bluuebunny/crossref_metadata_2025 huggingface dataset:
In Brain and in Vein Detection of Antibiotics Using Electrochemical-DNA Biosensors
Authors: Dauphin Ducharme Philippe
Published: May 2020

Current approaches towards drug dosing rely on venous draws measurements performed on test patients which are laboratory-analyzed and returned the following days. This practice forces physicians to administer potentially toxic or ineffective concentrations of drugs to patients since dosages are determined based on weight and age of this test group even though pharmacokinetics may differ in each individuals. Having a technology that would in contrast allow, direct, continuous, real-time monitoring of drugs in the living body would revolutionize healthcare and allow personalized drug dosage and adjustment while enabling the development of artificial organs responsible of adjusting these levels.

Motivated by this goal, we have developed a class of electrochemical aptamer-based (E-AB) sensors[1]. These sensors are comprised of a redox-reporter-modified DNA “probe” that is attached by one terminus to a self-assembled monolayer deposited on an interrogating gold electrode. The binding of an analyte to this probe alters the kinetics with which electrons exchange to/from the redox reporter via binding-induced conformational changes producing an easily measured change in current when the sensor is interrogated using square-wave voltammetry (see Figure) [2]. E-AB sensors are capable of detecting with high specificity their molecular targets in flowing whole blood and directly in the living body. I will present during this presentation some of these sensors deployed in the vein [3] and in the brain of sedated rats to monitor the pharmacokinetics of the antibiotic, vancomycin. The ability of acquiring high frequency measurements of drug plasma levels using these biosensors has also allowed us to develop a technology that improves our ability to deliver them [3]. Due to their small size, these sensors can also be deployed directly in the brain of freely moving animals to monitor molecules with unmatched temporal resolution [4]. All these advancement in developing E-AB sensors are aimed towards developing new analytical tools for personalized medicine while improving our understanding of drug metabolism.

[1]: Dauphin Ducharme, P. and Plaxco, K. W. Anal. Chem.
2016 88: 11654–11662.

[2]: Li, H., Dauphin Ducharme, P., Ortega, G., Plaxco, K. W. J Am. Chem. Soc.
2017, 139, 11207-11213.

[3]: Dauphin-Ducharme, P., Yang, K., Arroyo-Currás, N., Ploense, L. K., Zhang, Y., Gerson, J., Kurnik, M., Kippin, T. E., Stojanovic, M., Plaxco, K. W. ACS Sensors 2019, 4, 2832-2837.

[4]: Ploense, K. L., Dauphin-Ducharme, P., Arroyo-Currás, N., Curtis, S. D., Williams, S., Schwarz, N., Kippin, T. E., Plaxco, K. W. 2019 In preparation.

Figure 1
Preparation of Low Invasive Type Glucose Sensor for Continuous Glucose Monitoring
Authors: Yasuzawa Mikito , Osugi Kazumasa , Li Jiang , Kurashina Masashi
Published: May 2020

Implantable glucose sensors for a continuous glucose monitoring (CGM) system are getting more attractive, since it not only provide an instant glucose value but also its continuous value trend, which help to provide an effective medical treatment. However, the current commercialized or presented conventional CGM sensor devise are required to have about an length of 1.0 cm to be inserted inside the skin. Therefore, it is desirable to develop a lower invasive type glucose sensor to improve the quality of life of diabetic patients.

We have previously proposed an unique glucose sensor, which has a sensing region at the tip of a fine tapered needle. Therefore, it only require a short tip of the sensor devise to be implanted to perform as an CGMS sensor. We attempted to implant this sensor device for a length of 1.0 mm in the skin, and the glucose monitoring was performed. As a result, we could obtain sensor response, which had a good correlation with blood glucose value trend. This result indicate that the glucose measurement in a lighter region than subcutaneous tissue, which might be in dermis, may also provide valuable information for diabetes patients’ blood glucose management. Nevertheless, low-invasive sensor, which is essential with miniaturization of sensing region, leads to a decrease of glucose response current. Therefore, the improvement of sensor sensitivity is also indispensable. In this study, we prepared glucose sensors in various procedures to develop a sensor with high sensor sensitivity.
Extracting Power from Biological Sources for Activating Sensors/Biosensors
Authors: Katz Evgeny , Bollella Paolo , Lee Inhee , Blaauw David
Published: May 2020

Implantable devices harvesting energy from biological sources and based on electrochemical transducers are currently receiving high attention. The energy collected from a biological environment can be utilized to activate various microelectronic and biosensor devices. This lecture is an overview of the recent research activity in the area of enzyme-based biofuel cells implanted in biological tissue and operating in vivo. The electrical power extracted from the biological sources presents use for activating microelectronic devices for biomedical and biosensor applications. While some microelectronic devices can work within a fairly broad range of electrical operating conditions, others, such as pacemakers, require precise voltage levels and voltage regulation for correct operation. Thus, certain classes of electronic devices powered by implantable energy sources will require careful attention not only to energy and power considerations, but also to voltage scaling and regulation. This requires appropriate interfacing between the energy harvesting device and the energy consuming microelectronic and biosensor devices. The lecture focuses on the problems in the present technology as well as offers their potential solutions. Lastly, perspectives and future applications of the implanted biofuel cells, particularly for powering biosensors are also discussed. The considered examples include a microelectronic sensor and a wireless signal-transfer system powered by implantable biofuel cell extracting electrical energy from biological sources.
(Invited) Receptor-Free and Label-Free Biomolecular Sensing Using Miniature Sensors
Authors: Thundat Thomas
Published: May 2020

