of the antenna makes the design suitable for Internet of Things (IoT) applications.
Electrolyte-Gated Organic Field-Effect Transistor for Ultra-Sensitive Cs Ion Sensor
Authors: Nguy Tin Phan , Hayakawa Ryoma , Kilinc Volkan , Petit Matthieu , Raimundo Jean-Manuel , Charrier Anne , Wakayama Yutaka
Published: May 2020

A main purpose of this work is to develop a new ultra-highly sensitive sensor in particular for the detection of Cs+ ions in natural water. The radioactivity of Cs+ ions produced in nuclear power stations (NPSs) causes serious impact on the health condition of humans, as well as aquatic plants and animals. Therefore, it should be strictly controlled. However, a large amount of radioactive Cs+ had been distributed from Fukushima NPS due to the tragic accident after the great earthquake in Japan. Because of these reasons, the detection and monitoring of Cs+ ions in natural water are necessary. To tackle this issue, we developed an organic field-effect transistor (OFET)-based ion sensor. The sensor is composed of three main components: (1) organic semiconducting channel with high stability in working with natural water, (2) monolayer lipid membrane working as ultra-thin dielectric layer to allow low operating voltage and high sensitivity, and (3) novel calixarene-crown ether probe for high selectivity to Cs+
, which is grafted with lipid layer.

Here, gate bias voltage is applied through electrolyte solution, in which the target ion and other competing ions are simultaneously contained. Once ion probes form metal-complex with Cs+, the electrical signal from the ion, the concentration of which is even on the ppb order, can be detected as a shift of threshold voltage. This is owing to the large electrical capacitance of monolayer lipid membrane. In comparison with other conventional methods like ICP-MS, our new sensor has many advantages: high sensitivity and selectivity, high-throughputs, integration and portability associated to real-time and on-site monitoring capabilities. In this presentation, we demonstrate a label-free sensor operation with the sensitivity of femtomolar (pg/l) concentrations of Cs+ ion with high selectivity.
Development of a Microfluidic Front-End, Sample-Processing Subsystem
Authors: Bywaters Kathryn Faye , Quinn Richard C. , Boone Travis D. , Ricco Antonio J.
Published: May 2020

One of the highest science risks during NASA missions involving living organisms, including the search for them and/or their biomarkers or signatures, is the quality and reliability of sample preparation and handling prior to in-situ analysis (1; 2). Afluidic instrument is being developed, Charged Info-storage Polymer Prep System (ChIPPS), that will enable automated preparation of an environmental sample by extracting, concentrating, and desalting information-storage polymers. Linear charged polymers with multiple functional block types—typified by, though not limited to, the nucleic acids DNA and RNA— are a class of molecules understood to be necessary for life’s function and replication (3). The capability to characterize charged polymers for detecting biosignatures is driven by the emergence of nanopore technology. ChIPPS will prepare environmental samples for downstream delivery to biosignatures detection instruments, such as those being developed using nanopore technologies.

References:

(1) La Duc, M.T.et al."Comparative analysis of methods for the purification of DNA from low‐bio-mass samples based on total yield and conserved microbial diversity," JRapid Methods & Automation Microbio17.3(2009): 350-68. (2) Salmon, K.et al."Global gene expression profiling in Escherichia coliK12 the effects of oxy-gen availability and FNR," J.BioChem278.32(2003): 29837-55. (3) Benner, Steven A., and Daniel Hutter. "Phosphates, DNA, and the search for nonterrean life: A second generation model for genetic molecules," BioorgChem30.1(2002): 62-80
(Invited) Microfluidics Enabled Protein Fractionation and Soft Wearable Robots
Authors: Ren Carolyn
Published: May 2020

Microfluidics is a science that deals with small amounts of fluids at the microscale. The confinement brings in many advantages such as reduced reagent consumption, shortened analysis time, increased throughput and potential for portable systems. These advantages and others make microfluidic systems ideal enabling platform technologies that can be applied in a wide range of applications spanning from material synthesis, life science research, drug screening and environmental monitoring. This presentation summarizes Ren’s work on microfluidics that is dedicated to protein fractionation and soft wearable robots towards well-being. Protein fractionation techniques will include a suite of techniques such as isoelectric focusing, free flow focusing and pH elution. The soft wearable robots enabled by microfluidics will start with a brief introduction of soft robots and follow up with the unique angle that Ren’s team took for developing inexpensive, comfortable daily wearable assistive robots. Its demonstration and validation towards patients suffering from arthritis will be provided and discussed.
(Invited) Considerations in the Scale-up of Lab-on-Chip and Microfluidics Products
Authors: Levine Leanna M.
Published: May 2020

