It was shown that bioluminescent enzymatic reactions can be carried out in droplet reactors for biological measurements of water quality. Early detection of pollutants in wastewater, water treatment facilities, drinking water, and water for agricultural needs is a challenging problem. Effective water quality monitoring requires development of new methods for express detection of pollutants. Enzymes from bioluminescent bacteria can be used for the development of new express enzyme-based bioassay systems. This work demonstrates for the first time a microfluidic generator of emulsion droplets containing two enzymes of the bacterial bioluminescent system (luciferase and NAD(P)H:FMN-oxidoreductase) with reaction substrates. The developed chip generated “water-in-oil” emulsion droplets with a volume of 0.1 μL and a frequency of up to 12 droplets per second. Portable PMT was used to measure the bioluminescent signal in each individual droplet, the signal-to-noise ratio was 3000/1. To ensure the mixing of the system components in the emulsion droplets, the geometry of the microchannels of the chip was numerically simulated. The intensity of luminescence in droplets is depending on the concentration of copper sulfate and benzoquinone inhibitors. The limit of detection (LOD) for copper sulfate and benzoquinone was 1 and 0.2 mg/L, respectively. The studies carried out are applicable for the development of early warning systems at wastewater discharge sites of industrial enterprises or at water treatment plants in addition to the existing certified methods for the registration of water-soluble pollutants. Our results showed new potential of microfluidic polyenzymatic sensing for the biological metrology applications.

Nowadays diabetes comes out as one of the most common diseases. It is estimated that over 400 million people suffer from this illness. Therefore, scientists are bound to find a solution and create a glucose sensor, which will be sensitive, selective, stable as well as easy to produce.

Here, we propose the nanoscale Au-Ti heterostructure functionalized with glucose oxidase specific towards glucose presence. The fabrication of the electrode was realized by anodization of Ti foil and chemical etching resulted in the ordered Ti nanodimples (TiND). Next, gold nanoparticles (AuLr) were prepared by thin Au layer sputtering followed by laser dewetting. Last but not least, the enzyme immobilization via entrapment into the chitosan matrix was performed.

The morphology of Ti nanodimples and Au nanoparticles was investigated by scanning electron microscopy and it is proven that nanoparticle size does not exceed the cavities dimensions. Fourier transformation infrared analysis was utilized to confirm the presence of glucose oxidase and chitosan. Experiments aimed at determining sensor parameters were conducted in 0.1 M PBS with glucose addition. The sensitivity factors of 23.67 and 10.05 µAcm^-2mM^-1 were determined and correspond to following linear ranges of 0.04 – 15.05 and 15.05 – 40.00 mM. The limit of detection equals only 1.77 µM. The selectivity of prepared electrode material was verified using NaCl, ascorbic acid, fructose, glycine, dopamine, acetylsalicylic acid, uric acid, and acetaminophen. No interference is observed and in addition the material is stable over multicyclic measurements. Moreover, validation in real samples such as human serum, sweat and saliva confirmed the potential application of the sensor for glucose monitoring in physiological fluids.

This work was financed by National Center for Research and Development under grant no LIDER/2/0003/L-8/16/NCBR/2017.

Non-enzymatic electrochemical glucose sensors have numerous potential advantages over traditional enzymatic ones. Among them, one can distinguish cheaper and easier fabrication route, as well as higher resistance towards pH and temperature changes. However, there are certain drawbacks of non-using enzymes, i.e. low selectivity towards glucose and threat of interference with other electroactive compounds such as ascorbic acid (AA), acetaminophen (AAp), acetylsalicylic acid (AsA), urea and aminoacids [1]. Therefore, there is a strong requirement for strategies enhancing the selectivity by eliminating interference and prolonging the sensing capability in human physiological fluids.

In here, we present glucose sensitive Au-Ti electrodes obtained via anodization of Ti foil and their subsequent chemical etching [2]. Later on, thin gold film is sputtered and further dewetted, so that gold nanoparticles are created and embedded in the titanium template. As a coating for studied electrode we propose photopolymerized sulfobetaine methacrylate crosslinked with ethylene glycol dimethacrylate (p(SBMA:EGDMA)). Polymeric zwitterions are a promising solution due to their superhydrophilicity and high resistivity to biofouling in media containing various biomoleclues and cells [3]. According to our results, pSBMA:EGDMA coating provides significant interference reduction from AA, aminoacids, AsA and urea. Moreover electrochemical activity is preserved in diluted human serum indicating possible application of fabricated material in glucose monitoring in real samples.

References:

[1] Hwang, D. W., Lee, S., Seo, M., & Chung, T. D. (2018). Recent advances in electrochemical non-enzymatic glucose sensors–a review. Analytica Chimica Acta, 1033, 1-34.

[2] Olejnik, A., Siuzdak, K., Karczewski, J., & Grochowska, K. (2020). A Flexible Nafion Coated Enzyme‐free Glucose Sensor Based on Au‐dimpled Ti Structures. Electroanalysis, 32(2), 323-332.

[3] Venault, A., & Chang, Y. (2018). Designs of zwitterionic interfaces and membranes. Langmuir, 35(5), 1714-1726.