Nano and microsensors sensors, such as micro/nano cantilevers, nanowires, inter-digital electrodes, etc., offer unprecedented sensitivity for real-time detection of chemical and biological molecules. These miniature sensor platforms offer all the much desired sensor characteristics such as size, low power consumption, simultaneous detection of multiple analytes, easy readout, and low cost, compared to conventional sensors. In general, molecular adsorption on a sensor surface changes one or more of its physical properties in proportion to the amount of molecules adsorbed. However, many of these miniature sensors do not offer any selectivity. Chemical and Biological selectivity is often accomplished by using labels or immobilized molecular receptors on their surfaces. Many successful demonstrations of chem/biomolecular detection with exceptional selectivity and sensitivity using immobilized receptors have been reported in the literature. However, reproducibility of the sensor response has not been addressed adequately in the literature. We have we have observed a wide distribution in the response data of microcantilevers, immobilized with the same receptors in identical fashion, to a specific target analyte. Because the measured variations in the resonance characteristics of bare cantilevers is less than one percentage, the observed distribution in the cantilever-based chemical and biological sensors data should be due to the variations in the immobilized layers. Receptor graft densities on the cantilever surfaces can vary during the immobilization process. The unpredictable variations in the graft density are the major source of irreproducibility in cantilever sensors and pose a formidable challenge for their practical use. In addition, bio-receptors such as antibodies suffer from disadvantages such as short shelf life, requirement of special storage conditions, and persistent nonspecific binding. Immobilized polymer layers and self assembled monolayers also show degradation with time. Therefore, developing concepts that can provide high selectivity without relying on immobilized chemical interfaces is very important. We have combined cantilever sensor and nano wire sensors with infrared spectroscopy for a novel sensor platform that offers excellent selectivity as well as sensitivity. Microfabricated sensors have a very small thermal mass and they are extremely sensitive to changes in temperature. When the physisorbed molecular species on a bi-material microcantilever sensor are excited into their vibrational levels by sequential exposure to pulsed infrared radiation (IR), the non-radiative decay of the excited species results in changes in the temperature of the sensor. Temperature changes of the sensor can be measured by many different methods and when plotted as a function of irradiating IR wavelength show peaks corresponding to molecular vibrations. Monitoring the IR spectra of adsorbed species mechanically offer very high sensitivity as well as selectivity. This technique can also be used for liquid analytes.
(Invited) Graphene-Based Field Effect Transistor Biosensor for Electrical and Label-Free Quantification of Exosomes
Authors: Zhang Guojun
Published: May 2020

Exosomes are small membrane-bound nanovesicles with a size of 50-150 nm, which contain many functional biomolecules, such as nucleic acids and proteins. Due to their high homology with parental generation, they are of great significance in clinical diagnosis. At present, the quantitative detection of low-concentration of cancer-derived exosomes present in biofluids is still a great challenge. In this study, we develop an electrical and label-free method to directly detect exosomes with high sensitivity based on reduced graphene oxide (RGO) field effect transistor (FET) biosensor. The RGO FET biosensor modified with specific antibody CD63 in the sensing area was fabricated, which was used for electrical and label-free quantification of exosomes. The method achieved a low limit of detection down to 33 particles/µL, which was lower than that of many other available methods. In addition, the FET biosensor was employed to detect exosomes in clinical serum samples, showing significant differences in detecting healthy people and prostate cancer (PCa) patients. Different from other technologies, this study provides a unique technology capable of directly quantifying exosomes without labeling, indicating its potential as a tool for early diagnosis of cancer.
Hydrothermal Synthesis, Characterization, and Fabrication of Tmdc Micro/Nanorods Based Sensor
Authors: Khan Saleem
Published: May 2020

In this work, hydrothermal synthesis of heavy metal (tungsten) based transition metal dichalcogenide (TMDC) with improved sensing phenomenon has been reported. WSe2 micro/nanorods were synthesized using electronics graded chemicals. After successful synthesis process the material containing micro/nanorods and particles was characterized using SEM, X-ray diffraction, and Raman spectroscopy. Inorder to fabricate the device, 190 nm SiO2 were grown over 2 inch p-type Si substrate were grown using thermal oxidation and thickness was confirmed using ellipsometry. Synthesized micro/nanorods were dispersed over SiO2/p-Si substrate and using one step lithography process 100 nm Au contacts were realized using sputtering method. Structural and electrical characterization of the device is carried out. I-V characteristics of the device carried to evaluate the voltage handing capability. The main aspect of the work was to test the device as low concentration gas sensor. A setup was developed and F2 gas concentration ranging from 0.5 ppm to 20 ppm was introduced in camber containing the sensor. Dynamic response of the device showed abrupt current shift of 2.6 nA/ppm at optimal temperature of 50 oC. The sensor has high and rapid response with good reproducibility.
A Highly Sensitive Electrochemical Sensor Based on Nanoflower-like MoS2-Ag-CNF Nanocomposites for Detection of VB2
Authors: Lin Jiaxin , Mei Qianwen , Duan Yingchun , Yu Chenhong , Ding Yaping , Li Li
Published: May 2020