Microfluidics-based products are particularly difficult to transition efficiently from a laboratory concept to a beta product that meets target costs for a consumable. The reasons for this has to do with the complexity of microfluidics products, including the use of multiple manufacturing methods and mixed materials to create complete devices, the integration of reagents and liquids, and the integration of sensors. This presentation will discuss the different manufacturing methods involved in the development of a microfluidic product, and present a road map for the timelines and costs for a model cartridge concept. Of particular interest is to consider the trade-offs in not considering design for manufacture during the later part of the research phase before design lock.

This presentation will guide start-ups in asking the right questions and getting the right data to their investors to hit milestones and be on track with a credible cost of goods.
(Invited) Study of Electrochemiluminescence Nanohybrid and Their Application in Biomarker Detection of Myocardial Infarction
Authors: Yang Xiurong
Published: May 2020

Electrochemiluminescence (ECL) as an analytical technique has attracted increasing attention in clinical diagnosis and environmental assays due to the controllability in temporal, space, and light emitting intensity, simple operation, cost-effectiveness, high sensitivity, and low background signal. Compared to other methods for biomarker detection of Myocardial Infarction, ECL shows high sensitivity and a wide detecting range.

The common biomarkers for myocardial infarction include troponin, creatine kinase, myoglobin copeptin, and miRNA. Among those biomarkers, cTnI not only has excellent cardiac specificity but also can provide a long detecting window for cardiac injury, which has been acknowledged as the principal biomarker for AMI.

We have developed ECL nanohybrid materials and detection methods for the applications in biomarker detection of myocardial infarction, which include Ru-MOF nanosheet, Ru linking BPEI-coated carbon dots, dual-wavelength ratiometric ECL biosensor, ratiometric ECL–electrochemical(EC) hybrid biosensor, wavelength-resolved ECL resonance energy transfer (ECL-RET) ratiometric immunosensor and so on. These ECL biosensors immunosensors exhibit excellent sensitivity, specificity, stability, and reproducibility. Therefore, they have great application prospects for biomarker detection in clinical diagnosis.

ACKNOWLEDGMENTS

This work was supported by the National Key Research and Development Program of China (2016YFA0201301), the National Natural Science Foundation of China (No. 21435005 and 21627808), the Key Research Program of Frontier Sciences, CAS (no. QYZDY-SSW-SLH019).
Effect of Nobel Metal Ions on the Synthesis of Metal Nanoclusters for Selective Detetction of Various Heavy Metals
Authors: Nain Amit , Tseng Fan Gang , Chang Huan Tsung
Published: May 2020

In this study, effect of noble metal ion (Au, Ag and Cu) on the synthesis of metal nanoclusters (MNCs) has been investigated. Through heating at 70ºC, TSA/BSA-Au, -Ag and -Cu NCs were separately prepared from Au3+, Ag+and Cu2+in the presence of bovine serum albumin (BSA) and thiosalicylic acid (TSA). They exhibit photoluminescence (PL) at 700, 624 and 430 nm,with average life times of 1500, 100 and 11.71 ns,respectively, when excited at 350 nm. X–ray photoelectronspectroscopy (XPS) data support the presence of metal core (M0) and metal–thiolate shell (Mn–SRm), each in the TSA/BSA-MNCs. Spectroscopic measurements reveal the formation of Au32–SR, Ag9–SR and (Cu4–Cu13)–SR species separately in the TSA/BSA-Au, -Ag and -Cu NCs. Through PL quenching of the TSA/BSA-Au, -Ag and -Cu NCs, they have been used separately for quantitation of Hg2+, As3+and Cr6+ , with linear rangesof 10-400, 4-18, and 40-400 nM and limits of detection (LODs) of 0.25, 2.34 and 3.54 nM, respectively. The PL quenching is mainly due to aggregationof the MNCs through metallophilic or metal–thiol complexation.The stable TSA/BSA–Au, -Ag and -Cu NCs have been employed separately for the determination of the concentrations of Hg2+, As3+and Cr6+ions in the spiked sea water samples, showing advantages of simplicity, rapidity, high selectivity, and sensitivity.
(Invited) Non-Invasive Plasmonic Based Real Time Characterization of Cardiac Drugs on Cardiomyocytes Functional Behavior
Authors: Mozneb Maedeh , Mirza Asad M , Li Chen Zhong
Published: May 2020