.Acknowledgements

This work has been financed by National Center for Research and Development under the LIDER program (LIDER/2/0003/L-8/16/NCBR/2017)

Organic Electrochemical Transistors (OECTs) are now well-known, robust and efficient as amplification devices for redox reactions, typically biologically ones. In contrast, Electrolyte-Gated Organic Field Effect Transistors (EGOFETs) have never been described for that kind of application because field-effect transistors are known as capacitive coupled devices, i.e. driven by changes in capacitance at the electrolyte/gate or electrolyte/semiconductor interface. For such kind of transistor, any current flowing at the gate electrode is seen as a drawback. However, we demonstrate in this paper that not only the gate potential can trigger the source-drain current of EGOFETs, which is the generally accepted mode of operation, but that the current flowing at the gate can also be used. We propose a complete interpretation for this original behavior. Because EGOFETs can work directly in water, and as an example of application, we demonstrate here the possibility to monitor microalgae photosynthesis through the direct measurement of photosynthetic O₂ production within the transistor’s electrolyte, thanks to its electroreduction on the EGOFET’s gate. In a second step, microalgae were directly immobilized on the platinum gate, for a better sensitivity. As an example of application, monitoring the presence of pollutants such as weed killer in water is investigated.

The abuse of illicit drugs has become a global concern considering the widespread use of these substances and the consequences it has on societies. The current methods used to quickly detect drugs on-site, such as color-tests, are presumptive tests and they lack selectivity, giving a high number of false negative and false positive results, due to the presence of adulterants and cutting agents. Their characterization is important from a forensic point of view, in order to link different seizures to one original batch, as well as from a toxicological point of view, for the health implications some of them might have. The purpose of the study was the development of a sensitive method for the detection of cathinones and their adulterants/cutting agents in street samples. The electrochemical fingerprinting was performed by means of square wave voltammetry using nanomaterials-modified electrodes. Several platforms were tested (graphene, carbon nanotubes, gold nanoparticles, platinum nanoparticles) and depending on the obtained signal for the oxidation of drugs, graphene and carbon-nanotubes based platforms were chosen to further test the cathinones. Several cathinones, such as methcathinone, chloroetcathinone were tested, as well as several adulterants/cutting agents such as procaine, benzocaine, creatine and mannitol, sorbitol, respectively. The effectiveness of the developed method was tested for the detection of drugs in simulated drugs samples. Electrochemical methods proved to be excellent techniques for the fast determination of drugs with high sensitivity and specificity, suitable for the development of miniaturized portable devices to be used in-field.

Acknowledgements: This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 833787, BorderSens.

Doxorubicin is an antitumor drug widely used in the treatment of cancer. It can be found on the market in different forms, alone or in combination with other molecules. Simvastatin is an inhibitor of HMG-CoA reductase, the most important enzyme from the process of cholesterol biosynthesis, and it is used in the treatment of hypercholesterolemia.

There are several studies in the literature which demonstrated the decrease of cellular proliferation in the presence of high dose simvastatin and that this molecule potentiates the cytotoxic activity of antitumor drugs. Therefore, various types of drug delivery systems containing both antitumor drug and statin started to be investigated for the improvement of cancer therapy.

The aim of this study was to develop a disposable, simple, fast and sensitive sensor for the simultaneous electrochemical detection of doxorubicin and simvastatin. Firstly, the electrochemical behavior of each molecule was analyzed regarding the influence of electrode material, electrolyte solution and scan rate. After each of these parameters was chosen, a LSV (Linear Sweep Voltammetry) procedure was optimized for their simultaneous detection. In the same time, two chronoamperometry procedures were tested, one for the detection of doxorubicin in the presence of simvastatin and the other one for the detection of doxorubicin and simvastatin together. Finally, calibration curves for doxorubicin and simvastatin in the presence of each other were obtained using both electrochemical methods and the results obtained were compared.

This detection strategy represents a promising tool in the development of new pharmaceutical forms or drug delivery systems containing both drugs whose association was proved to bring benefits in the treatment of cancer.

Achnowledgements:

This work was supported by a grant of the Romanian Minister of Research and Innovation, CCCDI – UEFISCDI, project number PNIII-P1-1.2-PCCDI-2017-0221/59PCCDI/2018 (IMPROVE), within PNCDI III. Iulia Rus acknowledges UMF Grant no. 1529/58/18.01.2019.

Brain seizures occur when there is abnormal neuronal firing, although the etiology of the effect is often unclear. In epilepsy, there is an occurrence of chronic aberrant neuronal and glial activity, Excitability may result from neurodegeneration or neurogenesis, abnormal synaptic connectivity, blood-brain barrier damage, or genetic channelopathies (mutations in ion-channels or the γ-aminobutyric acid A receptor (GABA_AR). Typically, in terms if diagnosis, electroencephalograms (EEG) are obtained to observe the electrical activity of the brain. Structural damage or abnormalities in the brain (if present) are then imaged with computerized tomography (CT) scans or magnetic resonance imaging (MRI). The fact that over 30 biomarkers related to epilepsy have been characterized leads to the conclusion that biosensor technology offers a potentially attractive approach to both diagnosis and real-time mentoring of the disease. These devices provide spatial and temporal signalling and the possibility for miniaturization and analyte multiplexing. However, despite the evident promise only devices for glutamate (Glu) and GABA have been the focus of research. This dissuasion will evaluate the significance of what has been achieved to date.