The sensitive determination of VB2 has broad analytical applications. In this work, a novel VB2 electrochemical sensor based on hydrothermal method was constructed to uniformly grow molybdenum disulfide and silver nanoparticles on the surface of electrospun carbon fiber. MoS2-Ag-CNF was characterized by scanning electron microscope, EDS spectrum, cyclic voltammetry, differential pulse voltammetry and electrochemical impedance spectroscopy. The sensor exhibited a high sensitivity of 0.05 μΜ to 40 μΜ with a fast response time and a low detection limit of 0.02 μM. The electrode also showed outstanding selectivity toward various interferences. These results indicate that the MoS2-Ag-CNF nanocomposites may be promising electrode materials for electrochemical biosensing.
Ti/TiO2ntas/RuO2 Probe for Amperometric Detection of Hypochlorite in Solution
Authors: Colominas Sergi , Abella Jordi , Lujan Enric
Published: May 2020

Tool to help provide a healthy environment. Disinfection is a process that is designed to kill actively growing and vegetative microbial microorganisms to a certain level. Generally, there are two methods of disinfection: chemical and physical1. The physical agents of disinfection that have been used include ultraviolet light (UV), electron beam, gamma-ray irradiation, sonication, and heat. Considering the chemical methods, there is a great variety of compounds such as chlorine, ozone, the metals copper and silver, phenolic compounds, quaternary ammonium salts, alcohols and hydrogen peroxide among others. Historically, the most widely used chemical disinfection procedure is chlorination because of its low cost, ease of application, and ability to inactivate a wide variety of pathogenic microorganisms.

Hypochlorite ion (ClO-) is widely used in daily life applications such as household bleach, disinfection of drinking water and cooling-water treatment among others. Nevertheless, it has been reported that the abnormal production or the excessive intake of ClO- can lead to numerous diseases, including cardiovascular disorders, neuron degeneration, arthritis or even cancer2. Hence, it is of utmost importance to develop rapid and sensitive methods for the determination of ClO-. So far, iodometric titration and colorimetric methods based on the reaction of ClO- with organic reagents have been widely used so as to determine hypochlorite concentration. These methodologies usually require tedious procedures.

In the present work, we propose the design of an amperometric sensor for fast hypochlorite analysis. The architecture of the sensor is a RuO2 coating onto a highly ordered titanium dioxide nanotube array (Ti/TiO2NTAs/RuO2). TiO2NTAs were grown by electrochemical anodization of a titanium metal disc in ethylene glycol containing ammonium fluoride (0.3%w/w) and water (2%w/w). The electrochemical synthesis was performed at 30V. Afterwards, RuO2 was deposited layer by layer onto the TiO2NTAs substrate and a final annealing process was performed at 500 oC in order to fix it to the nanostructure.

The fundamental analytical parameters (linear range, limit of detection and sensitivity) of the probe were characterized in the presence of hypochlorite. The sensor working potential was also optimized and then fixed at 0.6 V. Finally, the hypochlorite content of different samples was measured using the sensor and compared with the DPD-method value (Standard Methods: 4500-Cl G)3. The proposed amperometric sensor offers an alternative tool to the classical DPD-method, with higher sensitivity, lower limit of quantification and analysis time.

References

[1] A. Kraft, Platin. Met. Rev. 52 (2008) 177–185. doi: 10.1595/147106708X329273

[2] K.Y. Zhang, J. Zhang, Y. Liu, S. Liu, P. Zhang, Q. Zhao, Y. Tang, W. Huang, Chem. Sci. 6 (2015) 301–307. doi: 10.1039/c4sc02600d

[3] 4500-Cl CHLORINE (RESIDUAL), Standard Methods For the Examination of Water and Wastewater, 2017. doi: 10.2105/SMWW.2882.078
Nano-Level DL-Methionine Biosensing in Blood Serum and Urine Using CuO/AgO Modified Graphite Electrode
Authors: Eduok Ubong
Published: May 2020

DL-methionine (DLM) is a common precursor for some amino acids essential to human physiology, (e.g. homocysteine and cysteine). Its contribution to detoxification and regulation of cell aging as well as fat build-up makes it an essential ingredient in the body fluids. Changes in blood level DL-methionine concentration may not be detrimental to human health, however, its contribution to regulating homocysteine level may contribute to some metabolic disorder in diabetic patients with non-cardiovascular diseases. The current research report features a new approach developed towards fabricating a new CuO/AgO modified graphite pencil electrode for sensing in human blood serum and urine samples at the nanoscale limit of detection. The fabricated sensor was characterized by means of X-ray Photoelectron Spectroscopy, Raman spectroscopy and scanning electron microscopy while being used to detect the DLM analyte. Electrode reactions were monitored using cyclic voltammetric and electrochemical impedance spectroscopic methods. The Ag-induced catalytic activity between pH 7-10 was observed following oxidation of the analyte at the electrode surface in the presence of hydroxide ions. DLM detection was ascribed to the unique electroactive Ag and Cu sites on the sensor electrode. The efficiency of this sensor towards analyte sensing within these biological samples in the presence of potential interferences was also investigated. This study features the success in DLM sensing in the presence of multiple amino acid interferences in complex biological samples. With the emergence of complications involving some neuro and cerebrovascular diseases associated with residual methionine, this work presents a biomolecular means of sensing of DLM as a disease biomarker at the nanoscale. The lowest DLM detection limit (DL) in this study was in the nanomolar level; 50 and 60 nM DLM in the serum and urine, respectively.
Ultrasensitive Biosensors Enabled By the Unique Electronic Properties of Graphene
Authors: Fu Wangyang
Published: May 2020

Graphene is the first material scientists discovered in a single layer of atoms. It has a wealth of chemical and physical properties that are ideal for a wide range of applications. We are currently working on graphene and other two-dimensional (2D) crystals, hoping to find new ways to benefit from their unique properties. This talk will summarize the research projects undertaken by me and my co-workers in recent years. The progress made in the development of low-noise, highly sensitive nanoelectronic biochemical sensors based on the unique properties of graphene, as well as the potential applications in biosensing and single molecule detection, will be presented.
Substrate Displacement Colorimety for the Detection of Diarylethylamines
Authors: Lowdon Joseph W. , Eersels Kasper , van Grinsven Bart , Rogosic Renato , Heidt Benjamin , Diliën Hanne , Peeters Marloes , Cleij Thomas J.
Published: May 2020

Introduction:

In this study a novel molecularly imprinted polymer (MIP) based dye displacement assay is introduced for the rapid detection of the new psychoactive substance (NPS) sub-class known as diarylethylamines. The competitive nature of the assay facilitates displacement of a pre-bound dye molecule by a selected target molecule in a process coined Substrate displacement colorimetry (SDC).