Monitoring functionality of cardiac tissue is of utmost importance for understanding the health and maturity of its constructing cells. One major gap in current research for monitoring cardiac tissue’s function in terms of its contraction rate is lack of a comprehensive system that can measure such features without interfering directly with tissue. Fluorescent labeling and micro sensors integrated within cells are known to change a variety of tissue’s phenotype, which in turn results in inaccurate readings. Here we have exploited the potential of Surface Plasmon Resonance as a label free technique to monitor cardiac tissue contraction rate under normal conditions and in response to chemical stimulation. Employing a microfluidic module, facilitated a perfusion-based system with an optimal flow rate of 10 μlit/min, which provided a more realistic pharmacokinetic of 10 μM drug (ATP and Blebbistatin) administration. The effect of chemicals was detected with high spatiotemporal sensitivity on contracting cardiomyocytes. Our drug screening has identified the source of SPR periodic signal to be directly cell contraction rather than action potentials or calcium signaling. Per our results, SPR has high potential in applications in least interference real-time and label-free tissue characterizations and cellular properties analysis from a functional and structural point of view.
A Paper-Based Surface-Enhanced Raman Scattering (SERS) Biosensor for Label-Free Detection of Serum Bilirubin for Diagnosis of Jaundice
Authors: Li Ming
Published: May 2020

Jaundice continues to be a serious health concern and is among the leading causes of deaths during the first days of newborn babies’ lives. Serum bilirubin is currently being exploited in the clinic as a key biomarker for the diagnosis and management of neonatal jaundice. The commonly used methods for serum bilirubin determination in clinical settings are direct spectroscopic measurement and the diazo reaction method. These methods have drawbacks such as low sensitivity, matrix interference, poor stability, high-cost, professional training, less specificity and tedious sample preparation. Thus, it is very urgent to develop a rapid and economical route for sensitive and specific detection of free bilirubin directly in human serum.

Surface-enhanced Raman scattering (SERS) has emerged as a powerful analytical technique for biosensing applications with high sensitivity, molecular specificity, powerful multiplex detection capability, and excellent photostability. This talk will present our recent study on the development of a paper-based SERS biosensor for label-free detection of bilirubin in serum. This biosensor comprises multifunctional graphene oxide-gold nanostar (GO-GNS) hybrids decorated on the filter paper. This biosensor combines the enrichment for serum bilirubin and plasmonic enhancement for Raman signals of bilirubin for boosting the label-free detection sensitivity directly in blood serum without the need for additional sample preparation. Our results demonstrated the excellent detection performance for detection of bilirubin directly in serum in a label-free manner, and the detection results were compared with the commercial diazo reaction method, which justifies the clinical effectiveness and suitability of the present paper-based SERS biosensor. We believe that the present paper-based SERS biosensor has great potential for clinical translation in accurate diagnosis of jaundice and other related diseases.
Carbon Monoxide Sensing for a Low-Cost Mobile Health Device
Authors: Shalforoosh Sarem , Sinoway Jordan , Pearlstein Larry , Hunter Rebecca
Published: May 2020

We explore the use of electrochemical sensors toward the creation of a personal carbon monoxide monitoring device. Our ultimate goal is the development of an inexpensive, highly integrated mobile health (mHealth) device for improving the outcomes, and decreasing the treatment costs, for smoking cessation therapy among low socioeconomic status (SES) patients. We will combine a number of proven modalities into a single device, which we call the T-COM. This hand-held personal device will integrate a breath carbon monoxide sensor, multilingual motivational text and audio messaging, gamification features and built-in wireless network connectivity.

The requirements relating to measuring the concentration of CO in exhaled breath are especially challenging. They include the following – low cost, minimal thickness, robust to a range of ambient temperatures and humidity, as well as being minimally affected by the high humidity in breath. Concentrations as low as a few ppm of CO must be measurable, with an accuracy of a few ppm. The device must not require field calibration. The sensor must be ready for use at virtually any time with no warm-up period, and must register an accurate measurement in under ten seconds. The required support circuitry must be available with similar constraints on cost, size and accuracy.

We experimented with several commercially available CO sensors and circuit topologies, and we report on our findings. In addition we have looked into methods for controlling the level of humidity that reaches the sensor, without otherwise affecting the measurement accuracy. Our results to date suggest that a practical solution is achievable, although further improvements would be valuable.

Figure 1