Our own research on biosensor technology with respect to epilepsy has been on micro-sensors for pH, Na+ and, in particular, K+. In recent years, considerable interest has been directed at the effect that alterations by mutation and malfunctions of a variety of K+ channels have on epileptic seizures Indeed, the definition “K+ channelepsies” has been specified in an attempt to describe the connection between channel characteristics and the epileptic condition. In order to monitor K+ concentration in the brain stem we have developed a sensor that combines the tandem properties of selective ion detection with anti-fouling capability. The device is based on micro-electrodes fabricated from Iridium wire. The consclusion conclude with a look at use of the electrode in biological tissue including nerves.

Energy recovery methods are currently receiving a very great deal of attention from the research community. Especially, in the case of implantable biosensors where wireless energy transfer has become the main technique in these applications. An implant is a medical device manufactured to replace a missing biological structure, support a damaged biological structure, or enhance an existing biological structure. Biosensors are man-made devices, in contrast to a transplant, which is a transplanted biomedical tissue. The method of energy transfer eliminates the risk of skin infection, as well as the need for invasive surgery to change the battery. In this paper, we present the efficient approach to design an optimized octagonal spiral inductor operating at a frequency of 2.4 GHz with an inductance L value of 4 nH and a maximum factor of quality-Q. The principle part of this work is based on the use of a collection of methods called metaheuristics, which are approaches used to solve a wide range of optimization problems, in order to achieve a high-performance optimized design. The problem is represented by an objective function that will be implemented using MATLAB script and then the validation of the results obtained will be performed using the ADS microwave circuit simulation software.

Hydrogen peroxide (H₂O₂) is an important oxidizing agent that plays a crucial role in the food and beverage industry, the pharmaceutical industry, environmental fields amongst others. However, as a by-product of metabolic oxidation processes, it poses an immediate danger to life and health when concentrations are beyond the minimum threshold limit of 75 ppm. The detection of H₂O₂ is therefore of prime importance. Herein, a simple colorimetric assay for the detection of H₂O₂ based on the peroxidase-like mimetic activity of Fe₃O₄@MIL-100(Fe)-Au nanozyme was established. The triad-component nanozyme was synthesized by growing a five-layer MIL-100(Fe) metal-organic framework(MOF) around the magnetic Fe₃O₄ nanorod core and finally deposited gold on the core-shell structure. The oxidation of colorless 3,3,5,5 - tetramethylbenzidine to blue by H₂O₂ is very slow. The addition of the nanozyme increases the oxidation process. The magnetic property of the nanozyme was further harnessed to enhance the oxidation process on a magnetic field. The versatility of the as-prepared Fe₃O₄@MIL-100(Fe)-Au was demonstrated by applying it for the catalytic degradation 4-nitrophenol. The magnetic property was subsequently harnessed to enhance the catalytic degradation of the organic pollutant and also to conveniently effect separation of the catalyst after application. Besides the catalysis, the magnetic property of the composite was utilized to enhance the adsorption of bacteria pathogen. We believe such magnetic MOF-based composites have potential applications in many fields including microreactor systems.

Major advances in cancer control can be greatly aided by early diagnosis and effective treatment in its preinvasive state. Lung cancer is the second most common cancer in men and women and the first leading cause of cancer deaths in the United States. A lot of research attention has been attracted to diagnose and treat lung cancer. Common method of lung cancer treatment is based on COX-2 inhibitors. This is because COX-2 is commonly over-expressed in lung cancer and also the the abundance of its enzymatic product Prostaglandin E2 (PGE₂). Instead of using traditional COX-2 inhibitors to treat lung cancer, here, we report a new anti-cancer strategy recently developed for lung cancer treatment. It adopts more abundant ω-6s such as dihomo-γ-linolenic acid (DGLA) in the daily diet and the commonly high levels of COX expressed in lung cancer to promote the formation of 8-hydroxyoctanoic acid (8-HOA) through delta-5-desaturase (D5Di) inhibitor. The D5Di will not only limit the metabolic product, PGE₂ but also promote the COX-2 catalyzed DGLA peroxidation to form 8-HOA, a novel anti-cancer free radical byproduct. Therefore, the measurement of the PGE₂ and 8-HOA levels in cancer cells can be an effective method to treat lung cancer by providing in-time guidance. We will report a novel, low-cost, accurate, and miniature sensor device based on a newly developed 2-dimensional nanosheets, Ti₃C₂ MXene to sensitively, selectively, precisely and effectively detect PGE₂ and 8-HOA in A549 lung cancer cells. Due to multilayered structure and extreme large surface area, metallic conductivity and easy and versatile in surface modification, Ti₃C₂ MXene based sensor will be able to selectively adsorb different molecules through physical adsorption or electrostatic attraction, and lead to a measurable change in the conductivity of the material with high signal to noise ratio.