Methods:

The assay was fully characterized by conducting affinity studies on the synthesized MIP, evaluating multiple dyes and expressing these affinities as binding factors (BF). The result of this study indicates the mathematical relationship between the established BF and the imprinting factor (IF) of the MIP towards the target analyte (2-MXP), allowing a prediction of efficacy towards dye displacement. Off the back of this study, dye-loaded MIPs were incubated with two common adulterants, two legal pharmacological, and the target diarylethylamine assessing the selective nature of the assay.

Results:

Of the dye’s tested malachite green was found to displace most readily when incubated with the target analyte, demonstrating easily quantifiable concentrations even when exposed to lower concentration of analyte. When incubated with the fore mentioned adulterants and pharmacological molecules, no dye displacement was observed; yet the target analyte stimulated clear dye displacement coloring the filtrate from the assay. This dye displacement was shown to be quantifiable, with a dose response being generated and the linear range of the assay determined by means of UV-visible spectroscopy.

Discussion:

The low–cost, robust and rapid nature of the proposed assay, combined with its tailorable selectivity and generic nature makes this an ideal tool for the screening of unknown seized samples. Displaying high sensitivity towards the desired analyte without sacrificing selectivity to other molecules, generating a highly reliable analytical protocol that can be both qualitative and quantitative depending upon the environment it is employed (Figure 1).

Figure 1. Dose response of the dye displacement assay when incubated with 2-MXP, and caffeine

Reference(s): Lowdon, J. W.; Eersels, K; Rogosic, R; Heidt, B; Diliën, H; Redeker, E. S; Peeters, M; Grinsven, B. v; Cleij, T. J. Substrate displacement colorimetry for the detection of diarylethylamine. Sensors & Actuators B: Chem.
2019, 282, p137-144

Figure 1
Room Temperature Synthesis and Fluorescence Visualization Sensing of Inorganic Perovskite Quantum Dots
Authors: Qiu Zhiwei , Chen Yuzhu , Zhang Yu , Gong Houjian , Zeng Jingbin
Published: May 2020

Perovskite Quantum Dots are widely used in the field of optoelectronics because of their good electron mobility.[1] As a fluorescent nanomaterial, they also have many excellent properties, such as high fluorescence quantum efficiency, emission wavelength coverage visible spectrum, narrow half-width and small Stokes shift, etc.[2] The synthesis of all-inorganic perovskite is currently commonly carried out by oil phase thermal injection.[3] This method is cumbersome and requires strict equipment and experimental conditions. In this paper, a simple method for the rapid synthesis of CsPbX3 (X=Cl-, Br-, I-) fluorescent quantum dots was explored. The high-quality fluorescent quantum dot solution was synthesized in one step by the principle of ligand-assisted coprecipitation at room temperature. According to the related characterization work, the product has excellent cubic crystal phase structure and strong fluorescence intensity.

Furthermore, this work focuses on the application of fluorescence colorimetric sensing of perovskite quantum dots and solving the problem of water annihilation. Fluorescence visualization colorimetric detection of Cl- and I- was successfully achieved by using heterogeneous halogen exchange to induce wavelength shift detection; Then, using the hydrophobic properties of PDMS, the products synthesized at room temperature as described above were coated with PDMS silicon film, and the stable existence of fluorescent quantum dots under water conditions was successfully realized, which improved the application range of perovskite fluorescent materials.

Figure 1
(Invited) Nanomaterials and Smart-Phone Based Biosensors for Point-of-Care Diagnostics
Authors: Du Dan , Lin Yuehe
Published: May 2020

In this talk, I will give an overview of recent works in our laboratory for hand-held biosensing devices based on smartphone and 3D-printing. We have synthesized various functional nanomaterials such as organic-inorganic hybrid nanoflowers, carbon quantum dots, single-atom nanozymes for signal enhancement in bioassays. Applications of these smartphone based nanosensors for biomedical diagnostics and food safety monitoring will be discussed.

References:

1. L. Jiao, H. Yan, Y. Wu, W. Gu, C. Zhu, D. Du, Y. Lin. When Nanozymes Meet Single-Atom Catalysis. Angew. Chem. Int. Ed. 2019, doi.org/10.1002/ange.201905645

2. C. Zhu, S. Fu, Q. Shi, D. Du, Y. Lin. Single-Atom Electrocatalysts. Angew. Chem. Int. Ed. 2017, 56, 13944-13960.

3. N. Cheng, J. Li, D. Liu, Y. Lin, D. Du. Single-Atom Nanozyme Based on Nanoengineered Fe-N-C Catalyst with Superior Peroxidase-Like Activity for Ultrasensitive Bioassays. Small 2019, 1901485.

4. X. Niu, Q. Shi, W. Zhu, D. Liu, H. Tian, S. Fu, N. Cheng, S. Li, J. N Smith, D. Du, Y. Lin, Unprecedented peroxidase-mimicking activity of single-atom nanozyme with atomically dispersed Fe-Nx moieties hosted by MOF derived porous carbon. Biosensors & Bioelectronics 2019, 142, 111495.

5. W. Wen, D. Du, Y. Lin. Recent Advance in Electrochemical Immunosensor. Analytical Chemistry 2017, 89, 138-156.

6. C. Zhu, G. Yang, H. Li, D. Du, Y. Lin. Electrochemical Sensors and Biosensors Based on Nanomaterials and Nanostructures. Analytical Chemistry 2015, 87, 230-249.

7. R. Ye, C. Zhu, Y. Song, Q. Lu, X. Ge, X. Yang, M. Zhu, D. Du, H. Li, Y. Lin, Bioinspired Synthesis of All‐in‐One Organic–Inorganic Hybrid Nanoflowers Combined with a Handheld pH Meter for On‐Site Detection of Food Pathogen. Small 2016, 12, 3094-3100.

8. Y. Wang, M. Zeinhom, M. Yang, R. Sun, S. Wang, J. Smith, C. Timchalk, L. Li, Y. Lin, D. Du, A 3D-Printed, Portable, Optical-Sensing Platform for Smartphones Capable of Detecting the Herbicide 2, 4-Dichlorophenoxyacetic Acid. Analytical Chemistry 2017, 89, 9339-9346.

9. N. Cheng, Y. Song, M. Zeinhom, Y. Chang, L. Sheng, H. Li, D. Du, L. Li, M. Zhu, Y. Luo, W. Xu, Y. Lin, Nanozyme mediated dual-immunoassay integrated with smartphone for use in simultaneous detection of pathogens. ACS Applied Materials & Interfaces 2017, DOI: 10.1021/acsami.7b12734
(Invited) Sensing Human Behavior with Smart Garments
Authors: Andrew Trisha L.
Published: May 2020

Apparel with embedded self-powered sensors can revolutionize human behavior monitoring by leveraging everyday clothing as the sensing substrate. The key is to inconspicuously integrate sensing elements and portable power sources into garments while maintaining the weight, feel, comfort, function and ruggedness of familiar clothes and fabrics. We use reactive vapor coating to transform commonly-available, mass-produced fabrics, threads or premade garments into comfortably-wearable electronic devices by directly coating them with uniform and conformal films of electronically-active conjugated polymers. By carefully choosing the repeat unit structure of the polymer coating, we access a number of fiber- or fabric-based circuit components, including resistors, depletion-mode transistors, diodes, thermistors, and pseudocapacitors. Further, vapor-deposited electronic polymer films are notably wash- and wear-stable and withstand mechanically-demanding textile manufacturing routines, enabling us to use sewing, weaving, knitting or embroidery procedures to create self-powered garment sensors. We will describe our efforts in monitoring heartrate, breathing, joint motion/flexibility, gait and sleep posture using loose-fitting garments.
Depositing Highly Uniform Au Nanoparticles on the Surface of High-Curvature Nanofibers for SERS Optophysiology
Authors: Zhao Xingjuan , Wallace Gregory Q , Bazuin Geraldine C. , Masson Jean-François
Published: May 2020

Nanofibers as biosensors have attracted great attention due to its facile removal from the biosystem after a period of intra- or extracellular measurements and site-specific measurement among others. The application of nanofibers covered with Au nanoparticles as SERS sensor circumvents the aggregation and accumulation of Au nanoparticles in vitro or in vivo, in addition to the greater Raman enhancement of signal than on planar surface. To achieve this, our group has reported a block copolymer-template method to deposit Au nanoparticles on the highly curved surface of nanofibers.[1] Here the versatility of this strategy is demonstrated by depositing nanoparticles with the different dimensions or shapes and varying the density of Au nanoparticles on the surface of the nanofibers. To the best of our knowledge, we believe this is the first work to show how to obtain such highly uniform distribution of anistropic nanoparticles on the surface of high-curvature nanofibers. Among all the nanosensors studied in this work, the label-free nanofibers covered with Au nanostars with shorter branches shows the biggest enhancement, which could detect neurotransmitter secretion such as dopamine with moderate laser power and low integration time. Furthermore, measurement of pH in the cell microenvironment and pH gradient in the cell medium can be realized by our biosensors as well. The rapid pH response to the external environment makes it very promising for the application of the dynamic pH measurement in vitro or in vivo. In addition to SERS sensing, these highly uniform nanosensors have other far-reaching implications, including medical diagnostics, therapeutics and so on.

[1] Zhu, H., Lussier, F., Ducrot, C., Bourque, M. J., Spatz, J. P., Cui, W., Yu, L., Peng, W., Trudeau, L. E., Bazuin, C. G. and Masson, J. F., ACS Appl. Mater. Interfaces, 2019, DOI: 10.1021/acsami.8b19161.

Figure 1
Novel Paper Based Hand-Fabricated Point of Care Prothrombin Time Sensing Platform Using Pencil and Correction Pen
Authors: Saha Anubhuti , Bhattacharya Shantanu
Published: May 2020

Cardiovascular diseases (CVDs) are reported to be the leading cause of death worldwide by World Health Organization (WHO) with an approximate of 31% of global deaths. Consequently, it has been noted that the largest sector of population which experiences coagulation or hemostatic imbalances or undergo oral anticoagulation therapy (OAT) are the major sector susceptible to the risk of mortality due to cardiovascular ailments such as atherosclerosis, deep vein thrombosis (DVT), stroke etc. These candidates are prescribed or administered using oral anticoagulation therapy (OAT) and are advised to take the Prothrombin Time (PT) test respectively. Prothrombin Time (PT) analyzers are the type of haemostasis analyzer mainly catering to the coagulation following the extrinsic pathways. Additionally, the candidates under OAT requires routine administration of the coagulation status for proper dosage of warfarin or its derivatives which shares a very narrow therapeutic window. A slight amount of imbalance in the coagulation chemistry can disrupt the cardiovascular functioning, hence a routine monitoring is strongly mandated by cardiac surgeons. It is important to realize a simplified hand held, low cost point of care solution for diagnosing hemostasis or coagulation status to cater both the rural and urban sectors resulting in lower casualties due to coagulation imbalance. The respective work proposes a handheld point of care PT sensing paper sensor using very inexpensive pencil and correction pen and Whattman filter paper. In addition the sensor has enhanced capability of carrying our sensitive detection of coagulation status compared to the existing complex and expensive sensors developed through a variety of methods like screen printing, lithography, flexography printing, wax printing, PDMS printing, stamping etc. The proposed device consists of two pencil marks as electrodes. The device is illustrated in Figure 1. The sensor monitors a change in impedance (resistance) w.r.t time. Blood being an ionic fluid whose chemistry changes with the ionic interactions during the process of coagulation results in a direct correlation of the coagulation process to the respective impedimetric signatures. The synthetic coagulation behavior and the response of the device has been measure using nail paint as an analyte. The points of maximum changes in resistance (first and second) denotes the application of the analyte to the sensor and initiation of coagulation or solidification respectively (shown in Figure 2) from which the coagulation time is further derived. Lab View has been used as an interfacing platform for processing the respective resistive data and generating corresponding coagulation status. Thus, the particular PDE-PAD (pencil drawn electrodes- paper-based analytical devices) can be considered as a promising future device for low cost sensitive detection platform for a point of care PT diagnosis.

Figure 1
Flexible Diamond-Based Sensors for Chemical Sensing
Authors: Rusinek Cory Allen
Published: May 2020

Flexible electrochemical sensors have been successfully used to detect a variety of biologically- and environmentally-relevant analytes, including neurotransmitters (NTs) and heavy metals, among others. Other flexible sensing materials (gold, bismuth, printed carbon, etc.) have shown promise, but are typically designed for individual applications. Our boron-doped diamond (BDD)-based flexible sensors offer several advantages including broad applicability, batch fabrication processes, wide potential window, low capacitive background current, and good biocompatibility. In this study, the applicability of the flexible BDD sensors to both NT and heavy metal sensing was investigated. Dopamine (DA), lead (Pb), and copper (Cu) were used as the model analytes. A detailed wafer-transfer process of the BDD film from silicon (Si) to flexible parylene C substrates is described. Through this novel fabrication process, the grown-side of the BDD film is exposed. DA was studied using square wave voltammetry (SWV) as the lone analyte, as well as in solution with ascorbic acid to verify potential inter-ference. Heavy metal analysis of Pb and Cu was performed using anodic stripping voltammetry (ASV) in solutions similar to the pH of human perspiration. The BDD electrode yielded limits of detection (LOD) of 10 and 30 ppb for Pb and Cu, respectively. For Pb and Cu, the calculated LOD (3 min deposition time) is well below values previously re-ported in human perspiration. These flexible (and potentially wearable) grown-side exposed BDD sensors further exemplify the capability and versatility of electroanalytical measurements.
Towards on-Site Detection of Cadmium in Human Urine
Authors: Gazica Kiera , FitzGerald Elizabeth , Dangel Gabrielle Rae , Haynes Erin , Yadav Jagjit , Alvarez Noe T.
Published: May 2020

Cadmium (Cd) is a non-essential toxic heavy metal. Human exposure to Cd occurs from multiple sources, including diet, tobacco smoke, fossil fuel combustion, and variously contaminated environments. This work reports a rapid method for Cd 2+ detection in simulated urine samples containing glucose (GLC) and actual human urine using the electrochemical technique of square wave anodic stripping voltammetry (ASV). Electrochemical techniques for onsite analysis and detection are preferred for their quick response time, application simplicity, inexpensive instrumentation, and potential portability. This approach is a step forward towards Cd 2+ detection in biological fluids, despite their composition complexity due to possible interference of its constituents. Application of a simple, well controlled, and uniform carbon nanotube (CNT) thin film generated through spinnable CNT arrays enabled us to increase the surface area of traditional glassy carbon electrodes and made possible the detection of nanomolar concentration of Cd ions in urine samples. Employing 120s deposition time on anodic stripping voltammetry led to 1.9 nM and 324 nM limit of detection (LOD) in simulated urine and human samples, respectively. The developed method would facilitate high throughput screening of human urine samples for assessing Cd exposure in future studies.
Strategies for Chemical Sensing Using High Purity Semiconducting Single-Walled Carbon Nanotube Electronic Devices
Authors: Lapointe François
Published: May 2020

Semiconducting single-walled carbon nanotubes (sc-SWCNTs) are attractive in chemical sensing [1] because of their peculiarities: As they present a single atom-thick wall and a quasi 1D form factor, sc-SWCNTs are especially sensitive to their surroundings’ electrostatics. Moreover, their band gap of approximately 1 eV is much greater than room-temperature thermal energy while being in a convenient range for electronic applications. Also, their electronic structure exhibits van Hove singularities (sharp spikes in the density of states) that drastically alters their conductivity and optical properties when charge carriers are injected. Although sc-SWCNT electronic devices are very sensitive, they lack in selectivity and they usually need to be functionalized to implement a lock-and-key detection mechanism.

In this talk, we will present various strategies for chemical sensing using enriched sc-SWCNTs. We will discuss the advantages and disadvantages of using sc-SWCNTs in electronic chemical sensing devices. Sub-ppm ammonia sensing will be demonstrated using a sc-SWCNT material wrapped with a decomposable polymer in a chemiresistor configuration. [2] Also using chemiresistors, CO2 detection has been achieved by designing a SWCNT-wrapping polymer with specific interactions. Finally, we will present a strategy to differentiate the response of sensor elements to a variety of volatile analytes by changing the polymer gate dielectrics in a three-terminal bottom gate chemitransistor configuration. [3] This methodology opens the way to the implementation of sc-SWCNT-based chemitransistors in a printed cross-reactive sensor array.

References

[1] Schroeder, V. et al. Carbon Nanotube Chemical Sensors. Chem. Rev.
119, 599–663 (2019)

[2] Li, Z. et al. Decomposable s-Tetrazine Copolymer Enables Single-Walled Carbon Nanotube Thin Film Transistors and Sensors with Improved Sensitivity. Adv. Funct. Mater. 1705568 (2018)

[3] Lapointe, F. et al. Carbon Nanotube Transistors as Gas Sensors: Response Differentiation using Polymer Gate Dielectrics. AC
S Appl. Polym. Mater.
https://doi.org/10.1021/acsapm.9b00707 (2019) – Accepted for publication
Synthesis of Psi/CuO/Cu2o Heterostructure for NH3 Vapor Detection at Room Temperature
Authors: Bouachma Soraya , Gabouze Noureddine
Published: May 2020

In this paper, we demonstrate the use of the heterostructure porous silicon PSi-n/CuO-p/Cu2O-n as an alternative structure for an efficient gas sensor for NH3 sensing. The porous silicon PSi was prepared using an electrochemical method and utilized as a substrate. Then, CuO homogeneous thin films were synthesized by thermal evaporation/oxidation on the pre-prepared PSi substrate, on which a uniform layer of Cu2O is deposited by electrodeposition method.

The structural, morphological and optical characterizations of the obtained CuO and Cu2O films were carried out by XRD, SEM, FTIR, UV spectroscopy and contact angle measurements. Likewise, the electrical properties of CuO-p/Cu2O-n thin films, deposited on PSi-n, were studied by current-voltage (I-V) measurements at room temperature, within the sandwich (semiconductor/oxide/oxide) configuration. The NH3 gas sensing characteristics: response/recovery time, sensitivity and repeatability, were evaluated and tested at different gas concentrations at room temperature, allowing the determination of the different parameters of the heterojunction PSi/CuO/Cu2O.

These results indicated that the PSi/CuO/Cu2O structure is a promising candidate for reliable high-performance NH3 gas sensors at room temperature, with a very high sensitivity to NH3 (80%) and with an extremely fast response time of the order of 1 second. These sensing performances enhancements at room temperature are due to the high surface area to volume ratio of PSi and the use of PSi/CuO/Cu2O heterostructure. The prospective sensing mechanism of the presented sensor has been discussed.
A study on Gas sensing Properties and Reaction Mechanism of Au@SnO2 Core-shell Structure Nanoparticles to H2S Gas
Authors: Yu Yeon-Tae
Published: May 2020

The H2S is a toxic and malodorous gas produced from coal mine, natural gas manufacturing processes, and wastewater treatment plants. Due to increased environmental concern, there is an increasing demand for semiconductor gas sensors that are selective and responsive towards H2S gas.

SnO2 has been known as a representative semiconductor gas sensing material because of chemical stability and high electron mobility. However SnO2 has a problem that H2S gas doesn’t detached after adsorbing on the surface on SnO2. To solve this problem, the use of noble metal catalysts has been suggested. Au nanoparticles (NPs) are reported to be a good catalyst for the H2S oxidation reaction. To investigate the effects of Au NPs on H2S adsorption and desorption, Au@SnO2 core-shell NPs were applied as a sensing material.

In this study, Au@SnO2 core-shell NPs has been synthesized by microwave-assisted hydrothermal method. Au@SnO2 core-shell NPs were calcined at various temperatures (350°C ~ 550°C) to control the surface morphology and crystallinity of SnO2 shell, and their gas sensing property were investigated towards H2S gas (2 ppm to 100 ppm). Based on the results of the sensing test of Au@SnO2 core-shell NPs, we examined the effect of Au NPs on H2S adsorption and desorption.

The Au@SnO2 core-shell structure NPs were successfully synthesized by microwave-assisted hydrothermal method, and the particle size was 26-30 nm and the shell thickness of SnO2 shell layer was 14-18 nm. The highest sensing responses of pure SnO2 and Au@SnO2 core-shell NPs showed at the working temperature of 200°C, the responses value to 100 ppm H2S gas were 4,748 and 517, respectively. The optimum working temperature for Au@SnO2 core-shell NPs for detecting H2S gas was at 300°C because the gas sensing response showed relatively high as compared to pure SnO2 and the recovery rate was the highest value. Moreover, the selectivity of H2S toward CO, CH4, C2H5OH gases appeared at this working temperature. The reason why Au@SnO2 core-shell NPs selectively reacted with H2S gas at 300°C was due to the catalytic activity of Au core for H2S oxidation reaction.

Keywords: Au@SnO2, nanoparticle, semiconductor gas sensor, H2S gas, adsorption
Supercritical Fluids Synthesis of Nanocatlayst-Decorated Nanocarbons for Amprometric Hydrogen Sensing
Authors: Liao Jin-Yi , Wang Shih-Han , Yang Cheng-Kang
Published: May 2020

It is getting more and more attention on the breathing gas monitoring since it is a non-invasive technique. Hydrogen gas is an important biomarker of gastrointestinal diseases in exhaled gas. The elevated hydrogen level correlated to gastrointestinal diseases. The average hydrogen concentration for healthy people is less than 20 ppm[1]. In this study, the structure of fuel cell was adapted to develop a highly sensitive electrochemical hydrogen sensor which could be apply for breath gas analysis. In the previous studies, platinum groups metals (PGM) were extensively applied for hydrogen oxidation reaction[2]. A serious platinum group metals and non-PGM metals, such as platinum, iridium and palladium, and non-PGM, Cu, were decorated on the nanocarbons surface to use as the working electrode. The nanometal catalysts were decorated on uniformly utilizing supercritical fluids technique. X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and in-situ Fourier transform infrared spectroscopy were used to characterize the microstructure, surface morphology, chemical structure and sensing mechanism. The electrochemical properties of the electrodes were analyzed. The amprometric sensing performance of the PtCu decorated nanocarbon showed high sensitivity. The sensing range was from 0-100 ppm and the lower detection limit was 0.52 ppm. Potential interferences, such some reducing gases and VOC were tested as well. This highly sensitive hydrogen sensor is suitable for environmental and health applications.

References

[1] A. Eisenmann, A. Amann, M. Said, B. Datta, M. Ledochowski, J. Breath Res 2, 046002 (2008); doi: 10.1088/1752-7155/2/4/046002

[2] E. S. Davydova, S. Mukerjee, F. Jaouen, and D. R. Dekel, ACS Catal 8, 6665-6690(2018); doi: 10.1021/acscatal.8b00689
Enhanced CO Sensing Properties of Pd Modified ZnO Porous Nanosheets
Authors: Xu Jiaqiang , Luo Na
Published: May 2020

Noble metal is usually used to improve the gas sensing performance of metal oxide semiconductor (MOS) due to its better catalytic properties. In this work, we reported a synthesis of Pd/ZnO composite by an in situ reduction with ascorbic acid (AA). It was found that Pd/ZnO sensor has excellent selectivity to CO and the response of the Pd/ZnO sensor towards 100 ppm CO was as high as 15 (Ra/Rg), obviously higher than that of the pristine ZnO sensor (1.4) when the working temperature is 220 oC. Moreover, the pure ZnO sensor almost has no selectivity to Coal mine gas (CH4, CO and H2S), but the Pd/ZnO sensor has excellent selectivity to CO, which may be ascribed to the electronic sensitization of Pd. Our present results demonstrate that the Pd can significantly improve the gas-sensing performance of metal oxide semiconductor and the obtained sensor has great potential in monitoring coal mine gas.

Figure 1
Novel Materials Design for Capture and Electrochemical Detection of Perfluoroalkyl Species
Authors: Khan Reem , Rehman Abd Ur , Deshpande Aaditya Sunil , Andreescu Silvana , Andreescu Daniel
Published: May 2020

Per and poly-fluoroalkyl substances (PFAS) are persistent organic pollutants, adversely affecting the environment. The strong carbon-fluorine bonds of PFASs make them resistant to physical and metabolic degradation leading to bioaccumulation, which can have serious effects on human’s health, wildlife and ecosystem. The conventional analytical techniques for the quantitative determination of PFASs in environmental matrices are HPLC, GC-MS, etc. Despite their high reliability and accuracy, these laboratory-based techniques are expensive and can analyze only a limited number of samples, which impedes their broad applicability. To advance analysis and fast screening of samples, there is a critical need to develop cost effective, sensitive, easy to handle and portable methods for field detection of PFASs. This presentation will describe rational design of materials with specific and characteristic binding abilities for PFAS that can be incorporated into passive samplers and sensors for on site detection. The interaction of several materials with selected PFAS species and their incorporation into passive samples and an electrochemical sensing design will be discussed. This approach provides a new method for achieving qualitative and quantitative analysis of PFASs in the field. The developed method has potential for the onsite, selective, and sensitive detection of PFASs.
Magnetic and Electrically Conductive Polypyrrole Nanoparticles As Highly Effective Materials for Heavy Metal Removal and Sensing
Authors: Hosseini Narouei Farideh , Frascatore Dominic , Andreescu Daniel
Published: May 2020

Heavy metals such as arsenic, cadmium, chromium, nickel, and lead are a well-known source of pollution of air, water, and soil. Their presence in the environment can cause harmful effects in plants, animals, and humans. To address the consequences of heavy metals pollution, there is a need for technology to detect, capture and remove heavy metal contamination from the environment. This presentation reports the synthesis and characterization of polypyrrole (PPy) - magnetite (Fe3O4-PPy) nanoparticles, prepared via a chemical oxidative polymerization process using polyvinyl alcohol as a surfactant. The Fe3O4-PPy nanoparticles have spherical shape and size ranging from 110 to 220 nm and are characterized by high magnetic properties and good electrical conductivity. The particles displayed high sorption capacity for arsenic removal from contaminated water, evaluated using Atomic Absorption Spectroscopy (AAS). The high affinity for contaminants was also used to develop a highly sensitive electrochemical technique for the detection of metal ion exposure.